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Sample records for awgn communication channels

  1. Square Root Law for Communication with Low Probability of Detection on AWGN Channels

    CERN Document Server

    Bash, Boulat A; Towsley, Don

    2012-01-01

    We present a square root limit on low probability of detection (LPD) communication over additive white Gaussian noise (AWGN) channels. Specifically, if a warden has an AWGN channel to the transmitter with non-zero noise power, we prove that $o(\\sqrt{n})$ bits can be sent from the transmitter to the receiver in $n$ AWGN channel uses with probability of detection by the warden less than $\\epsilon$ for any $\\epsilon>0$. Moreover, in most practical scenarios, a lower bound on the noise power on the warden's channel to the transmitter is known and $O(\\sqrt{n})$ bits can be covertly sent in $n$ channel uses. Conversely, attempting to transmit more than $O(\\sqrt{n})$ bits either results in detection by the warden with probability one or a non-zero probability of decoding error as $n\\rightarrow\\infty$. Further, we show that LPD communication on the AWGN channel allows one to send a non-zero symbol on \\emph{every} channel use, in contrast to what might be expected from the square root law found recently in image-based...

  2. Study and Analysis Capacity of MIMO Systems for AWGN Channel Model Scenarios

    Directory of Open Access Journals (Sweden)

    Hussain Bohra

    2014-10-01

    Full Text Available Future wireless communication systems can utilize the spatial properties of the wireless channel to enhance the spectral efficiency and therefore increases its channel capacity. This can be designed by deploying multiple antennas at both the transmitter side and receiver side. The basic measure of performance is the capacity of a channel; the maximum rate of communication for which arbitrarily small error probability can be achieved. The AWGN (additive white Gaussian noise channel introduces the notion of capacity through a heuristic argument. The AWGN channel is then used as a basic building block to check the capacity of wireless fading channels in contrast to the AWGN channel. There is no single definition of capacity for fading channels that is applicable in all situations. Several notions of capacity are developed, and together they form a systematic study of performance limits of fading channels. The various capacity measures allow us to observe clearly the various types of resources available in fading channels: degrees of freedom, power and diversity. The MIMO systems capacity can be enhanced linearly with large the number of antennas. This paper elaborates the study of MIMO system capacity using the AWGN Channel Model, Channel Capacity, Channel Fast Fading, Spatial Autocorrelation and Power delay profile for various channel environments.

  3. Performance of Turbo Code for UMTS in AWGN channel

    Directory of Open Access Journals (Sweden)

    Bhavana Shrivastava

    2011-09-01

    Full Text Available This paper deals with “Turbo codes”. The turbo code encoder is built using a parallel concatenation of two RSC codes and associated decoder is SOVA. Simulation carried out for different BER, iterations, constraint lengths and frame sizes (FS to show performance properties of turbo codes in AWGN channel and using binary shift keying modulation.

  4. Downsampling of DFT Precoded Signals for the AWGN Channel

    DEFF Research Database (Denmark)

    Jensen, Tobias Lindstrøm; Fyhn, Karsten; Arildsen, Thomas;

    2012-01-01

    In this paper we propose and analyze a method for downsampling discrete Fourier transform (DFT) precoded signals. Since the symbols (in frequency) are in the constellation set, which is a subset of the entire complex plane, it is possible to detect N symbols from the DFT precoded signal when...... transmitting M analysis on so-called simple vectors, and show that it is possible to detect in the noise-less case with high probability down to approximately M ≥ N/4 for BPSK and M ≥ N/2 for QPSK. We develop extensions from the noise-less to the noisy case......, and propose two different detectors for the AWGN channel. Simulations show that using the two proposed detectors in the AWGN channel, we observe empirically a phase transition at M ≈ N/2 for QPSK. Further, it is shown how downsampled QPSK signals can achieve the same BER and data rate as 8PSK at a lower...

  5. Analysis and Simulation of CDMA QAM-16 for AWGN and RAYLEIGH Channel

    Directory of Open Access Journals (Sweden)

    Arun Kumar

    2014-07-01

    Full Text Available In a Code Division Multiple Access (CDMA system, a lot of users use concurrently the entire frequency band to transmit their data and users’ data is separated on the basis of their unique spreading code. The aim of Communication System i.e. Communication at anytime, anywhere and by anybody is still not fulfilled but the technology like CDMA can fulfill the aim of communication system if it is properly analyzed. For a downlink transmission Quadrature Amplitude Modulation (QAM, Quadrature Phase Shift Keying (QPSK and Binary Phase Shift Keying (BPSK modulation Techniques are considered in a Wideband Code Division Multiple Access System. The work design and evaluate CDMA Transmitter and Receiver for QAM-16 modulation Scheme and deal with BER performance of WCDMA, when the design is subjected to a number of users as well as noise and interference in the AWGN channel and Rayleigh Fading channel

  6. Repeat-punctured superorthogonal convolutional turbo codes on AWGN and flat Rayleigh fading channels

    Directory of Open Access Journals (Sweden)

    Fambirai Takawira

    2010-10-01

    Full Text Available Repeat-punctured turbo codes, an extension of the conventional turbo-coding scheme, has shown a significant increase in bit-error rate performance at moderate to high signal-to-noise ratios for short frame lengths. Superorthogonal convolutional turbo codes (SCTC makes use of superorthogonal signals to improve the performance of the conventional turbo codes and a coding scheme that applies the repeat-punctured technique into SCTC has shown to perform better. We investigated two new low-rate coding schemes, repeat-punctured superorthogonal convolutional turbo codes (RPSCTC and dual-repeat-punctured superorthogonal convolutional turbo codes (DRPSCTC, that make use of superorthogonal signaling, together with repetition and puncturing, to improve the performance of SCTC for reliable and effective communications. Simulation results in the additive white Gaussian noise (AWGN channel and the frequency non-selective Rayleigh fading channel are presented together with analytical bounds of bit error probabilities, derived from transfer function bounding techniques. From the simulation results and the analytical bounds presented, it is evident that RPSCTC and DRPSCTC offer a more superior performance than SCTC in the AWGN channel, as well as in flat Rayleigh non-line-of-sight fading channels. The distance spectrum is also presented for the new schemes and accounts for the performance improvement rendered in simulations. It is important to note that the improved performance that SCTC, and consequently RPSCTC and DRPSCTC, exhibit is achieved at the expense of bandwidth expansion and complexity and would be ideal for power-limited satellite communication links or interference-limited systems.

  7. A Novel MLC Scheme with M2-QAM Constellations over AWGN and Rayleigh Fading Channels

    Institute of Scientific and Technical Information of China (English)

    YUANDongfeng; ZHANGPeng; WayneE.Stark

    2003-01-01

    Optimal multilevel codes (MLC) with M2-QAM constellations are considered with focus on both AWGN and Rayleigh fading channels. With the proposition of three new set partitioning rules for M2-QAM constellations, a novel simplified MLC scheme with a very simple MSD (Multistage decoding) structure comes into being, which is operated on the capacity rule. Compared with traditional MLC/MSD scheme the new MLC/MSD structure greatly reduces the calculation of the individual capacities in MLC system because the new set partitioning rules ensure the independency of two dimensions symbols. Furthermore the new MLC/MSD system cannot enhance any performance loss and the time delay is just 1/2 of that with traditional partitioning rules. As an example 64-QAM constellation with three new set partitioning rules are provided. Their performance is simulated over AWGN and Rayleigh fading channels by choosing BCH codes as the component codes.

  8. On Lattice Sequential Decoding for The Unconstrained AWGN Channel

    KAUST Repository

    Abediseid, Walid

    2013-04-04

    In this paper, the performance limits and the computational complexity of the lattice sequential decoder are analyzed for the unconstrained additive white Gaussian noise channel. The performance analysis available in the literature for such a channel has been studied only under the use of the minimum Euclidean distance decoder that is commonly referred to as the \\\\textit{lattice decoder}. Lattice decoders based on solutions to the NP-hard closest vector problem are very complex to implement, and the search for low complexity receivers for the detection of lattice codes is considered a challenging problem. However, the low computational complexity advantage that sequential decoding promises, makes it an alternative solution to the lattice decoder. In this work, we characterize the performance and complexity tradeoff via the error exponent and the decoding complexity, respectively, of such a decoder as a function of the decoding parameter --- the bias term. For the above channel, we derive the cut-off volume-to-noise ratio that is required to achieve a good error performance with low decoding complexity.

  9. On Lattice Sequential Decoding for The Unconstrained AWGN Channel

    KAUST Repository

    Abediseid, Walid

    2012-10-01

    In this paper, the performance limits and the computational complexity of the lattice sequential decoder are analyzed for the unconstrained additive white Gaussian noise channel. The performance analysis available in the literature for such a channel has been studied only under the use of the minimum Euclidean distance decoder that is commonly referred to as the lattice decoder. Lattice decoders based on solutions to the NP-hard closest vector problem are very complex to implement, and the search for low complexity receivers for the detection of lattice codes is considered a challenging problem. However, the low computational complexity advantage that sequential decoding promises, makes it an alternative solution to the lattice decoder. In this work, we characterize the performance and complexity tradeoff via the error exponent and the decoding complexity, respectively, of such a decoder as a function of the decoding parameter --- the bias term. For the above channel, we derive the cut-off volume-to-noise ratio that is required to achieve a good error performance with low decoding complexity.

  10. Research of RA Coding Algorithm Based on AWGN Channel

    Directory of Open Access Journals (Sweden)

    Xianzhong Chen

    2012-04-01

    Full Text Available In order to study the performance of RA, and the impacts of iterations and code length to the compiled code characteristics, we respectively made simulation analysis on RA, LDPC and TURBO with different parameters. We did it by designing code length, rate and iterations to analyze signals to noise ratio changes. With three patterns comparing the simulation analysis, it turned out that volume reaches the limit of Shannon when RA is in the condition of maximum likelihood decoding. The bit error ratio reduces as the message length goes up, and the performance comes near channel capacity. As the iterations increase, and bit error ratio reduces, and the performance will be better. Research shows that RA has more advantages and wide application propects whether in complexity or in performance.

  11. REALISATION OF AWGN CHANNEL EMULATION MODULES UNDER SISO AND SIMO ENVIRONMENTS FOR 4G LTE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Dr. R. Shantha Selva Kumari

    2014-12-01

    Full Text Available The testing of a wireless transmitter and receiver in the real-world channel is tedious. So, a channel emulator using FPGA helps in the testing of transmitter and receiver by providing a test environment that simulates a real-world wireless channel. Since FPGAs are flexible, cheap and reconfigurable, they are used in designing an AWGN channel emulator for 4G LTE for Single Input Single Output (SISO and Single Input Multiple Output (SIMO environments. In this paper, three basic modules: transmitter, channel estimation and receiver modules are synthesized. In the transmitter module, the input data is 64- QAM modulated and transmitted into the channel. In the channel estimation module, the transmitter data gets multiplied with the channel coefficients and then added with the noise present in the channel. In the receiver module, the data is detected using MMSE estimation. These are implemented in Virtex-5 device using PlanAhead tool and the Resource and Power Estimations are discussed.

  12. Performance Analysis of Mobile WiMAX System using Turbo Coding Technique for Different Modulation Schemes under AWGN and Rayleigh Channel

    Directory of Open Access Journals (Sweden)

    P. Samundiswary

    2013-02-01

    Full Text Available In wireless communication, future demands must be met using more data throughput wireless technologies. Since bandwidth is limited and user demand continues to grow. This problem could be solved by WiMAX technology based on IEEE 802.16e specifications, which provides high data services on mobile environment. So, to support high data rate traffic, the error correction could be enhanced by incorporating a better channel coding technique in mobile WiMAX physical layer. Further, coding technique is used for providing reliable information through the transmission channel to the user. It is used to reduce the level of noise and interferences in electronic medium. The amount of error detection and correction required and its effectiveness depends on the signal to noise ratio. The advantages of Forward Error Correction (FEC are that a back-channel is not required, or that retransmission of data can often be avoided, at the cost of higher bandwidth requirements on average. In this paper, the performance of mobile WiMAX system with convolutional turbo coding is determined and analyzed for various modulation schemes under different channels. The BER performance of mobile WiMAX system using convolutional turbo Coding is determined and compared with the existing concatenated Reed Solomon(RS coding in the presence of AWGN and Rayleigh Channel. From the simulation results, it is verified that convolutional turbo coding provides better BER performance than concatenated RS coding

  13. Performance-complexity tradeoff in sequential decoding for the unconstrained AWGN channel

    KAUST Repository

    Abediseid, Walid

    2013-06-01

    In this paper, the performance limits and the computational complexity of the lattice sequential decoder are analyzed for the unconstrained additive white Gaussian noise channel. The performance analysis available in the literature for such a channel has been studied only under the use of the minimum Euclidean distance decoder that is commonly referred to as the lattice decoder. Lattice decoders based on solutions to the NP-hard closest vector problem are very complex to implement, and the search for low complexity receivers for the detection of lattice codes is considered a challenging problem. However, the low computational complexity advantage that sequential decoding promises, makes it an alternative solution to the lattice decoder. In this work, we characterize the performance and complexity tradeoff via the error exponent and the decoding complexity, respectively, of such a decoder as a function of the decoding parameter - the bias term. For the above channel, we derive the cut-off volume-to-noise ratio that is required to achieve a good error performance with low decoding complexity. © 2013 IEEE.

  14. GENETIC ALGORITHM FOR DECODING LINEAR CODES OVER AWGN AND FADING CHANNELS

    Directory of Open Access Journals (Sweden)

    H. BERBIA

    2011-08-01

    Full Text Available This paper introduces a decoder for binary linear codes based on Genetic Algorithm (GA over the Gaussian and Rayleigh flat fading channel. The performances and compututional complexity of our decoder applied to BCH and convolutional codes are good compared to Chase-2 and Viterbi algorithm respectively. It show that our algorithm is less complex for linear block codes of large block length; furthermore it's performances can be improved by tuning the decoder's parameters, in particular the number of individuals by population and the number of generations

  15. Turbo-TCM在AWGN和Rayleigh衰落信道下的性能研究%Turbo-TCM Performance under AWGN and Rayleigh Fading Channels

    Institute of Scientific and Technical Information of China (English)

    任俊涛; 王睦重; 邵定蓉

    2003-01-01

    A simple algorithm for Turbo-TCM decoding was given in this paper.With this algorithm, Turbo-TCM can easily be used to real systems with various code rates and modulations of QPSK, 8PSK, 16QAM or 64QAM.The bit error ratio performance was studied under AWGN and fading channels.The simulation results were also given in this paper.%给出了一种简单的Turbo-TCM解调译码方法,使用这种方法可较容易地把Turbo码用于各种编码速率和QPSK,8PSK,16QAM或64QAM等各种调制方式下的TCM系统中.研究了各种编码速率和调制方式的Turbo-TCM在AWGN和Rayleigh 衰落信道下的性能,并给出了仿真试验结果.

  16. Error Performance of Multidimensional Lattice Constellations-Part I: A Parallelotope Geometry Based Approach for the AWGN Channel

    CERN Document Server

    Pappi, Koralia N; Chronis, Theodore N; Karagiannidis, George K

    2012-01-01

    Multidimensional lattice constellations which present signal space diversity (SSD) have been extensively studied for single-antenna transmission over fading channels, with focus on their optimal design for achieving high diversity gain. In this two-part series of papers we present a novel combinatorial geometrical approach based on parallelotope geometry, for the performance evaluation of multidimensional finite lattice constellations with arbitrary structure, dimension and rank. In Part I, we present an analytical expression for the exact symbol error probability (SEP) of multidimensional signal sets, and two novel closed-form bounds, named Multiple Sphere Lower Bound (MLSB) and Multiple Sphere Upper Bound (MSUB). Part II extends the analysis to the transmission over fading channels, where multidimensional signal sets are commonly used to combat fading degradation. Numerical and simulation results show that the proposed geometrical approach leads to accurate and tight expressions, which can be efficiently us...

  17. Capacity of 60 GHz Wireless Communication Systems over Fading Channels

    Directory of Open Access Journals (Sweden)

    Jingjing Wang

    2012-01-01

    Full Text Available This paper considers the channel capacity of 60GHz wireless communications systems over Rayleigh fading channels and Ricean fading channels. The SNR and therefore capacity varies according to the communication distance. The capacity is presented for line-of-sight (LOS and non-line-of-sight (NLOS channels given based on a 60GHz link budget model. Phase shift keying (PSK modulation is considered under FCC power constraints for the unlicensed 59-64GHz radio spectrum. The channel capacity over Rayleigh fading channels is compared with the capacity in additive white Gaussian noise channels. The paper also investigates the channel capacity of 60GHz wireless communications systems over Ricean fading channels and gives the channel capacity compariasion with q-ary PSK modulation over Ricean fading channel, AWGN channel and Rayleigh channel when the SNR per symbol is given. The results show that a 60GHz wireless system is more suitable for short range communications less than 100 meters rather than long distances

  18. Multicarrier chaotic communications in multipath fading channels without channel estimation

    Directory of Open Access Journals (Sweden)

    Shilian Wang

    2015-01-01

    Full Text Available A multi-carrier chaotic shift keying(MC-CSK communication scheme with low probability of interception(LPI is proposed in this article. We apply chaotic spreading sequences in the frequency domain, mapping a different chip of a chaotic sequence to an individual orthogonal frequency division multiplexing(OFDM subcarrier. In each block size of $M$ OFDM symbols, we use one pilot OFDM symbol inserted time-spaced in all-frequency to transmit the reference chaotic signal and use the other M-1 OFDM symbols to transmit the information-bearing signals each spreaded by the reference chaotic signal. At the receiver, we construct a differential detector after DFT and recover the information bits from the correlations between the pilot OFDM symbol and the other M-1 OFDM symbols in each block size of M. Performance analysis and computer simulations show that the MC-CSK outperforms differential chaos shift keying(DCSK in AWGN channels with high bandwidth efficiency for the block size of M=2 and that the MC-CSK exploits effectively the frequent diversity of the multipath channel.

  19. Multicarrier chaotic communications in multipath fading channels without channel estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shilian, E-mail: wangsl@nudt.edu.cn; Zhang, Zhili [College of Electrical Science and Engineering, National University of Defense Technology, Changsha, 410073, P R China (China)

    2015-01-15

    A multi-carrier chaotic shift keying(MC-CSK) communication scheme with low probability of interception(LPI) is proposed in this article. We apply chaotic spreading sequences in the frequency domain, mapping a different chip of a chaotic sequence to an individual orthogonal frequency division multiplexing(OFDM) subcarrier. In each block size of $M$ OFDM symbols, we use one pilot OFDM symbol inserted time-spaced in all-frequency to transmit the reference chaotic signal and use the other M-1 OFDM symbols to transmit the information-bearing signals each spreaded by the reference chaotic signal. At the receiver, we construct a differential detector after DFT and recover the information bits from the correlations between the pilot OFDM symbol and the other M-1 OFDM symbols in each block size of M. Performance analysis and computer simulations show that the MC-CSK outperforms differential chaos shift keying(DCSK) in AWGN channels with high bandwidth efficiency for the block size of M=2 and that the MC-CSK exploits effectively the frequent diversity of the multipath channel.

  20. Multicarrier chaotic communications in multipath fading channels without channel estimation

    International Nuclear Information System (INIS)

    A multi-carrier chaotic shift keying(MC-CSK) communication scheme with low probability of interception(LPI) is proposed in this article. We apply chaotic spreading sequences in the frequency domain, mapping a different chip of a chaotic sequence to an individual orthogonal frequency division multiplexing(OFDM) subcarrier. In each block size of $M$ OFDM symbols, we use one pilot OFDM symbol inserted time-spaced in all-frequency to transmit the reference chaotic signal and use the other M-1 OFDM symbols to transmit the information-bearing signals each spreaded by the reference chaotic signal. At the receiver, we construct a differential detector after DFT and recover the information bits from the correlations between the pilot OFDM symbol and the other M-1 OFDM symbols in each block size of M. Performance analysis and computer simulations show that the MC-CSK outperforms differential chaos shift keying(DCSK) in AWGN channels with high bandwidth efficiency for the block size of M=2 and that the MC-CSK exploits effectively the frequent diversity of the multipath channel

  1. Molecular communication in fluid media: The additive inverse Gaussian noise channel

    CERN Document Server

    Srinivas, K V; Eckford, Andrew W

    2010-01-01

    We consider molecular communication, with information conveyed in the time of release of molecules. The main contribution of this paper is the development of a theoretical foundation for such a communication system. Specifically, we develop the additive inverse Gaussian (IG) noise channel model: a channel in which the information is corrupted by noise with an inverse Gaussian distribution. We show that such a channel model is appropriate for molecular communication in fluid media - when propagation between transmitter and receiver is governed by Brownian motion and when there is positive drift from transmitter to receiver. Taking advantage of the available literature on the IG distribution, upper and lower bounds on channel capacity are developed, and a maximum likelihood receiver is derived. Theory and simulation results are presented which show that such a channel does not have a single quality measure analogous to signal-to-noise ratio in the AWGN channel. It is also shown that the use of multiple molecule...

  2. Opening Channels of Communication

    Directory of Open Access Journals (Sweden)

    Clarice Moura Costa

    2009-03-01

    Full Text Available Psychosis, as described through a psychodynamic perspective, is conceptualized as an attempt to deny the enveloping reality to avoid contact with the other. Music therapy is a way to break this barrier of non-communication raised by the patients. The music therapy process is configured as a trinomial – action (making music/ relationship (action with the other/communication (musical or verbal voluntary expression of feelings and conflicts, which, although intrinsically connected, is perceived in a sequential process. Aulagnier asserts that psychic activity represents the conjunction of three modes of functioning: the original process, the primary process and the secondary process. The perception of sound passes through three phases, corresponding to each manner of functioning of the psychic system – the pleasure of hearing, the desire to listen (to the other and the imperative of meaning. The music therapy process offers a significant similarity with the theory proposed by Aulagnier. We propose the hypothesis that in music therapy, there is an opportunity to (reexperience very archaic phases in the constitution of the ego, but in a new manner, so helping to open communication channels. This theoretical hypothesis is illustrated by real examples of patients.

  3. Performance Evaluation of Wimax Physical Layer under Adaptive Modulation Techniques and Communication Channels

    CERN Document Server

    Islam, Md Ashraful; Hasan, Md Zahid

    2009-01-01

    Wimax (Worldwide Interoperability for Microwave Access) is a promising technology which can offer high speed voice, video and data service up to the customer end. The aim of this paper is the performance evaluation of an Wimax system under different combinations of digital modulation (BPSK, QPSK, 4 QAM and 16 QAM) and different communication channels AWGN and fading channels (Rayleigh and Rician). And the Wimax system incorporates Reed Solomon (RS) encoder with Convolutional encoder with half and two third rated codes in FEC channel coding. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255, 239, 8) with two third rated Convolutional code under BPSK modulation technique is highly effective to combat in the Wimax communication system. To complete this performance analysis in Wimax based systems, a segment of audio signal is used for analysis. The transmitted audio message is found to have retrieved effectively under noisy situation.

  4. Opening Channels of Communication

    OpenAIRE

    Clarice Moura Costa

    2009-01-01

    Psychosis, as described through a psychodynamic perspective, is conceptualized as an attempt to deny the enveloping reality to avoid contact with the other. Music therapy is a way to break this barrier of non-communication raised by the patients. The music therapy process is configured as a trinomial – action (making music)/ relationship (action with the other)/communication (musical or verbal voluntary expression of feelings and conflicts), which, although intrinsically connected, is perceiv...

  5. Quantum channel capacities - multiparty communication

    CERN Document Server

    Demianowicz, M; Demianowicz, Maciej; Horodecki, Pawel

    2006-01-01

    We analyze different aspects of multiparty communication over quantum memoryless channels and generalize some of key results known from bipartite channels to that of multiparty scenario. In particular, we introduce multiparty versions of minimal subspace transmission fidelity and entanglement transmission fidelity. We also provide alternative, local, versions of fidelities and show their equivalence to the global ones in context of capacity regions defined. The equivalence of two different capacity notions with respect to two types of the fidelities is proven. In analogy to bipartite case it is shown, via sufficiency of isometric encoding theorem, that additional classical forward side channel does not increase capacity region of any quantum channel with $k$ senders and $m$ receivers which represents a compact unit of general quantum networks theory. The result proves that recently provided capacity region of multiple access channel ([M. Horodecki et al, Nature {\\bf 436} 673 (2005)], [J.Yard et al, quant-ph/0...

  6. Wireless Communication over Dispersive Channels

    NARCIS (Netherlands)

    Fang, K.

    2010-01-01

    Broadband wireless communication systems require high transmission rates, where the bandwidth of the transmitted signal is larger than the channel coherence bandwidth. This gives rise to time dispersion of the transmitted symbols or frequency-selectivity with different frequency components exhibitin

  7. Channel simulation via interactive communications

    CERN Document Server

    Yassaee, Mohammad Hossein; Aref, Mohammad Reza

    2012-01-01

    In this paper, we study the problem of channel simulation via interactive communication, known as the coordination capacity, in a two-terminal network. We assume that two terminals observe i.i.d.\\ copies of two random variables and would like to generate i.i.d.\\ copies of two other random variables jointly distributed with the observed random variables. The terminals are provided with two-way communication links, and shared common randomness, all at limited rates. Two special cases of this problem are the interactive function computation studied by Ma and Ishwar, and the tradeoff curve between one-way communication and shared randomness studied by Cuff. The latter work had inspired Gohari and Anantharam to study the general problem of channel simulation via interactive communication stated above. However only inner and outer bounds for the special case of no shared randomness were obtained in their work. In this paper we settle this problem by providing an exact computable characterization of the multi-round ...

  8. Efficient communication channels towards the researchers

    OpenAIRE

    Mammadova, Zaira

    2012-01-01

    Aalto University has over 4000 researchers. While reaching out and informing them about Aalto Center for Entrepreneurship (ACE) and its services is one of the tasks of ACE, maintaining a relationship via various channels with the researchers who are aware of ACE is equally important. Project is part of the development of communication channels towards the stakeholders of ACE. The purpose of the given project was to identify the best communications channels. ACE aims to use these chann...

  9. Covert Communication over Classical-Quantum Channels

    OpenAIRE

    Sheikholeslami, Azadeh; Bash, Boulat A.; Towsley, Donald; Goeckel, Dennis; Guha, Saikat

    2016-01-01

    Recently, the fundamental limits of covert, i.e., reliable-yet-undetectable, communication have been established for general memoryless channels and for lossy-noisy bosonic (quantum) channels with a quantum-limited adversary. The key import of these results was the square-root law (SRL) for covert communication, which states that $O(\\sqrt{n})$ covert bits, but no more, can be reliably transmitted over $n$ channel uses with $O(\\sqrt{n})$ bits of secret pre-shared between communicating parties....

  10. Secure refinements of communication channels

    OpenAIRE

    Cheval, Vincent; Cortier, Véronique; Le Morvan, Eric

    2015-01-01

    International audience It is a common practice to design a protocol (say Q) assuming some secure channels. Then the secure channels are implemented using any standard protocol, e.g. TLS. In this paper, we study when such a practice is indeed secure. We provide a characterization of both confidential and authenticated channels. As an application, we study several protocols of the literature including TLS and BAC protocols. Thanks to our result, we can consider a larger number of sessions wh...

  11. Cooperative communications hardware, channel and PHY

    CERN Document Server

    Dohler, Mischa

    2010-01-01

    Facilitating Cooperation for Wireless Systems Cooperative Communications: Hardware, Channel & PHY focuses on issues pertaining to the PHY layer of wireless communication networks, offering a rigorous taxonomy of this dispersed field, along with a range of application scenarios for cooperative and distributed schemes, demonstrating how these techniques can be employed. The authors discuss hardware, complexity and power consumption issues, which are vital for understanding what can be realized at the PHY layer, showing how wireless channel models differ from more traditional

  12. Two-way quantum communication channels

    CERN Document Server

    Childs, A M; Lo, H K; Childs, Andrew M.; Leung, Debbie W.; Lo, Hoi-Kwong

    2005-01-01

    We consider communication between two parties using a bipartite quantum operation, which constitutes the most general quantum mechanical model of two-party communication. We primarily focus on the simultaneous forward and backward communication of classical messages. For the case in which the two parties share unlimited prior entanglement, we give inner and outer bounds on the achievable rate region that generalize classical results due to Shannon. In particular, using a protocol of Bennett, Harrow, Leung, and Smolin, we give a one-shot expression in terms of the Holevo information for the entanglement-assisted one-way capacity of a two-way quantum channel. As applications, we rederive two known additivity results for one-way channel capacities: the entanglement-assisted capacity of a general one-way channel, and the unassisted capacity of an entanglement-breaking one-way channel.

  13. Concurrent signal combining and channel estimation in digital communications

    Science.gov (United States)

    Ormesher, Richard C.; Mason, John J.

    2011-08-30

    In the reception of digital information transmitted on a communication channel, a characteristic exhibited by the communication channel during transmission of the digital information is estimated based on a communication signal that represents the digital information and has been received via the communication channel. Concurrently with the estimating, the communication signal is used to decide what digital information was transmitted.

  14. Channel Coding in Random Access Communication over Compound Channels

    CERN Document Server

    Wang, Zheng

    2011-01-01

    Due to the short and bursty incoming messages, channel access activities in a wireless random access system are often fractional. The lack of frequent data support consequently makes it difficult for the receiver to estimate and track the time varying channel states with high precision. This paper investigates random multiple access communication over a compound wireless channel where channel realization is known neither at the transmitters nor at the receiver. An achievable rate and error probability tradeoff bound is derived under the non-asymptotic assumption of a finite codeword length. The results are then extended to the random multiple access system where the receiver is only interested in decoding messages from a user subset.

  15. Secure Bidirectional Communication Protocol without Quantum Channel

    OpenAIRE

    Zhang, Z. J.; Man, Z. X.

    2004-01-01

    In this letter we propose a theoretical deterministic secure direct bidirectional quantum communication protocol by using swapping quantum entanglement and local unitary operations, in which the quantum channel for photon transmission can be discarded, hence any attack with or without eavesdropping or even the destructive attack without scruple is impossible.

  16. Secure quantum communication using classical correlated channel

    Science.gov (United States)

    Costa, D.; de Almeida, N. G.; Villas-Boas, C. J.

    2016-10-01

    We propose a secure protocol to send quantum information from one part to another without a quantum channel. In our protocol, which resembles quantum teleportation, a sender (Alice) and a receiver (Bob) share classical correlated states instead of EPR ones, with Alice performing measurements in two different bases and then communicating her results to Bob through a classical channel. Our secure quantum communication protocol requires the same amount of classical bits as the standard quantum teleportation protocol. In our scheme, as in the usual quantum teleportation protocol, once the classical channel is established in a secure way, a spy (Eve) will never be able to recover the information of the unknown quantum state, even if she is aware of Alice's measurement results. Security, advantages, and limitations of our protocol are discussed and compared with the standard quantum teleportation protocol.

  17. Secure quantum communication using classical correlated channel

    Science.gov (United States)

    Costa, D.; de Almeida, N. G.; Villas-Boas, C. J.

    2016-07-01

    We propose a secure protocol to send quantum information from one part to another without a quantum channel. In our protocol, which resembles quantum teleportation, a sender (Alice) and a receiver (Bob) share classical correlated states instead of EPR ones, with Alice performing measurements in two different bases and then communicating her results to Bob through a classical channel. Our secure quantum communication protocol requires the same amount of classical bits as the standard quantum teleportation protocol. In our scheme, as in the usual quantum teleportation protocol, once the classical channel is established in a secure way, a spy (Eve) will never be able to recover the information of the unknown quantum state, even if she is aware of Alice's measurement results. Security, advantages, and limitations of our protocol are discussed and compared with the standard quantum teleportation protocol.

  18. Nonperturbative approach to relativistic quantum communication channels

    Science.gov (United States)

    Landulfo, André G. S.

    2016-05-01

    We investigate the transmission of both classical and quantum information between two arbitrary observers in globally hyperbolic spacetimes using a quantum field as a communication channel. The field is supposed to be in some arbitrary quasifree state and no choice of representation of its canonical commutation relations is made. Both sender and receiver possess some localized two-level quantum system with which they can interact with the quantum field to prepare the input and receive the output of the channel, respectively. The interaction between the two-level systems and the quantum field is such that one can trace out the field degrees of freedom exactly and thus obtain the quantum channel in a nonperturbative way. We end the paper determining the unassisted as well as the entanglement-assisted classical and quantum channel capacities.

  19. New Channel Coding Methods for Satellite Communication

    Directory of Open Access Journals (Sweden)

    J. Sebesta

    2010-04-01

    Full Text Available This paper deals with the new progressive channel coding methods for short message transmission via satellite transponder using predetermined length of frame. The key benefits of this contribution are modification and implementation of a new turbo code and utilization of unique features with applications of methods for bit error rate estimation and algorithm for output message reconstruction. The mentioned methods allow an error free communication with very low Eb/N0 ratio and they have been adopted for satellite communication, however they can be applied for other systems working with very low Eb/N0 ratio.

  20. AWGN和衰落信道下具有改进型Code-matched交织器的Turbo码%Turbo Codes with Modified Code-matched Interleaver over AWGN and Rayleigh Fading Channel

    Institute of Scientific and Technical Information of China (English)

    罗骥; 张曦林; 袁东风

    2005-01-01

    提出了一种改进型的Code-Matched交织器,它能减少低重量码的数量,从而提高Turbo码的性能.这种改进型的Code-Matched交织器可以适用于多种不同生成矩阵产生的Turbo码,而且不会影响Turbo码在中高信噪比处的性能.同时,在Rayleigh信道下,这种交织器能降低错误平台.%A novel Code-Matched interleaver is proposed which decreases the number of the low weight codewords to improve the performance of the Turbo code. The modified design can adapt more kinds of Turbo codes determined by the generator matrix, while it doesn't decrease the bit error rate performance of Turbo codes at moderate to high signal to noise ratio. At the same time, in Rayleigh fading channel, the new Code-Matched interleaver can also debase the error floor.

  1. Nonperturbative approach to relativistic quantum communication channels

    OpenAIRE

    Landulfo, Andre G. S.

    2016-01-01

    We investigate the transmission of both classical and quantum information between two arbitrary observers in globally hyperbolic spacetimes using a quantum field as a communication channel. The field is supposed to be in some arbitrary quasifree state and no choice of representation of its canonical commutation relations is made. Both sender and receiver possess some localized two-level quantum system with which they can interact with the quantum field to prepare the input and receive the out...

  2. INFORMATION CHARACTERIZATION OF COMMUNICATION CHANNELS FOR SYSTEM IDENTIFICATION

    Institute of Scientific and Technical Information of China (English)

    Le Yi WANG; G. George YIN

    2007-01-01

    This paper studies identification of systems in which the system output is quantized,transmitted through a digital communication channel, and observed afterwards. The concept of the CR Ratio is introduced to characterize impact of communication channels on identification. The relationship between the CR Ratio and Shannon channel capacity is discussed. Identification algorithms are further developed when the channel error probability is unknown.

  3. Optimization of bandwidth of communication channels of corporate networks

    OpenAIRE

    G. I. Bondarenko; P. M. Korobenkov

    2014-01-01

    Introduction. This article contains overview of the organization of communication between applications on the corporate network. It is stated that the main digital channel (channel B - 64 kbit/s) and the primary digital channel (channel E1 the digital stream - 2048 kbit/s) are used as the main channels in corporate networks. Problem areas of the functioning of the corporate network are identified. There are the rent of communication channels, which is growing rapidly with increasing the quali...

  4. Energy and channels of international communication

    Energy Technology Data Exchange (ETDEWEB)

    Tehranian, M.; Fesharaki, F.; Tehranian, T.M.

    The authors, in an extract from their original manuscript, study world energy and international communication, with a focus on the political economy of world public opinion formation in such areas as energy, nuclear weapons, and other topics of significance. This excerpt covers the economic and political implications of changing energy markets, specifically oil. Public opinion formation is the result of interpersonal relations between world leaders, academicians, scientists at research institutes, consultants, and conference participants and institutional networks, including international, government, and corporate. Media channels make up the third major element. 8 tables.

  5. Quantum communication using a multiqubit entangled channel

    International Nuclear Information System (INIS)

    We describe a protocol in which two senders each teleport a qubit to a receiver using a multiqubit entangled state. The multiqubit channel used for teleportation is genuinely 4-qubit entangled and is not equivalent to a product of maximally entangled Bell pairs under local unitary operations. We discuss a scenario in which both senders must participate for the qubits to be successfully teleported. Such an all-or-nothing scheme cannot be implemented with standard two-qubit entangled Bell pairs and can be useful for different communication and computing tasks

  6. Quantum communication using a multiqubit entangled channel

    Energy Technology Data Exchange (ETDEWEB)

    Ghose, Shohini, E-mail: sghose@wlu.ca [Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario (Canada); Institute for Quantum Computing, University of Waterloo, Ontario (Canada); Hamel, Angele [Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario (Canada)

    2015-12-31

    We describe a protocol in which two senders each teleport a qubit to a receiver using a multiqubit entangled state. The multiqubit channel used for teleportation is genuinely 4-qubit entangled and is not equivalent to a product of maximally entangled Bell pairs under local unitary operations. We discuss a scenario in which both senders must participate for the qubits to be successfully teleported. Such an all-or-nothing scheme cannot be implemented with standard two-qubit entangled Bell pairs and can be useful for different communication and computing tasks.

  7. Channel Equalization for Chaos-Based Communication Systems

    Institute of Scientific and Technical Information of China (English)

    冯久超; 鲁瑞华

    2002-01-01

    We study the equalization of the channel for chaotic communication systems. A channel equalizer is designed and realized by a modified recurrent neural network for eliminating channel distortions. The results from computer simulations demonstrate the effectiveness of the equalizer as applied to a chaotic communication system.

  8. Channel coding techniques for wireless communications

    CERN Document Server

    Deergha Rao, K

    2015-01-01

    The book discusses modern channel coding techniques for wireless communications such as turbo codes, low-density parity check (LDPC) codes, space–time (ST) coding, RS (or Reed–Solomon) codes and convolutional codes. Many illustrative examples are included in each chapter for easy understanding of the coding techniques. The text is integrated with MATLAB-based programs to enhance the understanding of the subject’s underlying theories. It includes current topics of increasing importance such as turbo codes, LDPC codes, Luby transform (LT) codes, Raptor codes, and ST coding in detail, in addition to the traditional codes such as cyclic codes, BCH (or Bose–Chaudhuri–Hocquenghem) and RS codes and convolutional codes. Multiple-input and multiple-output (MIMO) communications is a multiple antenna technology, which is an effective method for high-speed or high-reliability wireless communications. PC-based MATLAB m-files for the illustrative examples are provided on the book page on Springer.com for free dow...

  9. Reliable quantum communication over a quantum relay channel

    Energy Technology Data Exchange (ETDEWEB)

    Gyongyosi, Laszlo, E-mail: gyongyosi@hit.bme.hu [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117, Hungary and Information Systems Research Group, Mathematics and Natural Sciences, Hungarian Ac (Hungary); Imre, Sandor [Quantum Technologies Laboratory, Department of Telecommunications, Budapest University of Technology and Economics, 2 Magyar tudosok krt, Budapest, H-1117 (Hungary)

    2014-12-04

    We show that reliable quantum communication over an unreliable quantum relay channels is possible. The coding scheme combines the results on the superadditivity of quantum channels and the efficient quantum coding approaches.

  10. Optimization of bandwidth of communication channels of corporate networks

    Directory of Open Access Journals (Sweden)

    G. I. Bondarenko

    2014-09-01

    Full Text Available Introduction. This article contains overview of the organization of communication between applications on the corporate network. It is stated that the main digital channel (channel B - 64 kbit/s and the primary digital channel (channel E1 the digital stream - 2048 kbit/s are used as the main channels in corporate networks. Problem areas of the functioning of the corporate network are identified. There are the rent of communication channels, which is growing rapidly with increasing the quality and speed of data transmission, and optimal use of bandwidth of communication channels. Setting of task. Optimal use of transmission channels bandwidth and minimizing the rent cost of channels is possible in two ways - the use of compression techniques of voice and video information and the application of variable structure of channels by using various-speed transmission channels. Differential pulse code modulation, adaptive differential pulse code modulation are the modern methods of speech signals processing. Organization of various-speed channels is performed in the structure of the BCC (for speech signals or PCR (for video. Suggestions for optimizing the structure of the channel signals. Proposed method of various-speed channels formation by using the channel intervals appropriate BCC (octets in the structure of signals E1 as envelopes containing various-speed channels. Channels can be selected for synchronization procedure CRC to simplify recognition of channels in the structure of E1. In this case, the minimal speed in the channel is 4 kbit/s. Conclusions. The proposed structure of envelopes is based on octet channel intervals of standard group signal of the primary group plesiochronous hierarchy E1 when transferring various-speed digital signals maximum allows to use the bandwidth at a fixed structure of channel interval, it makes possible to agree on the structure of the various-speed signals with the existing in communication networks.

  11. Real-time Covert Communications Channel for Audio Signals

    Directory of Open Access Journals (Sweden)

    Ashraf Seleym

    2012-09-01

    Full Text Available Covert communications channel is considered as a type of secure communications that creates capability to transfer information between entities while hiding the contents of the channel. Multimedia data hiding techniques can be used to establish a covert channel for secret communications within a media carrier. In this paper, a high-rate covert communications channel is developed to exploit an audio stream as a carrier signal using multiple embedding in the Quantization Index Modulation framework. The proposed approach uses multi quantization vectors to increase data transmission rate. The embedding algorithms consider the embedding process as a communications problem, that it uses structured scheme of Multiple Trellis-Coded Quantization jointed with Multiple Trellis-Coded Modulation. Using convolution codes based trellis coding returns a real-time communications, because it can be continuously encoded and decoded. The proposed approach exhibits a high channel capacity due to the increase in data embedding rate without severely increasing in embedding distortion.

  12. Covert Communication Gains from Adversary's Ignorance of Transmission Time

    OpenAIRE

    Bash, Boulat A.; Goeckel, Dennis; Towsley, Don

    2014-01-01

    The recent square root law (SRL) for covert communication demonstrates that Alice can reliably transmit $\\mathcal{O}(\\sqrt{n})$ bits to Bob in $n$ uses of an additive white Gaussian noise (AWGN) channel while keeping ineffective any detector employed by the adversary; conversely, exceeding this limit either results in detection by the adversary with high probability or non-zero decoding error probability at Bob. This SRL is under the assumption that the adversary knows when Alice transmits (i...

  13. Quantum Communication Scheme Using Non-symmetric Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    CAO Hai-Jing; CHEN Zhong-Hua; SONG He-Shan

    2008-01-01

    A theoretical quantum communication scheme based on entanglement swapping and superdense coding is proposed with a 3-dimensional Bell state and 2-dimensional Bell state function as quantum channel quantum key distribution and quantum secure direct communication can be simultaneously accomplished in the scheme. The scheme is secure and has high source capacity. At last, we generalize the quantum communication scheme to d-dimensional quantum channel.

  14. Acoustic MIMO Communications in a Very Shallow Water Channel

    Institute of Scientific and Technical Information of China (English)

    Yuehai Zhou; Xiuling Cao; Feng Tong

    2015-01-01

    Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication.

  15. Characterization of an Acoustic Communication Channel with Pseudorandom Binary Sequences

    NARCIS (Netherlands)

    Walree, P.A. van; Bertolotto, G.

    2007-01-01

    The joint European project "UUV Covert Acoustic Communications" explores methods for underwater communication at low signal-to-noise ratios. The first phase of the project focuses on characterization of the communication channel. Sea trials were conducted in two littoral environments in September 20

  16. Appropriateness of Internal Communication Channels : A Stakeholder Approach

    OpenAIRE

    Safarova, Julia; Holmin, Jenny

    2015-01-01

    Internal communication is pivotal for the effectiveness of company procedures and ultimately the success of the company. Understanding more about the communicative needs of different employee groups is therefore important in order to convey a message in a satisfying manner to those employees. This explorative study is investigating communication preferences from a stakeholder perspective to find out what influences the appropriateness of using different communication channels when transmittin...

  17. Stasistically constrained operator associated with additivity of communication channel

    OpenAIRE

    Fukumi, Toshio

    2004-01-01

    Additivity of quantum communication channel is discussed in terms of Poisson process to show it is additive in probability. Poisson process is shown to be responsible for entanglement which is a rare event.

  18. A communication-channel-based representation system for software

    NARCIS (Netherlands)

    Demirezen, Zekai; Tanik, Murat M.; Aksit, Mehmet; Skjellum, Anthony

    2014-01-01

    We observed that before initiating software development the objectives are minimally organized and developers introduce comparatively higher organization throughout the design process. To be able to formally capture this observation, a new communication channel representation system for software is

  19. A DISTRIBUTED DYNAMIC CHANNEL ALLOCATION IN CELLULAR COMMUNICATION

    Directory of Open Access Journals (Sweden)

    Dipti Varpe

    2011-07-01

    Full Text Available Now a days, mobile users are growing rapidly and the available frequency spectrum is limited. Therefore the available spectrum must be efficiently utilized. In response a large number of channel assignment and allocation policies have been proposed. Mostly Dynamic Channel Allocation (DCA has become an important subject of research and development for cellular networks. In this paper, we propose a distributed dynamic channel allocation (DDCA algorithm for originating calls. This algorithm is executed at each base station and to allocate the channel to mobile station, base station communicates with each other. In DDCA, the total number of channels is divided into three groups. Any cell in the cluster can acquire the channel group as long as no one of its adjacent cells is holding the same group. Due to this the cochannel interference is avoided. The result show blocking rate of distributed dynamic channel allocation is reduced as compared to dynamic channel allocation algorithm with non-uniform traffic distribution

  20. Establishing Internal Communication Channels That Work.

    Science.gov (United States)

    Wood, Julie

    1999-01-01

    Uses a case study to examine the trends in current and preferred methods of communication within an institution of higher education, the Manukau Institute of Technology, New Zealand. Interviews and questionnaires identified ways in which leaders and staff received information, the communication methods they considered most effective, and…

  1. The role of digital channels in industrial marketing communications

    OpenAIRE

    Karjaluoto, Heikki; Mustonen, Nora; Ulkuniemi, Pauliina

    2015-01-01

    Purpose – The purpose of this research is to investigate industrial marketing communications tools and the role of digital channels. The research draws from the literature on industrial marketing communications to examine its goals and intended utilization in industrial firms. Design/methodology/approach – An empirical multiple case study conducted among six industrial firms examines the current state of digital marketing communications (DMC). Findings – The study gleans thre...

  2. Communication flow, channels, content and climate in downsizing

    OpenAIRE

    Illia, Laura; Lurati, Francesco; La Rocca, Antonella

    2006-01-01

    Effective internal communication contributes to the overall organizational communication that aims to maintain a sustainable reputation during times of change. Arising from this belief, this paper aims to develop a theoretical framework in which the type of communication content, flows, channels, and climate better fits into the planning, implementation, and revitalization phases within the downsizing process. To this end, a literature review on downsizing studies has been conducted, resultin...

  3. A NOVEL MODULATION FOR MOBILE SATELLITE COMMUNICATIONS

    Institute of Scientific and Technical Information of China (English)

    Xie Zhidong; Bian Dongming; Hu Jing; Sun Qian

    2011-01-01

    It is a challenging problem to design a high performance modulation for mobile satellite communications due to the limited power and bandwidth resource.The paper improves Feher patented Quadrature Phase Shift Keying (FQPSK) by redefining the waveform.The novel FQPSK,with constant envelope,can be used to improve the power efficiency and frequency efficiency of mobile satellite communication.The study shows that the improved FQPSK outperforms conventional FQPSK over AWGN and is immune to the non-linearity of high power amplifier.At last,the impact of flat fading and multi-path fading of channel on the BER performance of improved modulation is analyzed.

  4. Integrated source and channel encoded digital communications system design study

    Science.gov (United States)

    Huth, G. K.

    1974-01-01

    Studies on the digital communication system for the direct communication links from ground to space shuttle and the links involving the Tracking and Data Relay Satellite (TDRS). Three main tasks were performed:(1) Channel encoding/decoding parameter optimization for forward and reverse TDRS links,(2)integration of command encoding/decoding and channel encoding/decoding; and (3) modulation coding interface study. The general communication environment is presented to provide the necessary background for the tasks and to provide an understanding of the implications of the results of the studies.

  5. Redundant uplink optical channel for visible light communication systems

    Science.gov (United States)

    Vladescu, Marian; Vuza, Dan Tudor

    2015-02-01

    The increased interest in optical wireless (OW), as a complementary solution for radio frequency (RF) wireless technology, in conjunction with the significant deployments in LED lighting technology, led to the need to achieve lighting and wireless communication simultaneously in indoor environments. Visible light communication (VLC) technology provides an opportunity and infrastructure for the high-speed low-cost wireless communication. There are still open issues in VLC such as: uplink channel, LED modulation bandwidth, and LED nonlinearity. In this paper we addressed the uplink channel implementation, being a key issue in the OW communication system in order to allow full connectivity for a terminal (duplex transmission). VLC in full duplex mode requires the usage of a hybrid technology, such as infrared optical uplink, retro-reflecting transceivers, or even RF. The solution we proposed is to create a redundant optical uplink channel, using near ultraviolet (UV) and near infrared (IR) spectra.

  6. Quantum-secure covert communication on bosonic channels

    Science.gov (United States)

    Bash, Boulat A.; Gheorghe, Andrei H.; Patel, Monika; Habif, Jonathan L.; Goeckel, Dennis; Towsley, Don; Guha, Saikat

    2015-10-01

    Computational encryption, information-theoretic secrecy and quantum cryptography offer progressively stronger security against unauthorized decoding of messages contained in communication transmissions. However, these approaches do not ensure stealth--that the mere presence of message-bearing transmissions be undetectable. We characterize the ultimate limit of how much data can be reliably and covertly communicated over the lossy thermal-noise bosonic channel (which models various practical communication channels). We show that whenever there is some channel noise that cannot in principle be controlled by an otherwise arbitrarily powerful adversary--for example, thermal noise from blackbody radiation--the number of reliably transmissible covert bits is at most proportional to the square root of the number of orthogonal modes (the time-bandwidth product) available in the transmission interval. We demonstrate this in a proof-of-principle experiment. Our result paves the way to realizing communications that are kept covert from an all-powerful quantum adversary.

  7. Multiplexed communication over a high-speed quantum channel

    CERN Document Server

    Heurs, M; Dunlop, A E; Harb, C C; Ralph, T C; Huntington, E H

    2010-01-01

    In quantum information systems it is of particular interest to consider the best way in which to use the non-classical resources consumed by that system. Quantum communication protocols are integral to quantum information systems and are amongst the most promising near-term applications of quantum information science. Here we show that a multiplexed, digital quantum communications system supported by comb of vacuum squeezing has a greater channel capacity per photon than a source of broadband squeezing with the same analogue bandwidth. We report on the time-resolved, simultaneous observation of the first dozen teeth in a 2.4 GHz comb of vacuum squeezing produced by a sub-threshold OPO, as required for such a quantum communications channel. We also demonstrate multiplexed communication on that channel.

  8. Multiplexed communication over a high-speed quantum channel

    Science.gov (United States)

    Heurs, M.; Webb, J. G.; Dunlop, A. E.; Harb, C. C.; Ralph, T. C.; Huntington, E. H.

    2010-03-01

    In quantum information systems it is of particular interest to consider the best way in which to use the nonclassical resources consumed by that system. Quantum communication protocols are integral to quantum information systems and are among the most promising near-term applications of quantum information science. Here we show that a multiplexed, digital quantum communications system supported by a comb of vacuum squeezing has a greater channel capacity per photon than a source of broadband squeezing with the same analog band width. We report on the time-resolved, simultaneous observation of the first dozen teeth in a 2.4-GHz comb of vacuum squeezing produced by a subthreshold optical parametric oscillator, as required for such a quantum communications channel. We also demonstrate multiplexed communication on that channel.

  9. Gaussian matrix product states for coding in bosonic communication channels

    CERN Document Server

    Schäfer, Joachim; Cerf, Nicolas J

    2012-01-01

    The communication capacity of Gaussian bosonic channels with memory has recently attracted much interest. Here, we investigate a method to prepare the multimode entangled input symbol states for encoding classical information into these channels. In particular, we study the usefulness of a Gaussian matrix product state (GMPS) [G. Adesso and M. Ericsson, Phys. Rev. A 74, 030305 (2006)] as an input symbol state, which can be sequentially generated although it remains heavily entangled for an arbitrary number of modes. We show that the GMPS can achieve more than 99.9% of the Gaussian capacity for Gaussian bosonic memory channels with a Markovian or non-Markovian correlated noise model in a large range of noise correlation strengths. Furthermore, we present a noise class for which the GMPS is the exact optimal input symbol state of the corresponding channel. Since GMPS are ground states of particular quadratic Hamiltonians, our results suggest a possible link between the theory of quantum communication channels a...

  10. Information transmission and recovery in neural communications channels

    Science.gov (United States)

    Eguia, M. C.; Rabinovich, M. I.; Abarbanel, H. D. I.

    2000-11-01

    Biological neural communications channels transport environmental information from sensors through chains of active dynamical neurons to neural centers for decisions and actions to achieve required functions. These kinds of communications channels are able to create information and to transfer information from one time scale to the other because of the intrinsic nonlinear dynamics of the component neurons. We discuss a very simple neural information channel composed of sensory input in the form of a spike train that arrives at a model neuron, then moves through a realistic synapse to a second neuron where the information in the initial sensory signal is read. Our model neurons are four-dimensional generalizations of the Hindmarsh-Rose neuron, and we use a model of chemical synapse derived from first-order kinetics. The four-dimensional model neuron has a rich variety of dynamical behaviors, including periodic bursting, chaotic bursting, continuous spiking, and multistability. We show that, for many of these regimes, the parameters of the chemical synapse can be tuned so that information about the stimulus that is unreadable at the first neuron in the channel can be recovered by the dynamical activity of the synapse and the second neuron. Information creation by nonlinear dynamical systems that allow chaotic oscillations is familiar in their autonomous oscillations. It is associated with the instabilities that lead to positive Lyapunov exponents in their dynamical behavior. Our results indicate how nonlinear neurons acting as input/output systems along a communications channel can recover information apparently ``lost'' in earlier junctions on the channel. Our measure of information transmission is the average mutual information between elements, and because the channel is active and nonlinear, the average mutual information between the sensory source and the final neuron may be greater than the average mutual information at an earlier neuron in the channel. This

  11. Agent Communication Channel Based on BACnet

    Institute of Scientific and Technical Information of China (English)

    Jiang Wen-bin; Zhou Man-li

    2004-01-01

    We analyze the common shortcoming in the existing agent MTPs (message transport protocols). With employing the File object and related service AtomicWriteFile of BACnet (a data communication protocol building automation and control networks), a new method of agent message transport is proposed and implemented. Every agent platform (AP) has one specified File object and agents in another AP can communicate with agents in the AP by using AtomicWriteFile service. Agent messages can be in a variety of formats. In implementation, BACnet/IP and Ethernet are applied as the BACnet data link layers respectively. The experiment results show that the BACnet can provide perfect support for agent communication like other conventional protocols such as hypertext transfer protocol(HTTP), remote method invocation (RMI) etc. and has broken through the restriction of TCP/IP. By this approach, the agent technology is introduced into the building automation control network system.

  12. Robust Quantum Secure Direct Communication and Deterministic Secure Quantum Communication over Collective Dephasing Noisy Channel

    Institute of Scientific and Technical Information of China (English)

    YUAN Hao; SONG Jun; HE Qin; HAN Lian-Fang; HOU Kui; HU Xiao-Yuan; SHI Shou-Hua

    2008-01-01

    We propose two schemes for quantum secure direct communication (QSDC) and deterministic secure quantum communication (DSQC) over collective dephasing noisy channel.In our schemes,four special two-qubit states are used as the quantum channel.Since these states are unchanged through the collective dephasing noisy channel,the effect of the channel noise can be perfectly overcome.Simultaneously,the security against some usual attacks can be ensured by utilizing the various checking procedures.Furthermore,these two schemes are feasible with present-day technique.

  13. Performance of Unequal Error Protection Using Maximum A- posteriori Probability Algorithm and Modified MAP in Additive White Gaussian Noise and Fading Channel

    Directory of Open Access Journals (Sweden)

    T. Gnanasekaran

    2008-01-01

    Full Text Available Problem statement: In this study we propose a method to improve the performance of Maximum A-Posteriori Probability Algorithm, which is used in turbo decoder. Previously the performance of turbo decoder is improved by means of scaling the channel reliability value. Approach: A modification in MAP algorithm proposed in this study, which achieves further improvement in forward error correction by means of scaling the extrinsic information in both decoders without introducing any complexity. The encoder is modified with a new puncturing matrix, which yields Unequal Error Protection (UEP. This modified MAP algorithm is analyzed with the traditional turbo code system Equal Error Protection (EEP and also with Unequal Error Protection (UEP both in AWGN channel and fading channel. Result: MAP and modified MAP achieve coding gain of 0.6 dB over EEP in AWGN channel. The MAP and modified MAP achieve coding gain of 0.4 dB and 0.9dB over EEP respectively in Rayleigh fading channel. Modified MAP in UEP class 1 and class 2 gained 0.8 dB and 0.6 dB respectively in AWGN channel where as in fading channel class 1 and 2 gained 0.4 dB and 0.6 dB respectively. Conclusion/Recommendations: The modified MAP algorithm improves the Bit Error Rate (BER performance in EEP as well as UEP both in AWGN and fading channels. We propose modified MAP error correction algorithm with UEP for broad band communication.

  14. Cuticular hydrocarbon divergence in the jewel wasp Nasonia : evolutionary shifts in chemical communication channels?

    NARCIS (Netherlands)

    Buellesbach, J.; Gadau, J.; Beukeboom, L. W.; Echinger, F.; Raychoudhury, R.; Werren, J. H.; Schmitt, T.

    2013-01-01

    The evolution and maintenance of intraspecific communication channels constitute a key feature of chemical signalling and sexual communication. However, how divergent chemical communication channels evolve while maintaining their integrity for both sender and receiver is poorly understood. In this s

  15. Multi-carrier Communications over Time-varying Acoustic Channels

    Science.gov (United States)

    Aval, Yashar M.

    Acoustic communication is an enabling technology for many autonomous undersea systems, such as those used for ocean monitoring, offshore oil and gas industry, aquaculture, or port security. There are three main challenges in achieving reliable high-rate underwater communication: the bandwidth of acoustic channels is extremely limited, the propagation delays are long, and the Doppler distortions are more pronounced than those found in wireless radio channels. In this dissertation we focus on assessing the fundamental limitations of acoustic communication, and designing efficient signal processing methods that cam overcome these limitations. We address the fundamental question of acoustic channel capacity (achievable rate) for single-input-multi-output (SIMO) acoustic channels using a per-path Rician fading model, and focusing on two scenarios: narrowband channels where the channel statistics can be approximated as frequency- independent, and wideband channels where the nominal path loss is frequency-dependent. In each scenario, we compare several candidate power allocation techniques, and show that assigning uniform power across all frequencies for the first scenario, and assigning uniform power across a selected frequency-band for the second scenario, are the best practical choices in most cases, because the long propagation delay renders the feedback information outdated for power allocation based on the estimated channel response. We quantify our results using the channel information extracted form the 2010 Mobile Acoustic Communications Experiment (MACE'10). Next, we focus on achieving reliable high-rate communication over underwater acoustic channels. Specifically, we investigate orthogonal frequency division multiplexing (OFDM) as the state-of-the-art technique for dealing with frequency-selective multipath channels, and propose a class of methods that compensate for the time-variation of the underwater acoustic channel. These methods are based on multiple

  16. Atmospheric Channel Characteristics for Quantum Communication with Continuous Polarization Variables

    CERN Document Server

    Heim, Bettina; Bartley, Tim; Sabuncu, Metin; Wittmann, Christoffer; Sych, Denis; Marquardt, Christoph; Leuchs, Gerd

    2009-01-01

    We investigate the properties of an atmospheric channel for free space quantum communication with continuous polarization variables. In our prepare-and-measure setup, coherent polarization states are transmitted through an atmospheric quantum channel of 100m length on the roof of our institute's building. The signal states are measured by homodyne detection with the help of a local oscillator (LO) which propagates in the same spatial mode as the signal, orthogonally polarized to it. Thus the interference of signal and LO is excellent and atmospheric fluctuations are autocompensated. The LO also acts as spatial and spectral filter, which allows for unrestrained daylight operation. Important characteristics for our system are atmospheric channel influences that could cause polarization, intensity and position excess noise. Therefore we study these influences in detail. Our results indicate that the channel is suitable for our quantum communication system in most weather conditions.

  17. Dynamic Propagation Channel Characterization and Modeling for Human Body Communication

    OpenAIRE

    Lei Wang; Jingjing Ma; Zhicheng Li; Hong Chen; Zedong Nie

    2012-01-01

    This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC). In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000) were acquired from five volunteers. Various path gains caused by di...

  18. Electronic communication channel within the patient data management system improves internal communication in the ICU.

    Science.gov (United States)

    Väisänen, Paula; Holopainen, Jaana

    2006-01-01

    The aim of this study was to improve the internal communication within the intensive care unit of the Kuopio University Hospital. We developed an intranet based internal communication channel within the patient data management system and studied the effectiveness of this system in improving communication in the ICU. The hypothesis was that the communication difficulties caused by the structure of the unit, large personnel and work schedule (three separate shifts) could be reduced by supplementing oral communication by this intranet based system. The results clearly indicate that this type of system can significantly improve communication within our unit. PMID:17102442

  19. Digital channels in the internal communication of a multinational corporation

    OpenAIRE

    Lipiäinen, Heini; Karjaluoto, Heikki; Nevalainen, Marjo

    2014-01-01

    Purpose: To examine how digital communication tools are used for internal communication (IC) in multinational corporations (MNCs). Specifically, the study illustrates the role of digital channels in IC, the benefits they bring and the difficulties involved in using them. Design/methodology/approach: This research features a single-case study focusing on a listed Finnish multinational industrial corporation with a long history. Data for the study come from semi-structured the...

  20. Comparison of channel equalization filtering techniques in underwater acoustic communications

    OpenAIRE

    Kuchler, Ryan J.

    2002-01-01

    In this thesis, underwater acoustic communications signal processing techniques, which are used to equalize the distortional effects associated with the ocean as a communications channel, are investigated for a shallow water ocean environment. The majority of current signal processing techniques employ a Finite Impulse Response (FIR) filter. Three equalization filters were investigated and presented as alternatives; they were the passive time-reversed filter, the inverse filter, and the Infin...

  1. Achieving single channel, full duplex wireless communication

    KAUST Repository

    Choi, Jung Il

    2010-01-01

    This paper discusses the design of a single channel full-duplex wireless transceiver. The design uses a combination of RF and baseband techniques to achieve full-duplexing with minimal effect on link reliability. Experiments on real nodes show the full-duplex prototype achieves median performance that is within 8% of an ideal full-duplexing system. This paper presents Antenna Cancellation, a novel technique for self-interference cancellation. In conjunction with existing RF interference cancellation and digital baseband interference cancellation, antenna cancellation achieves the amount of self-interference cancellation required for full-duplex operation. The paper also discusses potential MAC and network gains with full-duplexing. It suggests ways in which a full-duplex system can solve some important problems with existing wireless systems including hidden terminals, loss of throughput due to congestion, and large end-to-end delays. Copyright 2010 ACM.

  2. A review of radio channel models for body centric communications

    Science.gov (United States)

    Cotton, Simon L.; D'Errico, Raffaele; Oestges, Claude

    2014-06-01

    The human body is an extremely challenging environment for the operation of wireless communications systems, not least because of the complex antenna-body electromagnetic interaction effects which can occur. This is further compounded by the impact of movement and the propagation characteristics of the local environment which all have an effect upon body centric communications channels. As the successful design of body area networks (BANs) and other types of body centric system is inextricably linked to a thorough understanding of these factors, the aim of this paper is to conduct a survey of the current state of the art in relation to propagation and channel models primarily for BANs but also considering other types of body centric communications. We initially discuss some of the standardization efforts performed by the Institute of Electrical and Electronics Engineers 802.15.6 task group before focusing on the two most popular types of technologies currently being considered for BANs, namely narrowband and Ultrawideband (UWB) communications. For narrowband communications the applicability of a generic path loss model is contended, before presenting some of the scenario specific models which have proven successful. The impacts of human body shadowing and small-scale fading are also presented alongside some of the most recent research into the Doppler and time dependencies of BANs. For UWB BAN communications, we again consider the path loss as well as empirical tap delay line models developed from a number of extensive channel measurement campaigns conducted by research institutions around the world. Ongoing efforts within collaborative projects such as Committee on Science and Technology Action IC1004 are also described. Finally, recent years have also seen significant developments in other areas of body centric communications such as off-body and body-to-body communications. We highlight some of the newest relevant research in these areas as well as discussing

  3. Optical wireless communications system and channel modelling with Matlab

    CERN Document Server

    Ghassemlooy, Z

    2012-01-01

    Detailing a systems approach, Optical Wireless Communications: System and Channel Modelling with MATLAB(R), is a self-contained volume that concisely and comprehensively covers the theory and technology of optical wireless communications systems (OWC) in a way that is suitable for undergraduate and graduate-level students, as well as researchers and professional engineers. Incorporating MATLAB(R) throughout, the authors highlight past and current research activities to illustrate optical sources, transmitters, detectors, receivers, and other devices used in optical wireless communications. The

  4. Optimal channel utilization and service protection in cellular communication systems

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk

    1997-01-01

    In mobile communications an efficient utilization of the channels is of great importance.In this paper we consider the basic principles for obtaining the maximum utilization, and we study strategies for obtaining these limits.In general a high degree of sharing is efficient, but requires service...

  5. Pedestrian effects in indoor UWB off-body communication channels

    NARCIS (Netherlands)

    Ali, A.J.; Scanlon, W.G.; Cotton, S.L.

    2010-01-01

    Ultra-wideband (UWB) technology offers a promising solution for future indoor high-speed, low-power wireless body centric communications. Development and design of such systems requires detailed understanding of the indoor off-body UWB channel, which to date has been scarcely investigated. This pape

  6. An Overview of ECCO (Episodic Communication Channels in Organization) Methodology.

    Science.gov (United States)

    Pacilio, John, Jr.; Rudolph, Evan E.

    Based upon Keith Davis's 1952 Ohio State doctoral dissertation on Episodic Communication Channels in Organizations (ECCO), further testing with ECCO methodology has found this analytic procedure to be basically sound, though it has expected weaknesses. Using a working situation as an example, surveys were taken to test the qualities of…

  7. Multiuser Detection and Channel Estimation for Multibeam Satellite Communications

    CERN Document Server

    Chaouech, Helmi; 10.5121/ijcnc.2012.4112

    2012-01-01

    In this paper, iterative multi-user detection techniques for multi-beam communications are presented. The solutions are based on a successive interference cancellation architecture and a channel decoding to treat the co-channel interference. Beams forming and channels coefficients are estimated and updated iteratively. A developed technique of signals combining allows power improvement of the useful received signal; and then reduction of the bit error rates with low signal to noise ratios. The approach is applied to a synchronous multi-beam satellite link under an additive white Gaussian channel. Evaluation of the techniques is done with computer simulations, where a noised and multi-access environment is considered. The simulations results show the good performance of the proposed solutions.

  8. Channel Estimation And Multiuser Detection In Asynchronous Satellite Communications

    CERN Document Server

    Chaouech, Helmi; 10.5121/ijwmn.2010.2411

    2010-01-01

    In this paper, we propose a new method of channel estimation for asynchronous additive white Gaussian noise channels in satellite communications. This method is based on signals correlation and multiuser interference cancellation which adopts a successive structure. Propagation delays and signals amplitudes are jointly estimated in order to be used for data detection at the receiver. As, a multiuser detector, a single stage successive interference cancellation (SIC) architecture is analyzed and integrated to the channel estimation technique and the whole system is evaluated. The satellite access method adopted is the direct sequence code division multiple access (DS CDMA) one. To evaluate the channel estimation and the detection technique, we have simulated a satellite uplink with an asynchronous multiuser access.

  9. A non-perturbative approach to relativistic quantum communication channels

    CERN Document Server

    Landulfo, Andre G S

    2016-01-01

    We investigate the transmission of both classical and quantum information between two arbitrary observers in globally hyperbolic spacetimes using a quantum field as a communication channel. The field is supposed to be in some arbitrary quasifree state and no choice of representation of its canonical commutation relations is made. Both sender and receiver posses some localized two-level quantum system with which they can interact with the quantum field to prepare the input and receive the output of the channel, respectively. The interaction between the two-level systems and the quantum field is such that one can trace out the field degrees of freedom exactly and thus obtain the quantum channel in a non-perturbative way. We end the paper determining the unassisted as well as the entanglement-assisted classical and quantum channel capacities.

  10. Quantum secure direct communication over the collective amplitude damping channel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An efficient quantum secure direct communication protocol is presented over the amplitude damping channel.The protocol encodes logical bits in two-qubit noiseless states,and so it can function over a quantum channel subjected to collective amplitude damping.The feature of this protocol is that the sender encodes the secret directly on the quantum states,the receiver decodes the secret by performing determinate measurements,and there is no basis mismatch.The transmission’s safety is ensured by the nonorthogonality of the noiseless states traveling forward and backward on the quantum channel.Moreover,we construct the efficient quantum circuits to implement channel encoding and information encoding by means of primitive operations in quantum computation.

  11. Optimal Feedback Communication via Posterior Matching

    CERN Document Server

    Shayevitz, Ofer

    2009-01-01

    In this paper we introduce a fundamental principle for optimal communication over general memoryless channels in the presence of noiseless feedback, termed \\textit{posterior matching}. Using this principle, we devise a (simple, sequential) generic feedback transmission scheme suitable for a large class of memoryless channels and input distributions, achieving any rate below the corresponding mutual information. This provides a unified framework for optimal feedback communication in which the Horstein scheme (BSC) and the Schalkwijk-Kailath scheme (AWGN channel) are special cases. Thus, as a corollary, we prove that the Horstein scheme indeed attains the BSC capacity, settling a longstanding conjecture. We further provide closed form expressions for the error probability of the scheme over a range of rates, and derive the achievable rates in a mismatch setting where the scheme is designed according to the wrong channel model. Finally, several illustrative examples of the posterior matching scheme for specific ...

  12. Information transmission and recovery in neural communications channels

    Energy Technology Data Exchange (ETDEWEB)

    Eguia, M. C.; Rabinovich, M. I.; Abarbanel, H. D. I.

    2000-11-01

    Biological neural communications channels transport environmental information from sensors through chains of active dynamical neurons to neural centers for decisions and actions to achieve required functions. These kinds of communications channels are able to create information and to transfer information from one time scale to the other because of the intrinsic nonlinear dynamics of the component neurons. We discuss a very simple neural information channel composed of sensory input in the form of a spike train that arrives at a model neuron, then moves through a realistic synapse to a second neuron where the information in the initial sensory signal is read. Our model neurons are four-dimensional generalizations of the Hindmarsh-Rose neuron, and we use a model of chemical synapse derived from first-order kinetics. The four-dimensional model neuron has a rich variety of dynamical behaviors, including periodic bursting, chaotic bursting, continuous spiking, and multistability. We show that, for many of these regimes, the parameters of the chemical synapse can be tuned so that information about the stimulus that is unreadable at the first neuron in the channel can be recovered by the dynamical activity of the synapse and the second neuron. Information creation by nonlinear dynamical systems that allow chaotic oscillations is familiar in their autonomous oscillations. It is associated with the instabilities that lead to positive Lyapunov exponents in their dynamical behavior. Our results indicate how nonlinear neurons acting as input/output systems along a communications channel can recover information apparently ''lost'' in earlier junctions on the channel. Our measure of information transmission is the average mutual information between elements, and because the channel is active and nonlinear, the average mutual information between the sensory source and the final neuron may be greater than the average mutual information at an earlier neuron in

  13. Modeling of optical wireless scattering communication channels over broad spectra.

    Science.gov (United States)

    Liu, Weihao; Zou, Difan; Xu, Zhengyuan

    2015-03-01

    The air molecules and suspended aerosols help to build non-line-of-sight (NLOS) optical scattering communication links using carriers from near infrared to visible light and ultraviolet bands. This paper proposes channel models over such broad spectra. Wavelength dependent Rayleigh and Mie scattering and absorption coefficients of particles are analytically obtained first. They are applied to the ray tracing based Monte Carlo method, which models the photon scattering angle from the scatterer and propagation distance between two consecutive scatterers. Communication link path loss is studied under different operation conditions, including visibility, particle density, wavelength, and communication range. It is observed that optimum communication performances exist across the wavelength under specific atmospheric conditions. Infrared, visible light and ultraviolet bands show their respective features as conditions vary. PMID:26366662

  14. A communication channel model of the software process

    Science.gov (United States)

    Tausworthe, Robert C.

    1988-01-01

    Beginning research into a noisy communication channel analogy of software development process productivity, in order to establish quantifiable behavior and theoretical bounds is discussed. The analogy leads to a fundamental mathematical relationship between human productivity and the amount of information supplied by the developers, the capacity of the human channel for processing and transmitting information, the software product yield (object size) the work effort, requirements efficiency, tool and process efficiency, and programming environment advantage. An upper bound to productivity is derived that shows that software reuse is the only means that can lead to unbounded productivity growth; practical considerations of size and cost of reusable components may reduce this to a finite bound.

  15. Channel Measurements and Modelling for Indoor Power Line Communications

    Directory of Open Access Journals (Sweden)

    Zhang Peiling

    2013-04-01

    Full Text Available In order to obtain power line communications channel transmission characteristics, impulse responses measurements were performed on the basis of PN sequence’s excellent periodic autocorrelation properties. Meanwhile, a compensation method in frequency domain was proposed to improve the measurement precision. Then, the empirical multipath channel model of power line is presented from the measured results. The simulation and experimental measurement results not only have verified the efficiency of the proposed model, but also showed that the measurement method has fast, simple and convenient characteristic. Finally, the statistical characteristics of path amplitude and the delay spread are obtained through the analysis of measured results.

  16. Power losses in diffuse ultraviolet optical communications channels.

    Science.gov (United States)

    Raptis, Nikos; Pikasis, Evangelos; Syvridis, Dimitris

    2016-09-15

    One of the most critical parameters in free-space optical communications systems operating in a non-line-of-sight regime are the optical losses. In this Letter, we numerically calculate these losses taking into account the scattering effects using the Monte Carlo simulation technique. The obtained results are compared with experimentally obtained data at 265 nm (solar-blind UV regime). A large set of measurements at distances up to 20 m, for different elevation angles of the transmitter (UV-LEDs) and receiver (photomultiplier tube) and for different atmospheric conditions has been taken for the characterization of the optical communications channel in terms of its loss properties. PMID:27628413

  17. Cai-Li Communication Protocol in Noisy Quantum Channel

    Institute of Scientific and Technical Information of China (English)

    L(U) Hua; YAN Xu-Dong; ZHANG Xian-Zhou

    2004-01-01

    @@ Since the original Cai-Li protocol [Chin. Phys. Lett. 21 (2004) 601] can be used only in an ideal quantum communication, we present the modified Cai-Li protocol that can be used in the a noisy quantum channel by using Calderbank-Shor-Steane (CSS) codes to correct errors. We also give a tight bound on the connection between information Eve eavesdropped with a measurement attack in line B → A and detection probability,which shows that the Cai-Li protocol can be used as a quasisecure direct quantum communication.

  18. Multiband channel characteristics for indoor visible light communications

    Science.gov (United States)

    Xiang, Yang; Zhang, Min; Kavehrad, Mohsen; Chowdhury, M. I. Sakib; Li, Cheng; Chen, Rong; Wu, Jian; Tang, Xiongyan

    2014-10-01

    We present a multiband ray tracing (MRT) algorithm to analyze the indoor multiband channel characteristics for visible light communications (VLC). As visible light spans a wide spectrum from 380 to 780 nm, spectral reflectivities of walls are wavelength dependent. This model is able to analyze the multiband channel in VLC and provide the channel information for implementing the wavelength division multiplexing VLC system. To validate the effectiveness of the MRT model, an extensive indoor measurement of the multipath channel characteristics has been presented. Effects of relative angles from lighting emitting diodes (LEDs) to receivers and the variation of receiver locations have been taken into consideration. Theoretical results from the MRT model are validated against the measurement results on the channel path loss of the typical wavelength at 420 nm. Furthermore, channel characteristics like the root mean square delay spread and the spectral response of the three typical wavelengths based on the red green blue (RGB) LEDs are analyzed by the MRT model simulation. Finally, comparisons of receiver positions, relative angle as well as field-of-view angles, for three wavelengths are considered.

  19. Channel Modeling for Air-to-Ground Wireless Communication

    Institute of Scientific and Technical Information of China (English)

    Yingcheng Shi; Di He; Bin Li; Jianwu Dou

    2015-01-01

    In this paper, we discuss several large⁃scale fading models for different environments. The COST231⁃Hata model is adapted for air⁃to⁃ground modeling. We propose two criteria for air⁃to⁃ground channel modelling based on test data derived from field testing in Beijing. We develop a new propagation model that is more suitable for air⁃to⁃ground communication that pre⁃vious models. We focus on improving this propagation model using the field test data.

  20. 39 CFR 223.2 - Channels of communication, headquarters with area offices.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Channels of communication, headquarters with area... RELATIONSHIPS AND COMMUNICATION CHANNELS § 223.2 Channels of communication, headquarters with area offices. (a) General. Headquarters organizational units formulate the directives to provide guidance to area...

  1. Dynamic Propagation Channel Characterization and Modeling for Human Body Communication

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2012-12-01

    Full Text Available This paper presents the first characterization and modeling of dynamic propagation channels for human body communication (HBC. In-situ experiments were performed using customized transceivers in an anechoic chamber. Three HBC propagation channels, i.e., from right leg to left leg, from right hand to left hand and from right hand to left leg, were investigated under thirty-three motion scenarios. Snapshots of data (2,800,000 were acquired from five volunteers. Various path gains caused by different locations and movements were quantified and the statistical distributions were estimated. In general, for a given reference threshold è = −10 dB, the maximum average level crossing rate of the HBC was approximately 1.99 Hz, the maximum average fade time was 59.4 ms, and the percentage of bad channel duration time was less than 4.16%. The HBC exhibited a fade depth of −4 dB at 90% complementary cumulative probability. The statistical parameters were observed to be centered for each propagation channel. Subsequently a Fritchman model was implemented to estimate the burst characteristics of the on-body fading. It was concluded that the HBC is motion-insensitive, which is sufficient for reliable communication link during motions, and therefore it has great potential for body sensor/area networks.

  2. Multiuser Detection in Asynchronous Multibeam Communications

    CERN Document Server

    Chaouech, Helmi; 10.5121/ijwmn.2012.4102

    2012-01-01

    This paper deals with multi-user detection techniques in asynchronous multibeam satellite communications. The proposed solutions are based on successive interference cancellation architecture (SIC) and channel decoding algorithms. The aim of these detection methods is to reduce the effect of cochannel interference due to co-frequency access, and consequently, improves the capacity of the mulitbeam communications systems, by improving frequency reuse. Channel estimation allows the determination of interference coefficients, which helps their effects compensation. The developed multiuser detections techniques are iterative. Therefore, detection quality is improved from a stage to another. Moreover, a signals combining method, which is integrated into these detection solutions, enhances their capability. The proposed solutions are evaluated through computer simulations, where an asynchronous multibeam satellite link is considered over an AWGN channel. The obtained simulation results showed the robustness of thes...

  3. Scheduling for Stable and Reliable Communication over Multiaccess Channels and Degraded Broadcast Channels

    CERN Document Server

    Sayee, K C V K S

    2006-01-01

    Information-theoretic arguments focus on modeling the reliability of information transmission, assuming availability of infinite data at sources, thus ignoring randomness in message generation times at the respective sources. However, in information transport networks, not only is reliable transmission important, but also stability, i.e., finiteness of mean delay incurred by messages from the time of generation to the time of successful reception. Usually, delay analysis is done separately using queueing-theoretic arguments, whereas reliable information transmission is studied using information theory. In this thesis, we investigate these two important aspects of data communication jointly by suitably combining models from these two fields. In particular, we model scheduled communication of messages, that arrive in a random process, (i) over multiaccess channels, with either independent decoding or joint decoding, and (ii) over degraded broadcast channels. The scheduling policies proposed permit up to a certa...

  4. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    Science.gov (United States)

    Cañete, Francisco J.; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J.; Paris, José F.

    2016-01-01

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression. PMID:26907281

  5. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications

    Directory of Open Access Journals (Sweden)

    Francisco J. Cañete

    2016-02-01

    Full Text Available Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  6. Measurement and Modeling of Narrowband Channels for Ultrasonic Underwater Communications.

    Science.gov (United States)

    Cañete, Francisco J; López-Fernández, Jesús; García-Corrales, Celia; Sánchez, Antonio; Robles, Encarnación; Rodrigo, Francisco J; Paris, José F

    2016-01-01

    Underwater acoustic sensor networks are a promising technology that allow real-time data collection in seas and oceans for a wide variety of applications. Smaller size and weight sensors can be achieved with working frequencies shifted from audio to the ultrasonic band. At these frequencies, the fading phenomena has a significant presence in the channel behavior, and the design of a reliable communication link between the network sensors will require a precise characterization of it. Fading in underwater channels has been previously measured and modeled in the audio band. However, there have been few attempts to study it at ultrasonic frequencies. In this paper, a campaign of measurements of ultrasonic underwater acoustic channels in Mediterranean shallow waters conducted by the authors is presented. These measurements are used to determine the parameters of the so-called κ-μ shadowed distribution, a fading model with a direct connection to the underlying physical mechanisms. The model is then used to evaluate the capacity of the measured channels with a closed-form expression.

  7. Robust Blind Adaptive Channel Equalization in Chaotic Communication Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-Shu

    2006-01-01

    Based on the bounded property and statistics of chaotic signal and the idea of set-membership identification,we propose a set-membership generalized least mean square (SM-GLMS) algorithm with variable step size for blind adaptive channel equalization in chaotic communication systems. The steady state performance of the proposed SM-GLMS algorithm is analysed, and comparison with an extended Kalman filter (EKF)-based adaptive algorithm and variable gain least mean square (VG-LMS) algorithm is performed for blind adaptive channel equalization. Simulations show that the proposed SM-GLMS algorithm can provide more significant steady state performance improvement than the EKF-based adaptive algorithm and VG-LMS algorithm.

  8. Cascaded Network Body Channel Model for Intrabody Communication.

    Science.gov (United States)

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement. PMID:26111404

  9. Cascaded Network Body Channel Model for Intrabody Communication.

    Science.gov (United States)

    Wang, Hao; Tang, Xian; Choy, Chiu Sing; Sobelman, Gerald E

    2016-07-01

    Intrabody communication has been of great research interest in recent years. This paper proposes a novel, compact but accurate body transmission channel model based on RC distribution networks and transmission line theory. The comparison between simulation and measurement results indicates that the proposed approach accurately models the body channel characteristics. In addition, the impedance-matching networks at the transmitter output and the receiver input further maximize the power transferred to the receiver, relax the receiver complexity, and increase the transmission performance. Based on the simulation results, the power gain can be increased by up to 16 dB after matching. A binary phase-shift keying modulation scheme is also used to evaluate the bit-error-rate improvement.

  10. Blind adaptive identification of FIR channel in chaotic communication systems

    Institute of Scientific and Technical Information of China (English)

    Wang Bao-Yun; Tommy W.S.Chow; K.T.Ng

    2004-01-01

    In this paper we study the problem of blind channel identification in chaotic communications. An adaptive algorithm is proposed, which exploits the boundness property of chaotic signals. Compared with the EKF-based approach, the proposed algorithm achieves a great complexity gain but at the expense of a slight accuracy degradation.However, our approach enjoys the important advantage that it does not require the a priori information such as nonlinearity of chaotic dynamics and the variances of measurement noise and the coefficient model noise. In addition,our approach is applicable to the ARMA system.

  11. Optimal state estimation over communication channels with random delays

    KAUST Repository

    Mahmoud, Magdi S.

    2013-04-01

    This paper is concerned with the optimal estimation of linear systems over unreliable communication channels with random delays. The measurements are delivered without time stamp, and the probabilities of time delays are assumed to be known. Since the estimation is time-driven, the actual time delays are converted into virtual time delays among the formulation. The receiver of estimation node stores the sum of arrived measurements between two adjacent processing time instants and also counts the number of arrived measurements. The original linear system is modeled as an extended system with uncertain observation to capture the feature of communication, then the optimal estimation algorithm of systems with uncertain observations is proposed. Additionally, a numerical simulation is presented to show the performance of this work. © 2013 The Franklin Institute.

  12. Remote optimal state estimation over communication channels with random delays

    KAUST Repository

    Mahmoud, Magdi S.

    2014-01-22

    This paper considers the optimal estimation of linear systems over unreliable communication channels with random delays. In this work, it is assumed that the system to be estimated is far away from the filter. The observations of the system are capsulized without time stamp and then transmitted to the network node at which the filter is located. The probabilities of time delays are assumed to be known. The event-driven estimation scheme is applied in this paper and the estimate of the states is updated only at each time instant when any measurement arrives. To capture the feature of communication, the system considered is augmented, and the arrived measurements are regarded as the uncertain observations of the augmented system. The corresponding optimal estimation algorithm is proposed and additionally, a numerical simulation represents the performance of this work. © 2014 The authors. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  13. Passing crisis and emergency risk communications: the effects of communication channel, information type, and repetition.

    Science.gov (United States)

    Edworthy, Judy; Hellier, Elizabeth; Newbold, Lex; Titchener, Kirsteen

    2015-05-01

    Three experiments explore several factors which influence information transmission when warning messages are passed from person to person. In Experiment 1, messages were passed down chains of participants using five different modes of communication. Written communication channels resulted in more accurate message transmission than verbal. In addition, some elements of the message endured further down the chain than others. Experiment 2 largely replicated these effects and also demonstrated that simple repetition of a message eliminated differences between written and spoken communication. In a final field experiment, chains of participants passed information however they wanted to, with the proviso that half of the chains could not use telephones. Here, the lack of ability to use a telephone did not affect accuracy, but did slow down the speed of transmission from the recipient of the message to the last person in the chain. Implications of the findings for crisis and emergency risk communication are discussed.

  14. The Channel Capacity of a Fiber Optics Communication System: perturbation theory

    OpenAIRE

    Narimanov, Evgenii; Mitra, Partha

    2000-01-01

    We consider the communication channel given by a fiber optical transmission line. We develop a method to perturbatively calculate the information capacity of a nonlinear channel, given the corresponding evolution equation. Using this technique, we compute the decrease of the channel capacity to the leading order in the perturbative parameter for fiber optics communication systems.

  15. Communication Channels and Word of Mouth: How the Medium Shapes the Message

    OpenAIRE

    Jonah Berger; Raghuram Iyengar

    2013-01-01

    Consumers share word of mouth face to face, over social media, and through a host of other communication channels. But do these channels affect what people talk about and, if so, how? Laboratory experiments, as well as analysis of almost 20,000 everyday conversations, demonstrate that communicating via oral versus written communication affects the products and brands consumers discuss. Compared to oral communication, written communication leads people to mention more interesting products and ...

  16. An Efficient Data Communication Using Conventional Codes

    Directory of Open Access Journals (Sweden)

    Mrs. Nikam Pratibha Madhavrao

    2014-07-01

    Full Text Available The BER performance of conventional FFT-OFDM system is compared with DWT-OFDM system and DCT-OFDM system in an AWGN environment and Saleh-Valenzuela (SV channel model at 60 GHz. Several wavelets such as Haar, Daubechies, Symlet, biorthogonal are considered. The BER is calculated for signaling format BPSK and the performance is analyzed at 60 GHz. Simulation results show that DCT based scheme yields the lowest average bit error rate. While out of all wavelet mother used Haar and Daubechies wavelet based scheme yields lower BER than FFT-OFDM for an AWGN channel. But it may include the implementation of forward error correction techniques such as convolution codes. An efficient channel estimation algorithm may be included for performance evaluation of DCT-OFDM and DWT- OFDM working at 60 GHz band. We introduce the Interfacing Techniques for Accessing data transfer data delivery. By using our approach we are increasing the efficiency of the data communication.

  17. Real time film analysis system (RTFAS). Communication subsystem. Interprogram communication channel on the DEC-10 computer

    International Nuclear Information System (INIS)

    Described is the general organization of the communication subsystem for Real Time Film Analysis System (RTFAS) developed for the automation of primary processing of films obtained in experiments at bubble chambers. Considered are the functional structure of the interprogram communication channel (IPCC) based on the DEC-10 computer which provide composition of particular system elements, its software, and dynamic store access. It is pointed out that the composition of a single program of the system based on IPCC is well suitable for on-line processing systems, because it provides the necessary flexibility of the system, high speed of its response, and simplicity of program interaction

  18. Equalization and detection for digital communication over nonlinear bandlimited satellite communication channels. Ph.D. Thesis

    Science.gov (United States)

    Gutierrez, Alberto, Jr.

    1995-01-01

    This dissertation evaluates receiver-based methods for mitigating the effects due to nonlinear bandlimited signal distortion present in high data rate satellite channels. The effects of the nonlinear bandlimited distortion is illustrated for digitally modulated signals. A lucid development of the low-pass Volterra discrete time model for a nonlinear communication channel is presented. In addition, finite-state machine models are explicitly developed for a nonlinear bandlimited satellite channel. A nonlinear fixed equalizer based on Volterra series has previously been studied for compensation of noiseless signal distortion due to a nonlinear satellite channel. This dissertation studies adaptive Volterra equalizers on a downlink-limited nonlinear bandlimited satellite channel. We employ as figure of merits performance in the mean-square error and probability of error senses. In addition, a receiver consisting of a fractionally-spaced equalizer (FSE) followed by a Volterra equalizer (FSE-Volterra) is found to give improvement beyond that gained by the Volterra equalizer. Significant probability of error performance improvement is found for multilevel modulation schemes. Also, it is found that probability of error improvement is more significant for modulation schemes, constant amplitude and multilevel, which require higher signal to noise ratios (i.e., higher modulation orders) for reliable operation. The maximum likelihood sequence detection (MLSD) receiver for a nonlinear satellite channel, a bank of matched filters followed by a Viterbi detector, serves as a probability of error lower bound for the Volterra and FSE-Volterra equalizers. However, this receiver has not been evaluated for a specific satellite channel. In this work, an MLSD receiver is evaluated for a specific downlink-limited satellite channel. Because of the bank of matched filters, the MLSD receiver may be high in complexity. Consequently, the probability of error performance of a more practical

  19. CHAOTIC DATA COMMUNICATION SYSTEM DESIGN BY USING RAMAN AMPLIFIER

    OpenAIRE

    Remzi YILDIRIM; ÇELEBİ, Fatih V.

    2010-01-01

    ABSTRACT In this study, an 80 km. long fiber-optic data communication system is designed by using Raman amplifier. Chaotic communication technique is used contrary to regular data communication principles. The  components of the chaotic signal are the optical noise by AWGN (Additive White Gaussian Noise,AWGN) technique and ONA (Optical Noise Adder,ONA) in addition to the modulated signal which is obtained by using external optical modulator. Non-return to zero (NRZ) technique is selected...

  20. Reliable communication over non-binary insertion/deletion channels

    CERN Document Server

    Yazdani, Raman

    2012-01-01

    We consider the problem of reliable communication over non-binary insertion/deletion channels where symbols are randomly deleted from or inserted in the transmitted sequence and all symbols are corrupted by additive white Gaussian noise. To this end, we utilize the inherent redundancy achievable in non-binary symbol sets by first expanding the symbol set and then allocating part of the bits associated with each symbol to watermark symbols. The watermark sequence, known at the receiver, is then used by a forward-backward algorithm to provide soft information for an outer code which decodes the transmitted sequence. Through numerical results and discussions, we evaluate the performance of the proposed solution and show that it leads to significant system ability to detect and correct insertions/deletions. We also provide estimates of the maximum achievable information rates of the system, compare them with the available bounds, and construct practical codes capable of approaching these limits.

  1. Evaluation of multiple-channel OFDM based airborne ultrasonic communications.

    Science.gov (United States)

    Jiang, Wentao; Wright, William M D

    2016-09-01

    Orthogonal frequency division multiplexing (OFDM) modulation has been extensively used in both wired and wireless communication systems. The use of OFDM technology allows very high spectral efficiency data transmission without using complex equalizers to correct the effect of a frequency-selective channel. This work investigated OFDM methods in an airborne ultrasonic communication system, using commercially available capacitive ultrasonic transducers operating at 50kHz to transmit information through the air. Conventional modulation schemes such as binary phase shift keying (BPSK) and quadrature amplitude modulation (QAM) were used to modulate sub-carrier signals, and the performances were evaluated in an indoor laboratory environment. Line-of-sight (LOS) transmission range up to 11m with no measurable errors was achieved using BPSK at a data rate of 45kb/s and a spectral efficiency of 1b/s/Hz. By implementing a higher order modulation scheme (16-QAM), the system data transfer rate was increased to 180kb/s with a spectral efficiency of 4b/s/Hz at attainable transmission distances up to 6m. Diffraction effects were incorporated into a model of the ultrasonic channel that also accounted for beam spread and attenuation in air. The simulations were a good match to the measured signals and non-LOS signals could be demodulated successfully. The effects of multipath interference were also studied in this work. By adding cyclic prefix (CP) to the OFDM symbols, the bit error rate (BER) performance was significantly improved in a multipath environment. PMID:27365316

  2. LDPC Decoding for Signal Dependent Visible Light Communication Channels

    Institute of Scientific and Technical Information of China (English)

    YUAN Ming; SHA Xiaoshi; LIANG Xiao; JIANG Ming; WANG Jiaheng; ZHAO Chunming

    2016-01-01

    Avalanche photodiodes (APD) are widely employed in visible light communication (VLC) systems. The general signal dependent Gaussian channel is investigated. Experiment results reveal that symbols on different constellation points under official illumi⁃nance inevitably suffer from different levels of noise due to the multiplication process of APDs. In such a case, conventional log likely⁃hood ratio (LLR) calculation for signal independent channels may cause performance loss. The optimal LLR calculation for decoder is then derived because of the existence of non⁃ignorable APD shot noise. To find the decoding thresholds of the optimal and suboptimal detection schemes, the extrinsic information transfer (EXIT) chat is further analyzed. Finally a modified minimum sum algorithm is suggested with reduced complexity and acceptable performance loss. Numerical simulations show that, with a reg⁃ular (3, 6) low⁃density parity check (LDPC) code of block length 20,000, 0.7 dB gain is achieved with our proposed scheme over the LDPC decoder designed for signal independent noise. It is also found that the coding performance is improved for a larger modulation depth.

  3. Enhancing the Communication Channel Through Secure Shell And Irrational DES

    Directory of Open Access Journals (Sweden)

    S.R.M.Krishna,

    2011-03-01

    Full Text Available As the internet grows in popularity and therefore also in size more and more transmission takes place mainly because the technology is more readily available and applications have become more user friendlyallowing entry to less sophisticated user over a broad spectrum.most data transfer are mainly text based not secure and vulnerable to various forms of security risks. So the model that uses SSH for securing channel like intranet/internet which provides client authentication encryption and decryption with high degree of security by transferring the data in an encrypted format, up on this model enhances the efficiency of data transmission by encrypting or decrypting the data with irrational DES.DES is a cryptographic standard however,the applications of it limited because of small key space based on irrational number.Moreover the permutation controlled by data can be performed at high speed in generic cpu.this scheme also expands the key space without costing more to run.and also finally through the combination of secure shell(ssh and irrational DES not only enhances the security of communication channel.it also provides varius applications like remote user creation,remote user deletion,remote command execution,remote system shutdown ,remote file transfer applications in an highly secure manner.

  4. Communication Channels and the Adoption of Web-Based Courses by University Professors

    Science.gov (United States)

    Reid, Scott

    2007-01-01

    This qualitative study examines the structure and importance of communication channels in the adoption of Web-based courses by university professors. This study provides insight into the importance of informal communication among peers, the changing nature of communication networks, factors that impede communication, the role of change agents in…

  5. The Time Division Multi-Channel Communication Model and the Correlative Protocol Based on Quantum Time Division Multi-Channel Communication

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-Hui; PEI Chang-Xing; NIE Min

    2010-01-01

    @@ Based on the classical time division multi-channel communication theory,we present a scheme of quantum time-division multi-channel communication(QTDMC).Moreover,the model of quantum time division switch(QTDS)and correlative protocol of QTDMC are proposed.The quantum bit error rate(QBER)is analyzed and the QBER simulation test is performed.The scheme shows that the QTDS can carry out multi-user communication through quantum channel,the QBER can also reach the reliability requirement of communication,and the protocol of QTDMC has high practicability and transplantable.The scheme of QTDS may play an important role in the establishment of quantum communication in a large scale in the future.

  6. Pulse Interval Modulation for Ultra-High Speed IR-UWB Communications Systems

    Directory of Open Access Journals (Sweden)

    Herceg Marijan

    2010-01-01

    Full Text Available This paper analyzes performances of the Pulse Interval Modulation (PIM scheme for impulse radio ultra-wideband (IR-UWB communication systems. Due to the PIM anisochronous nature, a tap delay line (TDL coded division multiple access (CDMA scheme based on strict optical orthogonal codes (SOOC is proposed. This scheme is suitable for multiuser high-speed data asynchronous transmission applications because the average symbol length is shorter than in Pulse Position Modulation (PPM schemes and it needs only chip synchronization. The error probability over the additive white Gaussian noise (AWGN channel is derived in the single- and multi-user environment and compared with other modulation schemes.

  7. Interpersonal influence as an alternative channel communication behavior in emerging markets: The case of China

    OpenAIRE

    Chenting Su; Zhilin Yang; Guijun Zhuang; Nan Zhou; Wenyu Dou

    2009-01-01

    Channel communications in emerging markets are embedded in the intricacy of economic and sociocultural environments. Managing channel relationships in emerging markets therefore requires more than formal interfirm communication to rely on interpersonal influence. Extending embeddedness theory, we offer a conceptualization incorporating three embedding elements – task environment, social relations, and institutional norms – into a preliminary model that specifies the antecedents, moderators, a...

  8. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    Science.gov (United States)

    Siu, Sam; Ji, Qing; Wu, Wenhao; Song, Gangbing; Ding, Zhi

    2014-12-01

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications.

  9. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    International Nuclear Information System (INIS)

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications. (paper)

  10. Design Considerations for Multi-Channel Picture Communication Networks

    OpenAIRE

    Scheibe, Paul O.

    1983-01-01

    Design of networks intended for communication of digitally-encoded pictures involves considerations different from those used in the design of text or voice communication networks. This paper provides an overview of the elements useful in the design of picture communication networks by relation and contrast with other communication networks. Particular emphasis is given to picture communication systems useful in medical applications.

  11. Formal and Informal Communication Channels in Creating Corporate Brand Image and Preference

    Directory of Open Access Journals (Sweden)

    Ivana First

    2011-06-01

    Full Text Available This study analyzes the effect that various communication channels have on corporate brand image creation among potential employees. Empirical data was collected by a survey conducted on a sample of 370 graduate students. The results revealed that more than ¾ of potential employees learn about the studied company through informal communication channels. Nevertheless, students of the faculties which organize formal company presentations are much better acquainted with such companies than the students of faculties where no formal presentations are held. Furthermore, within the scope of mono-channeled communication, there is no difference in the manner in which formal and informal channels influence brand knowledge and feelings. On the other hand, multi-channeled communication has a greater influence on both knowledge and feelings than mono-channeled communication. Finally, brand feelings are a stronger factor than brand knowledge in determining brand preference but knowledge also determines feelings. These results have several practical implications. Although informal communication has a wider range of resonance, formal communication is more important and should not be neglected by practitioners. Formal communication is not only able to create positive brand image equally well but it also acts as a trigger for informal communication. Practitioners facing limited resources are further advised to give priority to the communication that creates brand feelings rather than brand knowledge.

  12. Blind adaptation of channel-matched receivers in free-space coherent laser communication

    OpenAIRE

    Belmonte Molina, Aniceto; Kahn, Joseph M.

    2012-01-01

    Channel-matched adaptive coherent receivers are implemented using aperture arrays. As an alternative to training-based channel estimation, we analyze the performance of sequential techniques for blind adaptation of multi-aperture channel-matched receivers in coherent laser communications.

  13. INVESTIGATION OF ASYNCHRONOUS OPTICAL COMMUNICATION CHANNEL THROUGHPUT CONTAINING A RECEIVER ON THE BASIS OF PHOTON COUNTER

    Directory of Open Access Journals (Sweden)

    I. R. Gulakov

    2013-01-01

    Full Text Available A mathematical model of asynchronous optical communication channel with a photon counter applied as a receiving module has been built. The expression for calculating of data throughput of this channel has been obtained. As a result of implemented experimental investigations it has been established that the data throughput of asynchronous optical communication channel containing a photon counter on the basis of avalanche photodetector as a receiving module depends on optical radiation and photodetector supply voltage.

  14. The Shannon capacity of a communication channel,graph Ramsey number anda conjecture of Erd(o)s

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We briefly introduce the connection betweenthe Shannon capacity of a communication channel andgraph Ramsey number, which may receive attention fromresearchers on communication theory and graph theory.

  15. Analysing Cognitive Radio Physical Layer on BER Performance over Rician Fading Channel

    Directory of Open Access Journals (Sweden)

    Amandeep Kaur Virk

    2011-09-01

    Full Text Available This paper analyzes the Bit Error Rate performance of Cognitive Radio Physical layer over Rician channel with AWGN noise under different channel encoding schemes, digital modulation schemes and channel conditions. The system outperforms with Reed Solomon along with convolution encoding for BPSK modulation technique as compared to other digital modulation schemes and the system is highly effective to combat inherent interferences under Rician fading channel. The system shows improved BER on using encoding schemes with error rate reduced by 10% using Reed Solomon encoding, 91% reduction on using convolutional encoding and 99% error reduction on applying Reed Solomon with convolution encoding. It has been anticipated from the simulation study that the performance of the communication system degrades with the increase of noise power.

  16. Comparison of Bit Error Rate Performance of Multi Tone Channel Utilising De-OQPSK and De-Off Set 16 QAM with Guard Interval

    Directory of Open Access Journals (Sweden)

    Ibrahim A.Z. Qatawneh

    2005-01-01

    Full Text Available Digital communications systems use Multi tone Channel (MC transmission techniques with differentially encoded and differentially coherent demodulation. Today there are two principle MC application, one is for the high speed digital subscriber loop and the other is for the broadcasting of digital audio and video signals. In this study the comparison of multi carriers with OQPSK and Offset 16 QAM for high-bit rate wireless applications are considered. The comparison of Bit Error Rate (BER performance of Multi tone Channel (MC with offset quadrature amplitude modulation (Offset 16 QAM and offset quadrature phase shift keying modulation (OQPSK with guard interval in a fading environment is considered via the use of Monte Carlo simulation methods. BER results are presented for Offset 16 QAM using guard interval to immune the multi path delay for frequency Rayleigh fading channels and for two-path fading channels in the presence of Additive White Gaussian Noise (AWGN. The BER results are presented for Multi tone Channel (MC with differentially Encoded offset 16 Quadrature Amplitude Modulation (offset 16 QAM and MC with differentially Encoded offset quadrature phase shift keying modulation (OQPSK using guard interval for frequency flat Rician channel in the presence of Additive White Gaussian Noise (AWGN. The performance of multitone systems is also compared with equivalent differentially Encoded offset quadrature amplitude modulation (Offset 16 QAM and differentially Encoded offset quadrature phase shift keying modulation (OQPSKwith and without guard interval in the same fading environment.

  17. Characterizing Social Networks and Communication Channels in a Web-Based Peer Support Intervention.

    Science.gov (United States)

    Owen, Jason E; Curran, Michaela; Bantum, Erin O'Carroll; Hanneman, Robert

    2016-06-01

    Web and mobile (mHealth) interventions have promise for improving health outcomes, but engagement and attrition may be reducing effect sizes. Because social networks can improve engagement, which is a key mechanism of action, understanding the structure and potential impact of social networks could be key to improving mHealth effects. This study (a) evaluates social network characteristics of four distinct communication channels (discussion board, chat, e-mail, and blog) in a large social networking intervention, (b) predicts membership in online communities, and (c) evaluates whether community membership impacts engagement. Participants were 299 cancer survivors with significant distress using the 12-week health-space.net intervention. Social networking attributes (e.g., density and clustering) were identified separately for each type of network communication (i.e., discussion board, blog, web mail, and chat). Each channel demonstrated high levels of clustering, and being a community member in one communication channel was associated with being in the same community in each of the other channels (φ = 0.56-0.89, ps communication channels, suggesting that each channel reached distinct types of users. Finally, membership in a discussion board, chat, or blog community was strongly associated with time spent engaging with coping skills exercises (Ds = 1.08-1.84, ps communication allow participants to expand the number of individuals with whom they are communicating, create opportunities for communicating with different individuals in distinct channels, and likely enhance overall engagement.

  18. An error-resilient approach for real-time packet communications by HF-channel diversity

    Science.gov (United States)

    Navarro, Antonio; Rodrigues, Rui; Angeja, Joao; Tavares, Joao; Carvalho, Luis; Perdigao, Fernando

    2004-08-01

    This paper evaluates the performance of a high frequency (HF) wireless network for transporting packet multimedia services. Beyond of allowing civil/amateur communications, HF bands are also used for long distance wireless military communications. Therefore, our work is based on NATO Link and Physical layer standards, STANAG 5066 and STANAG 4539 respectively. At each HF channel, a typical transmission bandwidth is about 3 kHz with the resulting throughput bit rate up to 12800 bps. This very low bit rate by itself imposes serious challenges for reliable and low delay real time multimedia communications. Thus, this paper discusses the performance of a real time communication system designed to allow an end-to-end communication through "best effort" networks. With HF channel diversity, the packet loss percentage, on average considering three channel conditions, is decreased by 16% in the channel SNR range from 0 to 45 dB.

  19. Digital portfolio for learning: A new communication channel for education

    Directory of Open Access Journals (Sweden)

    Judit Coromina

    2011-04-01

    Full Text Available Purpose: The Catalonian Government has the intention of introducing the digital portfolio before 2017, an initiative related to new approaches for learning. Taking in consideration the increasing interest for digital portfolio as a new communication channel for education, the article aims are: on the one hand to describe how the digital portfolio works and on the other hand, to identify a list of criteria that should be useful for educative centers to select the best application to create the digital portfolio according to their needs.Design/methodology/approach: Firstly, a theoretical framework for portfolio functioning is described. After, applications to support the digital portfolio are classified. Next, a requirement analysis on an ideal application to support the portfolio is made, according to those phases for the portfolio creation identified in the theoretical framework. Lastly, a list of criteria is established to select the application for creating the digital portfolio.Findings and Originality/value: The article contributes to structure the portfolio creation process in some stages and phases in a wider way that it is described in the literature. In addition, a list of criteria is defined to help educative centers to select the application for managing the portfolio that fits better with their objectives. These criteria have been obtained with an exhaustive methodology.Research limitations/implications: In order to put in practice the identified criteria it is proposed to complete the multi-criteria decision model in a new study. It should include processes to weigh criteria and define normalizations. Afterwards it would be able to analyze the value of the model studying the satisfaction for using it by a sample of educative centers.Practical implications: The list of criteria identified should facilitate the selection of the more adequate application to create the learning portfolio to the educative centers, according to their

  20. On Parameterized Gallager's First Bounds for Binary Linear Codes over AWGN Channels

    CERN Document Server

    Ma, Xiao; Bai, Baoming

    2012-01-01

    In this paper, nested Gallager regions with a single parameter is introduced to exploit Gallager's first bounding technique (GFBT). We present a necessary and sufficient condition on the optimal parameter. We also present a sufficient condition (with a simple geometrical explanation) under which the optimal parameter does not depend on the signal-to-noise ratio (SNR). With this general framework, three existing upper bounds are revisited, including the tangential bound (TB) of Berlekamp, the sphere bound (SB) of Herzberg and Poltyrev, and the tangential-sphere bound (TSB) of Poltyrev. This paper also reveals that the SB of Herzberg and Poltyrev is equivalent to the SB of Kasami et al., which was rarely cited in literature.

  1. Channel capacity study of underwater wireless optical communications links based on Monte Carlo simulation

    International Nuclear Information System (INIS)

    Channel capacity of ocean water is limited by propagation distance and optical properties. Previous studies on this problem are based on water-tank experiments with different amounts of Maalox antacid. However, propagation distance is limited by the experimental set-up and the optical properties are different from ocean water. Therefore, the experiment result is not accurate for the physical design of underwater wireless communications links. This letter developed a Monte Carlo model to study channel capacity of underwater optical communications. Moreover, this model can flexibly configure various parameters of transmitter, receiver and channel, and is suitable for physical underwater optical communications links design. (paper)

  2. Quantum Communications Made Easy: Deterministic Models of Bosonic Channels

    OpenAIRE

    Smith, Graeme; Smolin, John A.

    2012-01-01

    Information theory establishes the ultimate limits on performance for noisy communication systems [Shannon48]. An accurate model of a physical communication device must include quantum effects, but typically including these makes the theory intractable. As a result communication capacities are not known, even for transmission between two users connected by an electromagnetic waveguide subject to gaussian noise. Here we present an exactly solvable model of communications with a fully quantum e...

  3. Cyclic Communication and the Inseparability of MIMO Multi-way Relay Channels

    KAUST Repository

    Chaaban, Anas

    2015-10-27

    The K-user MIMO multi-way relay channel (Ychannel) consisting of K users with M antennas each and a common relay node with N antennas is studied in this paper. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed for this channel. The proposed strategy is based on two steps: channel diagonalization and cyclic communication. The channel diagonalization is applied by using zero-forcing beam-forming. After channel diagonalization, the channel is decomposed into parallel sub-channels. Cyclic communication is then applied, where signal-space alignment for network-coding is used over each sub-channel. The proposed strategy achieves the optimal DoF region of the channel if N M. To prove this, a new degrees-of-freedom outer bound is derived. As a by-product, we conclude that the MIMO Y-channel is not separable, i.e., independent coding on separate sub-channels is not enough, and one has to code jointly over several sub-channels.

  4. Load-Adaptive Practical Multi-Channel Communications in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Choong Seon Hong

    2010-09-01

    Full Text Available In recent years, a significant number of sensor node prototypes have been designed that provide communications in multiple channels. This multi-channel feature can be effectively exploited to increase the overall capacity and performance of wireless sensor networks (WSNs. In this paper, we present a multi-channel communications system for WSNs that is referred to as load-adaptive practical multi-channel communications (LPMC. LPMC estimates the active load of a channel at the sink since it has a more comprehensive view of the network behavior, and dynamically adds or removes channels based on the estimated load. LPMC updates the routing path to balance the loads of the channels. The nodes in a path use the same channel; therefore, they do not need to switch channels to receive or forward packets. LPMC has been evaluated through extensive simulations, and the results demonstrate that it can effectively increase the delivery ratio, network throughput, and channel utilization, and that it can decrease the end-to-end delay and energy consumption.

  5. Asymmetric Joint Source-Channel Coding for Correlated Sources with Blind HMM Estimation at the Receiver

    Directory of Open Access Journals (Sweden)

    Ser Javier Del

    2005-01-01

    Full Text Available We consider the case of two correlated sources, and . The correlation between them has memory, and it is modelled by a hidden Markov chain. The paper studies the problem of reliable communication of the information sent by the source over an additive white Gaussian noise (AWGN channel when the output of the other source is available as side information at the receiver. We assume that the receiver has no a priori knowledge of the correlation statistics between the sources. In particular, we propose the use of a turbo code for joint source-channel coding of the source . The joint decoder uses an iterative scheme where the unknown parameters of the correlation model are estimated jointly within the decoding process. It is shown that reliable communication is possible at signal-to-noise ratios close to the theoretical limits set by the combination of Shannon and Slepian-Wolf theorems.

  6. Asymmetric Joint Source-Channel Coding for Correlated Sources with Blind HMM Estimation at the Receiver

    Directory of Open Access Journals (Sweden)

    Ser Javier Del

    2005-01-01

    Full Text Available We consider the case of two correlated sources, S 1 and S 2 . The correlation between them has memory, and it is modelled by a hidden Markov chain. The paper studies the problem of reliable communication of the information sent by the source S 1 over an additive white Gaussian noise (AWGN channel when the output of the other source S 2 is available as side information at the receiver. We assume that the receiver has no a priori knowledge of the correlation statistics between the sources. In particular, we propose the use of a turbo code for joint source-channel coding of the source S 1 . The joint decoder uses an iterative scheme where the unknown parameters of the correlation model are estimated jointly within the decoding process. It is shown that reliable communication is possible at signal-to-noise ratios close to the theoretical limits set by the combination of Shannon and Slepian-Wolf theorems.

  7. Efficacy of Interpersonal Communication Channels in the Diffusion and Adoption of Zero Grazing Technology

    OpenAIRE

    Sammy Cheboi; Hellen Mberia

    2014-01-01

    This study was an investigation of the effectiveness of interpersonal communication channels in aiding diffusion and adoption of zero grazing innovation in Tot Division, Kenya. The problem of this study was that past innovation-diffusion studies have had limited focus on the importance of interpersonal communication channels on diffusion and adoption of zero grazing as an agricultural technology, hence a gap that demands specific studies are undertaken to fill it. The study’s general objectiv...

  8. Communicating with first year students; so many channels but is anyone listening? A Practice Report

    OpenAIRE

    Jason Lodge

    2010-01-01

    Communicating with first year students has become a far more complex prospect in the digital age. There is a lot of competition for limited attentional resources from media sources in almost endless channels. Getting important messages to students when there is so much competing information is a difficult prospect for academic and professional divisions of the university alike. Students’ preferences for these communication channels are not well understood and are constantly changing wit...

  9. Formal and Informal Communication Channels in Creating Corporate Brand Image and Preference

    OpenAIRE

    Ivana First; Marija Tomić

    2011-01-01

    This study analyzes the effect that various communication channels have on corporate brand image creation among potential employees. Empirical data was collected by a survey conducted on a sample of 370 graduate students. The results revealed that more than ¾ of potential employees learn about the studied company through informal communication channels. Nevertheless, students of the faculties which organize formal company presentations are much better acquainted with such companies than the s...

  10. Channel Characterization and Robust Tracking for Diversity Reception over Time-Variant Off-Body Wireless Communication Channels

    Science.gov (United States)

    Van Torre, Patrick; Vallozzi, Luigi; Rogier, Hendrik; Moeneclaey, Marc; Verhaevert, Jo

    2010-12-01

    In the 2.45 GHz band, indoor wireless off-body data communication by a moving person can be problematic due to time-variant signal fading and the consequent variation in channel parameters. Off-body communication specifically suffers from the combined effects of fading, shadowing, and path loss due to time-variant multipath propagation in combination with shadowing by the human body. Measurements are performed to analyze the autocorrelation, coherence time, and power spectral density for a person equipped with a wearable receive system moving at different speeds for different configurations and antenna positions. Diversity reception with multiple textile antennas integrated in the clothing provides a means of improving the reliability of the link. For the dynamic channel estimation, a scheme using hard decision feedback after MRC with adaptive low-pass filtering is demonstrated to be successful in providing robust data detection for long data bursts, in the presence of dramatic channel variation.

  11. Channel-Specific Daily Patterns in Mobile Phone Communication

    OpenAIRE

    Aledavood, Talayeh; López, Eduardo; Roberts, Sam G. B.; Reed-Tsochas, Felix; Moro, Esteban; Robin I M Dunbar; Saramäki, Jari

    2015-01-01

    Humans follow circadian rhythms, visible in their activity levels as well as physiological and psychological factors. Such rhythms are also visible in electronic communication records, where the aggregated activity levels of e.g. mobile telephone calls or Wikipedia edits are known to follow their own daily patterns. Here, we study the daily communication patterns of 24 individuals over 18 months, and show that each individual has a different, persistent communication pattern. These patterns m...

  12. A Parameter Modulation Chaotic Secure Communication Scheme with Channel Noises

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ying-Qian; WANG Xing-Yuan

    2011-01-01

    @@ We propose a new communication system which is able to separate noise successfully by using independent component analysis (ICA), and a parameter modulation method based on a Lorenz chaotic system is employed for recovery of the source signals.The results indicate that our proposed secure communication has robustness against noise.%We propose a new communication system which is able to separate noise successfully by using independent component analysis (ICA), and a parameter modulation method based on a Lorenz chaotic system is employed for recovery of the source signals. The results indicate that our proposed secure communication has robustness against noise.

  13. Deterministic secure quantum communication over a collective-noise channel

    Institute of Scientific and Technical Information of China (English)

    GU Bin; PEI ShiXin; SONG Biao; ZHONG Kun

    2009-01-01

    We present two deterministic secure quantum communication schemes over a collective-noise. One is used to complete the secure quantum communication against a collective-rotation noise and the other is used against a collective-dephasing noise. The two parties of quantum communication can exploit the correlation of their subsystems to check eavesdropping efficiently. Although the sender should prepare a sequence of three-photon entangled states for accomplishing secure communication against a collective noise, the two parties need only single-photon measurements, rather than Bell-state measurements, which will make our schemes convenient in practical application.

  14. Fixed channel assignment in cellular communication systems considering the whole set of packed patterns

    DEFF Research Database (Denmark)

    Borges, Pedro Manuel F. C.; Vidal, Rene Victor Valqui

    2000-01-01

    This paper addresses the problem of fixed channel assignment in cellular communication systems with nonuniform traffic distribution. The objective of the channel assignment is to minimise the average blocking probability. Methods for finding a good allocation can be based on first building a numb...

  15. Improved Analysis of Co-Channel Interference in Cellular Communications Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zu-fan; DU Hui-ping; ZHU Wei-le

    2005-01-01

    In terms of the carrier-to-interference-ratio, the performance of co-channel interference in cellular communications systems is studied. The approach is based on an improved analysis, which allows to take into account some area in the desired sector may not be interfered by some co-channel sectors with exact geometrical analysis, instead of the entire sector interfered by some co-channel sectors. Other features, such as power control and the number of interferences are also included.

  16. Initial Design of an Acoustic Communication Channel Simulator

    NARCIS (Netherlands)

    Bertolotto, G.; Jenserud, T.; Walree, P.A. van

    2007-01-01

    The joint European project “UUV Covert Acoustic Communications” aims at the design of an acoustic communication system between an unmanned underwater vehicle and a support mother ship. To achieve the objective of covert communication over long ranges in littoral waters, knowledge is required on the

  17. Characterizing Social Networks and Communication Channels in a Web-Based Peer Support Intervention.

    Science.gov (United States)

    Owen, Jason E; Curran, Michaela; Bantum, Erin O'Carroll; Hanneman, Robert

    2016-06-01

    Web and mobile (mHealth) interventions have promise for improving health outcomes, but engagement and attrition may be reducing effect sizes. Because social networks can improve engagement, which is a key mechanism of action, understanding the structure and potential impact of social networks could be key to improving mHealth effects. This study (a) evaluates social network characteristics of four distinct communication channels (discussion board, chat, e-mail, and blog) in a large social networking intervention, (b) predicts membership in online communities, and (c) evaluates whether community membership impacts engagement. Participants were 299 cancer survivors with significant distress using the 12-week health-space.net intervention. Social networking attributes (e.g., density and clustering) were identified separately for each type of network communication (i.e., discussion board, blog, web mail, and chat). Each channel demonstrated high levels of clustering, and being a community member in one communication channel was associated with being in the same community in each of the other channels (φ = 0.56-0.89, ps < 0.05). Predictors of community membership differed across communication channels, suggesting that each channel reached distinct types of users. Finally, membership in a discussion board, chat, or blog community was strongly associated with time spent engaging with coping skills exercises (Ds = 1.08-1.84, ps < 0.001) and total time of intervention (Ds = 1.13-1.80, ps < 0.001). mHealth interventions that offer multiple channels for communication allow participants to expand the number of individuals with whom they are communicating, create opportunities for communicating with different individuals in distinct channels, and likely enhance overall engagement. PMID:27327066

  18. Entanglement-enhanced classical communication through generalized amplitude damping channel

    Institute of Scientific and Technical Information of China (English)

    Hou Li-Zhen; Fang Mao-Fa

    2007-01-01

    The problem of sending a single classical bit through a generalized amplitude damping channel is considered.When two transmissions through the channel are available as a resource, we find that two entangled transmissions can enhance the capability of receiver's judging information correctly under certain conditions compared with two productstate transmissions. In addition, we find a special case in which the two entangled transmissions can always make a classical bit more effectively disable the noise influence.

  19. Designing Effective Persuasive Systems Utilizing the Power of Entanglement: Communication Channel, Strategy & Affect

    Science.gov (United States)

    Li, Haiqing

    2010-01-01

    With rapid advancements in information and communication technologies, computer-mediated communication channels such as email, web, mobile smart-phones with SMS, social networking websites (Facebook), multimedia websites, and OEM devices provide users with multiple technology choices to seek information. However, no study has compared the…

  20. Communication Channels as Implementation Determinants of Performance Management Framework in Kenya

    Science.gov (United States)

    Sang, Jane

    2016-01-01

    The purpose of this study to assess communication channels as implementation determinants of performance management framework In Kenya at Moi Teaching and Referral Hospital (MTRH). The communication theory was used to inform the study. This study adopted an explanatory design. The target sampled 510 respondents through simple random and stratified…

  1. Conversations around Design Sketches: Use of Communication Channels for Sharing Mental Models during Concept Generation

    Science.gov (United States)

    Ariff, Nik Shahman Nik Ahmad; Badke-Schaub, Petra; Eris, Ozgur

    2012-01-01

    In this paper, we present an exploratory protocol study on the use of different communication channels during design sketching. We focus on how individual designers share their mental models with other designers in a group, and analyse their use of graphical, textual, and verbal communications during concept generation. Our findings suggest that…

  2. Conversations around design sketches: use of communication channels for sharing mental models during concept generation

    NARCIS (Netherlands)

    Nik Ahmad Ariff, N.S.; Badke-Schaub, P.G.; Eris, O.

    2012-01-01

    In this paper, we present an exploratory protocol study on the use of different communication channels during design sketching. We focus on how individual designers share their mental models with other designers in a group, and analyze their use of graphical, textual, and verbal communications durin

  3. Digital Channels in Teacher-Parent Communication: The Case of Estonia

    Science.gov (United States)

    Palts, Karmen; Kalmus, Veronika

    2015-01-01

    The aim of this paper is to analyse the attitudes of Estonian primary school teachers and parents regarding the role of mutual digital communication in socialising the child and in the child's academic progress, their communication channel preferences, and related experiences and opinions. The main starting points are Bronfenbrenner's (1979)…

  4. Science communication on YouTube: Factors that affect channel and video popularity.

    Science.gov (United States)

    Welbourne, Dustin J; Grant, Will J

    2016-08-01

    YouTube has become one of the largest websites on the Internet. Among its many genres, both professional and amateur science communicators compete for audience attention. This article provides the first overview of science communication on YouTube and examines content factors that affect the popularity of science communication videos on the site. A content analysis of 390 videos from 39 YouTube channels was conducted. Although professionally generated content is superior in number, user-generated content was significantly more popular. Furthermore, videos that had consistent science communicators were more popular than those without a regular communicator. This study represents an important first step to understand content factors, which increases the channel and video popularity of science communication on YouTube.

  5. Science communication on YouTube: Factors that affect channel and video popularity.

    Science.gov (United States)

    Welbourne, Dustin J; Grant, Will J

    2016-08-01

    YouTube has become one of the largest websites on the Internet. Among its many genres, both professional and amateur science communicators compete for audience attention. This article provides the first overview of science communication on YouTube and examines content factors that affect the popularity of science communication videos on the site. A content analysis of 390 videos from 39 YouTube channels was conducted. Although professionally generated content is superior in number, user-generated content was significantly more popular. Furthermore, videos that had consistent science communicators were more popular than those without a regular communicator. This study represents an important first step to understand content factors, which increases the channel and video popularity of science communication on YouTube. PMID:25698225

  6. High-data rate laser communication field experiment in the turbulence channel

    Science.gov (United States)

    Sun, Jianfeng; Zhi, Ya'nan; Lu, Wei; Wang, Lijuan; Dai, Enwen; Liu, Liren

    2012-10-01

    At present inter-satellite laser communications have made great success, such as SILEX, TerraSAR-X LCT etc. But satellite to ground laser communications still at the experimental stages because of the atmosphere turbulence channel and the clouds. Once the satellite to ground laser communication technology obtains a breakthrough, the all laser spacebased communication era is coming. In this paper, we suggest a DPSK modulation/self-coherent homodyne reception scheme to overcome the atmosphere turbulence. The key in the scheme lies in the phase error compensation with the external environment change. In our experiment, we use two parallel plates rotating to compensate the phase error. The communication data rate reaches 2.5Gbps in the field experiment. The real time bit error rate was obtained with the variation of the communication channel's turbulence.

  7. Integrated source and channel encoded digital communication system design study. [for space shuttles

    Science.gov (United States)

    Huth, G. K.

    1976-01-01

    The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.

  8. Analysis and Optimization of Error Performance of a WiMAX Transceiver using Novel Adaptive Cyclic Prefix Strategy under AWGN and Rayleigh Fading Scenario

    Directory of Open Access Journals (Sweden)

    Budhaditya Bhattacharyya

    2012-12-01

    Full Text Available In order to increase channel capacity at lowchannel SNR selection of higher order modulation and coderates are crucial. However, poor channel condition causessevere ISI resulting in asynchronous phase error betweenthe subcarriers hindering the selection of higher ordermodulation schemes at low channel SNR condition. In thispaper, a complete novel and unique selection strategy forAdaptive Cyclic Prefix (ACP is proposed for IEEE 802.16e-WiMAX Physical Layer (PHY using a Simulink-VSA basedsimulation model. ACP selects higher order modulation andcode rates for low channel SNR condition by dynamicselection of Cyclic Prefix (CP. Better Quality of Service(QoS is guaranteed in the form of lowest average error(0.034 dB for low channel SNR condition, compared to theexisting Fixed Cyclic Prefix (FCP scenario (3dB inWiMAX. In addition to implementing ACP algorithm forAWGN scenario, a Modified ACP (MACP algorithm is alsoproposed for a Rayleigh multipath fading scenario.Simulation results reflect the efficiency of both ACP andMACP for low channel SNR condition in the selection ofhigher order modulation and coding schemes in a WiMAXbased system. Moreover, an elaborate performance study onthe effect of EVM and RCE on Symbol Error Probability(SEP for all possible modulations has been addressed inthis paper. Results confirm that effective reduction in EVMand RCE, reduces SEP significantly and thus selection ofhigher order modulation and code rates is possible even inlow channel SNR condition (0dB -20dB.

  9. An FPGA-Based Adaptable 200 MHz Bandwidth Channel Sounder for Wireless Communication Channel Characterisation

    Directory of Open Access Journals (Sweden)

    David L. Ndzi

    2011-01-01

    Full Text Available This paper describes the development of a fast adaptable FPGA-based wideband channel sounder with signal bandwidths of up to 200 MHz and channel sampling rates up to 5.4 kHz. The application of FPGA allows the user to vary the number of real-time channel response averages, channel sampling interval, and duration of measurement. The waveform, bandwidth, and frequency resolution of the sounder can be adapted for any channel under investigation. The design approach and technology used has led to a reduction in size and weight by more than 60%. This makes the sounder ideal for mobile time-variant wireless communication channels studies. Averaging allows processing gains of up to 30 dB to be achieved for measurement in weak signal conditions. The technique applied also improves reliability, reduces power consumption, and has shifted sounder design complexity from hardware to software. Test results show that the sounder can detect very small-scale variations in channels.

  10. RF channel performance assessment for a multiple carrier millimeter-wave communication system

    Institute of Scientific and Technical Information of China (English)

    Thomas WONG; Ming YAN

    2004-01-01

    Channel capacity, system versatility and ease of maintenance are factors of prime concern in future generations of wireless communication systems. As a result, millimeter-wave can offer considerable advantages in providing broadband interface. Nonlinearity and noise effects, including parametric fluctuations, are two significant causes for signal degradation in broadband communication systems. Two methods to assess the performance of an RF channel in a multi-carrier system are described. By measuring the forward transfer function from transmitter IF to receiver IF as the frequency is swept across the channel bandwidth, characteristics such as gain flatness, channel dispersion, and saturation effects are revealed. To evaluate the ability of the communication link in preserving the synchronization between two carriers, their heterodyned spectrum at the receiver IF output is studied. Both measurement methods employ standard equipment and have been found to be effective when applied to a multi-carrier millimeter-wave system with over 1 GHz instantaneous bandwidth.

  11. Average capacity for optical wireless communication systems over exponentiated Weibull distribution non-Kolmogorov turbulent channels.

    Science.gov (United States)

    Cheng, Mingjian; Zhang, Yixin; Gao, Jie; Wang, Fei; Zhao, Fengsheng

    2014-06-20

    We model the average channel capacity of optical wireless communication systems for cases of weak to strong turbulence channels, using the exponentiation Weibull distribution model. The joint effects of the beam wander and spread, pointing errors, atmospheric attenuation, and the spectral index of non-Kolmogorov turbulence on system performance are included. Our results show that the average capacity decreases steeply as the propagation length L changes from 0 to 200 m and decreases slowly down or tends to a stable value as the propagation length L is greater than 200 m. In the weak turbulence region, by increasing the detection aperture, we can improve the average channel capacity and the atmospheric visibility as an important issue affecting the average channel capacity. In the strong turbulence region, the increase of the radius of the detection aperture cannot reduce the effects of the atmospheric turbulence on the average channel capacity, and the effect of atmospheric visibility on the channel information capacity can be ignored. The effect of the spectral power exponent on the average channel capacity in the strong turbulence region is higher than weak turbulence region. Irrespective of the details determining the turbulent channel, we can say that pointing errors have a significant effect on the average channel capacity of optical wireless communication systems in turbulence channels.

  12. Information-guided communications in MIMO systems with channel state impairments

    KAUST Repository

    Yang, Yuli

    2013-06-20

    Information-guided channel hopping (IGCH) is a promising technique for high-data-rate communications using multiple antennas for information mapping at the transmitter and optional antenna diversity at the receiver. Compared with some popular multi-antenna techniques, the advantage of this scheme is proven in ideal channel conditions, where the channel is spatially white and the perfect channel state information is assumed available at the receiver. The main objective of this paper is to present an information theoretical study on IGCH in realistic propagation environments with channel degeneracy due to spatial correlation and keyhole phenomena as well as imperfect channel estimation. It is proven that good performance promised by IGCH can be achieved in a variety of non-ideal channel conditions. Moreover, the analysis in this paper provides a convenient tool for the corresponding system design in practical operating environments. © 2013 John Wiley & Sons, Ltd.

  13. Channel-Specific Daily Patterns in Mobile Phone Communication

    CERN Document Server

    Aledavood, Talayeh; Roberts, Sam G B; Reed-Tsochas, Felix; Moro, Esteban; Dunbar, Robin I M; Saramäki, Jari

    2015-01-01

    Humans follow circadian rhythms, visible in their activity levels as well as physiological and psychological factors. Such rhythms are also visible in electronic communication records, where the aggregated activity levels of e.g. mobile telephone calls or Wikipedia edits are known to follow their own daily patterns. Here, we study the daily communication patterns of 24 individuals over 18 months, and show that each individual has a different, persistent communication pattern. These patterns may differ for calls and text messages, which points towards calls and texts serving a different role in communication. For both calls and texts, evenings play a special role. There are also differences in the daily patterns of males and females both for calls and texts, both in how they communicate with individuals of the same gender vs. opposite gender, and also in how communication is allocated at social ties of different nature (kin ties vs. non-kin ties). Taken together, our results show that there is an unexpected ri...

  14. Gaussian matrix-product states for coding in bosonic communication channels

    Science.gov (United States)

    Schäfer, Joachim; Karpov, Evgueni; Cerf, Nicolas J.

    2012-01-01

    The communication capacity of Gaussian bosonic channels with memory has recently attracted much interest. Here, we investigate a method to prepare the multimode entangled input symbol states for encoding classical information into these channels. In particular, we study the usefulness of a Gaussian matrix-product state (GMPS) as an input symbol state, which can be sequentially generated although it remains heavily entangled for an arbitrary number of modes. We show that the GMPS can achieve more than 99.9% of the Gaussian capacity for Gaussian bosonic memory channels with a Markovian or non-Markovian correlated noise model in a large range of noise correlation strengths. Furthermore, we present a noise class for which the GMPS is the exact optimal input symbol state of the corresponding channel. Since GMPS are ground states of particular quadratic Hamiltonians, our results suggest a possible link between the theory of quantum communication channels and quantum many-body physics.

  15. Compressive sensing based Bayesian sparse channel estimation for OFDM communication systems: high performance and low complexity.

    Science.gov (United States)

    Gui, Guan; Xu, Li; Shan, Lin; Adachi, Fumiyuki

    2014-01-01

    In orthogonal frequency division modulation (OFDM) communication systems, channel state information (CSI) is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI) over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE) methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE) method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods.

  16. Compressive sensing based Bayesian sparse channel estimation for OFDM communication systems: high performance and low complexity.

    Science.gov (United States)

    Gui, Guan; Xu, Li; Shan, Lin; Adachi, Fumiyuki

    2014-01-01

    In orthogonal frequency division modulation (OFDM) communication systems, channel state information (CSI) is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI) over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE) methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE) method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods. PMID:24983012

  17. Compressive Sensing Based Bayesian Sparse Channel Estimation for OFDM Communication Systems: High Performance and Low Complexity

    Directory of Open Access Journals (Sweden)

    Guan Gui

    2014-01-01

    Full Text Available In orthogonal frequency division modulation (OFDM communication systems, channel state information (CSI is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods.

  18. Phase-Type Models of Channel-Holding Times in Cellular Communication Systems

    DEFF Research Database (Denmark)

    Christensen, Thomas Kaare; Nielsen, Bo Friis; Iversen, Villy Bæk

    2004-01-01

    In this paper, we derive the distribution of the channel-holding time when both cell-residence and call-holding times are phase-type distributed. Furthermore, the distribution of the number of handovers, the conditional channel-holding time distributions, and the channel-holding time when cell re...... residence times are correlated are derived. All distributions are of phase type, making them very general and flexible. The channel-holding times are of importance in performance evaluation and simulation of cellular mobile communication systems....

  19. Gaussian bosonic synergy: quantum communication via realistic channels of zero quantum capacity

    CERN Document Server

    Smith, Graeme; Yard, Jon

    2011-01-01

    As with classical information, error-correcting codes enable reliable transmission of quantum information through noisy or lossy channels. In contrast to the classical theory, imperfect quantum channels exhibit a strong kind of synergy: there exist pairs of discrete memoryless quantum channels, each of zero quantum capacity, which acquire positive quantum capacity when used together. Here we show that this "superactivation" phenomenon also occurs in the more realistic setting of optical channels with attenuation and Gaussian noise. This paves the way for its experimental realization and application in real-world communications systems.

  20. A Novel Concatenated Chaotic Communication System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A strategy for a novel concatenated chaotic communication system is presented. The transmitter system comprises chaotic turbo encoder and logistic CSK block in a serially concatenated form. Chaotic turbo code is capable of reducing bit error rate (BER) of the chaotic system in the AWGN channel. Through the chaotic turbo encoder, the coded sequence, which has quasi-chaotic properties, will be transmitted into the logistic CSK block. Having a very sensitive dependence on initial conditions of the map, the logistic CSK block can also be taken as the chaotic authentication method. The receiver, which has logistic demodulation block and chaotic decoder, is a linear asymptotic approximation to the inverse of the transmitter system. A chaotic iterative soft-decision decoding algorithm is also developed based on conventional maximum A posteriori decoding algorithm. At last, a two-step authentication method of this chaotic system is also presented.

  1. Coded throughput performance simulations for the time-varying satellite channel. M.S. Thesis

    Science.gov (United States)

    Han, LI

    1995-01-01

    The design of a reliable satellite communication link involving the data transfer from a small, low-orbit satellite to a ground station, but through a geostationary satellite, was examined. In such a scenario, the received signal power to noise density ratio increases as the transmitting low-orbit satellite comes into view, and then decreases as it then departs, resulting in a short-duration, time-varying communication link. The optimal values of the small satellite antenna beamwidth, signaling rate, modulation scheme and the theoretical link throughput (in bits per day) have been determined. The goal of this thesis is to choose a practical coding scheme which maximizes the daily link throughput while satisfying a prescribed probability of error requirement. We examine the throughput of both fixed rate and variable rate concatenated forward error correction (FEC) coding schemes for the additive white Gaussian noise (AWGN) channel, and then examine the effect of radio frequency interference (RFI) on the best coding scheme among them. Interleaving is used to mitigate degradation due to RFI. It was found that the variable rate concatenated coding scheme could achieve 74 percent of the theoretical throughput, equivalent to 1.11 Gbits/day based on the cutoff rate R(sub 0). For comparison, 87 percent is achievable for AWGN-only case.

  2. Frequency Diversity for OFDM Mobile Communication via Underwater Acoustic Channels

    Institute of Scientific and Technical Information of China (English)

    Gang Qiao; Wei Wang; Ran Guo; Rehan Khan; Yue Wang

    2012-01-01

    The major constraint on the performance of orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication is to keep subcarriers orthogonal.In this paper,Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange.In practice,for mobile communication,adjustment and tuning of transducers in order to get spatial diversity is extremely difficult.Considering the relatively low coherence bandwidth in UWA,the frequency diversity design with the Doppler compensation function was elaborated here.The outfield experiments of mobile underwater acoustic communication (UWAC) based on OFDM were carried out with 0.17 bit/(s.Hz) spectral efficiency.The validity and the dependability of the scheme were also analyzed.

  3. Integrated source and channel encoded digital communication system design study

    Science.gov (United States)

    Alem, W. K.; Huth, G. K.; Simon, M. K.

    1978-01-01

    The particular Ku-band carrier, PN despreading, and symbol synchronization strategies, which were selected for implementation in the Ku-band transponder aboard the orbiter, were assessed and evaluated from a systems performance viewpoint, verifying that system specifications were met. A study was performed of the design and implementation of tracking techniques which are suitable for incorporation into the Orbiter Ku-band communication system. Emphasis was placed on maximizing tracking accuracy and communication system flexibility while minimizing cost, weight, and system complexity of Orbiter and ground systems hardware. The payload communication study assessed the design and performance of the forward link and return link bent-pipe relay modes for attached and detached payloads. As part of this study, a design for a forward link bent-pipe was proposed which employs a residual carrier but which is tracked by the existing Costas loop.

  4. Mitigation Technique for Receiver Performance Variation of Multi-Color Channels in Visible Light Communication

    Directory of Open Access Journals (Sweden)

    Yeong Min Jang

    2011-06-01

    Full Text Available “Green” and energy-efficient wireless communication schemes have recently experienced rapid development and garnered much interest. One such scheme is visible light communication (VLC which is being touted as one of the next generation wireless communication systems. VLC allows communication using multi-color channels that provide high data rates and illumination simultaneously. Even though VLC has many advantageous features compared with RF technologies, including visibility, ubiquitousness, high speed, high security, harmlessness for the human body and freedom of RF interference, it suffers from some problems on the receiver side, one of them being photo sensitivity dissimilarity of the receiver. The photo sensitivity characteristics of a VLC receiver such as Si photo-detector depend on the wavelength variation. The performance of the VLC receiver is not uniform towards all channel colors, but it is desirable for receivers to have the same performance on each color channel. In this paper, we propose a mitigation technique for reducing the performance variation of the receiver on multi-color channels. We show received power, SNR, BER, output current, and outage probability in our simulation for different color channels. Simulation results show that, the proposed scheme can reduce the performance variation of the VLC receiver on multi-color channels.

  5. Evaluation of Kolmogorov - Smirnov Test and Energy Detector Techniques for Cooperative Spectrum Sensing in Real Channel Conditions

    Directory of Open Access Journals (Sweden)

    D. Lekomtcev

    2015-06-01

    Full Text Available The cognitive radio technology allows solving one of the main issues of current wireless communication technologies, namely a deficit of vacant spectrum. A dynamic spectrum access used in the cognitive radio networks (CRN gives an ability to access an unused spectrum in real time. Cooperative spectrum sensing is the most effective method for spectrum holes detecting. It combines sensing information of multiple cognitive radio users. In this paper, an experimental evaluation of spectrum sensing methods based on the Kolmogorov - Smirnov statistical test and Energy Detector using the Universal Software Radio Peripheral (USRP devices synchronized through a MIMO cable and with further processing in the GNU Radio and Matlab software are presented. Three hard decision fusion schemes are analyzed. Simulation comparison between these rules is presented via Receiver Operating Characteristic (ROC curves. The influence of real channel with interferences is compared in contrast to commonly assumed AWGN channel model of vacant channel noise.

  6. The design and analysis of channel transmission communication system of XCTD profiler

    Science.gov (United States)

    Zheng, Yu; Wang, Xiao-Rui; Jin, Xiang-Yu; Song, Guo-Min; Shang, Ying-Sheng; Li, Hong-Zhi

    2016-10-01

    In this paper, a channel transmission communication system of expendable conductivity-temperature-depth is established in accordance to the operation characteristics of the transmission line to more accurately assess the characteristics of deep-sea abandoned profiler channel. The wrapping inductance is eliminated to maximum extent through the wrapping pattern of the underwater spool and the overwater spool and the calculation of the wrapping diameter. The feasibility of the proposed channel transmission communication system is verified through theoretical analysis and practical measurement of the transmission signal error rate in the amplitude shift keying (ASK) modulation. The proposed design provides a new research method for the channel assessment of complex abandoned measuring instrument and an important experiment evidence for the rapid development of the deep-sea abandoned measuring instrument.

  7. Performance analysis of Turbo-Codes in communication channels with impulsive noise

    Institute of Scientific and Technical Information of China (English)

    Li Chong; Deng Weibo; Duan Lingjie

    2009-01-01

    Performance of Turbo-Codes in communication channels with impulsive noise is analyzed. First, mathematical model of impulsive noise is presented because it has non-Gaussian nature and is found in many wireless channels due to impulsive phenomena of radio-frequency interference. Then, with linear Log-MAP decoding algorithm for its low complexity, Turbo-Codes are adopted and analyzed in such communication channels. To confirm the performance of the proposed method, simulations on both static and fully interleaved fiat Rayleigh fading channels with impulsive noise have been carried out. It is shown that Turbo-Codes have a better performance than the conventional methods (e.g. convolutionally coded system).

  8. Robust Distributed Kalman Filter for Wireless Sensor Networks with Uncertain Communication Channels

    Directory of Open Access Journals (Sweden)

    Du Yong Kim

    2012-01-01

    Full Text Available We address a state estimation problem over a large-scale sensor network with uncertain communication channel. Consensus protocol is usually used to adapt a large-scale sensor network. However, when certain parts of communication channels are broken down, the accuracy performance is seriously degraded. Specifically, outliers in the channel or temporal disconnection are avoided via proposed method for the practical implementation of the distributed estimation over large-scale sensor networks. We handle this practical challenge by using adaptive channel status estimator and robust L1-norm Kalman filter in design of the processor of the individual sensor node. Then, they are incorporated into the consensus algorithm in order to achieve the robust distributed state estimation. The robust property of the proposed algorithm enables the sensor network to selectively weight sensors of normal conditions so that the filter can be practically useful.

  9. Chaotic Free-Space Laser Communication over Turbulent Channel

    OpenAIRE

    Rulkov, N. F.; Vorontsov, M. A.; Illing, L.

    2002-01-01

    The dynamics of errors caused by atmospheric turbulence in a self-synchronizing chaos based communication system that stably transmits information over a $\\sim$5 km free-space laser link is studied experimentally. Binary information is transmitted using a chaotic sequence of short-term pulses as carrier. The information signal slightly shifts the chaotic time position of each pulse depending on the information bit. We report the results of an experimental analysis of the atmospheric turbulenc...

  10. Robust GPS - SMS Communication Channel for the AVL System

    CERN Document Server

    Skobla, J; Skobla, Joseph; Young, Andrew

    2002-01-01

    Universal Preprocessing GPS SMS Communication Unit (UPCU) was developed as a part of the UWI microtracking system. A GSM cellular Short Messaging Service is the main method of delivering tracking information to the central base station. The information includes asset ID, longitude, latitude, altitude, speed and direction as well as the time the message was sent. The design of the unit is implemented as a bi-directional SMS system.

  11. Possible existence of optical communication channels in the brain

    OpenAIRE

    Sourabh KUMAR; Boone, Kristine; Tuszynski, Jack,; Barclay, Paul E.; Simon, Christoph

    2016-01-01

    Given that many fundamental questions in neuroscience are still open, it seems pertinent to explore whether the brain might use other physical modalities than the ones that have been discovered so far. In particular it is well established that neurons can emit photons, which prompts the question whether these biophotons could serve as signals between neurons, in addition to the well-known electro-chemical signals. For such communication to be targeted, the photons would need to travel in wave...

  12. A probabilistic quantum communication protocol using mixed entangled channel

    Science.gov (United States)

    Choudhury, Binayak S.; Dhara, Arpan

    2016-05-01

    Qubits are realized as polarization state of photons or as superpositions of the spin states of electrons. In this paper we propose a scheme to probabilistically teleport an unknown arbitrary two-qubit state using a non-maximally entangled GHZ- like state and a non-maximally Bell state simultaneously as quantum channels. We also discuss the success probability of our scheme. We perform POVM in the protocol which is operationally advantageous. In our scheme we show that the non-maximal quantum resources perform better than maximal resources.

  13. 80-Channel Multiplexer-Demultiplexer Module for DWDM Communications using Hybrid AWG -- Interleaver Technology

    Science.gov (United States)

    Rablau, Corneliu; Bredthauer, Lance

    2007-10-01

    Aside from the more traditional data, voice and e-mail communications, new bandwidth intensive applications in the larger consumer markets, such as music, digital pictures and movies, have led to an explosive increase in the demand for transmission capacity for optical communications networks. This has resulted in a widespread deployment of Dense Wavelength Division Multiplexing (DWDM) as a means of increasing the communications capacity by multiplexing and transmitting signals of different wavelengths (establishing multiple communication channels) through a single strand of fiber. We report on the design, assembly and characterization of a 50-GHz, 80-channel Mux-Demux module for DWDM systems. The module has been assembled from two commercially available 100 GHz, 40-channel Array Waveguide Grating (AWG) modules and a 50-GHz to 100-GHz interleaver. Relevant performance parameters such as insertion loss, channel uniformity, next-channel isolation (crosstalk) and integrated cross-talk are presented and discussed in contrast with the performance of other competing technologies such as Thin-Film-Filter-based Mux-Demux devices.

  14. Communication systems, transceivers, and methods for generating data based on channel characteristics

    Science.gov (United States)

    Forman, Michael A; Young, Derek

    2012-09-18

    Examples of methods for generating data based on a communications channel are described. In one such example, a processing unit may generate a first vector representation based in part on at least two characteristics of a communications channel. A constellation having at least two dimensions may be addressed with the first vector representation to identify a first symbol associated with the first vector representation. The constellation represents a plurality of regions, each region associated with a respective symbol. The symbol may be used to generate data, which may stored in an electronic storage medium and used as a cryptographic key or a spreading code or hopping sequence in a modulation technique.

  15. Communication channel modeling of human forearm with muscle fiber tissue characteristics.

    Science.gov (United States)

    Zhang, Shuang; Pun, Sio Hang; Mak, Peng Un; Qin, Yu-Ping; Liu, Yi-He; Vai, Mang I

    2016-09-14

    Human-Body Communication (HBC) is a wireless communication method using the human body tissue as a transmission medium for signals. This paper on the basis of human muscle fiber tissues' characteristics, it is first proposed to establish the analytical model of galvanic coupling human-body communication channel. In this model, the parallel and the transverse electrical characteristics of muscular tissue are fully considered, and the model accurately presents the transmission mechanism of galvanic coupling human-body communication signals in the channel. At last, through compare with the experimental results and calculation results, the maximum error of the model is 22.4% and the average error is 14.2% within the frequency range.

  16. Implementation of an Ethernet-Based Communication Channel for the Patmos Processor

    DEFF Research Database (Denmark)

    Pezzarossa, Luca; Kenn Toft, Jakob; Lønbæk, Jesper;

    The Patmos processor, which is used as the intellectual property of the T-CREST platform, is only equipped with a RS-232 serial port for communication with the outside world. The serial port is a minimal input/output device with a limited speed and without native networking features. An Ethernet 10....../100BASE-T IEEE 802.3 based communication channel is a reliable and high speed communication interface (10/100 Mbits/s) that also supports networking. This technical report presents an implementation of an Ethernet-based communication channel for the Patmos processor, targeting the Terasic DE2......-115 development board. We have designed the hardware to interface the EthMac Ethernet controller from OpenCores to Patmos and to the physical chip of the development board, and we have implemented a software library to drive the controller and to support some essential protocols. The design was implemented...

  17. Channel Equalization for Single Carrier MIMO Underwater Acoustic Communications

    Directory of Open Access Journals (Sweden)

    Zheng YahongRosa

    2010-01-01

    Full Text Available Multiple-input multiple-output (MIMO underwater acoustic (UWA channels introduce both space-time interference (STI and time-varying phase distortion for transmitted signals. In such cases, the equalized symbols produced by conventional equalizer aiming for STI cancelation suffer phase rotation and thus cannot be reliably detected. In this paper, we propose a new equalization scheme for high data rate single carrier MIMO UWA channels. Different from existing methods employing joint equalization and symbolwise phase tracking technology, the proposed scheme decouples the interference cancelation (IC operation and the phase compensation operation, leading to a generalized equalizer structure combining an IC equalizer with a phase compensator. The decoupling of the two functionalities leads to robust signal detection, which is most desirable in practical UWA applications. MIMO linear equalizer (LE is adopted to remove space-time interference, and a groupwise phase estimation and correction method is used to compensate the phase rotation. In addition, the layered space-time processing technology is adopted to enhance the equalization performance. The proposed equalization scheme is tested to be very robust with extensive experimental data collected at Kauai, Hawaii, in September 2005, and Saint Margaret's Bay, Nova Scotia, Canada, in May 2006.

  18. A Novel Quantum Covert Channel Protocol Based on Any Quantum Secure Direct Communication Scheme

    Institute of Scientific and Technical Information of China (English)

    XU Shu-Jiang; CHEN Xiu-Bo; NIU Xin-Xin; YANG Yi-Xian

    2013-01-01

    By analyzing the basic properties of unitary transformations used in a quantum secure direct communication (QSDC) protocol,we show the main idea why a covert channel can be established within any QSDC channel which employs unitary transformations to encode information.On the basis of the fact that the unitary transformations used in a QSDC protocol are secret and independent,a novel quantum covert channel protocol is proposed to transfer secret messages with unconditional security.The performance,including the imperceptibility,capacity and security of the proposed protocol are analyzed in detail.

  19. Low-sampling-rate M-ary multiple access UWB communications in multipath channels

    KAUST Repository

    Alkhodary, Mohammad T.

    2015-08-31

    The desirable characteristics of ultra-wideband (UWB) technology are challenged by formidable sampling frequency, performance degradation in the presence of multi-user interference, and complexity of the receiver due to the channel estimation process. In this paper, a low-rate-sampling technique is used to implement M-ary multiple access UWB communications, in both the detection and channel estimation stages. A novel approach is used for multiple-access-interference (MAI) cancelation for the purpose of channel estimation. Results show reasonable performance of the proposed receiver for different number of users operating many times below Nyquist rate.

  20. Fairness based channel borrowing strategy in multimedia LEO satellite communications

    Institute of Scientific and Technical Information of China (English)

    HUANG Fei; XU Hui; WU Shiqi

    2007-01-01

    A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources.It provides the network with better quality-of-service (QoS) guarantees,such as new call blocking probability (CBP) and handoff call dropping probability (CDP) in multimedia low earth orbit (LEO) satellite networks.Simulation results show that,compared with other bandwidth allocation schemes,the proposed scheme offers very low call dropping probability for real-time connections while,at the same time,keeping resource utilization high.Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods.

  1. CSR Communication - An Employee Perspective : Tailoring Internal Communication using Employee Preferences for Content, Style and Channel.

    OpenAIRE

    Jonsson, Viktoria; Linnér, Rebecka

    2016-01-01

    Corporate Social Responsibility (CSR) represents a theory and practice that is well-known and communicating its content has shown to play an important role in order to exploit its advantages and engage stakeholders on CSR issues. Even though, CSR communication has shown to be a real challenge, since corporations are encouraged to engage in CSR, but not to communicate too loud about this engagement. This study was inspired by Jenny Dawkins (2005) and her initial idea that tailoring CSR message...

  2. Experimental Evaluation of Wireless Communication Channels under Radiation Environment

    International Nuclear Information System (INIS)

    Deployment of wireless systems in nuclear power plants has attracted a lot of attention recently. However, before wireless systems can be installed in a nuclear power plant, it is necessary to evaluate the effect of radiation environment on electromagnetic wave which is the communication media for all radio wave based wireless systems. This is particular important if the wireless systems are expected to work in a harsh and radioactive environment following a severe accident. This paper presents some results of an experiment for evaluating the effect of radiation on electromagnetic wave. The experiments involve placing transmitter antenna and receiver antenna in a hot cell with variable strength of radiation to study the attenuation effects of the radioactive media. The results indicate that radiation does not effect on the electromagnetic wave propagation. This fact should be considered during the design and deployment wireless systems in a potentially radioactive environment

  3. Possible existence of optical communication channels in the brain

    CERN Document Server

    Kumar, Sourabh; Tuszynski, Jack; Barclay, Paul E; Simon, Christoph

    2016-01-01

    Given that many fundamental questions in neuroscience are still open, it seems pertinent to explore whether the brain might use other physical modalities than the ones that have been discovered so far. In particular it is well established that neurons can emit photons, which prompts the question whether these biophotons could serve as signals between neurons, in addition to the well-known electro-chemical signals. For such communication to be targeted, the photons would need to travel in waveguides. Here we show, based on detailed theoretical modeling, that myelinated axons could serve as photonic waveguides, taking into account realistic optical imperfections. We propose experiments, both \\textit{in vivo} and \\textit{in vitro}, to test our hypothesis. We discuss the implications of our results, including the question whether photons could mediate long-range quantum entanglement in the brain.

  4. Visible Light Communication Channel Models and Simulation of Coal Workface Energy Coupling

    Directory of Open Access Journals (Sweden)

    Yanrong Zhai

    2015-01-01

    Full Text Available Due to their low energy consumption and small size, visible light communication systems have been widely used to eliminate communication-blind areas in coal workfaces. A workface visible light communication channel model and a mathematic model of energy coupling from the mining machine’s workspace to its footpath were established to investigate the characteristics of optical signal transmission on the workface. This paper studies the effects of coal dust (double-layer particles encapsulated by moisture on optical signal degradation. Simulation results revealed the presence of an optimized transmitter location, which maximized the coupled energy of the two space signals due to the blocking effect of metal columns.

  5. Training sequence based channel estimation for indoor visible light communication system

    Institute of Scientific and Technical Information of China (English)

    WANG Jun-bo; JIAO Yuan; DANG Xiao-yu; CHEN Ming; XIE Xiu-xiu; CAO Ling-ling

    2011-01-01

    Channel estimation is a key technology in indoor wireless visible light communications (VLCs). Using the training se- quence (TS), this paper investigates the channel estimation in indoor wireless visible light communications. Based on the propagation and signal modulation characteristics of visible light, a link model for the indoor wireless visible light commu- nications is established. Using the model, three channel estimation methods, i.e., the correlation method, the least square (LS) method and the minimum mean square error (MMSE) method, are proposed. Moreover, the performances of the proposed three methods are evaluated by computer simulation. The results show that the performance of the correlation method is the worst, the LS method is suitable for higher signal to noise ratio (SNR), and the MMSE method obtains the best performance at the expense of highest complexity.

  6. Performance limits of energy harvesting communications under imperfect channel state information

    KAUST Repository

    Zenaidi, Mohamed Ridha

    2016-07-26

    In energy harvesting communications, the transmitters have to adapt transmission to availability of energy harvested during the course of communication. The performance of the transmission depends on the channel conditions which vary randomly due to mobility and environmental changes. In this paper, we consider the problem of power allocation taking into account the energy arrivals over time and the degree of channel state information (CSI) available at the transmitter, in order to maximize the throughput. Differently from previous work, the CSI at the transmitter is not perfect and may include estimation errors. We solve this problem with respect to the causality and energy storage constraints. We determine the optimal offline policy in the case where the channel is assumed to be perfectly known at the receiver. Also, we obtain the power policy when the transmitter has no CSI. Furthermore, we analyze the asymptotic average throughput in a system where the average recharge rate goes asymptotically to zero. © 2016 IEEE.

  7. Communicating with first year students; so many channels but is anyone listening? A Practice Report

    Directory of Open Access Journals (Sweden)

    Jason Lodge

    2010-07-01

    Full Text Available Communicating with first year students has become a far more complex prospect in the digital age. There is a lot of competition for limited attentional resources from media sources in almost endless channels. Getting important messages to students when there is so much competing information is a difficult prospect for academic and professional divisions of the university alike. Students’ preferences for these communication channels are not well understood and are constantly changing with the introduction of new technology. A first year group was surveyed about their use and preference for various sources of information. Students were generally positive about the use of social networking and other new online media but strongly preferred more established channels for official academic and administrative information. A discussion of the findings and recommendations follows.

  8. Consumer Relevant Online Communication Channels in Czech Republic in the Consumer Goods Category

    Directory of Open Access Journals (Sweden)

    Alena Farková

    2014-03-01

    Full Text Available A lot has been said and written about online communication in the past several years, and just as any new phenomenon, online communication is a disputable topic in many companies. The objective of this article is to analyse the behaviour of Czech consumers online and their preferences for the different online communication channels in the consumer goods category. We have examined what digital media are and how companies can use them, including a close examination of the Czech Internet population. As many of the research studies and data lead to different conclusions, especially concerning communication on social media, we have decided to apply the theoretical knowledge on a case of the Tassimo brand, a capsule coffee machine maker. This study lead us to the conclusion that consumer relevant online communication is about ensuring easily accessible clear information, especially via websites, reviews and recommendations, while social media play a minor role at the moment.

  9. Online Friendship Formation, Communication Channels, and Social Closeness

    Directory of Open Access Journals (Sweden)

    Ilan Talmud

    2006-03-01

    Full Text Available Studies of the quality of online social relationships are divided in their conclusions regarding the strength of social ties. Early conceptualizations described the weakness of electronic media in supporting social ties. By contrast, others have emphasized the compensating character of the Internet for specific social groups. This study investigated differences between adolescents who created online friendships and those who did not, and how far the place where a friend was met (online or face to face was related to the quality of social relationships, namely the perceived strength of social ties. Examining the dyadic friendship structure of a representative sample of Israeli adolescents, the study provides important contributions to the rapidly growing literature on online social relationships in general, and on youth networks in particular. The results support the social compensation approach to the study of online social relationship formation. The motivation for online friendship formation proved to be related to adolescents’ attempts to compensate for a lack of social support by using the Internet for communication. Furthermore, while face-to-face relationships remained highly important, for those adolescents who found in the Internet others with whom they developed intimacy, online ties were strong and meaningful. Additionally, adolescents with strong virtual ties were found to be distinctive in their social background. Our findings call for a qualification of the theoretical approach to online social ties, and imply that it is not the technology per se that obstructs or facilitates the formation of social friendship but the social embeddedness of the ties.

  10. The role of chaos in quantum communication through a dynamical dephasing channel

    CERN Document Server

    Lemos, Gabriela Barreto

    2010-01-01

    In this article we treat the subject of chaotic environments with few degrees of freedom in quantum communication by investigating a conservative dynamical map as a model of a dephasing quantum channel. When the channel's dynamics is chaotic, we investigate the model's semi-classical limit and show that the entropy exchange grows at a constant rate which depends on a single parameter (the interaction strength), analogous to stochastic models of dephasing channels. We analyze memory effects in the channel and present strong physical arguments to support that the present model is forgetful in the chaotic regime while memory effects in general cannot be ignored when channel dynamics is regular. In order to render the non-chaotic channel forgetful, it becomes necessary to apply a reset to the channel and this reset can efficiently be modeled by application of a chaotic map. We may then refer to encoding theorems (valid in the case of forgetful channels) to present evidence of a transition from noiseless to noisy ...

  11. Role of chaos in quantum communication through a dynamical dephasing channel

    Science.gov (United States)

    Lemos, Gabriela Barreto; Benenti, Giuliano

    2010-06-01

    In this article we treat the subject of chaotic environments with few degrees of freedom in quantum communication by investigating a conservative dynamical map as a model of a dephasing quantum channel. When the channel’s dynamics is chaotic, we investigate the model’s semi-classical limit and show that the entropy exchange grows at a constant rate which depends on a single parameter (the interaction strength), analogous to stochastic models of dephasing channels. We analyze memory effects in the channel and present strong physical arguments to support that the present model is forgetful in the chaotic regime while memory effects in general cannot be ignored when channel dynamics is regular. In order to render the nonchaotic channel forgetful, it becomes necessary to apply a reset to the channel and this reset can efficiently be modeled by application of a chaotic map. We may then refer to encoding theorems (valid in the case of forgetful channels) to present evidence of a transition from noiseless to noisy channel due to the environment’s transition from regular to chaotic dynamics.

  12. Five channel WDM communication using a single a:SiC-H double pin photo device

    Science.gov (United States)

    Silva, V.; Barata, M.; Louro, P.; Vieira, M. A.; Vieira, M.

    2016-09-01

    Amorphous SiC heterostructures built as a double pin device has a non linear spectral gain which is a function of the signal wavelength that impinges on its front or back surface. Illuminating the device with several single wavelength data channels in the visible spectrum allows for Wavelength Division Multiplexing (WDM) digital communication. Using fixed ultra-violet illumination at the front or back surfaces enables the recovery of the multiplexed channels. Five channels, each using a single wavelength which is modulated by a Manchester coded signal at 12,000 bps, form a frame with 1024 bits with a preamble for signal intensity and synchronisation purposes. Results show that the clustering of the received signal enables the successful recovery of the five channel data using the front and back illumination of the surfaces of the double pin photo device.

  13. Adaptive Modulation with Channel Estimation in High-Speed Packet-Based OFDM Communication Systems

    Institute of Scientific and Technical Information of China (English)

    HOU Xiao-lin; WU Jun-li; YIN Chang-chuan; YUE Guang-xin

    2004-01-01

    In this paper, adaptive modulation with channel estimation in high-speed packet-based Orthogonal Frequency Division Multiplexing (OFDM) communication systems for beyond 3G are discussed. Different adaptive modulation and channel estimation methods are presented and compared, then those methods suitable for our intended application are chosen. Conclusions can be drawn from computer simulations that with proper selection of packet length and subband width, wide subband adaptive modulation with Least Square plus Discrete-time Fourier Transform (LS-DFT) channel estimation can give an acceptable performance with low complexity for channel with low Doppler shift and small path delay. Otherwise, narrow subband or subcarrier adaptive modulation together with LS-DFT plus Decision Directed (LS-DFT-DD) must be used.

  14. A tone-aided dual vestigial sideband system for digital communications on fading channels

    Science.gov (United States)

    Hladik, Stephen M.; Saulnier, Gary J.; Rafferty, William

    1989-01-01

    A spectrally efficient tone-aided dual vestigial sideband (TA/DVSB) system for digital data communications on fading channels is presented and described analytically. This PSK (phase-shift-keying) system incorporates a feed-forward, tone-aided demodulation technique to compensate for Doppler frequency shift and channel- induced, multipath fading. In contrast to other tone-in-band-type systems, receiver synchronization is derived from the complete data VSBs. Simulation results for the Rician fading channel are presented. These results demonstrate the receiver's ability to mitigate performance degradation due to fading and to obtain proper data carrier synchronization, suggesting that the proposed TA/DVSB system has promise for this application. Simulated BER (bit-error rate) data indicate that the TA/DVSB system effectively alleviates the channel distortions of the land mobile satellite application.

  15. Channel modelling and performance analysis of V2I communication systems in blind bend scattering environments

    KAUST Repository

    Chelli, Ali

    2014-01-01

    In this paper, we derive a new geometrical blind bend scattering model for vehicle-to- infrastructure (V2I) communications. The proposed model takes into account single-bounce and double- bounce scattering stemming from fixed scatterers located on both sides of a curved street. Starting from the geometrical blind bend model, the exact expression of the angle of departure (AOD) is derived. Based on this expression, the probability density function (PDF) of the AOD and the Doppler power spectrum are determined. Analytical expressions for the channel gain and the temporal autocorrelation function (ACF) are provided under non-line-of-sight (NLOS) conditions. Additionally, we investigate the impact of the position of transmitting vehicle relatively to the receiving road-side unit on the channel statistics. Moreover, we study the performance of different digital modulations over a sum of singly and doubly scattered (SSDS) channel. Note that the proposed V2I channel model falls under the umbrella of SSDS channels since the transmitted signal undergoes a combination of single-bounce and double-bounce scattering. We study some characteristic quantities of SSDS channels and derive expressions for the average symbol error probability of several modulation schemes over SSDS channels with and without diversity combining. The validity of these analytical expressions is confirmed by computer-based simulations.

  16. New coherent laser communication detection scheme based on channel-switching method.

    Science.gov (United States)

    Liu, Fuchuan; Sun, Jianfeng; Ma, Xiaoping; Hou, Peipei; Cai, Guangyu; Sun, Zhiwei; Lu, Zhiyong; Liu, Liren

    2015-04-01

    A new coherent laser communication detection scheme based on the channel-switching method is proposed. The detection front end of this scheme comprises a 90° optical hybrid and two balanced photodetectors which outputs the in-phase (I) channel and quadrature-phase (Q) channel signal current, respectively. With this method, the ultrahigh speed analog/digital transform of the signal of the I or Q channel is not required. The phase error between the signal and local lasers is obtained by simple analog circuit. Using the phase error signal, the signals of the I/Q channel are switched alternately. The principle of this detection scheme is presented. Moreover, the comparison of the sensitivity of this scheme with that of homodyne detection with an optical phase-locked loop is discussed. An experimental setup was constructed to verify the proposed detection scheme. The offline processing procedure and results are presented. This scheme could be realized through simple structure and has potential applications in cost-effective high-speed laser communication. PMID:25967184

  17. Research on Power Line as Communication Channel with Multi-Tap and Multi-Branch Configuration

    Directory of Open Access Journals (Sweden)

    Yanhua Zheng

    2013-12-01

    Full Text Available To study the effect of different branch configuration on transmission characteristic in-home low-voltage (LV communication power line communication (PLC channel, the influences of branch length, number of branch and tap, and branch terminal impedance on the performance of PLC are investigated. The two type power line network structures of the one-tap with multi-branch (OTMB and the multi-tap with multi-branch (MTMB are studied. The transmission characteristics of the PLC channel are simulated by varying the length and terminal impedance of the branch for two configurations. Simulation results show that the length and terminal impedance of the branch have significant influence on the amplitude and phase response of the transfer function. The position and number of notches and crests in the amplitude responses are affected by different branch types and the configurations of branch length and branch terminal impedance. The models developed in this paper can easily handle an arbitrary topology of power line channel and provide accurate calculation for the channel responses of the all kinds of channel branch structures in indoor LV power line network

  18. A training-based scheme for communicating over unknown channels with feedback

    CERN Document Server

    Mahajan, Aditya

    2009-01-01

    We consider communication with noiseless feedback over a channel that is either BSC(p) or BSC(1-p); neither the transmitter nor the receiver know which one. The parameter $p \\in [0, 1/2]$ is known to both. We propose a variable length training-based scheme for this channel. The error exponent of this scheme is within a constant fraction of the best possible error exponent. Thus, contrary to popular belief, variable length training-based schemes need not have poor error exponents. Moreover, training-based schemes can preserve the main advantage of feedback -- an error exponent with non-zero slope at rates close to capacity.

  19. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    Aitor del Coso

    2007-11-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of N wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, 𝒞=log⁡2(W0(N. Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  20. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    del Coso Aitor

    2007-01-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, . Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  1. PInCom project: SaaS Big Data Platform for and Communication Channels

    Directory of Open Access Journals (Sweden)

    Juan Manuel Lombardo

    2016-03-01

    Full Text Available The problem of optimization will be addressed in this article, based on the premise that the successful implementation of Big Data solutions requires as a determining factor not only effective -it is assumed- but the efficiency of the responsiveness of management information get the best value offered by the digital and technological environment for gaining knowledge. In adopting Big Data strategies should be identified storage technologies and appropriate extraction to enable professionals and companies from different sectors to realize the full potential of the data. A success story is the solution PInCom: Intelligent-Communications Platform that aims customer loyalty by sending multimedia communications across heterogeneous transmission channels.

  2. Joint source-channel coding for wireless object-based video communications utilizing data hiding.

    Science.gov (United States)

    Wang, Haohong; Tsaftaris, Sotirios A; Katsaggelos, Aggelos K

    2006-08-01

    In recent years, joint source-channel coding for multimedia communications has gained increased popularity. However, very limited work has been conducted to address the problem of joint source-channel coding for object-based video. In this paper, we propose a data hiding scheme that improves the error resilience of object-based video by adaptively embedding the shape and motion information into the texture data. Within a rate-distortion theoretical framework, the source coding, channel coding, data embedding, and decoder error concealment are jointly optimized based on knowledge of the transmission channel conditions. Our goal is to achieve the best video quality as expressed by the minimum total expected distortion. The optimization problem is solved using Lagrangian relaxation and dynamic programming. The performance of the proposed scheme is tested using simulations of a Rayleigh-fading wireless channel, and the algorithm is implemented based on the MPEG-4 verification model. Experimental results indicate that the proposed hybrid source-channel coding scheme significantly outperforms methods without data hiding or unequal error protection.

  3. Investigation of Channel Modeling and Simulation of OFDM Based Communication Near Northern Regions of Arabian Sea

    Directory of Open Access Journals (Sweden)

    Rehan Khan

    2013-02-01

    Full Text Available Wideband nature of oceanic channel when dealing with multicarrier acoustic subcarriers introduces severe Doppler shifts, little variations may cause overlapping of subcarriers such that entire signal can get completely distorted. Therefore, one of the major problems in OFDM based underwater acoustic communication is the sensitive nature of wideband acoustic subcarriers. In this study, Bellhop beam tracing is used to model two regions in the north of Arabian Sea and the two-step receiver algorithm is used over these channel models. Multipath with delay channel model is obtained using the Bellhop ray tracing algorithm while random Doppler shift is induced in MATLAB on each block and also in the complete OFDM packet. In the first step, resembling converts a wideband problem in to narrowband problem and in the second step; high resolution Carrier Offset Frequency (CFO tracking compensates the residual Doppler. Cyclic Prefix (CP OFDM scheme based on block-by-block processing is deliberated here for fast varying channel. In the proposed algorithm, null subcarriers are facilitated for Doppler removal while pilot bits are used for Least Square (LS channel estimation. Simulation on MATLAB is carried out on both channels, i.e., near Gawadar Coast and Karachi Harbor; satisfactory results are achieved in terms Low Bit Error Rates (BER even in high relative speed between transmitter and receiver. These results further suggested and make convinced for the experimental test/ trials, specifically in the region of north Arabian Sea.

  4. Multiphoton communication in lossy channels with photon-number entangled states

    CERN Document Server

    Usenko, V C; Paris, Matteo G. A.; Usenko, Vladyslav C.

    2006-01-01

    We address M-ary communication channels based on correlated multiphoton two-mode states of radiation in the presence of losses. In particular, we focus on channels build using feasible photon-number entangled states (PNES) as two-mode coherently-correlated (TMC) or twin-beam (TWB) states and compare their performances with that of channels built using feasible classically correlated (separable) states. We found that PNES provide larger channel capacity in the presence of loss, and that TWB-based channels may transmit a larger amount of information than TMC-based ones at fixed energy and overall loss. Optimized bit discrimination thresholds, as well as the corresponding maximized mutual information, are explicitly evaluated as a function of the beam intensity and the loss parameter for binary and quaternary alphabets. The propagation of TMC and TWB in lossy channels is analyzed and the joint photon number distribution is evaluated, showing that the beam statistics, either sub-Poissonian for TMC or super-Poisso...

  5. Preprocessing communication unit (PCU) with short message service (SMS) communication channels for AVL tracking

    Science.gov (United States)

    Young, Andrew S.; Skobla, Joseph

    2003-08-01

    The Preprocessing GPS - SMS Communication Unit (PCU) is a mobile tracking device used within AVL tracking systems for determining the location of vehicles. It was designed primarily to utilize the SMS service of the GSM network for communicating. The use of SMS messages is part of an effort aimed at providing a cost effective alternative for tracking the location of vehicles. Its primary function is to send information about user location across a GSM network to a Central Base Station (CBS) from which assets are being tracked. Though SMS is the main bearer, the unit is also capable of using Circuit Switch Data Service (CSD) to send and receive data from the Base Station (BS). The PCU was developed as a small hardware unit based on the Microchip microcontroller, with a multiplexer switching two RS 232 serial inputs. One input is dedicated to the GPS receiver and the second one to the wireless modem.

  6. Modelling of disturbing efects within communication channel for safety-related communication system

    OpenAIRE

    Maria Franekova; Karol Rastocny

    2007-01-01

    The aim of the paper is using of modelling within development of safety–related communication systems presented in the areas where guaranty of safety integrity level is required. In the paper basic principles used in the process of safety evaluation in closed transmission systems are summarised. Dangerous states of system are mainly caused by random failures of HW within non-trusted transmission system, by electromagnetic interference caused with noise or interferences and by systematic failu...

  7. Channel Equalization and Beamforming for Quaternion-Valued Wireless Communication Systems

    OpenAIRE

    Liu, Wei

    2015-01-01

    Quaternion-valued wireless communication systems have been studied in the past. Although progress has been made in this promising area, a crucial missing link is lack of effective and efficient quaternion-valued signal processing algorithms for channel equalization and beamforming. With most recent developments in quaternion-valued signal processing, in this work, we fill the gap to solve the problem by studying two quaternion-valued adaptive algorithms: one is the reference signal based quat...

  8. The application of Internet marketing communication channels in increasing brand awareness : Lipton case

    OpenAIRE

    Kisurina, Anastasiya

    2013-01-01

    The main objective of the research was to analyse the most effective and prospective e-marketing communication channels that would be of great importance in planning brand promotion campaigns in 2013 and several years ahead. The research was based on the case campaign study for Lipton, with the company-employer full service digital marketing agency situated in Moscow, Russia – Nectarin. The thesis consists of four main parts through which a reader can promote his knowledge on the current...

  9. Reasoning About Information Flow Security of Separation Kernels with Channel-based Communication

    OpenAIRE

    Zhao, Yongwang; Sann, David; Zhang, Fuyuan; Liu, Yang

    2015-01-01

    Assurance of information flow security by formal methods is mandated in security certification of separation kernels. As an industrial standard for separation kernels, ARINC 653 has been complied with by mainstream separation kernels. Security of functionalities defined in ARINC 653 is thus very important for the development and certification of separation kernels. This paper presents the first effort to formally specify and verify separation kernels with ARINC 653 channel-based communication...

  10. Communication channels with All-inclusive hostel of Selina in Panama

    OpenAIRE

    Dinh, Huong

    2016-01-01

    The purpose of this thesis was to introducing the newly innovative concept “All-inclusive hostel” applying by Selina Hostel in Panama. Based on the scenario, the paper aims to focus on Panamanian hospitality industry, which is defined as a heaven for entrepreneurs. Since the concept is completely new, communication channels act as an important role for the case company to market its concept which is the last but not least objective of the paper. The theoretical part includes qualitative r...

  11. A channel- and QoS-adaptive turbo coded modulation architecture for mobile multimedia communication

    Institute of Scientific and Technical Information of China (English)

    Zuo Jiancun; Song Wentao; Luo Hanwen; Xu Youyun

    2009-01-01

    This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile multimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service (QoS) of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.

  12. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    KAUST Repository

    Yang, Liang

    2014-04-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min{α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link.

  13. Channel estimation for asymmetrically clipped optical orthogonal frequency division multiplexing communication system

    Science.gov (United States)

    Zhao, Hui; Li, Minghui; Wang, Ruyan; Wu, Dapeng

    2013-07-01

    The channel estimation problem for asymmetrically clipped optical orthogonal frequency division multiplexing wireless communication systems is investigated. In order to resolve the noise-sensitive problem of traditional least squares-based channel estimation method, a new channel estimation method which is based on superimposed training sequence and guarantees the linear minimum mean square error estimate is proposed. Cycle training sequence is added at variable power ratio to the information sequence at the transmitter prior to transmission. Then, statistical average method is employed to separate training and information sequences at the receiver. Simulation results show that the power ratio of training sequence needs to balance between the mean square error (MSE) of estimation and the error bit rate. Moreover, compared with the traditional least squares-based method, the proposed method has significantly improved the estimation performance under the condition of low signal-to-noise ratio, especially, when the MSE of the estimation reduces 1 to 2 orders.

  14. What does Big Data tell? Sampling the social network by communication channels

    CERN Document Server

    Török, János; Jo, Hang-Hyun; Kertész, János; Kaski, Kimmo

    2015-01-01

    Big Data has become the primary source of understanding the structure and dynamics of the society at large scale. The network of social interactions can be considered as a multiplex, where each layer corresponds to one communication channel and the aggregate of all them constitutes the entire social network. However, usually one has information only about one of the channels, which should be considered as a sample of the whole. Here we show by simulations and analytical methods that this sampling may lead to bias. For example, while it is expected that the degree distribution of the whole social network has a maximum at a value larger than one, we get with reasonable assumptions about the sampling process a monotonously decreasing distribution as observed in empirical studies of single channel data. Also we find, that assortativity may occur or get strengthened due to the sampling process. We analyze the far-reaching consequences of our findings.

  15. Mothers "Google It Up:" Extending Communication Channel Behavior in Diffusion of Innovations Theory.

    Science.gov (United States)

    Sundstrom, Beth

    2016-01-01

    This study employed qualitative methods, conducting 44 in-depth interviews with biological mothers of newborns to understand women's perceptions and use of new media, mass media, and interpersonal communication channels in relation to health issues. Findings contribute to theoretical and practical understandings of the role of communication channels in diffusion of innovations theory. In particular, this study provides a foundation for the use of qualitative research to advance applications of diffusion of innovations theory. Results suggest that participants resisted mass media portrayals of women's health. When faced with a health question, participants uniformly started with the Internet to "Google it up." Findings suggest new media comprise a new communication channel with new rules, serving the functions of both personal and impersonal influence. In particular, pregnancy and the postpartum period emerged as a time when campaign planners can access women in new ways online. As a result, campaign planners could benefit from introducing new ideas online and capitalizing on the strength of weak ties favored in new media. Results expand the innovativeness/needs paradox in diffusion of innovations theory by elaborating on the role of new media to reach underserved populations. These findings provide an opportunity to better understand patient information seeking through the lens of diffusion of innovations theory.

  16. Designing Effective Persuasive Systems Utilizing the Power of Entanglement: Communication Channel, Strategy and Affect

    Science.gov (United States)

    Li, Haiqing; Chatterjee, Samir

    With rapid advances in information and communication technology, computer-mediated communication (CMC) technologies are utilizing multiple IT platforms such as email, websites, cell-phones/PDAs, social networking sites, and gaming environments. However, no studies have compared the effectiveness of a persuasive system using such alternative channels and various persuasive techniques. Moreover, how affective computing impacts the effectiveness of persuasive systems is not clear. This study proposes (1) persuasive technology channels in combination with persuasive strategies will have different persuasive effectiveness; (2) Adding positive emotion to a message that leads to a better overall user experience could increase persuasive effectiveness. The affective computing or emotion information was added to the experiment using emoticons. The initial results of a pilot study show that computer-mediated communication channels along with various persuasive strategies can affect the persuasive effectiveness to varying degrees. These results also shows that adding a positive emoticon to a message leads to a better user experience which increases the overall persuasive effectiveness of a system.

  17. Application of Recurrent Wavelet Neural Networks to the Digital Communications Channel Blind Equalization

    Institute of Scientific and Technical Information of China (English)

    HeShichun; HeZhenya

    1997-01-01

    This paper investigates the application of a Recurrent Wavelet Neural Network(RWNN)to the blind equalization of nonlinear communication channels.In contrast to the wavelet networks introduced in,the RWNN is well suited for use in real time adaptive signal processing.Furthermore,the RWNN has the advantage that a priori information of the underlying system need not be known,the dynamics of the system are configured in the recurrent connections and the network approximates the system over time.An RWNN based structure and a novel training approach for blind equalization was proposed and its performance evaluated via computer simulations for nolnlinear communication channel model.It is shown that the RWNN blind equalizer performs much better than the linear Constant Modulus Algorithm(CMA) and the Recurrent Radial Basis Function(RRBF) Networks based blind equalizers in nonlinear channel case.The small size and high performance of the RWNN equalizer make it suitable for high speed channel blind equalization.

  18. On the outage capacity of the block fading channel at low-power regime

    KAUST Repository

    Rezki, Zouheir

    2014-06-01

    Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated at low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a short-term power constraint. We show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. © 2014 IEEE.

  19. A Survey of Channel Measurements and Models for Current and Future Railway Communication Systems

    Directory of Open Access Journals (Sweden)

    Paul Unterhuber

    2016-01-01

    Full Text Available Modern society demands cheap, more efficient, and safer public transport. These enhancements, especially an increase in efficiency and safety, are accompanied by huge amounts of data traffic that need to be handled by wireless communication systems. Hence, wireless communications inside and outside trains are key technologies to achieve these efficiency and safety goals for railway operators in a cost-efficient manner. This paper briefly describes nowadays used wireless technologies in the railway domain and points out possible directions for future wireless systems. Channel measurements and models for wireless propagation are surveyed and their suitability in railway environments is investigated. Identified gaps are pointed out and solutions to fill those gaps for wireless communication links in railway environments are proposed.

  20. Cryptography and Authentication Placement to Provide Secure Channel for SCADA Communication

    Directory of Open Access Journals (Sweden)

    AAmir Shahzad

    2012-06-01

    Full Text Available Supervisory control and data acquisition (SCADA systems and Distributed control systems (DCS were developed to reduce labor costs, and to allow system-wide monitoring and remote control from a central location. Control systems are widely used in critical infrastructures such as electric grid, natural gas, water, and wastewater industries. While control systems can be vulnerable to a variety of types of cyber attacks that could have devastating consequences, however, little attention is given to security considerations in the initial design and deployment of these systems, which has caused an urgent need to upgrade existing systems to withstand unauthorized intrusions potentially leading to communication attacks [1]. The current paper take a Hybrid-based Cryptography (combination of Symmetric AES and Asymmetric RSA solution to enable confidentiality and authentication placed at each end of SCADA communication and provides secure channel for communication between MTU Terminal Unit (MTU to Remote Terminal Units (RTUs and/or RTUs to MTU.

  1. Cryptography and Authentication Placement to Provide Secure Channel for SCADA Communication

    Directory of Open Access Journals (Sweden)

    AAmir Shahzad

    2012-06-01

    Full Text Available Supervisory Control and Data Acquisition (SCADA systems are real-time process controlsystems that are widely deployed throughout critical infrastructure sectors including power, gas,oil, railroads and water. . However, little attention is given to security considerations in the initialdesign and deployment of these systems, which has caused an urgent need to upgrade existingsystems to withstand unauthorized intrusions potentially leading to communication attacks [1].The current paper take a Hybrid-based Cryptography (combination of Symmetric AES andAsymmetric RSA solution to enable confidentiality and authentication placed at each end ofSCADA communication and provides secure channel for communication between MasterTerminal Unit (MTU to Remote Terminal Units (RTUs and/or RTUs to MTU.

  2. EVALUATION OF BER FOR VARIOUS FADING CHANNEL IN DWT BASED MIMO-OFDM SYSTEM

    Directory of Open Access Journals (Sweden)

    D. Meenakshi

    2013-04-01

    Full Text Available MIMO communication is mainly use in the OFDM to improve the communication performance and capacity. DWT based MIMO-OFDM is used in this paper. Compare to the FFT based MIMO-OFDM it has lot advantages. There is no need for cyclic prefix, flexibility and optimal resolution. Ripple(Wavelet concept has developed as a fresh scientific implement with the aim of preserve be functional in several applications such as processing of image, biomedical manufacturing, radar, physics, organize systems also message systems. The essential region of purpose of ripples in communication system: numerous accesses. A fresh modulation/multiplexing scheme consuming ripple transform remained planned for (3rd production organization project 3GPP systems. This fresh modulation system implemented in (orthogonal frequency division multiplexing OFDM scheme in addition to conventional based(FFT transform blocks is replaced by wavelet transform blocks. There are many multiplicity of ripple transforms are offered, out of which four were chosen. They are Haar, Daubechies, Bi-orthogonal and reverse Bi-orthogonal transforms. Haar wavelet is best one of among all types of wavelet. The performance of DWT based MIMO-OFDM is calculated by bit error rate (BER in various channel that is AWGN channel and Rayleigh channel. Using MATLAB-Simulation which channel is best for the DWT based MIMO-OFDM.

  3. Channel capacity and receiver deployment optimization for multi-input multi-output visible light communications.

    Science.gov (United States)

    Wang, Jin-Yuan; Dai, Jianxin; Guan, Rui; Jia, Linqiong; Wang, Yongjin; Chen, Ming

    2016-06-13

    Multi-input multi-output (MIMO) technique is attractive for visible light communication (VLC), which exploits the high signal-to-noise ratio (SNR) of a single channel to overcome the capacity limitation due to the small modulation bandwidth of the light emitting diode. This paper establishes a MIMO VLC system under the non-negativity, peak power and dimmable average power constraints. Assume that perfect channel state information at the transmitter is known, the MIMO channel is changed to parallel, non-interfering sub-channels by using the singular value decomposition (SVD). Based on the SVD, the lower bound on the channel capacity for MIMO VLC is derived by employing entropy power inequality and variational method. Moreover, by maximizing the derived lower bound on the capacity under the given constraints, the receiver deployment optimization problem is formulated. The problem is solved by employing the principle of particle swarm optimization. Numerical results verify the derived capacity bound and the proposed deployment optimization scheme. PMID:27410325

  4. Channel capacity and receiver deployment optimization for multi-input multi-output visible light communications.

    Science.gov (United States)

    Wang, Jin-Yuan; Dai, Jianxin; Guan, Rui; Jia, Linqiong; Wang, Yongjin; Chen, Ming

    2016-06-13

    Multi-input multi-output (MIMO) technique is attractive for visible light communication (VLC), which exploits the high signal-to-noise ratio (SNR) of a single channel to overcome the capacity limitation due to the small modulation bandwidth of the light emitting diode. This paper establishes a MIMO VLC system under the non-negativity, peak power and dimmable average power constraints. Assume that perfect channel state information at the transmitter is known, the MIMO channel is changed to parallel, non-interfering sub-channels by using the singular value decomposition (SVD). Based on the SVD, the lower bound on the channel capacity for MIMO VLC is derived by employing entropy power inequality and variational method. Moreover, by maximizing the derived lower bound on the capacity under the given constraints, the receiver deployment optimization problem is formulated. The problem is solved by employing the principle of particle swarm optimization. Numerical results verify the derived capacity bound and the proposed deployment optimization scheme.

  5. A Comprehensive Study and Performance Comparison of M-ary Modulation Schemes for an Efficient Wireless Mobile Communication System

    CERN Document Server

    Haque, Md Emdadul; Kabir, M Hasnat

    2012-01-01

    Wireless communications has become one of the fastest growing areas in our modern life and creates enormous impact on nearly every feature of our daily life. In this paper, the performance of M-ary modulations schemes (MPSK, MQAM, MFSK) based wireless communication system on audio signal transmission over Additive Gaussian Noise (AWGN) channel are analyzed in terms of bit error probability as a function of SNR. Based on the results obtained in the present study, MPSK and MQAM are showing better performance for lower modulation order whereas these are inferior with higher M. The BER value is smaller in MFSK for higher M, but it is worse due to the distortion in the reproduce signal at the receiver end. The lossless reproduction of recorded voice signal can be achieved at the receiver end with a lower modulation order.

  6. Corporate Social Responsibility : Effects of CSR in the introduction of new products and services: the role of communication channels

    OpenAIRE

    Xia, Jane

    2010-01-01

    This paper identifies the variables to why the effectiveness of CSR when introducing new products and services is different based on choice of communication channels; PR and advertising. This study was achieved by means of a questionnaire of 119 students at Norwegian School of Economics and Business Administration. Previous empirical studies have revealed that the choice of communication channel can present different effects to consumers, and it is established that PR has a stronger effect...

  7. The Effect of Information Sources and Communication Channels on the diffusion of Innovation in a Data Base Development Environment

    OpenAIRE

    Sree Nilakanta; Richard W. Scamell

    1990-01-01

    Increasing importance of emerging information technology, especially the data base component, has prompted the examination of the process of diffusion of innovations in the context of data base system development. This paper (1) examines the extent to which information sources and communication channels facilitate the diffusion of data base design tools and techniques, (2) studies how different information sources and communication channels influence diffusion and (3) assesses whether data ba...

  8. NEW BINARY USER CODES FOR DS CDMA COMMUNICATION

    Directory of Open Access Journals (Sweden)

    NEELAM SRIVASTAVA

    2011-12-01

    Full Text Available Spread spectrum (SS is a modulation technique in which the signal occupies a bandwidth much larger than the minimum necessary to send the information. A synchronized reception with the code at the receiver is used for despreading the information before data recovery. From a long period, Walsh codes and Gold codes have been used as spread spectrum codes in Code Division Multiple Access (CDMA communications because of their ease of generation than the efficiency of these codes. Walsh codes are perfectly orthogonal binary user codes that have many popular applications in synchronous multicarrier communications although they perform poorly for asynchronous multi-user communications. Therefore, the nearly orthogonal Gold codes with their superior performance are the preferred user codes in asynchronous CDMA communications with small number of simultaneous users in the system due to their good auto-correlation (intracode correlation and cross-correlation (inter-code properties. Major drawback of these codes is that they are limited in number and in their lengths. In this paper, we performed MATLAB (7.1version algorithm to obtain the new orthogonal sets of binary space for multiuser spread-spectrum communications. We compared their performance with existing codes like Gold and Walsh code families. Our comparisons include their time domain properties like auto and cross-correlations along with bit error rate (BER performances in additive white Gaussian noise (AWGN and Rayleigh channel for the synchronous and asynchronous DS-CDMA communications. It is shown that these codes outperform the Walsh codes significantly and they match in performance with the popular nearly orthogonal Gold codes closely for asynchronous multiuser communications in AWGN noise. It is also shown that all of the binary code families considered performed comparable for Rayleigh flat-fading channels. So these new codes can be used both for asynchronous and synchronous direct sequence

  9. Multicarrier Communications Based on the Affine Fourier Transform in Doubly-Dispersive Channels

    Directory of Open Access Journals (Sweden)

    Djurović Igor

    2010-01-01

    Full Text Available The affine Fourier transform (AFT, a general formulation of chirp transforms, has been recently proposed for use in multicarrier communications. The AFT-based multicarrier (AFT-MC system can be considered as a generalization of the orthogonal frequency division multiplexing (OFDM, frequently used in modern wireless communications. AFT-MC keeps all important properties of OFDM and, in addition, gives a new degree of freedom in suppressing interference caused by Doppler spreading in time-varying multipath channels. We present a general interference analysis of the AFT-MC system that models both time and frequency dispersion effects. Upper and lower bounds on interference power are given, followed by interference power approximation that significantly simplifies interference analysis. The optimal parameters are obtained in the closed form followed by the analysis of the effects of synchronization errors and the optimal symbol period. A detailed interference analysis and optimal parameters are given for different aeronautical and land-mobile satellite (LMS channel scenarios. It is shown that the AFT-MC system is able to match changes in these channels and efficiently reduce interference with high-spectral efficiency.

  10. Energy Efficient and Performance Analysis of Multihop Wireless Communication Over Nakagami-m Fading Channel

    KAUST Repository

    Randrianantenaina, Itsikiantsoa

    2015-06-01

    The concept of multihop communications (where the source communicates with the destination via many intermediate nodes) has been revisited and adapted to mitigate wireless channel impairments and ensure broader coverage. It has been shown in the literature that, in addition to extending coverage, overcoming shadowing and reducing the transmit power, multihop communications can increase the capacity of the network at a low additional cost. On the other hand, the problem of energy efficiency is one of the current biggest challenges towards green radio communications. Morevover, electromagnetic radiation is at its limit in many contexts, while for battery-powered devices, transmit and circuit energy consumption has to be minimized for better battery lifetime and performance. In this work, the performance of multihop communication over Nakagami-m fading is investigated for both cases without and with diversity combining. Closed form expressions of the average ergodic capacity are derived for each of these cases. Then, an expression of the outage probability is obtained using the inverse of Laplace transform and the average bit error rate is bounded using the Moment-Generating-Function approach. The energy efficiency is analyzed using the "consumption factor" as a metric, and it is derived in closed-form. And based on the obtained expressions, we propose a power allocation strategy maximizing this consumption factor.

  11. Ultrasonic Digital Communication System for a Steel Wall Multipath Channel: Methods and Results

    Energy Technology Data Exchange (ETDEWEB)

    TL Murphy

    2006-02-16

    As of the development of this thesis, no commercially available products have been identified for the digital communication of instrumented data across a thick ({approx} 6 n.) steel wall using ultrasound. The specific goal of the current research is to investigate the application of methods for digital communication of instrumented data (i.e., temperature, voltage, etc.) across the wall of a steel pressure vessel. The acoustic transmission of data using ultrasonic transducers prevents the need to breach the wall of such a pressure vessel which could ultimately affect its safety or lifespan, or void the homogeneity of an experiment under test. Actual digital communication paradigms are introduced and implemented for the successful dissemination of data across such a wall utilizing solely an acoustic ultrasonic link. The first, dubbed the ''single-hop'' configuration, can communicate bursts of digital data one-way across the wall using the Differential Binary Phase-Shift Keying (DBPSK) modulation technique as fast as 500 bps. The second, dubbed the ''double-hop'' configuration, transmits a carrier into the vessel, modulates it, and retransmits it externally. Using a pulsed carrier with Pulse Amplitude Modulation (PAM), this technique can communicate digital data as fast as 500 bps. Using a CW carrier, Least Mean-Squared (LMS) adaptive interference suppression, and DBPSK, this method can communicate data as fast as 5 kbps. A third technique, dubbed the ''reflected-power'' configuration, communicates digital data by modulating a pulsed carrier by varying the acoustic impedance at the internal transducer-wall interface. The paradigms of the latter two configurations are believed to be unique. All modulation methods are based on the premise that the wall cannot be breached in any way and can therefore be viably implemented with power delivered wirelessly through the acoustic channel using ultrasound. Methods

  12. Bidirectional MIMO Channel Tracking Based on PASTd and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Shayevitz Ofer

    2010-01-01

    Full Text Available Abstract We consider a bidirectional time division duplex (TDD multiple-input multiple-output (MIMO communication system with time-varying channel and additive white Gaussian noise (AWGN. A blind bidirectional channel tracking algorithm, based on the projection approximation subspace tracking (PAST algorithm, is applied in both terminals. The resulting singular value decomposition (SVD of the channel matrix is then used to approximately diagonalize the channel. The proposed method is applied to an orthogonal frequency-division multiplexing-(OFDM-MIMO setting with a typical indoor time-domain reflection model. The computational cost of the proposed algorithm, compared with other state-of-the-art algorithms, is relatively small. The Kalman filter is utilized for establishing a benchmark for the obtained performance of the proposed tracking algorithm. The performance degradation relative to a full channel state information (CSI due to the application of the tracking algorithm is evaluated in terms of average effective rate and the outage probability and compared with alternative tracking algorithms. The obtained results are also compared with a benchmark obtained by the Kalman filter with known input signal and channel characteristics. It is shown that the expected degradation in performance of frequency-domain algorithms (which do not exploit the smooth frequency response of the channel is only minor compared with time-domain algorithms in a range of reasonable signal-to-noise ratio (SNR levels. The proposed bidirectional frequency-domain tracking algorithm, proposed in this paper, is shown to attain communication rates close to the benchmark and to outperform a competing algorithm. The paper is concluded by evaluating the proposed blind tracking method in terms of the outage probability and the symbol error rate (SER versus. SNR for binary phase shift keying (BPSK and 4-Quadrature amplitude modulation (QAM constellations.

  13. Cooperative jamming power control to enhance secrecy communications of AF Relaying systems for Rayleigh fading channel

    KAUST Repository

    Park, Kihong

    2012-09-01

    In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods. © 2012 IEEE.

  14. A clustering technique for digital communications channel equalization using radial basis function networks.

    Science.gov (United States)

    Chen, S; Mulgrew, B; Grant, P M

    1993-01-01

    The application of a radial basis function network to digital communications channel equalization is examined. It is shown that the radial basis function network has an identical structure to the optimal Bayesian symbol-decision equalizer solution and, therefore, can be employed to implement the Bayesian equalizer. The training of a radial basis function network to realize the Bayesian equalization solution can be achieved efficiently using a simple and robust supervised clustering algorithm. During data transmission a decision-directed version of the clustering algorithm enables the radial basis function network to track a slowly time-varying environment. Moreover, the clustering scheme provides an automatic compensation for nonlinear channel and equipment distortion. Computer simulations are included to illustrate the analytical results.

  15. Joint Relay Selection and Power Allocation for Cooperative Communication over Frequency Selective Fading Channels

    Directory of Open Access Journals (Sweden)

    Youhua Ma

    2012-08-01

    Full Text Available In this paper, we consider the joint problem of relay selection and optimal power allocation for multi-relay amplify-and-forward (AF cooperative communication system over frequency selective fading channels. An optimization model combined relay selection and power allocation under a total transmission power budget is formulated. Then, this combinatorial problem is solved in a distributed strategy. Relay selection with a new threshold-based multiple-relay selection (MRS scheme is implemented at first, and then power is allocated between source and the selected relays in an optimized way to maximize channel capacity. Simulation result shows that the proposed joint scenario with relay selection and power allocation achieves better throughput performance than that of parallel-relay scenario (means that random relay is selected to forward data and allocated part of total power on average. Furthermore, the performances of the new MRS scheme and other relay selection strategies are also investigated.

  16. On the Performance Analysis of Digital Communications over Weibull-Gamma Channels

    KAUST Repository

    Ansari, Imran Shafique

    2015-05-01

    In this work, the performance analysis of digital communications over a composite Weibull-Gamma (WG) multipath-fading and shadowing channel is presented wherein WG distribution is appropriate for modeling fading environments when multipath is superimposed on shadowing. More specifically, in this work, exact closed-form expressions are derived for the probability density function, the cumulative distribution function, the moment generating function, and the moments of a composite WG channel. Capitalizing on these results, new exact closed-form expressions are offered for the outage probability, the higher- order amount of fading, the average error rate for binary and M-ary modulation schemes, and the ergodic capacity under various types of transmission policies, mostly in terms of Meijer\\'s G functions. These new analytical results were also verified via computer-based Monte-Carlo simulation results. © 2015 IEEE.

  17. Evaluation of a 2-Channel NIRS-Based Optical Brain Switch for Motor Disabilities' Communication Tools

    Science.gov (United States)

    Sagara, Kazuhiko; Kido, Kunihiko

    We have developed a portable NIRS-based optical BCI system that features a non-invasive, facile probe attachment and does not require muscle movement to control the target devices. The system consists of a 2-channel probe, a signal-processing unit, and an infrared-emission device, which measures the blood volume change in the participant's prefrontal cortex in a real time. We use the threshold logic as a switching technology, which transmits a control signal to a target device when the electrical waveforms exceed the pre-defined threshold. Eight healthy volunteers participated in the experiments and they could change the television channel or control the movement of a toy robot with average switching times of 11.5±5.3s and the hit rate was 83.3%. These trials suggest that this system provides a novel communication aid for people with motor disabilities.

  18. Adoption of ICT in Science Education: A Case Study of Communication Channels in a Teachers' Professional Development Project

    Science.gov (United States)

    Juuti, Kalle; Lavonen, Jari; Aksela, Maija; Meisalo, Veijo

    2009-01-01

    This paper analyses the use of various communication channels in science teachers' professional development project aiming to develop versatile uses for ICT (Information and Communication Technologies) in science teaching. A teacher network was created specifically for this project, and the researchers facilitated three forms of communication…

  19. Adaptivity and Reconfigurability in Wireless Communications

    OpenAIRE

    Rauwerda, G.K.; Smit, G.J.M.

    2003-01-01

    A key issue of future wireless communication systems is that they have to be adaptive. In the Adaptive Wireless Networking (AWGN) project we aim at the implementation of adaptive wireless communication systems in a heterogeneous reconfigurable System-on-a-Chip (HRSoC). We introduce our methodologies for analyzing and mapping DSP functionality in dynamically reconfigurable heterogeneous hardware. A possible implementation of a multi-mode communication system in the MONTIUM architecture is disc...

  20. An Off-Grid Turbo Channel Estimation Algorithm for Millimeter Wave Communications

    Directory of Open Access Journals (Sweden)

    Lingyi Han

    2016-09-01

    Full Text Available The bandwidth shortage has motivated the exploration of the millimeter wave (mmWave frequency spectrum for future communication networks. To compensate for the severe propagation attenuation in the mmWave band, massive antenna arrays can be adopted at both the transmitter and receiver to provide large array gains via directional beamforming. To achieve such array gains, channel estimation (CE with high resolution and low latency is of great importance for mmWave communications. However, classic super-resolution subspace CE methods such as multiple signal classification (MUSIC and estimation of signal parameters via rotation invariant technique (ESPRIT cannot be applied here due to RF chain constraints. In this paper, an enhanced CE algorithm is developed for the off-grid problem when quantizing the angles of mmWave channel in the spatial domain where off-grid problem refers to the scenario that angles do not lie on the quantization grids with high probability, and it results in power leakage and severe reduction of the CE performance. A new model is first proposed to formulate the off-grid problem. The new model divides the continuously-distributed angle into a quantized discrete grid part, referred to as the integral grid angle, and an offset part, termed fractional off-grid angle. Accordingly, an iterative off-grid turbo CE (IOTCE algorithm is proposed to renew and upgrade the CE between the integral grid part and the fractional off-grid part under the Turbo principle. By fully exploiting the sparse structure of mmWave channels, the integral grid part is estimated by a soft-decoding based compressed sensing (CS method called improved turbo compressed channel sensing (ITCCS. It iteratively updates the soft information between the linear minimum mean square error (LMMSE estimator and the sparsity combiner. Monte Carlo simulations are presented to evaluate the performance of the proposed method, and the results show that it enhances the angle

  1. An Off-Grid Turbo Channel Estimation Algorithm for Millimeter Wave Communications.

    Science.gov (United States)

    Han, Lingyi; Peng, Yuexing; Wang, Peng; Li, Yonghui

    2016-09-22

    The bandwidth shortage has motivated the exploration of the millimeter wave (mmWave) frequency spectrum for future communication networks. To compensate for the severe propagation attenuation in the mmWave band, massive antenna arrays can be adopted at both the transmitter and receiver to provide large array gains via directional beamforming. To achieve such array gains, channel estimation (CE) with high resolution and low latency is of great importance for mmWave communications. However, classic super-resolution subspace CE methods such as multiple signal classification (MUSIC) and estimation of signal parameters via rotation invariant technique (ESPRIT) cannot be applied here due to RF chain constraints. In this paper, an enhanced CE algorithm is developed for the off-grid problem when quantizing the angles of mmWave channel in the spatial domain where off-grid problem refers to the scenario that angles do not lie on the quantization grids with high probability, and it results in power leakage and severe reduction of the CE performance. A new model is first proposed to formulate the off-grid problem. The new model divides the continuously-distributed angle into a quantized discrete grid part, referred to as the integral grid angle, and an offset part, termed fractional off-grid angle. Accordingly, an iterative off-grid turbo CE (IOTCE) algorithm is proposed to renew and upgrade the CE between the integral grid part and the fractional off-grid part under the Turbo principle. By fully exploiting the sparse structure of mmWave channels, the integral grid part is estimated by a soft-decoding based compressed sensing (CS) method called improved turbo compressed channel sensing (ITCCS). It iteratively updates the soft information between the linear minimum mean square error (LMMSE) estimator and the sparsity combiner. Monte Carlo simulations are presented to evaluate the performance of the proposed method, and the results show that it enhances the angle detection

  2. The Model of Communication Channel in the 802.11b Standard Wireless Network

    Directory of Open Access Journals (Sweden)

    Zdenek Silar

    2008-01-01

    Full Text Available The paper deals with software modelling of a communication channel in the 802.11b standard wireless network physical layer. A computer model of signal processing was created to verify possibility of the proposal of localisation system. Functionality of the signal generation and processing model was verified by the Spectrum Analyzer. Simulations run inSimulink/Matlab SW. The Simulink is used for the signal processor model and a pure Matlab software is used for mathematical evaluations of data processor model and for determination of initial conditions.

  3. Communication of emotions in vocal expression and music performance: different channels, same code?

    Science.gov (United States)

    Juslin, Patrik N; Laukka, Petri

    2003-09-01

    Many authors have speculated about a close relationship between vocal expression of emotions and musical expression of emotions. but evidence bearing on this relationship has unfortunately been lacking. This review of 104 studies of vocal expression and 41 studies of music performance reveals similarities between the 2 channels concerning (a) the accuracy with which discrete emotions were communicated to listeners and (b) the emotion-specific patterns of acoustic cues used to communicate each emotion. The patterns are generally consistent with K. R. Scherer's (1986) theoretical predictions. The results can explain why music is perceived as expressive of emotion, and they are consistent with an evolutionary perspective on vocal expression of emotions. Discussion focuses on theoretical accounts and directions for future research. PMID:12956543

  4. How Human Resource Professionals Use Electronic Channels to Communicate CSR : A case study focused on Solvay's French industrial sites

    OpenAIRE

    Fournet, Clara; Pauly, Marissa

    2015-01-01

    Corporate Social Responsibility (CSR) has become a large concern for many companies with the rise of globalization. Oftentimes, companies are encouraged to communicate CSR externally, but not internally. This research focuses upon the internal communication of CSR, specifically how Human Resource (HR) professionals use electronic channels to communicate to employees. The scope of this research is focused solely upon HR professionals within Solvay’s French industrial sites, which produce chemi...

  5. Information revolutions and spreading of communication channels: overview of divergence and/or convergence of the media

    OpenAIRE

    Anita Papić; Tomislav Jakopec; Milijana Mičunović

    2012-01-01

    The paper provides an overview of the so-called information revolutions, with a special emphasis on the spreading of communication channels. The notion 'information revolution' is used conditionally – not in the sense of disruptive changes in communication models, but in the sense of expansion of communication possibilities. The revolutions were identified using Irving E. Fang's criteria. He defined six revolutions: writing, printing, mass media, using media for entertainment, the 'toolshe...

  6. Reducing interferences in wireless communication systems by mobile agents with recurrent neural networks-based adaptive channel equalization

    Science.gov (United States)

    Beritelli, Francesco; Capizzi, Giacomo; Lo Sciuto, Grazia; Napoli, Christian; Tramontana, Emiliano; Woźniak, Marcin

    2015-09-01

    Solving channel equalization problem in communication systems is based on adaptive filtering algorithms. Today, Mobile Agents (MAs) with Recurrent Neural Networks (RNNs) can be also adopted for effective interference reduction in modern wireless communication systems (WCSs). In this paper MAs with RNNs are proposed as novel computing algorithms for reducing interferences in WCSs performing an adaptive channel equalization. The method to provide it is so called MAs-RNNs. We perform the implementation of this new paradigm for interferences reduction. Simulations results and evaluations demonstrates the effectiveness of this approach and as better transmission performance in wireless communication network can be achieved by using the MAs-RNNs based adaptive filtering algorithm.

  7. Self-Assembled Resonance Energy Transfer Keys for Secure Communication over Classical Channels.

    Science.gov (United States)

    Nellore, Vishwa; Xi, Sam; Dwyer, Chris

    2015-12-22

    Modern authentication and communication protocols increasingly use physical keys in lieu of conventional software-based keys for security. This shift is primarily driven by the ability to derive a unique, unforgeable signature from a physical key. The sole demonstration of an unforgeable key, thus far, has been through quantum key distribution, which suffers from limited communication distances and expensive infrastructure requirements. Here, we show a method for creating unclonable keys by molecular self-assembly of resonance energy transfer (RET) devices. It is infeasible to clone the RET-key due to the inability to characterize the key using current technology, the large number of input-output combinations per key, and the variation of the key's response with time. However, the manufacturer can produce multiple identical devices, which enables inexpensive, secure authentication and communication over classical channels, and thus any distance. Through a detailed experimental survey of the nanoscale keys, we demonstrate that legitimate users are successfully authenticated 99.48% of the time and the false-positives are only 0.39%, over two attempts. We estimate that a legitimate user would have a computational advantage of more than 10(340) years over an attacker. Our method enables the discovery of physical key based multiparty authentication and communication schemes that are both practical and possess unprecedented security. PMID:26525314

  8. A general method for selecting quantum channel for bidirectional controlled state teleportation and other schemes of controlled quantum communication

    Science.gov (United States)

    Thapliyal, Kishore; Verma, Amit; Pathak, Anirban

    2015-12-01

    Recently, a large number of protocols for bidirectional controlled state teleportation (BCST) have been proposed using n-qubit entangled states (nin {5,6,7}) as quantum channel. Here, we propose a general method of selecting multiqubit (n>4) quantum channels suitable for BCST and show that all the channels used in the existing protocols of BCST can be obtained using the proposed method. Further, it is shown that the quantum channels used in the existing protocols of BCST form only a negligibly small subset of the set of all the quantum channels that can be constructed using the proposed method to implement BCST. It is also noted that all these quantum channels are also suitable for controlled bidirectional remote state preparation. Following the same logic, methods for selecting quantum channels for other controlled quantum communication tasks, such as controlled bidirectional joint remote state preparation and controlled quantum dialogue, are also provided.

  9. Mapping DSP algorithms to a reconfigurable architecture Adaptive Wireless Networking (AWGN)

    OpenAIRE

    Rauwerda, Gerard

    2003-01-01

    This report will discuss the Adaptive Wireless Networking project. The vision of the Adaptive Wireless Networking project will be given. The strategy of the project will be the implementation of multiple communication systems in dynamically reconfigurable heterogeneous hardware. An overview of a wireless LAN communication system, namely HiperLAN/2, and a Bluetooth communication system will be given. Possible implementations of these systems in a dynamically reconfigurable architecture are dis...

  10. Spot detection accuracy analysis in turbulent channel for free space optical communication

    Science.gov (United States)

    Liu, Yan-Fei; Dai, Yong-Hong; Yu, Sheng-Lin; Xin, Shan; Chen, Jing; Ai, Yong

    2015-10-01

    Increasingly importance has been taken seriously for high frame rate CMOS camera to optical communication acquisition pointing and tacking (APT) system, with its compact structure, easy to developed and adapted to beacon light spot detection in atmospheric channel. As spot position accuracy directly determines the performance of space optical communication, it is very important to design a high precision spot center algorithm. Usually spot location algorithm uses gravity algorithm, shape center capturing algorithm or self-adaption threshold algorithm. In experiments we analyzed the characteristics of the spots which transmitted through atmospheric turbulence and studied light transmission characteristics in turbulent channel. We carried out a beacon light detection experiments in a distance of 3.4km, collected the beacon spots on CMOS camera and signal light power. We calculated spot position with two different algorithm and compared the calculation accuracy between field dispersive spot and ideal Gaussian laser spot. Experiment research show that, gravity center algorithm should be more suitable for beacon beam spot which accuracy can be improved about 1.3 pixels for a Gaussian spot. But the shape center algorithm has higher precision. The reasons were analyzed which made an important preparation for subsequent testing.

  11. Threshold-based detection for amplify-and-forward cooperative communication systems with channel estimation error

    KAUST Repository

    Abuzaid, Abdulrahman I.

    2014-09-01

    Efficient receiver designs for cooperative communication systems are becoming increasingly important. In previous work, cooperative networks communicated with the use of $L$ relays. As the receiver is constrained, it can only process $U$ out of $L$ relays. Channel shortening and reduced-rank techniques were employed to design the preprocessing matrix. In this paper, a receiver structure is proposed which combines the joint iterative optimization (JIO) algorithm and our proposed threshold selection criteria. This receiver structure assists in determining the optimal $U-{opt}$. Furthermore, this receiver provides the freedom to choose $U ≤ U-{opt}$ for each frame depending upon the tolerable difference allowed for mean square error (MSE). Our study and simulation results show that by choosing an appropriate threshold, it is possible to gain in terms of complexity savings without affecting the BER performance of the system. Furthermore, in this paper the effect of channel estimation errors is investigated on the MSE performance of the amplify-and-forward (AF) cooperative relaying system.

  12. Development of Personal Radiation Detector Instrument with Multi Channel Analyzer and Wireless Communication

    International Nuclear Information System (INIS)

    According to the Department of Homeland Security specifications regarding illicit traffic of nuclear materials, a Personal Radiation Detector has been developed. Personal Radiation Detectors are small, lightweight radiation monitors worn on the body, used to detect the presence of or to search for gamma and neutron radiation. This type of instrument can be supplied to unprofessional radiation trained personnel for detection and alert of radioactive materials. A wireless connection of Personal Radiation Detector instruments to a remote risk assessment center increases the possibly to contain a radiological incident in its beginning, until the nuclear Hazards Materials specialists estimate and evaluate the event. Integrating spectrometry capability and wireless communication into the Personal Radiation Detector has many advantages. For example, energy spectrum can be transmitted from the field in real time, enabling the specialist at the risk assessment center to manage the control actions in an event involving the presence of radioactive materials. A Personal Radiation Detector developed instrument, the Personal Detector system-100, includes internal low power Multi Channel Analyzer and Blue Tooth wireless communication. The detector includes neutron and gamma scintillators, a tube, novel pulse processing electronics and sophisticated software. In order to decrease the power consumption, a Cockcroft Walton type power supply was developed. The Personal Radiation Detector software enables fast alert in case of radiation increase over background. This work introduces the Multi Channel Analyzer design approach and experiments results showing the actual performances of the Personal Detector system-100

  13. Secured optical fiber communication using polarization restoration technique and channel characterization

    Science.gov (United States)

    Punekar, Nikhil; Darunkar, Bhagyashri; Verma, Pramode

    2016-02-01

    Optical fiber channels are used as media to transfer the information globally. This paper presents an implementation of a novel procedure using which a secured communication between two parties can be carried out using polarized beam of light over an optical fiber. The paper presents the experimental results obtained of the procedure in the lab environment and a security analysis of the same. It is observed that polarization state of a light pulse cannot be retained as it travels over an optical fiber because of the birefringence phenomenon. Multiple environmental factors such as pressure, vibration, temperature, etc. also add a non-linearity to the birefringence of an optical fiber leading towards an unpredictable polarization state changes over the course of an optical fiber. The proposed procedure helps the receiving party to successfully retrieve the data in the form of a polarization state transmitted by the sending party without having any knowledge about the state of polarization at the transmitting end. The paper also explains an added layer of security the procedure provides to the communicating parties to make it difficult for an adversary to fetch the data being transferred. The proposed system does not depend on the wavelength of the light being used, nor does it depend upon the type of the optical fiber used for the communication. Using this procedure, multiple bits of secured information can be sent over an optical fiber in a single polarized pulse and retrieved at the receiving end, also known as Polarization Shift Keying.

  14. Taipei's use of a multi-channel mass risk communication program to rapidly reverse an epidemic of highly communicable disease.

    Directory of Open Access Journals (Sweden)

    Muh-Yong Yen

    Full Text Available BACKGROUND: In September 2007, an outbreak of acute hemorrhagic conjunctivitis (AHC occurred in Keelung City and spread to Taipei City. In response to the epidemic, a new crisis management program was implemented and tested in Taipei. METHODOLOGY AND PRINCIPAL FINDINGS: Having noticed that transmission surged on weekends during the Keelung epidemic, Taipei City launched a multi-channel mass risk communications program that included short message service (SMS messages sent directly to approximately 2.2 million Taipei residents on Friday, October 12th, 2007. The public was told to keep symptomatic students from schools and was provided guidelines for preventing the spread of the disease at home. Epidemiological characteristics of Taipei's outbreak were analyzed from 461 sampled AHC cases. Median time from exposure to onset of the disease was 1 day. This was significantly shorter for cases occurring in family clusters than in class clusters (mean+/-SD: 2.6+/-3.2 vs. 4.39+/-4.82 days, p = 0.03, as well as for cases occurring in larger family clusters as opposed to smaller ones (1.2+/-1.7 days vs. 3.9+/-4.0 days, p<0.01. Taipei's program had a significant impact on patient compliance. Home confinement of symptomatic children increased from 10% to 60% (p<0.05 and helped curb the spread of AHC. Taipei experienced a rapid decrease in AHC cases between the Friday of the SMS announcement and the following Monday, October 15, (0.70% vs. 0.36%. By October 26, AHC cases reduced to 0.01%. The success of this risk communication program in Taipei (as compared to Keelung is further reflected through rapid improvements in three epidemic indicators: (1 significantly lower crude attack rates (1.95% vs. 14.92%, p<0.001, (2 a short epidemic period of AHC (13 vs. 34 days, and (3 a quick drop in risk level (1 approximately 2 weeks in Taipei districts that border Keelung (the original domestic epicenter. CONCLUSIONS AND SIGNIFICANCE: The timely launch of this systematic

  15. Internet as a new communication, retail and distribution channel for young consumers

    Directory of Open Access Journals (Sweden)

    Vatroslav Škare

    2006-12-01

    Full Text Available Marketing aspects of the Internet can be examined through a great number of researches on marketing practices conducted via the Internet. A number of authors consider the Internet as new marketplace (marketspace, where the exchange of both traditional and new values (i.e. digital products and services takes place. The Internet supports almost all aspects of a company’s business activities and can be applied with respect to all the elements of marketing mix. The subject of this paper is the role of adoption and use of the Internet as a new communication, retail and distribution channel for young consumers. The research was conducted in January 2006 and included 869 students from nine faculties at the University of Zagreb. Students represent an important marketing segment for Internet marketing activities since they are considered to be advanced users of the Internet. The relevance of students’ Internet adoption and use is determined by the following reasons: students are consumers; senior students will soon become young employed professionals with their own income (their spending will increase rapidly; in the near future, senior students will, to some extent, be decision makers on the implementation of business activities via the Internet. Research results show that students actively use the Internet, primarily as a communication channel. The student use of the Internet for purchasing tangible products is rare but their use of services via the Internet is considerable. Students find using the Internet to be a non-complex activity. There is no significant difference in the perception of complexity of the Internet usage among respondents with different computer and English language skills or with respect to their majoring fields (Arts, Biomedicine, Biotechnology, Engineering, Humanities, Natural and Social Sciences. A perception of the complexity of product purchase and service usage via the Internet is influenced by the experience that

  16. On the quantum-channel capacity for orbital angular momentum-based free-space optical communications.

    Science.gov (United States)

    Zhang, Yequn; Djordjevic, Ivan B; Gao, Xin

    2012-08-01

    Inspired by recent demonstrations of orbital angular momentum-(OAM)-based single-photon communications, we propose two quantum-channel models: (i) the multidimensional quantum-key distribution model and (ii) the quantum teleportation model. Both models employ operator-sum representation for Kraus operators derived from OAM eigenkets transition probabilities. These models are highly important for future development of quantum-error correction schemes to extend the transmission distance and improve date rates of OAM quantum communications. By using these models, we calculate corresponding quantum-channel capacities in the presence of atmospheric turbulence. PMID:22859154

  17. Eavesdropping on quantum secure direct communication in quantum channels with arbitrarily low loss rate

    Science.gov (United States)

    Zawadzki, Piotr

    2016-04-01

    Quantum attacks that provide an undetectable eavesdropping of the ping-pong protocol operating over lossy quantum channels have already been demonstrated by Wójcik (Phys Rev Lett 90(15):157901, 2003) and Zhang et al. (Phys Lett A 333(12):46-50, 2004). These attacks provide a maximum information gain of 0.311 bits per protocol cycle as long as the induced loss rate remains acceptable. Otherwise, the skipping of some protocol cycles is advised to stay within an accepted loss limit. Such policy leads to a reduction in information gain proportional to the number of skipped cycles. The attack transformation parametrized by the induced loss ratio is proposed. It provides smaller reduction in information gain when the losses accepted by the communicating parties are too low to mount the most effective attack. Other properties of the attack remain the same.

  18. MIMO Free-Space Optical Communication Employing Subcarrier Intensity Modulation in Atmospheric Turbulence Channels

    Science.gov (United States)

    Ghassemlooy, Zabih; Popoola, Wasiu O.; Ahmadi, Vahid; Leitgeb, Erich

    In this paper, we analyse the error performance of transmitter/receiver array free-space optical (FSO) communication system employing binary phase shift keying (BPSK) subcarrier intensity modulation (SIM) in clear but turbulent atmospheric channel. Subcarrier modulation is employed to eliminate the need for adaptive threshold detector. Direct detection is employed at the receiver and each subcarrier is subsequently demodulated coherently. The effect of irradiance fading is mitigated with an array of lasers and photodetectors. The received signals are linearly combined using the optimal maximum ratio combining (MRC), the equal gain combining (EGC) and the selection combining (SelC). The bit error rate (BER) equations are derived considering additive white Gaussian noise and log normal intensity fluctuations. This work is part of the EU COST actions and EU projects.

  19. Research on diversity receive technology for wireless optical communication using PPM in weak turbulence atmosphere channel

    Science.gov (United States)

    Liu, Yang; Zhang, Guo-an

    2014-09-01

    In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is analyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining technologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wireless communication systems.

  20. Configurable Transmitter and Systolic Channel Estimator Architectures for Data-Dependent Superimposed Training Communications Systems

    Directory of Open Access Journals (Sweden)

    E. Romero-Aguirre

    2012-01-01

    Full Text Available In this paper, a configurable superimposed training (ST/data-dependent ST (DDST transmitter and architecture based on array processors (APs for DDST channel estimation are presented. Both architectures, designed under full-hardware paradigm, were described using Verilog HDL, targeted in Xilinx Virtex-5 and they were compared with existent approaches. The synthesis results showed a FPGA slice consumption of 1% for the transmitter and 3% for the estimator with 160 and 115 MHz operating frequencies, respectively. The signal-to-quantization-noise ratio (SQNR performance of the transmitter is about 82 dB to support 4/16/64-QAM modulation. A Monte Carlo simulation demonstrates that the mean square error (MSE of the channel estimator implemented in hardware is practically the same as the one obtained with the floating-point golden model. The high performance and reduced hardware of the proposed architectures lead to the conclusion that the DDST concept can be applied in current communications standards.

  1. Impulsive interference in communication channels and its mitigation by SPART and other nonlinear filters

    Science.gov (United States)

    Nikitin, Alexei V.; Epard, Marc; Lancaster, John B.; Lutes, Robert L.; Shumaker, Eric A.

    2012-12-01

    A strong digital communication transmitter in close physical proximity to a receiver of a weak signal can noticeably interfere with the latter even when the respective channels are tens or hundreds of megahertz apart. When time domain observations are made in the signal chain of the receiver between the first mixer and the baseband, this interference is likely to appear impulsive. The impulsive nature of this interference provides an opportunity to reduce its power by nonlinear filtering, improving the quality of the receiver channel. This article describes the mitigation, by a particular nonlinear filter, of the impulsive out-of-band (OOB) interference induced in High Speed Downlink Packet Access (HSDPA) by WiFi transmissions, protocols which coexist in many 3G smartphones and mobile hotspots. Our measurements show a decrease in the maximum error-free bit rate of a 1.95 GHz HSDPA receiver caused by the impulsive interference from an OOB 2.4 GHz WiFi transmission, sometimes down to a small fraction of the rate observed in the absence of the interference. We apply a nonlinear SPART filter to recover a noticeable portion of the lost rate and maintain an error-free connection under much higher levels of the WiFi interference than a receiver that does not contain such a filter. These measurements support our wider investigation of OOB interference resulting from digital modulation, which appears impulsive in a receiver, and its mitigation by nonlinear filters.

  2. Channel modeling and performance evaluation of FSO communication systems in fog

    KAUST Repository

    Esmail, Maged Abdullah

    2016-07-01

    Free space optical (FSO) communication has become more exciting during the last decade. It has unregulated spectrum with a huge capacity compared to its radio frequency (RF) counterpart. Although FSO has many applications that cover indoor and outdoor environments, its widespread is humped by weather effects. Fog is classified as an extreme weather impairment that may cause link drop. Foggy channel modeling and characterization is necessary to analyze the system performance. In this paper, we first address the statistical behavior of the foggy channel based on a set of literature experimental data and develop a probability distribution function (PDF) model for fog attenuation. We then exploit our PDF model to derive closed form expressions and evaluate the system performance theoretically and numerically, in terms of average signal-to-noise ratio (SNR), and outage probability. The results show that for 10-3 outage probability and 22 dBm transmitted power, the FSO system can work over 80 m, 160 m, 310 m, and 460 m link length under dense, thick, moderate, and light fog respectively. Increasing the transmitted power will have high impact when the fog density is low. However, under very dense fog, it has almost no effect. © 2016 IEEE.

  3. Frequency-selective fading statistics of shallow-water acoustic communication channel with a few multipaths

    Science.gov (United States)

    Bae, Minja; Park, Jihyun; Kim, Jongju; Xue, Dandan; Park, Kyu-Chil; Yoon, Jong Rak

    2016-07-01

    The bit error rate of an underwater acoustic communication system is related to multipath fading statistics, which determine the signal-to-noise ratio. The amplitude and delay of each path depend on sea surface roughness, propagation medium properties, and source-to-receiver range as a function of frequency. Therefore, received signals will show frequency-dependent fading. A shallow-water acoustic communication channel generally shows a few strong multipaths that interfere with each other and the resulting interference affects the fading statistics model. In this study, frequency-selective fading statistics are modeled on the basis of the phasor representation of the complex path amplitude. The fading statistics distribution is parameterized by the frequency-dependent constructive or destructive interference of multipaths. At a 16 m depth with a muddy bottom, a wave height of 0.2 m, and source-to-receiver ranges of 100 and 400 m, fading statistics tend to show a Rayleigh distribution at a destructive interference frequency, but a Rice distribution at a constructive interference frequency. The theoretical fading statistics well matched the experimental ones.

  4. Optimization of MQAM Modulation Schemes in Mobile Communications(Ⅱ)--Analysis of MQAM BER Performance in Rayleigh Channel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The transmission error code performance of square MQAM and star MQAM modulation schemes for the AGWN Rayleigh fading channel is analyzed. The corresponding BER formulas and computer aided numeric results are given. Therefore it provides a theoretical basis for choosing MQAM modulation schemes in mobile communications.

  5. Role of Information Sources and Communication Channels in Adoption of Improved Practices by Farmers in M. P. State, India.

    Science.gov (United States)

    Sharma, Devendra Kumar

    A study was made of information sources and channels whereby new ideas about improved farming methods are communicated to farmers. Questionnaire interviews were held with 200 farmers in Madhya Pradesh, India. Of the five information sources studied, neighbors were named by all respondents, village level workers by 72%, chairmen of village…

  6. On the Degrees of Freedom of $K$-User SISO Interference and X Channels with Delayed CSIT

    CERN Document Server

    Abdoli, Mohammad Javad; Khandani, Amir Keyvan

    2011-01-01

    The $K$-user SISO (single-input single-output) AWGN interference channel and $2\\times K$ SISO AWGN X channel in i.i.d. fading environment are considered where the transmitters have the past channel state information (CSI) through noiseless feedback links. New transmission schemes are proposed for these channels that achieve degrees of freedom (DoF) values greater than one (except for two-user interference channel). The achieved DoFs are strictly increasing in $K$ and asymptotically approach limiting values of $\\approx 1.2663$ and $\\approx 1.4427$ for interference and X channels, respectively. The achieved DoFs are greater than the best previously reported DoFs for these channels with delayed CSI at transmitters.

  7. Channel and delay estimation for base-station–based cooperative communications in frequency-selective fading channels

    Directory of Open Access Journals (Sweden)

    Hongjun Xu

    2011-07-01

    Full Text Available A channel and delay estimation algorithm for both positive and negative delay, based on the distributed Alamouti scheme, has been recently discussed for base-station–based asynchronous cooperative systems in frequency-flat fading channels. This paper extends the algorithm, the maximum likelihood estimator, to work in frequency-selective fading channels. The minimum mean square error (MMSE performance of channel estimation for both packet schemes and normal schemes is discussed in this paper. The symbol error rate (SER performance of equalisation and detection for both time-reversal space-time block code (STBC and single-carrier STBC is also discussed in this paper. The MMSE simulation results demonstrated the superior performance of the packet scheme over the normal scheme with an improvement in performance of up to 6 dB when feedback was used in the frequency-selective channel at a MSE of 3 x 10–2. The SER simulation results showed that, although both the normal and packet schemes achieved similar diversity orders, the packet scheme demonstrated a 1 dB coding gain over the normal scheme at a SER of 10–5. Finally, the SER simulations showed that the frequency-selective fading system outperformed the frequency-flat fading system.

  8. Choosing channels while acting as a channel: Perceptions of cross-border managers on mediated and strategy communication

    OpenAIRE

    Blom, Päivi

    2010-01-01

    Objective of the Study The objective of the study was to examine internal mediated communication and strategy communication within a multinational company from the perspective of a cross-border manager. The case organization of the study was a financial group operating in Northern Europe. Organized mainly by function, the company operates as cross-national organization and employs hundreds of cross-border managers (CBM), i.e. managers whose subordinates are situated in other countries than...

  9. Long-distance multi-channel bidirectional chaos communication based on synchronized VCSELs subject to chaotic signal injection

    Science.gov (United States)

    Xie, Yi-Yuan; Li, Jia-Chao; He, Chao; Zhang, Zhen-Dong; Song, Ting-Ting; Xu, Chang-Jun; Wang, Gui-Jin

    2016-10-01

    A novel long-distance multi-channel bidirectional chaos communication system over multiple paths based on two synchronized 1550 nm vertical-cavity surface-emitting lasers (VCSELs) is proposed and studied theoretically. These two responding VCSELs (R-VCSELs) can output similar chaotic signals served as chaotic carrier in two linear polarization (LP) modes with identical signal injection from a driving VCSEL (D-VCSEL), which is subject to optical feedback and optical injection, simultaneously. Through the numerical simulations, high quality chaos synchronization between the two R-VCSELs can be obtained. Besides, the effects of varied qualities of chaos synchronization on communication performances in 20 km single mode fiber (SMF) channels are investigated by regulating different internal parameters mismatch after adopting chaos masking (CMS) technique. With the decrease of the maximum cross correlation coefficient (Max-C) between the two R-VCSELs, the bit error rate (BER) of decoded message increase. Meanwhile, the BER can still be less than 10-9 when the Max-C degrades to 0.982. Based on high quality synchronization, when the dispersion compensating fiber (DCF) links are introduced, 4n messages of 10 Gbit/s can transmit in 180 km SMF channels over n coupling paths, bidirectionally and simultaneously. Thorough tests are carried out with detailed analysis, demonstrating long-distance, multi-channel, bidirectional chaos communication based on VCSELs with chaotic signal injection.

  10. Outage Analysis of Train-to-Train Communication Model over Nakagami-m Channel in High-Speed Railway

    Directory of Open Access Journals (Sweden)

    Pengyu Liu

    2013-01-01

    Full Text Available This paper analyzes the end-to-end outage performance of high-speed-railway train-to-train communication model in high-speed railway over independent identical and nonidentical Nakagami-m channels. The train-to-train communication is inter-train communication without an aid of infrastructure (for base station. Source train uses trains on other rail tracks as relays to transmit signals to destination train on the same track. The mechanism of such communication among trains can be divided into three cases based on occurrence of possible-occurrence relay trains. We first present a new closed form for the sum of squared independent Nakagami-m variates and then derive an expression for the outage probability of the identical and non-identical Nakagami-m channels in three cases. In particular, the problem is improved by the proposed formulation that statistic for sum of squared Nakagami-m variates with identical m tends to be infinite. Numerical analysis indicates that the derived analytic results are reasonable and the outage performance is better over Nakagami-m channel in high-speed railway scenarios.

  11. Investigation of the phase fluctuation effect on the BER performance of DPSK space downlink optical communication system on fluctuation channel

    Science.gov (United States)

    Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Chang, Lingqian; Chen, Yuan

    2016-05-01

    Phase fluctuation effect is an important phenomenon on bit error rate (BER) performance on fluctuation channel in space downlink optical communication system. During research process, both intensity scintillation and phase fluctuation caused by atmospheric turbulence have been considered on fluctuation channel. Through the analysis of simulation results, the influence of phase fluctuation is not sensitive for wavelength and APD gain factor at high data rate. Besides, receiving diameter and divergence angle can be adjusted properly in order to obtain optimal BER performance. This work is helpful to the research of phase fluctuation and the design of practical system.

  12. Channel characterization for high-speed W-band wireless communication links

    DEFF Research Database (Denmark)

    Rommel, Simon; Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José;

    2015-01-01

    We present and discuss results from an experimental characterization of the W-band indoor wireless channel, including both large and small scale fading phenomena as well as corresponding channel parameters and their impact on system performance.......We present and discuss results from an experimental characterization of the W-band indoor wireless channel, including both large and small scale fading phenomena as well as corresponding channel parameters and their impact on system performance....

  13. Cyclostationary signature design for common control channel of cognitive radio

    Institute of Scientific and Technical Information of China (English)

    QI Yuan; PENG Tao; WANG Wen-bo; LUO Shi-feng

    2009-01-01

    Embedding specific signatures in transmitted signals for identifying common control channels of cognitive radio are addressed in research laboratories because availability of the spectrum occupied by the common control channel might change in time. A novel solution to embed a unique cyclostationary signature for the common control channel of cognitive radio is proposed in this article. Based on linear periodically time-variant transformation (LPTV) model, the cyclic autocorrelation expression of the proposed signature is derived, which characterizes its cyclostationarity. Analysis of the cyclostationary signature is presented considering effects of additive white Gaussian noise(AWGN)and multiplath channels. Simulation results illustrating the reliability of signatures are given.

  14. Analysis of the Channel Influence to Power Line Communications Based on ITU-T G.9904 (PRIME

    Directory of Open Access Journals (Sweden)

    Asier Llano

    2016-01-01

    Full Text Available ITU-T G.9904 standard, also known as PoweRline Intelligent Metering Evolution (PRIME, is a Power Line Communications standard for advanced metering, grid control and asset monitoring defined by the International Telecommunication Union (ITU. In this paper, an analysis about how different characteristics of the communication channel and types of noise might affect the system performance is carried out. This study is based on simulations of the PRIME physical layer using different channel characteristics and transmission parameters. The conclusions obtained are very valuable for better understanding the behavior of the ITU-T G.9904 (PRIME standard in the field, allowing future improvements in deployment strategies and equipment design.

  15. In-service communication channel sensing based on reflectometry for TWDM-PON systems

    Science.gov (United States)

    Iida, Daisuke; Kuwano, Shigeru; Terada, Jun

    2014-05-01

    Many base stations are accommodated in TWDM-PON based mobile backhaul and fronthaul networks for future radio access, and failed connections in an optical network unit (ONU) wavelength channel severely degrade system performance. A cost effective in-service ONU wavelength channel monitor is essential to ensure proper system operation without failed connections. To address this issue we propose a reflectometry-based remote sensing method that provides wavelength channel information with the optical line terminal (OLT)-ONU distance. The method realizes real-time monitoring of ONU wavelength channels without signal quality degradation. Experimental results show it achieves wavelength channel distinction with high distance resolution.

  16. Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120.

    Science.gov (United States)

    Omairi-Nasser, Amin; Mariscal, Vicente; Austin, Jotham R; Haselkorn, Robert

    2015-08-11

    The filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Several fra gene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N- media. Cryopreservation combined with electron tomography were used to investigate the role of three fra gene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

  17. Both channel coding and wavefront correction on the turbulence mitigation of optical communications using orbital angular momentum multiplexing

    Science.gov (United States)

    Zhao, Shengmei; Wang, Le; Zou, Li; Gong, Longyan; Cheng, Weiwen; Zheng, Baoyu; Chen, Hanwu

    2016-10-01

    A free-space optical (FSO) communication link with multiplexed orbital angular momentum (OAM) modes has been demonstrated to largely enhance the system capacity without a corresponding increase in spectral bandwidth, but the performance of the link is unavoidably degraded by atmospheric turbulence (AT). In this paper, we propose a turbulence mitigation scheme to improve AT tolerance of the OAM-multiplexed FSO communication link using both channel coding and wavefront correction. In the scheme, we utilize a wavefront correction method to mitigate the phase distortion first, and then we use a channel code to further correct the errors in each OAM mode. The improvement of AT tolerance is discussed over the performance of the link with or without channel coding/wavefront correction. The results show that the bit error rate performance has been improved greatly. The detrimental effect of AT on the OAM-multiplexed FSO communication link could be removed by the proposed scheme even in the relatively strong turbulence regime, such as Cn2 = 3.6 ×10-14m - 2 / 3.

  18. Marketing hygiene behaviours: the impact of different communication channels on reported handwashing behaviour of women in Ghana.

    Science.gov (United States)

    Scott, Beth E; Schmidt, Wolf P; Aunger, Robert; Garbrah-Aidoo, Nana; Animashaun, Rasaaque

    2008-06-01

    In 2003-04, a National Handwashing Campaign utilizing mass media and community events took place in Ghana. This article describes the results of the evaluation of the campaign in a sample of 497 women with children communication channels was that hands were not 'truly' clean unless washed with soap. The campaign reached 82% of the study population. Sixty-two per cent of women knew the campaign song, 44% were exposed to one channel and 36% to two or more. Overall, TV and radio had greater reach and impact on reported handwashing than community events, while exposure to both a mass media channel and an event yielded the greatest effect, resulting in a 30% increase in reported handwashing with soap after visiting the toilet or cleaning a child's bottom. Our evaluation questions wide-held belief that community events are more effective agents of behaviour change than mass media commercials, at least in the case of hygiene promotion. However, failure of mass media to reach the entire target audience, particularly in specific regions and lower socio-economic groups, and the additive effect of exposure, underscores the need to implement integrated communication programmes utilizing a variety of complementary channels. PMID:18000025

  19. Marketing hygiene behaviours: the impact of different communication channels on reported handwashing behaviour of women in Ghana.

    Science.gov (United States)

    Scott, Beth E; Schmidt, Wolf P; Aunger, Robert; Garbrah-Aidoo, Nana; Animashaun, Rasaaque

    2008-06-01

    In 2003-04, a National Handwashing Campaign utilizing mass media and community events took place in Ghana. This article describes the results of the evaluation of the campaign in a sample of 497 women with children communication channels was that hands were not 'truly' clean unless washed with soap. The campaign reached 82% of the study population. Sixty-two per cent of women knew the campaign song, 44% were exposed to one channel and 36% to two or more. Overall, TV and radio had greater reach and impact on reported handwashing than community events, while exposure to both a mass media channel and an event yielded the greatest effect, resulting in a 30% increase in reported handwashing with soap after visiting the toilet or cleaning a child's bottom. Our evaluation questions wide-held belief that community events are more effective agents of behaviour change than mass media commercials, at least in the case of hygiene promotion. However, failure of mass media to reach the entire target audience, particularly in specific regions and lower socio-economic groups, and the additive effect of exposure, underscores the need to implement integrated communication programmes utilizing a variety of complementary channels.

  20. On limits of Wireless Communications in a Fading Environment: a General Parameterization Quantifying Performance in Fading Channel

    Directory of Open Access Journals (Sweden)

    Amit Grover

    2014-08-01

    Full Text Available The reliable services along with high throughput can be achieved by using wireless communication systems. These systems also provides a wide coverage because of their features, no doubt MIMO Communication System [1] is one among them. Features provided by these systems ensure the improved system coverage and increased data transmission rate by considering multiple numbers of transmitter and receiver antennas. In this article, the concept of equalization has been considered and finally the performance of the MIMO Systems in Rician flat fading [5] channel is compared with the Rayleigh flat fading channel. It has also been observed that the performance of these Systems in Rician Flat Fading Channel is the best as compare to the Rayleigh Flat Fading Channel [10]. It has been concluded that the successive interference methods provide better performance as compare to others, but their complexity is high. Simulation results shows that ML provides the better performance in comparison to other equalizers but Sphere decoder provides the best performance.

  1. Doppler spectrum type contribution to BER in fiber optic communication channel

    OpenAIRE

    Vujović, Igor; Šoda, Joško; Kuzmanić, Ivica

    2016-01-01

    Integrated ship communication systems require reliable and safe communication media that is suitable for fiber optic cables. This paper investigates such systems. The focus of this paper is on the research into the influences of different Doppler spectrum types to measure bit error rate in communications based on fiber optics. The results show that the highest BER is obtained for Asymmetrical Jakes and the lowest for the Jakes spectrum type. Although we are interested in communications aboard...

  2. Performance Analysis of a Six-Port Receiver in a WCDMA Communication System including a Multipath Fading Channel

    Directory of Open Access Journals (Sweden)

    A. O. Olopade

    2014-01-01

    Full Text Available Third generation communication systems require receivers with wide bandwidth of operation to support high transmission rates and are also reconfigurable to support various communication standards with different frequency bands. An ideal software defined radio (SDR will be the absolute answer to this requirement but it is not achievable with the current level of technology. This paper proposes the use of a six-port receiver (SPR front-end (FE in a WCDMA communication system. A WCDMA end-to-end physical layer MATLAB demo which includes a multipath channel distortion block is used to determine the viability of the six-port based receiver. The WCDMA signal after passing through a multipath channel is received using a constructed SPR FE. The baseband signal is then calibrated and corrected in MATLAB. The six-port receiver performance is measured in terms of bit error rate (BER. The signal-to-noise ratio (SNR of the transmitted IQ data is varied and the BER profile of the communication system is plotted. The effect of the multipath fading on the receiver performance and the accuracy of the calibration algorithm are obtained by comparing two different measured BER curves for different calibration techniques to the simulated BER curve of an ideal receiver.

  3. Channel Capacity Limitations versus Hardware Implementation for UWB Impulse Radio Communications

    CERN Document Server

    Lecointre, Aubin; Plana, Robert

    2010-01-01

    Starting from the Shannon channel capacity, we propose an IR-UWB channel capacity based on the delay spread for multipath time variant channels. This IR-UWB channel capacity is obtained from the no ISI (Inter Symbol Interference) assumption and for binary modulations. The impact of the kind of implementation is considered on the IR-UWB channel capacity. This study is lead for mixed and mostly digital implementation. The key parameters and theirs impacts on the channel capacity are exposed in each case: the data converters for mostly digital implementations and the pulse generator capabilities for mixed implementations. Finally, these two implementations are compared from a data rate point of view. Their behaviors regarding an increase of the operating frequency are also studied.

  4. Entanglement-enhanced classical communication through an amplitude-damping channel

    Institute of Scientific and Technical Information of China (English)

    Hou Li-Zhen; Fang Mao-Fa

    2007-01-01

    We consider the problem of trying to send a single classical bit through an amplitude-damping channel when two transmissions through the channel are available as a resource. It is demonstrated that two entangled transmissions can enhance the receiver's capability of making a correct inference under certain conditions compared with two product-state transmissions.

  5. Channel Estimation on the (EW RLS Algorithm Model of MIMO OFDM in Wireless Communication

    Directory of Open Access Journals (Sweden)

    Sarnin Suzi Seroja

    2016-01-01

    (correspond to different mobility speeds and Monte Carlo simulations are performed and the MSE and BER performance versus SNR are obtained by averaging over 10000 channel realization. For comparisons, the BER performance is also presented for perfectly known channel at the receiver. In all the simulations, perfect synchronization between the transmitter and the receiver is assumed.

  6. RFI channels

    Science.gov (United States)

    Mceliece, R. J.

    1980-01-01

    A class of channel models is presented which exhibit varying burst error severity much like channels encountered in practice. An information-theoretic analysis of these channel models is made, and conclusions are drawn that may aid in the design of coded communication systems for realistic noisy channels.

  7. The Use of Celebrity Endorsement with the Help of Electronic Communication Channel (Instagram) : Case study of Magnum Ice Cream in Thailand

    OpenAIRE

    Kutthakaphan, Rangsima; Chokesamritpol, Wahloonluck

    2013-01-01

    TITLE The Use of Celebrity Endorsement with the Help of Electronic Communication Channel (Instagram): Case Study of Magnum Ice Cream Thailand RESEARCH QUESTION How does the use of celebrity endorsement with the help of electronic communication channel (Social media: Instagram) affect the buying behavior of generation Y consumers in Thailand? STRATEGIC QUESTION How can marketers use this marketing technique in an effective way to increase the number of consumers? PURPOSE OF THE STUDY The pu...

  8. Strong Converse Exponents for a Quantum Channel Discrimination Problem and Quantum-Feedback-Assisted Communication

    Science.gov (United States)

    Cooney, Tom; Mosonyi, Milán; Wilde, Mark M.

    2016-06-01

    This paper studies the difficulty of discriminating between an arbitrary quantum channel and a "replacer" channel that discards its input and replaces it with a fixed state. The results obtained here generalize those known in the theory of quantum hypothesis testing for binary state discrimination. We show that, in this particular setting, the most general adaptive discrimination strategies provide no asymptotic advantage over non-adaptive tensor-power strategies. This conclusion follows by proving a quantum Stein's lemma for this channel discrimination setting, showing that a constant bound on the Type I error leads to the Type II error decreasing to zero exponentially quickly at a rate determined by the maximum relative entropy registered between the channels. The strong converse part of the lemma states that any attempt to make the Type II error decay to zero at a rate faster than the channel relative entropy implies that the Type I error necessarily converges to one. We then refine this latter result by identifying the optimal strong converse exponent for this task. As a consequence of these results, we can establish a strong converse theorem for the quantum-feedback-assisted capacity of a channel, sharpening a result due to Bowen. Furthermore, our channel discrimination result demonstrates the asymptotic optimality of a non-adaptive tensor-power strategy in the setting of quantum illumination, as was used in prior work on the topic. The sandwiched Rényi relative entropy is a key tool in our analysis. Finally, by combining our results with recent results of Hayashi and Tomamichel, we find a novel operational interpretation of the mutual information of a quantum channel {mathcal{N}} as the optimal Type II error exponent when discriminating between a large number of independent instances of {mathcal{N}} and an arbitrary "worst-case" replacer channel chosen from the set of all replacer channels.

  9. Characterizing New Channels of Communication: A Case Study of Municipal 311 Requests in Edmonton, Canada

    Directory of Open Access Journals (Sweden)

    Qing Lu

    2016-06-01

    Full Text Available City governments around the world are developing and expanding how they connect to citizens. Technologies play an important role in making this connection, and one frequent way that cities connect with citizens is through 311-style request systems. 311 is a non-emergency municipal notification system that uses telephone, email, web forms, and increasingly, mobile applications to allow citizens to notify government of infrastructure issues and make requests for municipal services. In many ways, this process of citizen contribution mirrors the provision of volunteered geographic information, that is spatially-referenced user generated content. This research presents a case study of the city of Edmonton, Canada, an early adopter of multi-channel 311 service request systems, including telephone, email, web form, and mobile app 311 request channels. Three methods of analysis are used to characterize and compare these different channels over three years of request data; a comparison of relative request share for each channel, a spatial hot spot analysis, and regression models to compare channel usage with sociodemographic variables. The results of this study indicate a shift in channel usage from traditional to Internet-enabled, that this shift is mirrored in the hotspots of request activity, and that specific digital inequalities exist that reinforce this distinction between traditional and Internet-enabled reporting channels.

  10. Jitter-Robust Orthogonal Hermite Pulses for Ultra-Wideband Impulse Radio Communications

    Directory of Open Access Journals (Sweden)

    Ryuji Kohno

    2005-03-01

    Full Text Available The design of a class of jitter-robust, Hermite polynomial-based, orthogonal pulses for ultra-wideband impulse radio (UWB-IR communications systems is presented. A unified and exact closed-form expression of the auto- and cross-correlation functions of Hermite pulses is provided. Under the assumption that jitter values are sufficiently smaller than pulse widths, this formula is used to decompose jitter-shifted pulses over an orthonormal basis of the Hermite space. For any given jitter probability density function (pdf, the decomposition yields an equivalent distribution of N-by-N matrices which simplifies the convolutional jitter channel model onto a multiplicative matrix model. The design of jitter-robust orthogonal pulses is then transformed into a generalized eigendecomposition problem whose solution is obtained with a Jacobi-like simultaneous diagonalization algorithm applied over a subset of samples of the channel matrix distribution. Examples of the waveforms obtained with the proposed design and their improved auto- and cross-correlation functions are given. Simulation results are presented, which demonstrate the superior performance of a pulse-shape modulated (PSM- UWB-IR system using the proposed pulses, over the same system using conventional orthogonal Hermite pulses, in jitter channels with additive white Gaussian noise (AWGN.

  11. Cooperative Communication over Multi-Scale and Multi-Lag Wireless Channels

    OpenAIRE

    Lu, H; XU, T; Nikookar, H.

    2012-01-01

    The development of wireless communication applications in the last few years is unprecedented. Wireless communication has evolved in various ways. The next generation of wireless systems should service more users while supporting mobility and high data rates. These requirements necessitate efficient use of available resources to provide acceptable service quality.

  12. Antenna Subset Selection for Cyclic Prefix Assisted MIMO Wireless Communications over Frequency Selective Channels

    Directory of Open Access Journals (Sweden)

    T. Kaiser

    2008-04-01

    Full Text Available Antenna (subset selection techniques are feasible to reduce the hardware complexity of multiple-input multiple-output (MIMO systems, while keeping the benefits of higher-order MIMO systems. Many studies of antenna selection schemes are based on frequency-flat channel models, which are inconsistent to broadband MIMO systems employing spatial-multiplexing. In broadband MIMO systems aiming to provide high-data-rate links, the employed signal bandwidth is typically larger than the coherence bandwidth of the channel so that the channel will be of frequency selective nature. Within this contribution we provide an overview on joint transmitter- and receiver-side antenna subset selection methods for frequency selective channels and deploy them in MIMO orthogonal frequency division multiplexing (OFDM systems and MIMO single-carrier (SC systems employing frequency domain equalization (FDE.

  13. Orbital angular momentum in four channel spatial domain multiplexing system for multi-terabit per second communication architectures

    Science.gov (United States)

    Murshid, Syed H.; Muralikrishnan, Hari P.; Kozaitis, Samuel P.

    2012-06-01

    Bandwidth increase has always been an important area of research in communications. A novel multiplexing technique known as Spatial Domain Multiplexing (SDM) has been developed at the Optronics Laboratory of Florida Institute of Technology to increase the bandwidth to T-bits/s range. In this technique, space inside the fiber is used effectively to transmit up to four channels of same wavelength at the same time. Experimental and theoretical analysis shows that these channels follow independent helical paths inside the fiber without interfering with each other. Multiple pigtail laser sources of exactly the same wavelength are used to launch light into a single carrier fiber in a fashion that resulting channels follow independent helical trajectories. These helically propagating light beams form optical vortices inside the fiber and carry their own Orbital Angular Momentum (OAM). The outputs of these beams appear as concentric donut shaped rings when projected on a screen. This endeavor presents the experimental outputs and simulated results for a four channel spatially multiplexed system effectively increasing the system bandwidth by a factor of four.

  14. Design and implementation of channel estimation for low-voltage power line communication systems based on OFDM

    Institute of Scientific and Technical Information of China (English)

    Zhao Huidong; Hei Yong; Qiao Shushan; Ye Tianchun

    2012-01-01

    An optimized channel estimation algorithm based on a time-spread structure in OFDM low-voltage power line communication (PLC) systems is proposed to achieve a lower bit error rate (BER).This paper optimizes the best maximum multi-path delay of the linear minimum mean square error (LMMSE) algorithm in time-domain spread OFDM systems.Simulation results indicate that the BER of the improved method is lower than that of conventional LMMSE algorithm,especially when the signal-to-noise ratio (SNR) is lower than 0 dB.Both the LMMSE algorithm and the proposed algorithm are implemented and fabricated in CSMC 0.18 μm technology.This paper analyzes and compares the hardware complexity and performance of the two algorithms.Measurements indicate that the proposed channel estimator has better performance than the conventional estimator.

  15. Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

    OpenAIRE

    Bing Du; Jun Zhang

    2010-01-01

    A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC) model, a common compact model in hierarchical wireless sensor networks (WSNs). The scheme uses Low-Density Parity-Check (LDPC) as the ...

  16. Group statistical channel coding dimming scheme in visible light communication system

    Science.gov (United States)

    Zhuang, Kaiyu; Huang, Zhitong; Zhang, Ruqi; Li, Jianfeng; Ji, Yuefeng

    2016-10-01

    In this paper, we propose a group statistical channel coding (GSCC) scheme, which achieves dimming by changing the ratio of the 0-1 symbol of the original data stream through probabilistic statistics method. The simulation under various brightness conditions displays that the GSCC maintains good performance comparing to PWM dimming with half satisfice of transmission rate and a larger dimming intensity. Simulation of GSCC after combining with other channel coding schemes reflects that GSCC has good compatibility to arbitrary access coded signal.

  17. A novel unified expression for the capacity and bit error probability of wireless communication systems over generalized fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2012-07-01

    Analysis of the average binary error probabilities (ABEP) and average capacity (AC) of wireless communications systems over generalized fading channels have been considered separately in past years. This paper introduces a novel moment generating function (MGF)-based unified expression for the ABEP and AC of single and multiple link communications with maximal ratio combining. In addition, this paper proposes the hyper-Fox\\'s H fading model as a unified fading distribution of a majority of the well-known generalized fading environments. As such, the authors offer a generic unified performance expression that can be easily calculated, and that is applicable to a wide variety of fading scenarios. The mathematical formulism is illustrated with some selected numerical examples that validate the correctness of the authors\\' newly derived results. © 1972-2012 IEEE.

  18. Performance of Fixed Channel Assignment for Uplink Transmission and Direct Peer-to-Peer Communications in Multihop Cellular Networks

    Institute of Scientific and Technical Information of China (English)

    Xue-Jun Li; Peter Han Joo Chong; Jie Zhan

    2008-01-01

    In this paper, we propose a clustered multihop cellular network (cMCN) architecture and study its performance using fixed channel assignment (FCA) scheme for uplink transmission. The proposed cMCN using FCA can be applied with some reuse factors. An analytical model based on Markov chain is developed to analyze its performance and validated through computer simulation. And then, we implement direct peer-to-peer communication (DC) in cMCN by considering more reasonable conditions in practice. DC means that two calls communicate directly instead of going through base stations. The results show that cMCN with FCA can reduce the call blocking probability significantly as compared with the traditional single-hop cellular networks with FCA and can be further reduced by using DC.

  19. Turbulence Mitigation Scheme for Optical Communications using Orbital Angular Momentum Multiplexing Based on Channel Coding and Wavefront Correction

    CERN Document Server

    Zhao, Shengmei; Zhou, Li; Gong, Longyan; Cheng, Wenwen; Sheng, Yubo; Zheng, Baoyu

    2014-01-01

    The free-space optical (FSO) communication links with orbital angular momentum (OAM) multiplexing have been demonstrated that they can largely enhance the systems' capacity without a corresponding increase in spectral bandwidth, but the performance of the system is unavoidably disturbed by atmospheric turbulence (AT). Different from the existed AT disturbance, the OAM-multiplexed systems will cause both the burst and random errors for a single OAM state carrier and the `crosstalk' interference between the different OAM states carriers. In this paper, we propose a turbulence mitigation method to improve AT tolerance of OAM-multiplexed FSO communication links. In the proposed scheme, we use channel codes to correct the burst and random errors caused by AT for a single OAM state carrier; And we use wavefront correction method to correct the `crosstalk' interference between the different OAM states carriers. The improvements of AT tolerance are discussed by comparing the performance of OAM-multiplexed FSO communi...

  20. Secured Communication over Frequency-Selective Fading Channels: A Practical Vandermonde Precoding

    Directory of Open Access Journals (Sweden)

    Mari Kobayashi

    2009-01-01

    Full Text Available We study the frequency-selective broadcast channel with confidential messages (BCC where the transmitter sends a confidential message to receiver 1 and a common message to receivers 1 and 2. In the case of a block transmission of N symbols followed by a guard interval of L symbols, the frequency-selective channel can be modeled as a N×(N+L Toeplitz matrix. For this special type of multiple-input multiple-output channels, we propose a practical Vandermonde precoding that projects the confidential messages in the null space of the channel seen by receiver 2 while superposing the common message. For this scheme, we provide the achievable rate region and characterize the optimal covariance for some special cases of interest. Interestingly, the proposed scheme can be applied to other multiuser scenarios such as the K+1-user frequency-selective BCC with K confidential messages and the two-user frequency-selective BCC with two confidential messages. For each scenario, we provide the secrecy degree of freedom (s.d.o.f. region of the corresponding channel and prove the optimality of the Vandermonde precoding. One of the appealing features of the proposed scheme is that it does not require any specific secrecy encoding technique but can be applied on top of any existing powerful encoding schemes.

  1. 短波信道盲均衡技术研究%Study on Blind Equalization for HF Communication Channel

    Institute of Scientific and Technical Information of China (English)

    肖毅; 王晓亚

    2014-01-01

    针对短波无线信道的衰落特性严重影响信号接收的问题,在分析研究短波信道特性的基础上,通过研究现有各种盲均衡算法的特点,合理设计均衡器的结构和参数,提出了适用于短波信道的盲均衡改进算法。理论分析和仿真试验均表明,盲均衡算法较好地改善了信道环境,提高了解调性能,具有不占用信道带宽的特点,易于工程实现。%The wireless fading channel always has a serious influence on the effect of signal demodulation receiving in HF communication system.To tackle this problem,the rational design of the structure and parameters of the equalizer had been proposed and the Modified blind equalization algorithm suitable for shortwave channel had been put forward,based on the analysis of the HF channel characteristics and various blind equalization algorithms.Theoretic analysis and simulation results show that the blind equalization algorithm can effec-tively improve the channel quality and improve the demodulation performance.It has the advantages of less occupied channel bandwidth and easy implementation in engineering.

  2. Range extension and channel capacity increase in impulse-radio ultra-wideband communications

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Yu, Xianbin; Caballero Jambrina, Antonio;

    2010-01-01

    and its performance is compared. By utilizing optimum UWB pulse design and employing a digital signal processing (DSP) receiver, a bit-error-rate above the forward error correction (FEC) limit for 8 meters of wireless emission is obtained in our photonic generation UWB system. A noticeable increase......We theoretically analyze the channel capacity of a 5th-order Gaussian pulse-based ultra-wideband (UWB) system and experimentally demonstrate 2 Gbit/s UWB-over-fiber transmission systems incorporating wireless transmission. Both electrical and photonic UWB pulse generation methods are employed...... in the channel capacity is achieved compared to previously reported results....

  3. Selecting the best performing online marketing communication channels to an international start-up Eve

    OpenAIRE

    Karatsevidis, Konstantinos

    2016-01-01

    In today’s technologically advanced world online marketers are constantly faced with ever-growing challenges of running successful marketing campaigns. The problem that most of digital marketers face is the overwhelming amount of marketing tools and channels available to them. “How to select which channel to focus on?”, “Should we invest in viral marketing or social media ads?”, “What’s the next big thing in marketing?” Those are the questions marketers face every day. This Bachelor...

  4. MIMO free-space optical communication employing coherent BPOLSK modulation in atmospheric optical turbulence channel with pointing errors

    Science.gov (United States)

    Prabu, K.; Kumar, D. Sriram

    2015-05-01

    An optical wireless communication system is an alternative to radio frequency communication, but atmospheric turbulence induced fading and misalignment fading are the main impairments affecting an optical signal when propagating through the turbulence channel. The resultant of misalignment fading is the pointing errors, it degrades the bit error rate (BER) performance of the free space optics (FSO) system. In this paper, we study the BER performance of the multiple-input multiple-output (MIMO) FSO system employing coherent binary polarization shift keying (BPOLSK) in gamma-gamma (G-G) channel with pointing errors. The BER performance of the BPOLSK based MIMO FSO system is compared with the single-input single-output (SISO) system. Also, the average BER performance of the systems is analyzed and compared with and without pointing errors. A novel closed form expressions of BER are derived for MIMO FSO system with maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques. The analytical results show that the pointing errors can severely degrade the performance of the system.

  5. Secured Communication over Frequency-Selective Fading Channels: a practical Vandermonde precoding

    CERN Document Server

    Kobayashi, Mari; Shamai, Shlomo

    2009-01-01

    In this paper, we study the frequency-selective broadcast channel with confidential messages (BCC) in which the transmitter sends a confidential message to receiver 1 and a common message to receivers 1 and 2. In the case of a block transmission of N symbols followed by a guard interval of L symbols, the frequency-selective channel can be modeled as a N * (N+L) Toeplitz matrix. For this special type of multiple-input multiple-output (MIMO) channels, we propose a practical Vandermonde precoding that consists of projecting the confidential messages in the null space of the channel seen by receiver 2 while superposing the common message. For this scheme, we provide the achievable rate region, i.e. the rate-tuple of the common and confidential messages, and characterize the optimal covariance inputs for some special cases of interest. It is proved that the proposed scheme achieves the optimal degree of freedom (d.o.f) region. More specifically, it enables to send l <= L confidential messages and N-l common mes...

  6. A secure and robust information hiding technique for covert communication

    Science.gov (United States)

    Parah, S. A.; Sheikh, J. A.; Hafiz, A. M.; Bhat, G. M.

    2015-08-01

    The unprecedented advancement of multimedia and growth of the internet has made it possible to reproduce and distribute digital media easier and faster. This has given birth to information security issues, especially when the information pertains to national security, e-banking transactions, etc. The disguised form of encrypted data makes an adversary suspicious and increases the chance of attack. Information hiding overcomes this inherent problem of cryptographic systems and is emerging as an effective means of securing sensitive data being transmitted over insecure channels. In this paper, a secure and robust information hiding technique referred to as Intermediate Significant Bit Plane Embedding (ISBPE) is presented. The data to be embedded is scrambled and embedding is carried out using the concept of Pseudorandom Address Vector (PAV) and Complementary Address Vector (CAV) to enhance the security of the embedded data. The proposed ISBPE technique is fully immune to Least Significant Bit (LSB) removal/replacement attack. Experimental investigations reveal that the proposed technique is more robust to various image processing attacks like JPEG compression, Additive White Gaussian Noise (AWGN), low pass filtering, etc. compared to conventional LSB techniques. The various advantages offered by ISBPE technique make it a good candidate for covert communication.

  7. Piezo-Phototronic Effect Controlled Dual-Channel Visible light Communication (PVLC) Using InGaN/GaN Multiquantum Well Nanopillars.

    Science.gov (United States)

    Du, Chunhua; Jiang, Chunyan; Zuo, Peng; Huang, Xin; Pu, Xiong; Zhao, Zhenfu; Zhou, Yongli; Li, Linxuan; Chen, Hong; Hu, Weiguo; Wang, Zhong Lin

    2015-12-01

    Visible light communication (VLC) simultaneously provides illumination and communication via light emitting diodes (LEDs). Keeping a low bit error rate is essential to communication quality, and holding a stable brightness level is pivotal for illumination function. For the first time, a piezo-phototronic effect controlled visible light communication (PVLC) system based on InGaN/GaN multiquantum wells nanopillars is demonstrated, in which the information is coded by mechanical straining. This approach of force coding is also instrumental to avoid LED blinks, which has less impact on illumination and is much safer to eyes than electrical on/off VLC. The two-channel transmission mode of the system here shows great superiority in error self-validation and error self-elimination in comparison to VLC. This two-channel PVLC system provides a suitable way to carry out noncontact, reliable communication under complex circumstances.

  8. Piezo-Phototronic Effect Controlled Dual-Channel Visible light Communication (PVLC) Using InGaN/GaN Multiquantum Well Nanopillars.

    Science.gov (United States)

    Du, Chunhua; Jiang, Chunyan; Zuo, Peng; Huang, Xin; Pu, Xiong; Zhao, Zhenfu; Zhou, Yongli; Li, Linxuan; Chen, Hong; Hu, Weiguo; Wang, Zhong Lin

    2015-12-01

    Visible light communication (VLC) simultaneously provides illumination and communication via light emitting diodes (LEDs). Keeping a low bit error rate is essential to communication quality, and holding a stable brightness level is pivotal for illumination function. For the first time, a piezo-phototronic effect controlled visible light communication (PVLC) system based on InGaN/GaN multiquantum wells nanopillars is demonstrated, in which the information is coded by mechanical straining. This approach of force coding is also instrumental to avoid LED blinks, which has less impact on illumination and is much safer to eyes than electrical on/off VLC. The two-channel transmission mode of the system here shows great superiority in error self-validation and error self-elimination in comparison to VLC. This two-channel PVLC system provides a suitable way to carry out noncontact, reliable communication under complex circumstances. PMID:26450795

  9. Experimental research and comparison of LDPC and RS channel coding in ultraviolet communication systems.

    Science.gov (United States)

    Wu, Menglong; Han, Dahai; Zhang, Xiang; Zhang, Feng; Zhang, Min; Yue, Guangxin

    2014-03-10

    We have implemented a modified Low-Density Parity-Check (LDPC) codec algorithm in ultraviolet (UV) communication system. Simulations are conducted with measured parameters to evaluate the LDPC-based UV system performance. Moreover, LDPC (960, 480) and RS (18, 10) are implemented and experimented via a non-line-of-sight (NLOS) UV test bed. The experimental results are in agreement with the simulation and suggest that based on the given power and 10(-3)bit error rate (BER), in comparison with an uncoded system, average communication distance increases 32% with RS code, while 78% with LDPC code.

  10. New Media Expands the Party -Mass Communication Channels%新媒体与党群沟通渠道的拓展

    Institute of Scientific and Technical Information of China (English)

    吕品

    2011-01-01

    The Party-mass communication channels, as indispensable tools to promote a sound Party -mass relationship, are critical to foster open dialogue between the Party and the Mass. Along with our economic and social transition and the rapid development of the new media, the defects of traditional Party - mass communication channels are appeared. New media, as channels of communications, is rising rapidly. This paper analyzes the advantages and disadvantages of the new media as the Party - mass communication channels, and discusses how to make the best use of the new media to expand the Party - mass communication channels.%党群沟通渠道是党群沟通中的重要要素,通畅的沟通渠道是推动党群关系良性运行不可或缺的手段和工具。随着我国经济社会转型和新媒体的迅速发展,传统的党群沟通渠道的弊端显现,而以新媒体为渠道的沟通则迅速兴起。本文分析了新媒体作为党群沟通渠道存在的优势和不足,并探讨了如何善用新媒体拓展党群沟通渠道。

  11. Performance study of terrestrial multi-hop OFDM FSO communication systems with pointing errors over turbulence channels

    Science.gov (United States)

    Nistazakis, H. E.; Ninos, M. P.; Tsigopoulos, A. D.; Zervos, D. A.; Tombras, G. S.

    2016-08-01

    The free-space optical communication systems attract significant research and commercial interest the last few years, due to their high performance and reliability characteristics along with their, relatively, low installation and operational cost. Moreover, due to the fact that these systems are using the atmosphere as propagation path, their performance is varying according to its characteristics. Here, we present the performance analysis of a serially relayed radio-on-free-space-optical (RoFSO) communication system which employs the orthogonal frequency division multiplexing technique, with a quadrature amplitude modulation scheme, over atmospheric turbulence channels modelled by either the Gamma-Gamma or the Gamma distribution model. For this RoFSO communication link, we derive closed-form mathematical expressions for the estimation of its average bit error rate and outage probability, taking into account the relays' number, the atmospheric turbulence and the pointing errors effect. Furthermore, for realistic parameter values, numerical results are presented using the derived mathematical expressions, which are verified through the corresponding numerical simulations.

  12. Social media as a new channel for company communication on the example of clothing company

    Directory of Open Access Journals (Sweden)

    A. Widawska-Stanisz

    2014-03-01

    Full Text Available The evolution of marketing orientations, issues of company and market communication are submitted in the article. The role of social media and its using by companies and their customers are pointed. The author of this article has presented the results of the research conducted with young citizens of Silesia Voivodeship.

  13. Computer-mediated communication as a channel for social resistance : The strategic side of SIDE

    NARCIS (Netherlands)

    Spears, R; Lea, M; Corneliussen, RA; Postmes, T; Ter Haar, W

    2002-01-01

    In two studies, the authors tested predictions derived from the social identity model of deindividuation effects (SIDE) concerning the potential of computer-mediated communication (CMC) to serve as a means to resist powerful out-groups. Earlier research using the SIDE model indicates that the anonym

  14. PERFORMANCE ANALYSIS OF S-ALOHA USED AS A RANDOM ACCES CHANNEL ON MOBILE COMMUNICATIONS

    Directory of Open Access Journals (Sweden)

    D. Covarrubias

    2005-04-01

    Full Text Available This paper evaluates the effects of Rayleigh fading, shadowing, and spatial distribution of the Mobile Terminals(MTs on the operating performance of Slotted Aloha (S-Aloha used as a Random Access Channel (RACH. Thispaper also evaluates the capture probability in a channel exhibiting Rayleigh fading, shadowing, and the effect ofspatial distribution of the MTs. In addition, this work presents a different version of the steady-sate probabilities ofthe Markov chain of S-Aloha considering capture effect. This article simulates the stabilization of S-Aloha by utilizingan algorithm that dynamically controls the retransmission probabilities. Finally, this paper presents a numericalanalysis of these simulations and identifies the operating of parameters that have shown to degrade systemresponse.

  15. Marketing communication channels and their use in student recruitment at Laurea University of Applied Sciences

    OpenAIRE

    Räisänen, Matias; Backman, Dunja

    2013-01-01

    The purpose of this thesis is to investigate the opinions and images that student applicants have of Laurea University of Applied Sciences, and to examine the factors which affect their decision to apply to Laurea. The study aims to uncover the most effective marketing channels of Laurea University of Applied Sciences, and to determine how they could be further improved from the viewpoint of student recruitment. The study was carried out as a quantitative research study, with a questionna...

  16. Gamma-gamma大气湍流下自由空间光通信的性能%Performance of free space optical communication over gamma-gamma atmosphere turbulence

    Institute of Scientific and Technical Information of China (English)

    韩立强; 王祁; 信太克归

    2011-01-01

    Free space optical (FSO) communication has attracted considerable attention recently for a variety of applications, but atmospheric turbulence can degrade the performance of FSO links. In this paper, the atmospheric turbulence channel was assumed to be memoryless, stationary and ergodic with additive white Gaussian noise (AWGN), the intensity modulation direct detection (ID/DD) with on-off keying (OOK) was used in FSO communication system. The performance of FSO communication systems was studied over gamma-gamma atmospheric turbulence-induced fading channels. A closed form expression of bit error rate (BER) for FSO communication was derived with Meijer G function and the closed form expressions of outage probability and the average channel capacity were simplified by using Meijer G function. Under different atmosphere turbulence conditions, simulations were done respectively according to the closed form expressions of BER, outage probability and the average capacity. Numerical examples show how the performance of FSO communication is affected by various parameters such as the refractive index structure parameter, the transmission distance, SNR. Simulation results are further demonstrated to confirm the analytical results.%自由空间光通信在各种应用中得到了广泛关注,但大气湍流效应导致系统链路性能恶化.假设大气湍流信道是无记忆平稳遍历并且为加性高斯白噪声(AWGN),自由空间光通信系统采用开关键控(OOK)强度调制直接检测(ID/DD),研究了gamma-gamma大气湍流信道下自由空间光通信的性能.利用MeijerG函数推导出了自由空间光通信的性能指标平均误码率的闭合表达式,简化了中断概率和平均信道容量的闭合表达式.在不同大气湍流强度下,根据平均误码率、中断概率、平均容量的闭合表达式分别给出了几个数值仿真实例,分析了大气折射率结构常数、传输距离、信噪比与自由空间光通信系统性能的关系.

  17. Channel Equalization in Filter Bank Based Multicarrier Modulation for Wireless Communications

    Science.gov (United States)

    Ihalainen, Tero; Hidalgo Stitz, Tobias; Rinne, Mika; Renfors, Markku

    2006-12-01

    Channel equalization in filter bank based multicarrier (FBMC) modulation is addressed. We utilize an efficient oversampled filter bank concept with 2x-oversampled subcarrier signals that can be equalized independently of each other. Due to Nyquist pulse shaping, consecutive symbol waveforms overlap in time, which calls for special means for equalization. Two alternative linear low-complexity subcarrier equalizer structures are developed together with straightforward channel estimation-based methods to calculate the equalizer coefficients using pointwise equalization within each subband (in a frequency-sampled manner). A novel structure, consisting of a linear-phase FIR amplitude equalizer and an allpass filter as phase equalizer, is found to provide enhanced robustness to timing estimation errors. This allows the receiver to be operated without time synchronization before the filter bank. The coded error-rate performance of FBMC with the studied equalization scheme is compared to a cyclic prefix OFDM reference in wireless mobile channel conditions, taking into account issues like spectral regrowth with practical nonlinear transmitters and sensitivity to frequency offsets. It is further emphasized that FBMC provides flexible means for high-quality frequency selective filtering in the receiver to suppress strong interfering spectral components within or close to the used frequency band.

  18. Channel Equalization in Filter Bank Based Multicarrier Modulation for Wireless Communications

    Directory of Open Access Journals (Sweden)

    Markku Renfors

    2007-01-01

    Full Text Available Channel equalization in filter bank based multicarrier (FBMC modulation is addressed. We utilize an efficient oversampled filter bank concept with 2x-oversampled subcarrier signals that can be equalized independently of each other. Due to Nyquist pulse shaping, consecutive symbol waveforms overlap in time, which calls for special means for equalization. Two alternative linear low-complexity subcarrier equalizer structures are developed together with straightforward channel estimation-based methods to calculate the equalizer coefficients using pointwise equalization within each subband (in a frequency-sampled manner. A novel structure, consisting of a linear-phase FIR amplitude equalizer and an allpass filter as phase equalizer, is found to provide enhanced robustness to timing estimation errors. This allows the receiver to be operated without time synchronization before the filter bank. The coded error-rate performance of FBMC with the studied equalization scheme is compared to a cyclic prefix OFDM reference in wireless mobile channel conditions, taking into account issues like spectral regrowth with practical nonlinear transmitters and sensitivity to frequency offsets. It is further emphasized that FBMC provides flexible means for high-quality frequency selective filtering in the receiver to suppress strong interfering spectral components within or close to the used frequency band.

  19. Modeling of the Simultaneous Influence of the Thermal Noise and the Phase Noise in Space Communication Systems

    Directory of Open Access Journals (Sweden)

    O. Baran

    2010-12-01

    Full Text Available Our work deals with studies of a noise behavior in space communication systems. Two most important noise types the additive thermal noise and the multiplicative phase noise, respectively, are included. A simple model of the narrowband communication system is created and simulated in the Ansoft Designer system simulator. The additive thermal noise is modeled as AWGN in a communication channel. The phase noise is produced in transmitter and receiver oscillators. The main intention is to investigate the receiver filter bandwidth decrease effect on powers of both noise types. Results proposed in this paper show that for defined system conditions and for a certain filter bandwidth value, the power of the multiplicative phase noise equals to the additive thermal noise power. Another decrease of the filter bandwidth causes the phase noise power exceeding. To demonstrate the noise behavior transparently, input system parameters are properly selected. All simulation results are documented by theoretical calculations. Simulation outcomes express a good coincidence with presumptions and calculations.

  20. 卫星通信中的信道编码与调制技术%Channel Coding and Modulation Technology for Satelite Communication

    Institute of Scientific and Technical Information of China (English)

    周珊; 沈永言

    2016-01-01

    本文首先研究了卫星通信中的信道编码与调制技术,并对广泛应用于卫星通信的DV B-S系列标准中的信道编码与调制技术进行了对比分析,最后提出了卫星通信采用更高级信道编码和调制技术的必然性。%This paper studies the channel coding and modulation technology for satellite communication firstly.Then the comparative analyses of channel coding and modulation technology in DVB-S Series standard which is widely used in satellite communications are made. Finally the inevitability of using more advanced channel coding and modulation technology in satellite communication is indicated.

  1. The impact of pulsed RFI on the coded BER performance of the nonlinear satellite communication channel

    Science.gov (United States)

    Weinberg, A.

    1980-01-01

    Communication links from low orbiting spacecraft to a central ground station, via satellite repeater, may be susceptible to significant performance degradation if high-level, pulsed radio frequency interference (RFI) must be contended with. The present paper examines the coded bit error rate (BER) performance of a communication system in which BPSK modulation is employed, pulsed CW or pulsed noise RFI is present, and the transponder contains a nonlinearity characterized by arbitrary AM/AM and AM/PM characteristics. A major result of this paper is an analytic method for determining soft decision statistics of the receiver demodulator output, in which pulsed RFI effects are accounted for. It is demonstrated that this result can be analytically applied to the approximate determination of the BER at the output of a Viterbi decoder, when convolutional coding is employed.

  2. Capacity of Underwater Wireless Communication Channel With Different Acoustic Propagation Loss Models

    Directory of Open Access Journals (Sweden)

    Susan Joshy

    2010-09-01

    Full Text Available In this paper, we calculate the capacity of a point-to-point communication link in an underwater acousticchannel. The analysis takes into account the effects of various acoustic propagation loss models. A physicalmodel of ambient noise power spectral density is also considered. We perform a comparative assessment ofthe influence of various acoustic transmission loss models on the acoustic bandwidth and the capacity

  3. Achieving Efficient Channel Utilization for Data Communications in IEEE 802.11 WLAN

    Institute of Scientific and Technical Information of China (English)

    ZHANG Liang; SHU Yantai

    2005-01-01

    In the IEEE 802. 11 protocol, the adoption of the exponential backoff technique leads to throughput performance strongly dependent on the initial contention window size and, most importantly, on the number of contending stations considered in the network. This paper proposes a simpie but accurate method to dynamically estimate the number of contending stations in a wireless local area network (WLAN). Based on estimation, all the mobile stations dynamically adjust the initial contention window in medium access control (MAC) layer to avoid collisions. The simulation results show that the proposed algorithm can achieve efficient channel utilization, higher system throughput, and better fairness performance.

  4. Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Du Bing

    2010-01-01

    Full Text Available A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC model, a common compact model in hierarchical wireless sensor networks (WSNs. The scheme uses Low-Density Parity-Check (LDPC as the surrogate to build up a layered structure which encapsulates the multiple constituent LDPC codes in the source and relay nodes. Specifically, the relay node decodes the messages from two sources, which are used to generate extra parity-check bits by a random network coding procedure to fill up the rate gap between Source-Relay and Source-Destination transmissions. Then, we derived the key algebraic relationships among multidimensional LDPC constituent codes as one of the constraints for code profile optimization. These extra check bits are sent to the destination to realize a cooperative diversity as well as to approach MARC decode-and-forward (DF capacity.

  5. Estimating Lower Bound and Upper Bound of a Markov chain over a noisy communication channel with Poisson distribution

    Directory of Open Access Journals (Sweden)

    Vinay Mahajan

    2012-06-01

    Full Text Available Under the assumption that the encoders’ observations are conditionally independent Markov chains given an unobserved time-invariant random variable, results on the structure of optimal real-time encoding and decoding functions are obtained. The problem with noiseless channels and perfect memory at the receiver is then considered. A new methodology to find the structure of optimal real-time encoders is employed. A sufficient statistic with a time-invariant domain is found for this problem. This methodology exploits the presence of common information between the encoders and the receiver when communication is over noiseless channels. In this paper we estimate the lower bond, upper bond and define the encoder. In the previous design approach they follow Markov Chain approach to estimating the upper bound and define the encoder. In this dissertation we follow poison distribution to finding the lower bound and upper bound. Poisson can be viewed as an approximation to the binomial distribution. The approximation is good enough to be useful even when the sample size (N is only moderately large (say N > 50 and the probability (p is only relatively small (p < .2 The advantage of the Poisson distribution, of course, is that if N is large you need only know p to determine the approximate distribution of events. With the binomial distribution you also need to know N.

  6. Performance analysis of a random ARQ initialized cooperative communication protocol in shadowed Nakagami-m wireless channel

    Institute of Scientific and Technical Information of China (English)

    AHMED Irfan; PENG MuGen; WANG WenBo; SHAH Syed Ismail

    2009-01-01

    In this paper, we develop and analyze an energy efficient ARQ (automatic repeat request) initialized transmit diversity protocol for cooperative communications. Medium access control (MAC) layer packet retransmission limit (similar to aShortRetryLimit or aLongRetryLimit [802.11-1997]) has been used as an actuator for transmit cooperative diversity initialization. We take the channel state information (CSI) as a function of retransmission tries and the number of retransmission tries is modeled as a random variable. Relays close to the source node are chosen for the transmit cooperation. Closed form expressions are obtained for symbol error rate (SER), outage capacity and outage probability for the proposed scheme in shadowed fading channels. This cooperative scheme achieves lower signal-to-noise ratio (SNR), stumpy outage probability, higher bandwidth, and transmit energy efficiencies for desired average symbol error rate (ASER) than the preceding ARQ based cooperative protocols. Finally, the results of computer simulations are included to demonstrate the efficacy of the proposed scheme and to verify the accuracy of the analytical expressions.

  7. Causing Communication Closure: Safe Program Composition with Reliable Non-FIFO Channels

    CERN Document Server

    Engelhardt, Kai

    2009-01-01

    A semantic framework for analyzing safe composition of distributed programs is presented. Its applicability is illustrated by a study of program composition when communication is reliable but not necessarily FIFO\\@. In this model, special care must be taken to ensure that messages do not accidentally overtake one another in the composed program. We show that barriers do not exist in this model. Indeed, no program that sends or receives messages can automatically be composed with arbitrary programs without jeopardizing their intended behavior. Safety of composition becomes context-sensitive and new tools are needed for ensuring it. A notion of \\emph{sealing} is defined, where if a program $P$ is immediately followed by a program $Q$ that seals $P$ then $P$ will be communication-closed--it will execute as if it runs in isolation. The investigation of sealing in this model reveals a novel connection between Lamport causality and safe composition. A characterization of sealable programs is given, as well as effic...

  8. Disentangling canid howls across multiple species and subspecies: Structure in a complex communication channel.

    Science.gov (United States)

    Kershenbaum, Arik; Root-Gutteridge, Holly; Habib, Bilal; Koler-Matznick, Janice; Mitchell, Brian; Palacios, Vicente; Waller, Sara

    2016-03-01

    Wolves, coyotes, and other canids are members of a diverse genus of top predators of considerable conservation and management interest. Canid howls are long-range communication signals, used both for territorial defence and group cohesion. Previous studies have shown that howls can encode individual and group identity. However, no comprehensive study has investigated the nature of variation in canid howls across the wide range of species. We analysed a database of over 2000 howls recorded from 13 different canid species and subspecies. We applied a quantitative similarity measure to compare the modulation pattern in howls from different populations, and then applied an unsupervised clustering algorithm to group the howls into natural units of distinct howl types. We found that different species and subspecies showed markedly different use of howl types, indicating that howl modulation is not arbitrary, but can be used to distinguish one population from another. We give an example of the conservation importance of these findings by comparing the howls of the critically endangered red wolves to those of sympatric coyotes Canis latrans, with whom red wolves may hybridise, potentially compromising reintroduced red wolf populations. We believe that quantitative cross-species comparisons such as these can provide important understanding of the nature and use of communication in socially cooperative species, as well as support conservation and management of wolf populations. PMID:26809021

  9. ART@CMS and SCIENCE&ART@SCHOOL: Novel Education and Communication Channels for Particle Physics

    Science.gov (United States)

    Hoch, Michael; Alexopoulos, Angelos

    2014-06-01

    This document presents new outreach projects set up by the CMS Collaboration at the intersection of science and the arts to act as a creative springboard for the inspiration and engagement of public and students in particle physics research. Two programmes, Art@CMS and Science&Art@School, aim to reach and engage via multiple channels, different from those traditionally used for scientific outreach events. Art@CMS is a collaboration with professional artists to trigger a dialogue between the LHC scientific community and the art world. Science&Art@School brings high-school students from arts and sciences curricula together during extended learning periods by exploring how researchers and artists work and view each other's world. Results of events, workshops and collaborations are presented to demonstrate the concept in practice and to suggest avenues for strengthening further the educational and societal impact of particle physics research.

  10. Statistical mechanical analysis of the Kronecker channel model for multiple-input multiple-output wireless communication.

    Science.gov (United States)

    Hatabu, Atsushi; Takeda, Koujin; Kabashima, Yoshiyuki

    2009-12-01

    The Kronecker channel model of wireless communication is analyzed using statistical mechanics methods. In the model, spatial proximities among transmission/reception antennas are taken into account as certain correlation matrices, which generally yield nontrivial dependence among symbols to be estimated. This prevents accurate assessment of the communication performance by naively using a previously developed analytical scheme based on a matrix integration formula. In order to resolve this difficulty, we develop a formalism that can formally handle the correlations in Kronecker models based on the known scheme. Unfortunately, direct application of the developed scheme is, in general, practically difficult. However, the formalism is still useful, indicating that the effect of the correlations generally increase after the fourth order with respect to correlation strength. Therefore, the known analytical scheme offers a good approximation in performance evaluation when the correlation strength is sufficiently small. For a class of specific correlation, we show that the performance analysis can be mapped to the problem of one-dimensional spin systems in random fields, which can be investigated without approximation by the belief propagation algorithm.

  11. Neural FIR adaptive Laguerre equalizer with a gradient adaptive amplitude for nonlinear channel in communication systems

    Institute of Scientific and Technical Information of China (English)

    ZHAO HaiQuan; ZHANG JiaShu

    2009-01-01

    To mitigate the linear and nonlinear distortions in communication systems, two novel nonlinear adaptive equalizers are proposed on the basis of the neural finite impulse response (FIR) filter, decision feedback architecture and the characteristic of the Laguerre filter. They are neural FIR adaptive decision feedback equalizer (SNNDFE) and neural FIR adaptive Laguerre equalizer (LSNN). Of these two equalizers, the latter is simple and with characteristics of both infinite impulse response (IIR) and FIR filters; it can use shorter memory length to obtain better performance. As confirmed by theoretical analysis, the novel LSNN equalizer is stable (0<α<1). Furthermore, simulation results show that the SNNDFE can get better equalized performance than SNN equalizer, while the latter exhibits better performance than others in terms of convergence speed, mean square error (MSE) and bit error rate (BER). Therefore, it can reduce the input dimension and eliminate linear and nonlinear interference effectively. In addition, it is very suitable for hardware implementation due to its simple structure.

  12. Iterative List Decoding of Concatenated Source-Channel Codes

    Directory of Open Access Journals (Sweden)

    Hedayat Ahmadreza

    2005-01-01

    Full Text Available Whenever variable-length entropy codes are used in the presence of a noisy channel, any channel errors will propagate and cause significant harm. Despite using channel codes, some residual errors always remain, whose effect will get magnified by error propagation. Mitigating this undesirable effect is of great practical interest. One approach is to use the residual redundancy of variable length codes for joint source-channel decoding. In this paper, we improve the performance of residual redundancy source-channel decoding via an iterative list decoder made possible by a nonbinary outer CRC code. We show that the list decoding of VLC's is beneficial for entropy codes that contain redundancy. Such codes are used in state-of-the-art video coders, for example. The proposed list decoder improves the overall performance significantly in AWGN and fully interleaved Rayleigh fading channels.

  13. A Novel Approach to Achieve the Perfect Security through AVK over Insecure Communication Channel

    Science.gov (United States)

    Banerjee, Subhasish; Dutta, Manash Pratim; Bhunia, Chandan Tilak

    2016-08-01

    To enhance the security level of the cryptosystem in shared encrypted data over the insecure channel; Automatic variable key (AVK) is a perfect mechanism as being experimented by many researchers. In AVK, after establishment of the secret key (through some IKE protocols, like IKEv2 or 2 PAKA or 3 PAKA, etc), the successive keys are generated that are variable in nature from session to session by using time variant key technique. In this work, it is shown that how AVK can provide higher security than fixed key from well-known plaintext attack (for example, brute force attack) and ciphertext only attack (for example, frequency attack etc) due to randomness of keys. In order to improve the level of randomness among the key set, a new method is proposed to generate keys where the randomness are achieved not only in terms of change in bits sequence but also flexible in size as well. Randomness of the key set is also compared with other related time variant key mechanisms to prove superiority.

  14. Optimization of MQAM Modulation Schemes in Mobile Communications(Ⅰ)--Analysis of MQAM BER Performance in AGWN Channel Based on Signal Space

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on signal space concepts, a transmission error code performance for MPSK, square MQAM and star MQAM modulation schemes on the AGWN channel is analyzed. The corresponding BER formulas and computer aided numeric results are also given. Therefore it provides a theoretical basis for choosing MQAM modulation schemes in mobile communications.

  15. Method and apparatus for a single channel digital communications system. [synchronization of received PCM signal by digital correlation with reference signal

    Science.gov (United States)

    Couvillon, L. A., Jr.; Carl, C.; Goldstein, R. M.; Posner, E. C.; Green, R. R. (Inventor)

    1973-01-01

    A method and apparatus are described for synchronizing a received PCM communications signal without requiring a separate synchronizing channel. The technique provides digital correlation of the received signal with a reference signal, first with its unmodulated subcarrier and then with a bit sync code modulated subcarrier, where the code sequence length is equal in duration to each data bit.

  16. Performance Analysis and Simulation of Turbo Codes over AWGN Channels%AWGN信道中Turbo码的性能和仿真

    Institute of Scientific and Technical Information of China (English)

    邱金刚; 陈自力; 何金义

    2005-01-01

    主要对Turbo码的解码算法进行了研究,分析了常用的MAP解码算法,对Turbo码在AWGN信道中应用不同的解码算法进行了仿真,针对不同解码算法和解码迭代次数等因素对Turbo码性能影响进行分析,结果表明Turbo码在AWGN信道中和低信噪比条件下具有优良的性能.

  17. PERFORMANCE EVALUATION OF TURBO CODED OFDM SYSTEMS AND APPLICATION OF TURBO DECODING FOR IMPULSIVE CHANNEL

    Directory of Open Access Journals (Sweden)

    Savitha H. M.

    2010-09-01

    Full Text Available A comparison of the performance of hard and soft-decision turbo coded Orthogonal Frequency Division Multiplexing systems with Quadrature Phase Shift Keying (QPSK and 16-Quadrature Amplitude Modulation (16-QAM is considered in the first section of this paper. The results show that the soft-decision method greatly outperforms the hard-decision method. The complexity of the demapper is reduced with the use of simplified algorithm for 16-QAM demapping. In the later part of the paper, we consider the transmission of data over additive white class A noise (AWAN channel, using turbo coded QPSK and 16-QAM systems. We propose a novel turbo decoding scheme for AWAN channel. Also we compare the performance of turbo coded systems with QPSK and 16-QAM on AWAN channel with two different channel values- one computed as per additive white Gaussian noise (AWGN channel conditions and the other as per AWAN channel conditions. The results show that the use of appropriate channel value in turbo decoding helps to combat the impulsive noise more effectively. The proposed model for AWAN channel exhibits comparable Bit error rate (BER performance as compared to AWGN channel.

  18. MIMO Channel Modeling and Capacity Analysis in Terahertz Communication%太赫兹通信中MIMO信道建模与容量分析

    Institute of Scientific and Technical Information of China (English)

    李伟琨; 姚信威; 王万良; 吴腾超

    2015-01-01

    With the development of nanotechnology and the graphene-based nano materials,terahertz communication, the preferred communication technology of nano network is becoming the new hotspot for wireless communication. However,the performance of Multiple Input Multiple Output( MIMO) channel in terahertz band is still unknown. A novel MIMO channel model in terahertz communications is proposed by using a discrete mathematical method. Combining the molecular absorption and the path loss in terahertz band,a model of channel capacity is presented based on the channel state information at the receiver. MIMO channel model in terahertz communications is verified in the simulation. Result shows that the MIMO channel in terahertz communication can support higher capacity and transmission bit-rates than the single terahertz channel.%随着纳米技术的不断发展与新型纳米材料石墨烯研究的不断深入,作为纳米网络通信技术的太赫兹通信成为无线通信的研究热点,然而现阶段对太赫兹通信中多输入多输出( MIMO)机制的研究较少。为此,采用离散化的数学方法,以接收端获取信道信息的遍历容量模型为基础,结合太赫兹信道的分子吸收噪声与传输路径损失,提出一种适用于太赫兹通信的MIMO信道模型。对建立的MIMO信道模型进行仿真与分析,结果表明,与单一太赫兹信道相比,太赫兹通信中的MIMO信道具有更高的信道容量与传输比特率。

  19. Spin-communication channels between Ln(III) bis-phthalocyanines molecular nanomagnets and a magnetic substrate

    Science.gov (United States)

    Candini, A.; Klar, D.; Marocchi, S.; Corradini, V.; Biagi, R.; de Renzi, V.; Del Pennino, U.; Troiani, F.; Bellini, V.; Klyatskaya, S.; Ruben, M.; Kummer, K.; Brookes, N. B.; Huang, H.; Soncini, A.; Wende, H.; Affronte, M.

    2016-02-01

    Learning the art of exploiting the interplay between different units at the atomic scale is a fundamental step in the realization of functional nano-architectures and interfaces. In this context, understanding and controlling the magnetic coupling between molecular centers and their environment is still a challenging task. Here we present a combined experimental-theoretical work on the prototypical case of the bis(phthalocyaninato)-lanthanide(III) (LnPc2) molecular nanomagnets magnetically coupled to a Ni substrate. By means of X-ray magnetic circular dichroism we show how the coupling strength can be tuned by changing the Ln ion. The microscopic parameters of the system are determined by ab-initio calculations and then used in a spin Hamiltonian approach to interpret the experimental data. By this combined approach we identify the features of the spin communication channel: the spin path is first realized by the mediation of the external (5d) electrons of the Ln ion, keeping the characteristic features of the inner 4 f orbitals unaffected, then through the organic ligand, acting as a bridge to the external world.

  20. Joint Adaptive Modulation Coding and Cooperative ARQ over Relay Channels-Applications to Land Mobile Satellite Communications

    CERN Document Server

    Mardani, Morteza; Lahouti, Farshad; Eliasi, Behrouz

    2008-01-01

    In a cooperative relay network, a relay node (R) facilitates data transmission to the destination node (D), when the latter is unable to decode the source node (S) data correctly. This paper considers such a system model and presents a cross-layer approach to jointly design adaptive modulation and coding (AMC) at the physical layer and cooperative truncated automatic repeat request (ARQ) protocol at the data link layer. We first derive a closed form expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme. Aiming at maximizing this performance measure, we then optimize two AMC schemes for S-D and R-D links, which directly satisfy a prescribed packet loss rate constraint. As an interesting application, we also consider the problem of joint link adaptation and blockage mitigation in land mobile satellite communications (LMSC). We also present a new relay-assisted transmission protocol for LMSC, which delivers the source data to the destination via the relaying link, when the S-D channel is...

  1. M-Ary Alpha-Stable Noise Modulation in Spread-Spectrum Communication

    Science.gov (United States)

    Cek, Mehmet Emre

    2015-04-01

    In this paper, a spread-spectrum communication system based on a random carrier is proposed which transmits M-ary information. The random signal is considered as a single realization of a random process taken from prescribed symmetric α-stable (SαS) distribution that carries digital M-ary information to be transmitted. Considering the noise model in the channel as additive white Gaussian noise (AWGN), the transmitter sends the information carrying random signal from non-Gaussian density. Alpha-stable distribution is used to encode the M-ary message. Inspired by the chaos shift keying techniques, the proposed method is called M-ary symmetric alpha-stable differential shift keying (M-ary SαS-DSK). The main purpose of preferring non-Gaussian noise instead of conventional pseudo-noise (PN) sequence is to overcome the drawback of self-repeating noise-like sequences which are detectable due to the periodic behavior of the autocorrelation function of PN sequences. Having infinite second order moment in α-stable random carrier offers secrecy of the information due to the non-constant autocorrelation behavior. The bit error rate (BER) performance of the proposed method is illustrated by Monte Carlo simulations with respect to various characteristic exponent values and different data length.

  2. Long-term exposure to mobile communication radiation: An analysis of time-variability of electric field level in GSM900 down-link channels

    International Nuclear Information System (INIS)

    Interest for knowing long-term human exposure levels due to mobile communications has increased in the last years. It has been shown that short-term exposure assessment made under standard procedural restrictions is not reliable when it comes to conclusions on long-term exposure levels. The present work is the result of a several week analysis of time variability of electric field level inside traffic and control channels of the GSM900 mobile communication down-link band and it indicates that a temporal model to allow future predictions of exposure on the long run is obtainable. Collecting, processing and statistically analysing the data provide expression of the maximum and weighted field strengths and their evolution in time. Specific electromagnetic footprints of the channels have been extracted, differentiations between their characteristics have been emphasised and practical advice is provided, with the scope of contributing to the development of reliable procedures for long-term exposure assessment. (authors)

  3. Low Connexin Channel-Dependent Intercellular Communication in Human Adult Hematopoietic Progenitor/Stem Cells: Probing Mechanisms of Autologous Stem Cell Therapy

    OpenAIRE

    Yang, Jian; Darley, Richard L.; Hallett, Maurice; Evans, W. Howard

    2010-01-01

    Human bone marrow is a clinical source of autologous progenitor stem cells showing promise for cardiac repair following ischemic insult. Functional improvements following delivery of adult bone marrow CD34+ cells into heart tissue may require metabolic/electrical communication between participating cells. Since connexin43 (Cx43) channels are implicated in cardiogenesis and provide intercellular connectivity in the heart, the authors analyzed the expression of 20 connexins (Cx) in CD34+ cells ...

  4. 限幅法降低 OFDM 雷达通信一体化系统PAPR 研究%Research on Deliberate Clipping for PAPR Reduction of Integrated Radar and Communication Systems Based on OFDM Signals

    Institute of Scientific and Technical Information of China (English)

    李自琦; 梅进杰; 胡登鹏; 马少博; 苏俊生

    2014-01-01

    为解决基于OFDM信号的雷达通信一体化系统峰均功率比较高的问题,分析了雷达与通信信号的特点,根据一体化系统实际,利用直接限幅算法对基于 OFDM 信号的雷达通信一体化系统 PAPR 进行抑制,并对不同限幅门限下 PAPR 抑制性能、系统误码率以及互相关函数进行了计算机仿真。研究表明,只要合理设置限幅门限,直接限幅法能够有效地降低一体化系统 PAPR,由于限幅模块位于发射端,因此对雷达分系统目标检测性能影响较小;对于通信分系统,对信号直接限幅后会对误码率带来一定的影响,但是在信噪比较小时,仿真结果表明不论在衰落信道还是 AWGN 信道,直接限幅对系统的误码率性能影响不大。%To deal with the PAPR of integrated radar and communication systems based on OFDM sig-nals,the properties of the signals for the radar and the communication are analyzed.A deliberate clipping al-gorithm is proposed and applied to restrain the PAPR.The computer simulations of the PAPR performance, bit error ratio and cross correlation function are made at different clipping thresholds.The research indicates that,when the clipping thresholds are set in reason,deliberate clipping can restrain the PAPR effectively.As the deliberate clipping module lies in transmitter,it brings few influence on the target detection of the radar subsystem.As to the communication subsystem,when the clipping threshold reaches more than 4 dB,the computer simulation indicates that no matter in the fading channel or AWGN channel,the deliberate clipping also has few effect on the performance of BER.

  5. Communications

    Science.gov (United States)

    Bailenson, Jeremy; Buzzanell, Patrice; Deetz, Stanley; Tewksbury, David; Thompson, Robert J.; Turow, Joseph; Bichelmeyer, Barbara; Bishop, M. J.; Gayeski, Diane

    2013-01-01

    Scholars representing the field of communications were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Jeremy Bailenson, Patrice Buzzanell, Stanley Deetz, David Tewksbury, Robert J. Thompson, and…

  6. Multi-channel Digital Receiver in Shortwave Communication%短波通信中多通道数字接收机的实现

    Institute of Scientific and Technical Information of China (English)

    梅冬; 黎琴; 王骏扬; 杨宇宸; 李康

    2014-01-01

    The frequency range of shortwave communication is from 3MHz to 30MHz. This kind of communication mode has the feature of narrow bandwidth and large channel number. The traditional receiver cannot receive multiple channels at the same time. But with the development of software radio, high speed digital sampling and digital signal processing technology, we can realize the multi-channel receiver and achieve high sensitivity. This paper presents a multi-channel digital channelized receiver scheme which can realize the direct sampling of the shortwave band signals and realize the receiving of arbitrary frequency signal frequency band by use of channel technology.%短波通信的频率范围在3MHz到30MHz之间,具有信道带宽小,信道个数多的特点。传统的接收机,一般只能同时接收较少的信道个数。随着软件无线电技术的发展,利用高速数字采样和信号处理技术,可实现多信道的同时接收,且可达到较高的接收灵敏度。本文提出一种多通道数字信道化接收机方案,可实现对短波波段信号的直接采样,并利用信道化技术实现频带内任意频点信号的接收。

  7. Optimization of wireless sensor communication channel based on adaptive noise cancellation%基于自适应噪声抵消的无线传感网络信道优化

    Institute of Scientific and Technical Information of China (English)

    龙清; 胡光波

    2016-01-01

    Wireless sensor network communication technology is widely applied in the field of Internet of things near field communication, underwater acoustic communication. The wireless sensor network communication channel often encounter the multi⁃path interference, which lead to an imbalance of channel. Based on the aboved, the paper develops the channel equalization model design. Proposed a wireless sensor communication channel based on adaptive noise cancellation optimization technique. Firstly, build the channel model of wireless sensor network communication. The wireless sensor network communication channel in the process of decay signal loss and various paths of the reorganization, the adaptive noise cancellation algorithm for channel multipath interference filter, combined with the least square ( RLS) criterion algorithm for wireless sensor communications channel equalization design. Simulation results show that using the communication channel equalization technique can effectively improve the quality of the wireless sensor network communication channel, reduce the communication transmission distortion and bit error rate, realize the adaptive channel equalization, therefore improve the anti⁃interference ability of communication.%无线传感器网络通信技术广泛应用在物联网近场通信、水声通信等领域。无线传感网络通信信道受到多途干扰,导致信道失衡,需要进行信道均衡模型设计。提出一种基于自适应噪声抵消的无线传感器网络通信信道优化技术,首先构建了无线传感器网络通信的信道模型,对无线传感器网络信道传播过程中衰减损失和各条路径的信号进行重组,采用自适应噪声抵消算法进行信道的多途干扰滤波,结合最小二乘( RLS)准则算法进行无线传感器网络通信信道均衡设计。仿真结果表明,采用该通信信道均衡技术能有效提高无线传感器网络通信的信道质量,降低通信传

  8. Multimedia communication

    OpenAIRE

    Vondra, Zdeněk

    2010-01-01

    Multimedia is a form of communication and sharing knowledge using synergic effect of parallel connected communication channels. Its main use is in producing communications products and services and in design of user interfaces. Main objective of this dissertation is to develop and create a model of multimedia communication for better understanding of the meaning and the purpose of using multimedia forms in communication process. The model will describe a system of elements and parameters of m...

  9. COMMUNICATIONS

    CERN Multimedia

    A. Petrilli

    2013-01-01

    The organisation of the Open Days at the end of September was the single biggest effort of the CMS Communications Group this year. We would like to thank all volunteers for their hard work to show our Point 5 facilities and explain science and technology to the general public. During two days more than 5,000 people visited the CMS detector underground and profited from the surface activities, which included an exhibition on CMS, a workshop on superconductivity, and an activity for our younger visitors involving wooden Kapla blocks. The Communications Group took advantage of the preparations to produce new CMS posters that can be reused at other venues. Event display images have been produced not just for this occasion but also for other exhibits, education purposes, publications etc. During the Open Days, Gilles Jobin, 2012 winner of CERN Collide@CERN prize, performed his Quantum show in Point 5, with the light installation of German artist Julius von Bismarck. Image 3: CERN Open Days at CMS wel...

  10. COMMUNICATIONS

    CERN Multimedia

    L. Taylor and D. Barney

    2010-01-01

    CMS Centres, Outreach and the 7 TeV Media Event The new CMS Communications group is now established and is addressing three areas that are critical to CMS as it enters the physics operations phase: - Communications Infrastructure, including almost 50 CMS Centres Worldwide, videoconferencing systems, and CERN meeting rooms - Information systems, including the internal and external Web sites as well as the document preparation and management systems - Outreach and Education activities, including working with print, radio and TV media, visits to CMS, and exhibitions. The group has been active in many areas, with the highest priority being accorded to needs of CMS operations and preparations for the major media event planned for 7 TeV collisions. Unfortunately the CMS Centre@CERN suffered a major setback when, on 21st December, a cooling water pipe froze and burst on the floor above the CMS Centre main room. Water poured through the ceiling, flooding the floor and soaking some of the consoles, before e...

  11. Study of IP covert timing channel's communication protocol%IP时间隐通道通信协议的研究

    Institute of Scientific and Technical Information of China (English)

    王昌达; 李志国; 管星星; 薄兆军

    2012-01-01

    针对现有IP时间隐通道通信工具之间因缺乏统一的协议约束而不能互联互通的问题,在OSI参考模型的基础上建立IP时间隐通道四层协议模型,分析了协议各分层的功能,给出了具体的设计方案,并实现了一个满足分层协议功能要求的IP时间隐通道实用通信软件.%To solve the problem that the existing IP covert timing channel tools can not communicate with each other due to the lack of uniform protocol constraint, based on the OSI/RM,this paper established four layer protocol model of IP covert timing channel and gave the specific design. Furthermore, implemented a practical IP covert timing channel software which meeting the requirements of the hierarchical communication protocol.

  12. Communication, Literacy and Citizenship: a conceptual orientation in a portuguese children’s television thematic channel, K SIC

    OpenAIRE

    Lopes, Maria da Conceição de Oliveira

    2011-01-01

    This paper highlights the consequential nature of communication, literacy and citizenship and the meta-pattern that connects everything together – the ecology of the human spirit. It argues that, just like human communication, literacy is consequential in nature for humankind. Through each of our different worlds of experience and processes of communication, we manifest both of these human conditions and co-construct everyday practices that engender a plurality of effects. Literacy is a conce...

  13. Performance Analysis of a Six-Port Receiver in a WCDMA Communication System including a Multipath Fading Channel

    OpenAIRE

    Olopade, A. O.; Helaoui, M.

    2014-01-01

    Third generation communication systems require receivers with wide bandwidth of operation to support high transmission rates and are also reconfigurable to support various communication standards with different frequency bands. An ideal software defined radio (SDR) will be the absolute answer to this requirement but it is not achievable with the current level of technology. This paper proposes the use of a six-port receiver (SPR) front-end (FE) in a WCDMA communication system. A WCDMA end-to-...

  14. On the Capacity of Compound State-Dependent Channels with States Known at the Transmitter

    CERN Document Server

    Piantanida, Pablo

    2010-01-01

    This paper investigates the capacity of compound state-dependent channels with non-causal state information available at only the transmitter. A new lower bound on the capacity of this class of channels is derived. This bound is shown to be tight for the special case of compound channels with stochastic degraded components, yielding the full characterization of the capacity. Specific results are derived for the compound Gaussian Dirty-Paper (GDP) channel. This model consists of an additive white Gaussian noise (AWGN) channel corrupted by an additive Gaussian interfering signal, known at the transmitter only, where the input and the state signals are affected by fading coefficients whose realizations are unknown at the transmitter. Our bounds are shown to be tight for specific cases. Applications of these results arise in a variety of wireless scenarios as multicast channels, cognitive radio and problems with interference cancellation.

  15. Wireless Channel Characterization: Modeling the 5 GHz Microwave Landing System Extension Band for Future Airport Surface Communications

    Science.gov (United States)

    Matolak, D. W.; Apaza, Rafael; Foore, Lawrence R.

    2006-01-01

    We describe a recently completed wideband wireless channel characterization project for the 5 GHz Microwave Landing System (MLS) extension band, for airport surface areas. This work included mobile measurements at large and small airports, and fixed point-to-point measurements. Mobile measurements were made via transmission from the air traffic control tower (ATCT), or from an airport field site (AFS), to a receiving ground vehicle on the airport surface. The point-to-point measurements were between ATCT and AFSs. Detailed statistical channel models were developed from all these measurements. Measured quantities include propagation path loss and power delay profiles, from which we obtain delay spreads, frequency domain correlation (coherence bandwidths), fading amplitude statistics, and channel parameter correlations. In this paper we review the project motivation, measurement coordination, and illustrate measurement results. Example channel modeling results for several propagation conditions are also provided, highlighting new findings.

  16. A Low-Delay Low-Complexity EKF Design for Joint Channel and CFO Estimation in Multi-User Cognitive Communications

    CERN Document Server

    Zhao, Pengkai

    2011-01-01

    Parameter estimation in cognitive communications can be formulated as a multi-user estimation problem, which is solvable under maximum likelihood solution but involves high computational complexity. This paper presents a time-sharing and interference mitigation based EKF (Extended Kalman Filter) design for joint CFO (carrier frequency offset) and channel estimation at multiple cognitive users. The key objective is to realize low implementation complexity by decomposing highdimensional parameters into multiple separate low-dimensional estimation problems, which can be solved in a time-shared manner via pipelining operation. We first present a basic EKF design that estimates the parameters from one TX user to one RX antenna. Then such basic design is time-shared and reused to estimate parameters from multiple TX users to multiple RX antennas. Meanwhile, we use interference mitigation module to cancel the co-channel interference at each RX sample. In addition, we further propose adaptive noise variance tracking ...

  17. An application of queueing theory to the design of channel requirements for special purpose communications satellites. Ph.D. Thesis

    Science.gov (United States)

    Hein, G. F.

    1974-01-01

    Special purpose satellites are very cost sensitive to the number of broadcast channels, usually will have Poisson arrivals, fairly low utilization (less than 35%), and a very high availability requirement. To solve the problem of determining the effects of limiting C the number of channels, the Poisson arrival, infinite server queueing model will be modified to describe the many server case. The model is predicated on the reproductive property of the Poisson distribution.

  18. Study on the Channel Characteristics of Power Carrier Communication%电力载波通信信道特性研究

    Institute of Scientific and Technical Information of China (English)

    张高境

    2015-01-01

    电力线信道是电力载波通信中安全、可靠传输信息载体,因此关于阻抗特性、衰减特性、噪声特性方面的分析是电力载波通信网络构建的前提。最后提出了PLC与Wi-Fi等多种网络融合是未来发展的趋势。%Power line channel is a power line carrier communication in safe and reliable transmission of information carrier, so on the characteristic impedance, attenuation characteristics and noise characteristics analysis is the premise of power line carrier communication network construction. In the end, the integration of PLC and Wi-Fi is the trend of the future development.

  19. An overview of channel modeling methods for power-line communication%电力线载波通信信道建模技术综述

    Institute of Scientific and Technical Information of China (English)

    蔡伟; 乐健; 靳超; 黄楚鸿; 郑雪

    2011-01-01

    Power-line communication(PLC) technology is an important communication method which has been widely used in power systems.Power line channel modeling and carrier frequency optimization are significant to the realization of high-speed data transmission over the power line.This paper starts with a brief introduction of the basic theories of signal transmission on power lines,and then an overview of power-line communication channel modeling methods together with the classification of existing modeling methods according to model parameters acquisition approaches is presented.The development process of each method is introduced,and it is followed by a detailed analysis of the advantages and disadvantages of each method.Finally,a channel model method of power line communication based on the graph theory is proposed,and its potential of being applied to smart grid medium-voltage power-line communication is studied.%电力线载波通信(power line communication,PLC)技术是电力系统中应用广泛的重要通信手段。电力线信道模型的建立和电力线载波频率的优化对于在电力线上实现高速数据传输具有重要意义。首先简要介绍电力线信号传输基本理论,然后按照建模所需参数的获取方法进行分类,对各种电力线信道建模技术进行了综述。介绍各类建模技术的发展历程,并分析了各种技术的优缺点。最后提出一种基于图论法的电力线载波信道建模方法,分析了该方法应用于智能电网中压电力线载波通信的可行性。

  20. Vectorial characterization of DVB-T propagation channel - Application to radio-Mobile communications : the CAVITE Project

    OpenAIRE

    Brousseau, Christian; Avrillon, Stéphane; Nivole, Franck; Bertel, Louis

    2007-01-01

    International audience In this paper, the whole project CAVITE is described. This project is proposed within the framework of sets of themes around "Sciences and Technologies of Information and Communication" for radio-mobile digital communication in order to increase the data rate or quality of transmission. One of the objectives is the reception of Digital Video Broadcasting on Terrestrial networks (DVB T) in vehicular condition (car, train ...).

  1. Performance of Wireless Optical Communication over Atmospheric Turbulence Channel%大气湍流下无线光通信信道性能研究

    Institute of Scientific and Technical Information of China (English)

    黄根全

    2011-01-01

    Based on different scintillation distribution channel model over atmospheric turbulence, the statistic model of outage probability and average channel capacity was founded,and the method on Gauss -Lager was applied to calculate outage probability and average channel capacity under weak to moderate and moderate to strong turbulence. The simulation results showed that outage probability increases with the increasing intensity of turbulence and normalized average electrical SNR, and average channel capacity also increases with the increasing of receiver average electrical SNR The increasing rate is faster and channel capacity is biger under weak turbulence than strong turbulence. The knowledge of the theory was provided for wireless optical access communication system.%无线光通信中大气湍流导致光信号在传输中产生光强起伏等现象,其影响成为无线光通信普及的一大障碍.基于大气湍流不同光强起伏信道模型,分别建立了弱、中及强湍流信道的中断概率与平均信道容量数学统计模型,研究了大气折射率结构常数和传输距离对湍流信道可靠性的影响.仿真结果表明,归一化阈值信噪比和通信距离的增加导致通信系统性能劣化.平均信道容量随着湍流强度的增大而降低,且随着接收机平均电信噪比增大,弱湍流下的信道容量增长速度明显大于强湍流.

  2. Phase-Quantized Block Noncoherent Communication

    CERN Document Server

    Singh, Jaspreet

    2011-01-01

    Analog-to-digital conversion (ADC) is a key bottleneck in scaling DSP-centric receiver architectures to multiGigabit/s speeds. Recent information-theoretic results, obtained under ideal channel conditions (perfect synchronization, no dispersion), indicate that low-precision ADC (1-4 bits) could be a suitable choice for designing such high speed systems. In this work, we study the impact of employing low-precision ADC in a {\\it carrier asynchronous} system. Specifically, we consider transmission over the block noncoherent Additive White Gaussian Noise (AWGN) channel, and investigate the achievable performance under low-precision output quantization. We focus attention on an architecture in which the receiver quantizes {\\it only the phase} of the received signal: this has the advantage of being implementable without automatic gain control, using multiple 1-bit ADCs preceded by analog multipliers. For standard uniform Phase Shift Keying (PSK) modulation, we study the structure of the transition density of the re...

  3. Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

    Directory of Open Access Journals (Sweden)

    Min Du

    2012-11-01

    Full Text Available Intra-Body Communication (IBC, which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.

  4. Study on the Communication Channels of Financial Information in Colleges and Universities%高校财务信息的传播渠道探讨

    Institute of Scientific and Technical Information of China (English)

    刘华坤

    2016-01-01

    One of the important contents in colleges and universities information disclosure is the financial information. In view of the characteristics of public or directional open financial information in colleges and universities, as well as the use of the financial information, three types of communication channels are analyzed. This paper also puts forward the com-munication channels of the financial information in colleges and universities under the triple play environment.%高校财务信息是高校信息公开的重要内容之一。针对高校完全公开类财务信息和指向性公开类财务信息的特点,以及高校财务信息的使用对象,分析高校财务信息的三类传播渠道,并提出三网融合信息环境下高校财务信息的传播渠道选择。

  5. Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

    Science.gov (United States)

    Chen, Xi Mei; Mak, Peng Un; Pun, Sio Hang; Gao, Yue Ming; Lam, Chan-Tong; Vai, Mang I.; Du, Min

    2012-01-01

    Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results. PMID:23443387

  6. High Spectrum Narrowing Tolerant 112 Gb/s Dual Polarization QPSK Optical Communication Systems Using Digital Adaptive Channel Estimation

    DEFF Research Database (Denmark)

    Zhang, Xu; Pang, Xiaodan; Dogadaev, Anton Konstantinovich;

    2012-01-01

    We experimentally demonstrate high spectrum narrowing tolerant 112-Gb/s QPSK polarization multiplex system based on digital adaptive channel estimation method. The proposed algorithm is able to detect severe spectrum-narrowed signal even with 20GHz 3dB bandwidth....

  7. 水声通信信道中的OPNET建模与仿真%Modeling and simulation of underwater acoustic communication channel using OPNET

    Institute of Scientific and Technical Information of China (English)

    Dao Van Phuong; 左加阔; Bui Thi Oanh; 方世良; 赵力

    2014-01-01

    To avoid the disadvantages of high cost and complexity of the underwater acoustic com-munication channel,a simulation method for analyzing the characteristics of underwater acoustic communication networks is developed.The proposed method uses Propagation-Delay-Stage,Receiv-er-Power-Stage and Background-Noise-Stage in OPNET simulation tool to simulate the propagation delay,transmitter power and underwater acoustic noise (underwater acoustic noise contains turbu-lence,shipping,wind driven waves and thermal noise)of underwater acoustic channel,respective-ly.In the OPNET tool,the Propagation-Delay-Stage employs MacKenzie model.The Receiver-Power-Stage employs three propagation loss model,Thorp,Schulkin&Marsh and Francois&Garri-son models.In the proposed method,different underwater acoustic channels are simulated when dif-ferent propagation loss models are chosen,and then a suitable underwater acoustic channel is selected according to the simulation results.After the underwater acoustic channel model is selected,the un-derwater acoustic communication network can be simulated with MACAW protocol.Finally,the throughput,bit error rate,packet loss ratio of the underwater acoustic communication network are simulated.Simulation results demonstrate that the proposed simulation method can efficiently simu-late the underwater acoustic communication network.%针对水声通信网络信道的实现开销大、复杂性高的特点,提出了一种能够仿真分析水声通信网络的有效方法。该方法分别使用OPNET中的Propagation-Delay-Stage,Receiver-Power-Stage和Background-Noise-Stage三个工具来仿真水声信道中的传播延迟、发射机功率和水声噪声(水声噪声包括紊流、船运、风波和热噪声)。其中,Propagation-Delay-Stage采用MacKenzie速度模型;Re-ceiver-Power-Stage中有Thorp,Schulkin&Marsh和Francois&Garrison 3种传播损失模型。在该方法中,首先仿真比较了取不同传播损失模型时的水

  8. Programming with Quantum Communication

    OpenAIRE

    Tafliovich, Anya; Hehner, Eric C. R.

    2009-01-01

    This work develops a formal framework for specifying, implementing, and analysing quantum communication protocols. We provide tools for developing simple proofs and analysing programs which involve communication, both via quantum channels and exhibiting the LOCC (local operations, classical communication) paradigm.

  9. Multi-channel data-communication system of laser shooting target%激光打靶多路数据通信系统设计

    Institute of Scientific and Technical Information of China (English)

    周锐; 周健

    2012-01-01

    Nowadays, data communication system is applied in comprehensive domains with the development of sensor techniques, fiber communication and information processing techniques. A laser shoot target multi- channel data-acquisition processing system of this paper is a multichannel serial communication system which realized based on the RS-485 serial communication theory and the army actual group-training demands. This paper expound the fact of RS-485 bus multi-channel data communication system’s design and the correlation problems.Computer can control the operation of Microcontroller, which can select the time of data- acquisition discretionarily. It is not only fit for data-acquisition of close quarters, but also fit for data-acquisition of telecommunication. Especially the software and hardware realization of microcontroller’s interface, the computer’s interface.%随着传感器、光纤、计算机和信息处理等技术的发展,数据通信系统在各个领域迅速地得到了应用。本文所述的激光模拟打靶多路数据通信系统是在现有RS485串行通信理论的基础上,根据部队实际群体训练需要而设计的一种多路串行通信系统。主要对RS485多路数据通信系统设计与实现的相关问题进行了研讨,微机可以控制单片机的运行,可以任意选择采集数据的时间,既适用于近距离数据采集,也适合于远距离数据采集,具体论述了单片机接口的软件硬件设计、微机接口的软件硬件设计。

  10. On the performance of free-space optical wireless communication systems over double generalized gamma fading channels

    KAUST Repository

    Al-Quwaiee, Hessa

    2014-03-01

    Starting with the double generalized Gamma (GG) model that was proposed in [1] to describe turbulence-induced fading in free-space optical (FSO) systems, we propose a new unified model which accounts for the impact of pointing errors and type of receiver detector. Based on this new unified model, we study the performance of FSO links operating over these kind of channels. All our analytical results are verified using computer based Monte-Carlo simulations. © 2014 IEEE.

  11. Experimental Investigation of Subject-Specific On-Body Radio Propagation Channels for Body-Centric Wireless Communications

    Directory of Open Access Journals (Sweden)

    Mohammad Monirujjaman Khan

    2014-01-01

    Full Text Available In this paper, subject-specific narrowband (2.45 GHz and ultra-wideband (3–10.6 GHz on-body radio propagation studies in wireless body area networks (WBANs were performed by characterizing the path loss for eight different human subjects of different shapes and sizes. The body shapes and sizes of the test subjects used in this study are characterised as thin, medium build, fatty, shorter, average height and taller. Experimental investigation was made in an indoor environment using a pair of printed monopoles (for the narrowband case and a pair of tapered slot antennas (for the ultra-wideband (UWB case. Results demonstrated that, due to the different sizes, heights and shapes of the test subjects, the path loss exponent value varies up to maximum of 0.85 for the narrowband on-body case, whereas a maximum variation of the path loss exponent value of 1.15 is noticed for the UWB case. In addition, the subject-specific behaviour of the on-body radio propagation channels was compared between narrowband and UWB systems, and it was deduced that the on-body radio channels are subject-specific for both narrowband and UWB system cases, when the same antennas (same characteristics are used. The effect of the human body shape and size variations on the eight different on-body radio channels is also studied for both the narrowband and UWB cases.

  12. 面向协作通信的忙音信道接入机制%A channel accessing scheme based on busy tone for cooperative communication

    Institute of Scientific and Technical Information of China (English)

    谢鲲; 谢可欣; 吉刚; 何施茗

    2014-01-01

    Compared with traditional wireless communication , although relay nodes in cooperative communication can help to increase the performance of a wireless network,relay nodes may cause the serious competition for wire-less channel accessing ,which makes the channel access problem in cooperative communication challenging .To solve the problem,a novel MAC ( media access control) scheme by concurrently considering RTS/CTS ( Request To Send/Clear To Send) and busy tone is proposed in the paper.In the scheme,three busy tones are proposed to iden-tify the state of channel occupation and solve the hidden terminal and exposed terminal problems in cooperative communication.Based on the busy tone,this paper also proposes a bandwidth efficient relay selection algorithm.The source can choose the best relay in a distributed way by sensing the busy tone .The theory and simulation results demonstrate that the proposed scheme can efficiently improve the channel utilization and solve the hidden terminal and exposed terminal problems in cooperative communication .The blocking time ratio of the proposed MAC scheme is less than 10% when the data packet size surpasses 3500B.%与传统无线传输相比,虽然协作中继节点的参与可以大大提高无线网络性能,然而协作中继会带来严重的信道竞争问题,这给协作通信环境中的信道访问控制带来挑战。为了解决这个问题,提出一种RTS/CTS(Request To Send/Clear To Send)与忙音结合的MAC(media access control)信道接入方案。该方案使用3个忙音来标识信道的使用状态,并解决协作通信中的隐藏终端和暴露终端问题。基于忙音信号,还提出了一种带宽节俭的协作节点选择算法。通过侦听忙音信号,源节点可分布式地选择最优的协作节点。理论分析和仿真实验表明所提方案能有效地提高协作通信中的信道利用率,很好地解决了协作通信中的隐藏终端暴露终端问

  13. Super-additivity in communication of classical information through quantum channels from a quantum parameter estimation perspective

    OpenAIRE

    Czajkowski, Jan; Jarzyna, Marcin; Demkowicz-Dobrzanski, Rafal

    2016-01-01

    We point out a contrasting role the entanglement plays in communication and estimation scenarios. In the first case it brings noticeable benefits at the measurement stage (output super-additvity), whereas in the latter it is the entanglement of the input probes that enables significant performance enhancement (input super-additvity). We identify a weak estimation regime where a strong connection between concepts crucial to the two fields is demonstrated; the accessible information and the Hol...

  14. SYSTEM OF FREQUENCY PROVIDING OF HF COMMUNICATION CHANNELS BASED ON THE NEW DIGITAL SOUNDER ON USRP PLATFORM

    OpenAIRE

    Ivanov, Dmitry; Ivanov, Vladimir; Ryabova, Natalya; Elsukov, Alexey; Ryabova, Mariya; Chernov, Andrey

    2015-01-01

    Studied the possibility of creating on USRP platform receiving terminal Ionosonde continuous chirp signal and to obtain compared results with the data of ionospheric sounding analog chirped probe. Created on USRP platform receiving terminal chirp ionosonde showed a higher noise immunity, lack of congestion own signal, the possibility of simultaneous studies of the characteristics of direct and global propagation. Developed an algorithm providing frequency HF communication systems based on pan...

  15. A Novel Criterion for Optimum MultilevelCoding Systems in Mobile Fading Channels

    Institute of Scientific and Technical Information of China (English)

    YUAN Dongfeng; WANG Chengxiang; YAO Qi; CAO Zhigang

    2001-01-01

    A novel criterion that is "capac-ity rule" and "mapping rule" for the design of op-timum MLC scheme over mobile fading channels isproposed.According to this theory,the performanceof multilevel coding with multistage decoding schemes(MLC/MSD) in mobile fading channels is investi-gated,in which BCH codes are chosen as componentcodes,and three mapping strategies with 8ASK mod-ulation are used.Numerical results indicate that whencode rates of component codes in MLC scheme are de-signed based on "capacity rule",the performance ofthe system with block partitioning (BP) is optimumfor Rayleigh fading channels,while the performance ofthe system with Ungerboeck partioning (UP) is bestfor AWGN channels.

  16. Integrated Joint Source-Channel Decoding for H.264 Video Transmission

    Institute of Scientific and Technical Information of China (English)

    WU Jing; CHEN Shuzhen

    2007-01-01

    This paper proposes an integrated joint source-channel decoder (I-JSCD) using Max-Log-MAP method for sources encoded with exp-Golomb codes and convolutional codes, and proposes a system applying this method to decoding the VLC data,e.g. motion vector differences (MVDs), of H.264 across an AWGN channel. This method combines the source code state-space and the channel code state-space together to construct a joint state-space, develops a 3-D trellis and a maximum a-posterior(MAP) algorithm to estimate the source sequence symbol by symbol, and then uses max-log approximation to simplify the algorithm. Experiments indicate that the proposed system gives significant improvements on peak signal-to-noise ratio (PSNR)(maximum about 15 dB) than a separate scheme. This also leads to a higher visual quality of video stream over a highly noisy channel.

  17. 电力通信网远动通道监测的实现方式%Implementation Way of Remote Channel Monitoring of Electric Power Communication Network

    Institute of Scientific and Technical Information of China (English)

    巢玉坚

    2012-01-01

    业务通道监测是电力通信管理系统的一个重要组成部分,本文主要阐述了模拟远动、数字远动及IP远动的监测方式,并分析了其特点和使用范围,最后给出了省公司和地市公司的远动信号监测方案.%The business channel monitoring is an important component of the electric power communication management system. The article focuses on the simulation remote, digital remote, and IP remote monitoring, analyzes its characteristics and the use scope, and gives the remote signal monitoring programs to provincial and municipal company.

  18. Simulation Model for DVB-SH Systems Based on OFDM for Analyzing Quasi-error-free Communication over Different Channel Models

    Science.gov (United States)

    Bačić, Iva; Malarić, Krešimir; Dumić, Emil

    2014-05-01

    Mobile users today expect wide range of multimedia services to be available in different mobility scenarios, and among the others is mobile TV service. The Digital Video Broadcasting - Satellite services to Handheld (DVB-SH) is designed to provide mobile TV services, supporting a wide range of mobile multimedia services, like audio and data broadcasting as well as file downloading services. In this paper we present our simulation model for the performance evaluation of the DVB-SH system following the ETSI standard EN 302 583. Simulation model includes complete DVB-SH system, supporting all standardized system modes and parameters. From transmitter to receiver, the information may be sent over different channel models, thus simulating real case scenarios. To the best of authors' knowledge, this is the first complete model of DVB-SH system that includes all standardized system parameters and may be used for examining real DVB-SH communication as well as for educational purposes.

  19. 基于多径分量重组的扩频通信信道均衡设计%Spread Spectrum Communication Channel Equalization Design Based on Multipath Component Recombination

    Institute of Scientific and Technical Information of China (English)

    王晓雯

    2016-01-01

    扩频通信中,由于扩频码序列所占的带宽度远大于所传信息的最小带宽,引起码间干扰和信道失衡,通过对扩频通信的信道均衡设计,降低扩频通信的误码率。传统方法采用子信道载波干扰抑制的扩频通信信道均衡算法,通过扩频码控制子信道载波线性调频变化,实现码间干扰抑制,但该算法会引起时分复用系统之间的相位畸变,信道均衡效果不好。提出一种基于多径分量重组的扩频通信信道均衡算法。先构建了扩频通信的信道模型,分析了扩频通信信道的时变特性,采用多径分量重组实现码间干扰抑制,结合多阵元被动时间反转镜技术实现扩频通信的信道均衡。仿真结果表明,采用该算法进行扩频通信信道均衡和码间干扰抑制,降低通信误码率,改善通信质量,提高了扩频通信系统的稳定性和可靠性。%In spread spectrum communication, because of the spread spectrum code sequence for the band width is much larger than the transmitted information minimum bandwidth, causing intersymbol interference and channel imbalance, through the spread spectrum communication channel equalization design, reduce the bit error rate of the spread spectrum communication. Traditional methods using sub carrier channel interference suppression in spread spectrum communication channel equalization algorithm, to achieve inter symbol interference suppression by spread spectrum codes control sub carrier channel linear FM changes, but the algorithm will phase distortion caused by time division multiplexing system, channel equalization effect is not good. A spread spectrum communication channel equalization algorithm based on multipath component is proposed. First, constructs the spread spectrum communication channel model, analysis of the spread spectrum communication channel characteristic and the multipath component of the reorganization of the realization of

  20. Simulation and performance Analysis of a Novel Model for Short Range Underwater Acoustic communication Channel Using Ray Tracing Method in Turbulent Shallow Water Regions of the Persian Gulf

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Dargahi

    2011-01-01

    Full Text Available High data rate acoustic transmission is required for diverse underwater operations such as the retrieval of large amounts of data from bottom packages and real time transmission of signals from underwater sensors. The major obstacle to underwater acoustic communication is the interference of multipath signals due to surface and bottom reflections. High speed acoustic transmission over a shallow water channel characterized by small grazing angles presents formidable difficulties. The reflection losses associated with such small angles are low, causing large amplitudes in multi-path signals. In this paper, based on the results obtained from practical measurements in the Persian Gulf and available data about sound speed variations in different depths, we propose a simple but effective model for shallow water short-range multipath acoustic channel. Based on the Ray theory, mathematical modeling of multipath effects is carried out. Also in channel modeling, the attenuation due to the wave scatterings at the surface and its bottom reflections for deferent grazing angles and bottom types is considered. In addition, we consider the attenuations due to the absorption of different materials and ambient noises such as see-state noise, shipping noise, thermal noise and turbulences. We use a three-dimensional hydrodynamic model (COHERENS in a fully prognostic mode to study the circulation and water mass properties of the Persian Gulf - a large inverse estuary. Maximum sound speed occurs during the summer in the Persian Gulf which decreases gradually moving from the Strait of Hormuz to the north western part of the Gulf. A gradual decrease in sound speed profiles with depth was commonly observed in almost all parts of the Gulf. However, an exception occurred in the Strait of Hormuz during the winter. The results of the model are in very good agreement with our observations.

  1. Business Communication Strategies

    OpenAIRE

    Lavinia Hulea

    2005-01-01

    General communication processes rely on messages implying contents, communication channels, a receiver and clear objectives. Once accepting the importance of defining objectives, three strategies, narrative, implicative, and decisional, seem to be specific for most business communications. While narrative business communications convey information with a view of simply transmitting information and depend on accuracy, complexity, and clarity, implicative business communications convey informat...

  2. The impact of pulsed RFI on the coded BER performance of the nonlinear satellite communication channel. [with BPSK modulation

    Science.gov (United States)

    Weinberg, A.

    1981-01-01

    An examination is conducted of the coded bit error rate (BER) performance of a satellite communication system in which binary phase-shift-keyed (BPSK) modulation is employed, pulsed CW or pulsed noise RFI is present, and the transponder contains a nonlinearity characterized by arbitrary AM/AM and AM/PM characteristics; the RFI pulse duration is further assumed to exceed that of the information symbol. Computed performance curves consider several hypothetical RFI scenarios in which either a hard limiter or an 8 dB clipper represent the transponder amplitude nonlinearity. Results demonstrate the potential seriousness of RFI duty cycles as low as 2 percent, and the fact that CW represents the most severe form of interference.

  3. An Adaptive Joint Source/Channel Coding Using Error Correcting Arithmetic Codes

    Institute of Scientific and Technical Information of China (English)

    LIU Jun-qing; PANG Yu-ye; SUN Jun

    2007-01-01

    An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcting in a single process, with superior performance compared with traditional separated techniques.The concept of adaptiveness is applied not only to the source model but also to the amount of coding redundancy.In addition,an improved branch metric computing algorithm and a faster sequential searching algorithm compared with the system proposed by Grangetto were proposed.The proposed system is tested in the case of image transmission over the AWGN channel, and compared with traditional separated system in terms of packet error rate and complexity.Both hard and soft decoding were taken into account.

  4. Performance of Parallel Concatenated Convolutional Codes (PCCC with BPSK in Nakagami Multipath M-Fading Channel

    Directory of Open Access Journals (Sweden)

    Mohamed Abd El-latif

    2012-01-01

    Full Text Available In this paper the encoder design of two parallel concatenated convolutional codes (PCCC have been introduced. Concept of puncturing is also considered. PCCC is also named as Turbo codes. Decoding process of turbo-codes using a maximum a posteriori (MAP algorithm has been discussed. Different parameters affect the BER performance of turbo codes are introduced .The previous studies focusing on the turbo-codes performance in (AWGN and Rayleigh multipath- fading channels. The real importance of Nakagami –m fading model lies in the fact that it can often be used to fit the indoor channel measurements for digital cellular systems such as global system mobile (GSM. In this paper, the BER performance and comparative study of turbo-codes in Nakagami multipath- fading channel is verified using Matlab simulation program.

  5. Error Performance of Multidimensional Lattice Constellations-Part II: Evaluation over Fading Channels

    CERN Document Server

    Pappi, Koralia N; Chronis, Theodore N; Karagiannidis, George K

    2012-01-01

    This is the second part of a two-part series of papers, where the error performance of multidimensional lattice constellations with signal space diversity (SSD) is investigated. In Part I, following a novel combinatorial geometrical approach which is based on parallelotope geometry, we have presented an exact analytical expression and two closed-form bounds for the symbol error probability (SEP) in Additive White Gaussian Noise (AWGN). In the present Part II, we extend the analysis and present a novel analytical expression for the Frame Error Probability (FEP) of multidimensional lattice constellations over Nakagami-m fading channels. As the FEP of infinite lattices is lower bounded by the Sphere Lower Bound (SLB), we propose the Sphere Upper Bound (SUB) for block fading channels. Furthermore, two novel bounds for the FEP of multidimensional lattice constellations over block fading channels, named Multiple Sphere Lower Bound (MSLB) and Multiple Sphere Upper Bound (MSUB), are presented. The expressions for the...

  6. 多光谱可见光通信信道串扰分析∗%Analysis of channel crosstalk in muliti-sp ectrum visible light communication system

    Institute of Scientific and Technical Information of China (English)

    崔璐; 唐义; 朱庆炜; 骆加彬; 胡珊珊

    2016-01-01

    In visible light communication, the wavelength division mutiplexing (WDM) technology can improve system data rate by increasing the number of channels. However, because the emission spectrum of the light emitting diode (LED) has a certain width, a phenomenon of spectral overlapping will occur when the number of channels increases and channel-spacing decreases, which results in channel crosstalk although optical filters are adopted. The channel crosstalk will restrict the capacity of WDM-VLC (visible light communication) system, which has great research significance. In this paper, the channel crosstalk based on LED spectra overapping is disscussed. The LED emission spectrum is modeled by combining the physical mechanism of LED emission with real shape of LED spectrum. According to the literature, the LED shape can be fitted greatly by Gauss function, and the full-width at half-maximum ∆E is in a range from about 4.3kBTj to 6.8kBTj when the peak wavelengths of InGaN and AlInGaN LEDs are both less than 560 nm, ∆E values range from 2.1kBTj to 3.3kBTj when the peak wavelength of InAlGaP LED is larger than 560 nm. In order to reduce the overall system complexity we use the following values: when the peak wavelength is less than 560 nm, ∆E =5.5kBTj;when the peak wavelength is larger than 560 nm,∆E=3.0kBTj. Then, according to the overlapping spectra and VLC channel with considering optical filter transmittance and detector spectral response, the channel crosstalk formula is derived. Some quantities are given before simulation such as the semi-angle at half illuminance of an LED is 60◦; all LEDs are so closely arranged together to mix light in free space that spacing between LEDs can be ignored with respect to the propagating distance; the strongest signal situation is considered. The simulation result shows that although at the same channel spacing, different channels have different crosstalks because spectra are different. And the crosstalk from one adjacent

  7. Multilevel LDPC Codes Design for Multimedia Communication CDMA System

    Directory of Open Access Journals (Sweden)

    Hou Jia

    2004-01-01

    Full Text Available We design multilevel coding (MLC with a semi-bit interleaved coded modulation (BICM scheme based on low density parity check (LDPC codes. Different from the traditional designs, we joined the MLC and BICM together by using the Gray mapping, which is suitable to transmit the data over several equivalent channels with different code rates. To perform well at signal-to-noise ratio (SNR to be very close to the capacity of the additive white Gaussian noise (AWGN channel, random regular LDPC code and a simple semialgebra LDPC (SA-LDPC code are discussed in MLC with parallel independent decoding (PID. The numerical results demonstrate that the proposed scheme could achieve both power and bandwidth efficiency.

  8. Error Resilient Image Transmission over Wireless Fading Channels

    Directory of Open Access Journals (Sweden)

    M Padmaja,

    2010-05-01

    Full Text Available Nowadays transferring images and video over wireless channels is becoming more use of the medium. However, a wireless medium is not very reliable in the way that it adds unwanted components and noise to the wireless transmission. So there may be a loss of data. Due to this possible loss of data without the capability of resending a correct version we need a system to protect and correct such losses. The transmission of images over wireless channels is examined using reorganization of the compressed images into error-resilient, product-coded streams. The product-code consists of Turbo-codes or Reed–Solomon codes which are optimized using an iterative process. The wireless channel used for the testing phase is a Rayleigh Fading channel with Additive White Gaussian Noise (AWGN added as a noisecomponent. In this paper we propose protection techniques for image transmission and compare the performance of various protection methods for all JPEG standards. The proposed image standard model was found to perform very well in protecting the images against quality degradation during transmission over wireless channels. The strength of the protection plays a large part in the protection of the image and should be chosen to suit the particular channel in use. Thedefault protection also provides very strong protection for the user who does not wish to choose their own setting.

  9. Evaluation and Verification of Channel Transmission Characteristics of Human Body for Optimizing Data Transmission Rate in Electrostatic-Coupling Intra Body Communication System: A Comparative Analysis.

    Directory of Open Access Journals (Sweden)

    Yuhwai Tseng

    Full Text Available Intra-body communication is a new wireless scheme for transmitting signals through the human body. Understanding the transmission characteristics of the human body is therefore becoming increasingly important. Electrostatic-coupling intra-body communication system in a ground-free situation that integrate electronic products that are discretely located on individuals, such as mobile phones, PDAs, wearable computers, and biomedical sensors, are of particular interest.The human body is modeled as a simplified Resistor-Capacitor network. A virtual ground between the transmitter and receiver in the system is represented by a resister-capacitor network. Value of its resistance and capacitance are determined from a system perspective. The system is characterized by using a mathematical unit step function in digital baseband transmission scheme with and without Manchester code. As a result, the signal-to-noise and to-intersymbol-interference ratios are improved by manipulating the load resistor. The data transmission rate of the system is optimized. A battery-powered transmitter and receiver are developed to validate the proposal.A ground-free system fade signal energy especially for a low-frequency signal limited system transmission rate. The system transmission rate is maximized by simply manipulating the load resistor. Experimental results demonstrate that for a load resistance of 10k-50k Ω, the high-pass 3 dB frequency of the band-pass channel is 400kHz-2MHz in the worst-case scenario. The system allows a Manchester-coded baseband signal to be transmitted at speeds of up to 20M bit per second with signal-to-noise and signal-to-intersymbol-interference ratio of more than 10 dB.The human body can function as a high speed transmission medium with a data transmission rate of 20Mbps in an electrostatic-coupling intra-body communication system. Therefore, a wideband signal can be transmitted directly through the human body with a good signal

  10. Characterizing head motor disorders to create novel interfaces for people with cerebral palsy: creating an alternative communication channel by head motion.

    Science.gov (United States)

    Raya, R; Rocon, E; Ceres, R; Harlaar, J; Geytenbeek, J

    2011-01-01

    This paper aims to validate a head mounted inertial interface to characterize disorder movements in people with cerebral palsy (CP). The kinematic patterns extracted from this study will be used to design an alternative communication channel (using head motion) adapted to user's capabilities and limitations. Four people with CP participated (GMFCS level V) and three healthy subjects as reference group. The main outcome measures were divided into 1) Time-domain, 2) Frequency-domain and 3) Spatial domain. Results showed that the inertial interface succeeds assessing the pathological motion. Firstly, the system differentiates between voluntary and involuntary motion in terms of motor control, frequency and range of motion. Secondly some motion disorders such as hypertonia, hypotonia can be identified. These results suggest that people with motor disorders could benefit from the developed inertial system in three fields: 1) diagnosis of motor disorder by means of an objective quantification, 2) physical and cognitive rehabilitation by means of proprioceptive enhancement through visual-motor feedback and 3) functional compensation by means of an inertial person-machine interface for controlling computer and assistive devices (e.g. wheelchairs or walkers). PMID:22275612

  11. CHANNEL ESTIMATION TECHNIQUE

    DEFF Research Database (Denmark)

    2015-01-01

    A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the communicat......A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the...... communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including...

  12. Automatic guided wave communication system using steel pipes as communication channel for flood detection in steel offshoreoilrigs; Sistema automatico de comunicacion de ondas guiadas para la deteccion de tubos de refuerzo inundados en plataformas petroleras costa fuera

    Energy Technology Data Exchange (ETDEWEB)

    Mijarez Cstro, Rito; Martinez Ramirez, Fernando [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2010-10-09

    An automatic guided wave Pulse Position Modulation (PPM) system, using steel tubes as communication channel, for detecting flooding in the hollow sub-sea structures of offshore oilrigs is presented. The system employs two smart piezoelectric based sensors and modulators and a demodulator based on a piezoelectric transducer, a Digital Signal Processor (DSP) and a microcontroller. Experiments performed in the laboratory, in a tubular steel heliport structure and the base of a deck of an oilrig under construction, have successfully distinguished automatically guided wave encoded information. [Spanish] Este articulo presenta un trabajo de investigacion en el cual se desarrolla un sistema automatico de comunicacion de ondas guiadas por modulacion por posicion de pulsos (PPM), orientado a la deteccion de miembros inundados en los tubos de refuerzo de las plataformas petroleras costa fuera. El sistema utiliza de manera novedosa tubos de acero como medio de comunicacion y emplea dos sensores/moduladores inteligentes compuestos de cristales piezoelectricos, electronica basada en un microcontrolador y baterias. La instrumentacion del demodulador consta de un transductor piezoelectrico de ultrasonido, un procesador digital de senales (DSP) y un microcontrolador, el cual lleva a cabo de manera automatica la deteccion de ondas guiadas. Los experimentos se realizaron en aire, en laboratorio, en una estructura tubular de acero del helipuerto y en la base de una plataforma bajo construccion.

  13. HIPPI and Fibre Channel

    International Nuclear Information System (INIS)

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background

  14. A Study of the Impact of Corporate Social Responsibility Strategy and Communication Channel on Brand Trust%CSR战略和传播渠道对品牌信任的影响研究

    Institute of Scientific and Technical Information of China (English)

    黄光; 魏婷婷; 黄匡熹; 周延风

    2014-01-01

    Enterprises have the new development thoughts on the way to undertake corporate social responsibility (CRS) along with the continuous change of the connotation of CRS,moreover,they realize the importance of the communication of social re-sponsibility information. Based on the literature review,the paper makes a study on the influencing mechanism of the way to un-dertake CRS and the channel to communicate CRS on brand trust. On one the hand, the CRS can be classified into strategic CRS and reactive CRS based on whether it combines with the enterprise’s core business. On the other hand, the information communication channel of CRS can be divided into internal communication channel and external communication channel based on whether it is controllable. The paper also explores the impacts of CRS strategy and CRS communication channel on the motive attribution and brand trust by introducing social driving attribution and self interest driving attribution as mediating variables.%随着企业社会责任内涵的持续变化,企业在承担社会责任的方式上有了新的发展思路,同时,企业也认识到了社会责任信息传播的重要性。基于文献回顾,文章研究企业承担企业社会责任不同方式及企业社会责任传播方式对品牌信任的影响机制,根据企业承担企业社会责任是否与自身的核心业务结合起来分为战略型企业社会责任和反应型企业社会责任,根据传播方式是否是公司可控的将企业社会责任信息传播方式分为内在传播方式和外在传播方式。并引入社会驱动归因和自利驱动归因作为中介变量,探讨企业社会责任战略、企业社会责任传播方式对归因及品牌信任的影响。

  15. CSR战略和传播渠道对品牌信任的影响研究%A Study of the Impact of Corporate Social Responsibility Strategy and Communication Channel on Brand Trust

    Institute of Scientific and Technical Information of China (English)

    黄光; 魏婷婷; 黄匡熹; 周延风

    2014-01-01

    Enterprises have the new development thoughts on the way to undertake corporate social responsibility (CRS) along with the continuous change of the connotation of CRS,moreover,they realize the importance of the communication of social re-sponsibility information. Based on the literature review,the paper makes a study on the influencing mechanism of the way to un-dertake CRS and the channel to communicate CRS on brand trust. On one the hand, the CRS can be classified into strategic CRS and reactive CRS based on whether it combines with the enterprise’s core business. On the other hand, the information communication channel of CRS can be divided into internal communication channel and external communication channel based on whether it is controllable. The paper also explores the impacts of CRS strategy and CRS communication channel on the motive attribution and brand trust by introducing social driving attribution and self interest driving attribution as mediating variables.%随着企业社会责任内涵的持续变化,企业在承担社会责任的方式上有了新的发展思路,同时,企业也认识到了社会责任信息传播的重要性。基于文献回顾,文章研究企业承担企业社会责任不同方式及企业社会责任传播方式对品牌信任的影响机制,根据企业承担企业社会责任是否与自身的核心业务结合起来分为战略型企业社会责任和反应型企业社会责任,根据传播方式是否是公司可控的将企业社会责任信息传播方式分为内在传播方式和外在传播方式。并引入社会驱动归因和自利驱动归因作为中介变量,探讨企业社会责任战略、企业社会责任传播方式对归因及品牌信任的影响。

  16. Digital Communication and Modulation

    DEFF Research Database (Denmark)

    Sørensen, John Aasted

    2011-01-01

    The course presents the fundamental principles for digital communication, e.g. fixed-wire modems or wireless communication channels, as applied in mobile phones, wireless computer networks or wireless systems in intelligent houses. Based on the functional blocks of a digital communication system...... system. Having passed the course, the student will be able to accomplish the following, within the areas shown below: Model for Communication System. Prepare and explain the functional block in a digital communication system, corresponding to the specific course contents. Model for Communication Channel...

  17. 基于正交信道的双M-ary扩频通信方案%Scheme of Double Mary Spread-spectrum Communication Based on Orthogonal Channels

    Institute of Scientific and Technical Information of China (English)

    曾志斌; 庄奕琪; 向新; 姚引娣

    2011-01-01

    To solve these problems that spread spectrum codes resource is lack and synchronization is difficult to realize in conventional M-ary spread spectrum system,a new double M-ary spread spectrum hybrid communication system utilizing orthogonal channel was proposed.The system adopts two orthogonal branches to transport information,that is,M-ary biorthogonal spread spectrum modulation in in-phase branch,and CPSK spread spectrum modulation in orthogonal branch.The system has the advantages which can achieve synchronization accurately and fleetly by itself,but rather offer additional synchronization resource.The simulation results demonstrate the system maintaining a comparable performance as the M-ary spread spectrum,but it needs only about quarter of spread spectrum codes of M-ary spread spectrum system,which saves source of spread spectrum codes effectively.%针对传统系统中伪码资源缺乏以及同步实现较困难等方面的问题,提出一种新的双M-ary扩频通信系统方案,该系统采用两条正交支路传输信息,其中在同相支路上采用M-ary双正交扩频调制,在正交支路上采用CPSK扩频调制。该方案能够利用信息自身扩频调制准确实现同步,不需要额外提供同步资源。仿真结果表明,它与传统M-ary扩频方案性能相一致,但在传输比特信息时,它只需约四分之一的传统M-ary扩频的条数,有效地节省了扩频码资源。

  18. A New Arithmetic Coding System Combining Source Channel Coding and MAP Decoding

    Institute of Scientific and Technical Information of China (English)

    PANG Yu-ye; SUN Jun; WANG Jia

    2007-01-01

    A new arithmetic coding system combining source channel coding and maximum a posteriori decoding were proposed.It combines source coding and error correction tasks into one unified process by introducing an adaptive forbidden symbol.The proposed system achieves fixed length code words by adaptively adjusting the probability of the forbidden symbol and adding tail digits of variable length.The corresponding improved MAP decoding metric was derived.The proposed system can improve the performance.Simulations were performed on AWGN channels with various noise levels by using both hard and soft decision with BPSK modulation.The results show its performance is slightly better than that of our adaptive arithmetic error correcting coding system using a forbidden symbol.

  19. 低压电力线通信信道的多径效应分析%Analysis on multipath effect of communication channel in low-voltage power line

    Institute of Scientific and Technical Information of China (English)

    王智博

    2014-01-01

    Aiming at multipath fading effect of low-voltage power line communication channel, based on analysis the noise,fading and multipath characteristic of low-voltage power line commu-nication channel,puts forward the solution of using diversity technology reduce the error rate of the communication system,and using a matrix laboratory verifies its model by simulation method. The simulation result shows that using diversity technology the power communication system with mini-mum shift-frequency keying modulation can resist multipath effect.%针对低压电力线信道的多径衰减效应,在分析低压电力线信道噪声、衰减和多径特性的基础上,提出采用分集技术降低通信系统误码率的解决方案,并使用矩阵实验对其模型进行仿真验证。仿真结果表明:最小频移键控的电力通信系统采用分集技术可抵抗多径效应。

  20. Performance analysis of precoding-based asymmetrically clipped optical orthogonal frequency division multiplexing wireless system in additive white Gaussian noise and indoor multipath channel

    Science.gov (United States)

    Ranjha, Bilal; Zhou, Zhou; Kavehrad, Mohsen

    2014-08-01

    We have compared the bit error rate (BER) performance of precoding-based asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and pulse amplitude modulated discrete multitone (PAM-DMT) optical wireless (OW) systems in additive white Gaussian noise (AWGN) and indoor multipath frequency selective channel. Simulation and analytical results show that precoding schemes such as discrete Fourier transform, discrete cosine transform, and Zadoff-Chu sequences do not affect the performance of the OW systems in the AWGN channel while they do reduce the peak-to-average power ratio (PAPR) of the OFDM output signal. However, in a multipath indoor channel, using zero forcing frequency domain equalization precoding-based systems give better BER performance than their conventional counterparts. With additional clipping to further reduce the PAPR, precoding-based systems also show better BER performance compared to nonprecoded systems when clipped relative to the peak of nonprecoded systems. Therefore, precoding-based ACO-OFDM and PAM-DMT systems offer better BER performance, zero signaling overhead, and low PAPR compared to conventional systems.

  1. 航空通信系统中信道编码理论及应用分析%Theoretical Analysis and Application of Channel Coding in Aviation Communication Systems

    Institute of Scientific and Technical Information of China (English)

    邹星; 李金喜; 丁勇飞; 方正

    2015-01-01

    Generally, the aviation communication system has some constraints, such as power, bandwidth and latency. To satisfy its requirements of high coding gain and low latency to channel coding, the paper derives the theoretical Shannon limit on the minimum SNR required for coded system, especially for the binary communication system. And then, the performance of several typical kinds of channel coding is analyzed through simulation. Finally, qualitative analysis is made to the application scope of the different channel coding methods with consideration of the technical indicators of them. The conclusion has engineering significance for the selection of channel coding in aviation communication systems.%一般地,航空通信系统具有功率受限、带宽受限、时延受限的特点。针对航空通信系统对信道编码高增益和低时延的要求,首先理论推导通信系统(特别是二进制通信系统)应用r码率信道编码获得编码增益的香农极限值,并仿真对比分析几类典型信道编码的编码性能,最后结合工程实现考虑的技术指标对几类信道编码的应用范围进行了定性分析,其对航空通信系统的信道编码选取具有工程指导意义。

  2. Pilot-based channel estimation for adaptive OFDM communication systems of indoor visible light%基于导频的室内可见光自适应OFDM通信系统信道估计

    Institute of Scientific and Technical Information of China (English)

    黄震宇; 郭树旭; 张择书

    2014-01-01

    使用自适应OFDM技术改善可见光通信系统性能,需要以准确的信道估计为前提。研究可见光自适应OFDM通信系统的基于导频的信道估计方法,引入射频通信中常用的LMS方法,与可见光信道基于LS的估计方法进行了比较,并对其特性进行了分析,仿真实验结果表明,采用LMS估计方法在BER为10-3水平时,SNR优于LS估计方法2 dB,LMS信道估计方法信道跟踪能力较强,比LS法抗干扰。%Based on accurate channel estimation,adaptive OFDM technology can be used to improve the visible light com-munication system performance. The method of pilot-based channel estimation used in visible light adaptive OFDM communica-tion systems is researched by introducing the LMS methods which is commonly used in the RF communication. Through com-pared with the existing LS-based estimation methods,their characteristics are analyzed. The simulation results show that when BER turns to be 10-3 with LMS estimation method,the SNR can be 2dB better than LS method. So the channel tracking ability of LMS channel estimation method is stronger,and the anti-jamming capability is better than LS method.

  3. Experimental study on the impact of HF channel characteristic parameters on communication error rate%短波信道特征参数对通信误码率影响的试验分析

    Institute of Scientific and Technical Information of China (English)

    王立夫; 孙凤娟

    2012-01-01

    介绍了一种融短波通信与电离层斜向探测于一体的联合试验平台,该平台信道探测与通信同时进行,共用一套硬件设备,克服了设备不匹配及探测信道参量失效等问题,并基于该平台实录数据提取了通信误码率及信道特征参量包括信噪比、衰落深度、衰落率、多径扩展、各模式信号幅度、群距离、主模式相位、多普勒频移及多普勒扩展等,统计分析了各信道参量对通信误码率的影响,得出了一些有意义的结论。%A test platform combined HF communication with ionospheric oblique sounding is introduced, with which the ionosphere channel sounding and communi- cation is carried out synchronously using the same hardware equipment. By this way, the problem of equipment mismatch and no real-time channel parameters could be solved. Based on the experimental data measured by this plat{orm the communication bit error ratio(BER) and the channel characteristic parameters, in- cluding signal to noise ratio (SNR), fading depth, fading rate, mulitipath spread, signal strength, group distance, the phase of major-mode, Doppler shift and Doppler spread, are extracted. The impact of the channel characteristic parameters on the communication BER is statistically analyzed. Significant conclusions are pro- posed in the end of this paper.

  4. Combined diversity and improved energy detection in cooperative spectrum sensing with faded reporting channels

    Directory of Open Access Journals (Sweden)

    Srinivas Nallagonda

    2016-04-01

    Full Text Available In this paper we evaluate the performance of cooperative spectrum sensing (CSS where each cognitive radio (CR employs an improved energy detector (IED with multiple antennas and uses selection combining (SC for detecting the primary user (PU in noisy and faded sensing (S channels. We derive an expression for the probability of false alarm and expressions for probability of missed detection in non-faded (AWGN and Rayleigh faded sensing environments in terms of cumulative distribution function (CDF. Each CR transmits its decision about PU via noisy and faded reporting (R channel to fusion center (FC. In this paper we assume that S-channels are noisy and Rayleigh faded while several cases of fading are considered for R-channels such as: (i Hoyt (or Nakagami-q, (ii Rayleigh, (iii Rician (or Nakagami-n, and (iv Weibull. A Binary Symmetric channel (BSC with a fixed error probability (r in the R-channel is also considered. The impact of fading in R-channel, S-channel and several network parameters such as IED parameter, normalized detection threshold, number of CRs, and number of antennas on missed detection and total error probability is assessed. The effects of Hoyt, Rician, and Weibull fading parameters on overall performance of IED-CSS are also highlighted.

  5. Introduction to Scholarly Communication

    OpenAIRE

    Das, Anup-Kumar

    2015-01-01

    In this Unit, Introduction to scholarly communications, author discusses different aspects of scholarly communication – particularly its genesis, importance and ethics of academic publishing, and different communication channels available in academic publishing. Some of these channels are commonly described as primary sources as they provide first-hand testimony or direct evidence concerning a topic under investigation. Historically, scientific journals were initiated by learned societies and...

  6. Extension and Simulation of Underwater Acoustic Communication Channel Based on NS2%基于NS2的水声通信信道的扩展与仿真

    Institute of Scientific and Technical Information of China (English)

    张亚斌; 刘建明; 李宏周; 彭智勇

    2012-01-01

    Underwater sensor network has extensive application prospects in marine data acquisition, and offshore survey with tactical monitoring. Underwater acoustic channel has complex characteristic, like long delay and low bandwidth, and the effect of the network simulation is intensively influenced by the underwater acoustic channel model. This paper proposed a model of underwater acoustic channel which mainly considers the influence of all kinds of noises, temperature and salinity in actual environment on acoustic signal transmission, then extended the underwater acoustic communication channel based on NS2. Ffinally, a multiple nodes simulation environment was established with this underwater acoustic communication channel model, testing similar degree between underwater acoustic channel and the practical underwater environment, and the performance of SMAC under the channel model. Simulation results verify the rationality of the channel model, and reflect some characteristics of the network protocol in the underwater environment.%研究水下信道通信优化问题,由于水下传感器网络在海洋数据采集有广泛的应用.水声信道具有高延迟、低带宽等复杂特点,影响信道通信质量.传统信道模型对网络仿真的效果比较差.为解决上述问题,对水声信道进行了建模,考虑了实际环境中各类噪声以及水温、盐度等因素对声信号传播的影响,并结合NS2进行了水声通信信道的扩展,最后在水声通信信道的基础上建立了一个多节点环境,对水声信道模型与实际水下环境的相似程度采用上述模型进行了仿真.仿真结果验证了信道模型的合理性,并反映出了水下环境中网络通信效果良好.

  7. The Effect of SRS on Signal Power in Single-mode Silica Fiber in DWDM Optical Communication System with Equally Spaced Channels

    Institute of Scientific and Technical Information of China (English)

    GONG Jiamin; FANG Qiang; LIU Juan; WANG Yongchang

    2000-01-01

    Assuming that the Raman gain profile of silica fiber is a triangular function, we derive analytic solutions of N-channel steady-state forward SRS coupling wave equation with equal (but arbitrary) channel spacing. Considering the SRS cross coupling among N-channels, the analytic solutions are applicable to arbitrary signal light power. The results point out that the sequence mi=pi(z)/pi(0) [pi(z) and pi(0) is the power of signal light of i-th channel at transmission length z and 0, respectively. i=1,2,...N] maintains a geometric progression with the common ratio q in the transmission process. The common ratio q varies as a exponential function of the effective transmission length, the sum of input light power and the channel spacing, respectively.

  8. COMMUNICATION - ORGANIZATIONS’ WORK DEVICE

    Directory of Open Access Journals (Sweden)

    LAVINIA HULEA

    2010-01-01

    Full Text Available Communication represents a complex process of transmitting messages, owing to which the emitter encodes the information transmitted through a specific channel towards a receiver that will decode it. Owing to communication, organizations transmit to their customers the fact that they are capable of meeting one of their needs, of settling a problem or of offering a profit. Non-verbal and para-verbal communications usually accompany verbal communication. The importance of assimilating the forms of communication is, at an organizational level, a complex device that determines the mastering of certain techniques, procedures, and algorithms of encoding and decoding intricate messages transmitted through various channels.

  9. Simulating Research of Simulink for OFDM Communication System under Power Line Channel%电力线信道模型下OFDM通信系统的Simulink仿真研究

    Institute of Scientific and Technical Information of China (English)

    赵建华; 李智; 马一森

    2011-01-01

    电力线通信技术是具有良好发展前景的一种宽带接入方式,但是噪声干扰严重,通信环境恶劣,正交频分复用是解决电力线通信问题的有效方法.文章运用Simulink建立了基于时间流的电力线通信信道模型和OFDM基带通信模型.通过对电力线信道模型下的采用OFDM的通信系统模型进行仿真验证,结果表明可以通过适当的编码和调制方式来提高系统的可靠性,并定性地分析了编码和误码率、调制方式和误码率之间的关系.%Power line communication is a kind of wide band access methods with optimistic prospect, but it's also have serious noise and poor communication environment. Orthogonal frequency division multiplexing(OFDM) is an effective method to solve this power line communication problem. This paper constructed the power line communication channel model and baseband transmission model of OFDM based on time-flow by using Simulink. Through simulating the OFDM communication system model under power line channel. It is shown that reliability of the system can be improved by appropriate encode and modulation, and we qualitatively analysis relation between encode and BER,relation between modulation and BER.

  10. Quantum broadcast channels

    CERN Document Server

    Yard, J; Devetak, I; Yard, Jon; Hayden, Patrick; Devetak, Igor

    2006-01-01

    We analyze quantum broadcast channels, which are quantum channels with a single sender and many receivers. Focusing on channels with two receivers for simplicity, we generalize a number of results from the network Shannon theory literature which give the rates at which two senders can receive a common message, while a personalized one is sent to one of them. Our first collection of results applies to channels with a classical input and quantum outputs. The second class of theorems we prove concern sending a common classical message over a quantum broadcast channel, while sending quantum information to one of the receivers. The third group of results we obtain concern communication over an isometry, giving the rates at quantum information can be sent to one receiver, while common quantum information is sent to both, in the sense that tripartite GHZ entanglement is established. For each scenario, we provide an additivity proof for an appropriate class of channels, yielding single-letter characterizations of the...

  11. Efficient and Robust Detection of GFSK Signals under Dispersive Channel, Modulation Index, and Carrier Frequency Offset Conditions

    Directory of Open Access Journals (Sweden)

    Stephan Weiss

    2005-09-01

    Full Text Available Gaussian frequency shift keying is the modulation scheme specified for Bluetooth. Signal adversities typical in Bluetooth networks include AWGN, multipath propagation, carrier frequency, and modulation index offsets. In our effort to realise a robust but efficient Bluetooth receiver, we adopt a high-performance matched-filter-based detector, which is near optimal in AWGN, but requires a prohibitively costly filter bank for processing of K bits worth of the received signal. However, through filtering over a single bit period and performing phase propagation of intermediate results over successive single-bit stages, we eliminate redundancy involved in providing the matched filter outputs and reduce its complexity by up to 90% (for K=9. The constant modulus signal characteristic and the potential for carrier frequency offsets make the constant modulus algorithm (CMA suitable for channel equalisation, and we demonstrate its effectiveness in this paper. We also introduce a stochastic gradient-based algorithm for carrier frequency offset correction, and show that the relative rotation between successive intermediate filter outputs enables us to detect and correct offsets in modulation index.

  12. An electromagnetic street scattering channel mo del for outdo or vehicular-to-vehicular communication systems%基于车载通信标准街道场景的电磁散射信道模型

    Institute of Scientific and Technical Information of China (English)

    周杰; 姚颖莉; 邵根富; 沈晓燕; 刘鹏

    2016-01-01

    The vehicular-to-vehicular (V2V) communications have recently received great attention due to some traffic telem-atic applications that make transportation safer, more efficient, and more environmentally friendly. Reliable traffic telematic applications and services require V2V wireless communication systems to be able to provide robust connectiv-ity. To develop such wireless communication systems and standards, accurate channel models for the V2V communication systems are required. In this paper, a geometric street scattering channel model for a V2V communication system is presented under line-of-sight (LOS) and non-LOS (NLOS) propagation conditions. Starting from the geometric model, a stochastic reference channel model is developed, where the scatterers are uniformly distributed in rectangles in the form of stripes parallel to both sides of the street. A typical propagation scenario for the proposed model is presented, where the buildings and the trees can be considered as scatterers. Analytical expressions for the probability density functions (PDFs) of the angle-of-departure (AOD) and the angle-of-arrival (AOA) are derived. By obtaining the PDF of the total Doppler frequency, the Doppler power spectral density (PSD) and the autocorrelation function (ACF) of the proposed model are also investigated and computed, assuming that the mobile transmitter (MT) and the mobile receiver (MR) are moving, while the surrounding scatterers are fixed. In this respect the underlying radio channel model differs from the traditional cellular channels. We can draw the conclusion that the PDFs of AOD and AOA first increase and then decrease within a certain angle range; the Doppler power spectral density of the signal in the outdoor street environment presents the peak value in fmax. In addition, while the Rice distribution factor is larger, the value of the autocorrelation function increases relatively, the stability of the fluctuation increases correspondingly as well. To

  13. Quantum Feedback Channels

    OpenAIRE

    Bowen, Garry

    2002-01-01

    In Shannon information theory the capacity of a memoryless communication channel cannot be increased by the use of feedback. In quantum information theory the no-cloning theorem means that noiseless copying and feedback of quantum information cannot be achieved. In this paper, quantum feedback is defined as the unlimited use of a noiseless quantum channel from receiver to sender. Given such quantum feedback, it is shown to provide no increase in the entanglement--assisted capacities of a memo...

  14. Digital Communication and Modulation

    DEFF Research Database (Denmark)

    Sørensen, John Aasted

    2011-01-01

    The course presents the fundamental principles for digital communication, e.g. fixed-wire modems or wireless communication channels, as applied in mobile phones, wireless computer networks or wireless systems in intelligent houses. Based on the functional blocks of a digital communication system......, the fundamental principles for modulation and detection in Gaussian noise is treated. This includes the principles for the determination of the bit-error rate for a digital communication system. During the course, a selection of small Matlab exercises are prepared, for simulation of parts of a communication...... system. Having passed the course, the student will be able to accomplish the following, within the areas shown below: Model for Communication System. Prepare and explain the functional block in a digital communication system, corresponding to the specific course contents. Model for Communication Channel...

  15. Communication - Organizations’ Work Device

    OpenAIRE

    LAVINIA HULEA

    2010-01-01

    Communication represents a complex process of transmitting messages, owing to which the emitter encodes the information transmitted through a specific channel towards a receiver that will decode it. Owing to communication, organizations transmit to their customers the fact that they are capable of meeting one of their needs, of settling a problem or of offering a profit. Non-verbal and para-verbal communications usually accompany verbal communication. The importance of assimilating the forms ...

  16. In-service communication channel sensing based on reflectometry for dynamic wavelength assigned wavelength- and time-division multiplexed passive optical network systems

    Science.gov (United States)

    Iida, Daisuke; Kuwano, Shigeru; Terada, Jun

    2015-04-01

    In future radio access systems, base stations will be mainly accommodated in wavelength- and time-division multiplexing passive optical network (PON) based mobile backhaul and fronthaul networks, and in such networks, failed connections in an optical network unit (ONU) wavelength channel will severely degrade mobile system performance. A cost-effective in-service ONU wavelength channel monitor is essential to ensure proper system operation without failed connections. To address this issue, we propose a reflectometry-based remote sensing method that provides ONU wavelength channel information with the optical line terminal-ONU distance. The proposed method enables real-time monitoring of ONU wavelength channels without data signal quality degradation and is also able to determine if the ONUs are connected to the PON. Experimental results show that it achieves wavelength channel distinction with a high distance resolution (˜10 m). Additionally, with the method, the distance resolution for distinguishing the ONUs after the PON splitter is determined by the received signal bandwidth or the test light modulation speed rather than by the pulse width as in conventional optical time-domain reflectometry.

  17. Design and Implementation of a Chaotic Scheme in Additive White Gaussian Noise Channel

    Directory of Open Access Journals (Sweden)

    Nizar Al Bassam

    2016-01-01

    Full Text Available A new chaotic scheme named Flipped Chaotic On-Off Keying (FCOOK is proposed for binary transmission. In FCOOK, the low correlation value between the stationary signal and its mirrored version is utilized. Transmitted signal for binary 1 is a chaotic segment added to its time flipped (mirrored version within one bit duration, while in binary 0, no transmission takes place within the same bit duration. The proposed scheme is compared with the standard chaotic systems: Differential Chaos Shift Keying (DCSK and Correlation Delay Shift Keying (CDSK. The Bit Error Rate (BER of FCOOK is studied analytically based on Gaussian approximation method. Results show that the BER performance of FCOOK outperforms DCSK and CDSK in AWGN channel environment and with various Eb/No levels. Additionally, FCOOK offers a double bit rate compared with the standard DCSK.

  18. Orthogonal Frequency Division Multiplexing Underwater Acoustic Communication Decision Directed Channel Equalization Algorithm%水声OFDM中基于Partial FFT和判决反馈的信道估计算法

    Institute of Scientific and Technical Information of China (English)

    董航; 黄蕾

    2015-01-01

    对于移动的水下接收机,接收到的信号首先进行重采样来补偿时间标尺的缩放,然而,重采样引入的误差、漂浮的发射机和接收机都会引起严重的剩余多普勒,数量级为10-4.本文针对剩余多普勒,提出一种基于判决反馈和Partial FFT的信道均衡算法.文章利用差错控制编码进行纠错判决,将纠错后的数据判决为导频进行信道估计.仿真和湖上实验结果表明,该算法在不降低频带利用率的情况下可以有效提高系统性能.%The complexities of the oceanic channel in underwater information exchange produces sub-carrier amplitude fading and phase distortion. Therefore, when channel is estimated through pilot tones, time variation of channel and interpolation error will affect the results. In this paper, a decision directed channel equalization algorithm for OFDM (i.e. orthogonal frequency division multiplexing) based communication systems is proposed. The algorithm first uses error control codes for the decision making in such a way that these data decisions can be utilized as pilots and finally from these pilots, channel estimation is carried out. Considering the different environment conditions, equalization can be carried out through decision directed scheme with block piloting and decision twice estimations scheme with comb piloting.

  19. The Degraded Poisson Wiretap Channel

    CERN Document Server

    Laourine, Amine

    2010-01-01

    Providing security guarantees for wireless communication is critically important for today's applications. While previous work in this area has concentrated on radio frequency (RF) channels, providing security guarantees for RF channels is inherently difficult because they are prone to rapid variations due small scale fading. Wireless optical communication, on the other hand, is inherently more secure than RF communication due to the intrinsic aspects of the signal propagation in the optical and near-optical frequency range. In this paper, secure communication over wireless optical links is examined by studying the secrecy capacity of a direct detection system. For the degraded Poisson wiretap channel, a closed-form expression of the secrecy capacity is given. A complete characterization of the general rate-equivocation region is also presented. For achievability, an optimal code is explicitly constructed by using the structured code designed by Wyner for the Poisson channel. The converse is proved in two dif...

  20. Performance of MMSE Receiver based Multi Input Multi Output-Interleave Division Multiple-Access System with Multi-user Detection over Frequency Selective Wireless Communication Channel

    Directory of Open Access Journals (Sweden)

    Kuttathatti S. Vishvaksenan

    2011-01-01

    Full Text Available Problem statement: This study presents the performance analysis of turbo assisted Interleave Division Multiple-Access (IDMA system with Multi Input Multi Output (MIMO support for multi user scenario over correlated frequency selective and uncorrelated frequency selective channel. Approach: The key principle of IDMA is that interleaver unique which distinguishes the users in contrast to spreading sequence in Code Division Multiple Access System (CDMA. Results: In this work, we assume that Interleavers are generated independently and randomly. At the receiver, we employed Ordered SIC (OSIC technique using ZF and MMSE criterion to combat Inter Antenna Interference (IAI and Multi User Interference (MUI problem along with iterative decoding to improve the performance in terms of BER. The performance of system has been discussed for different channel conditions with realistic channel model using extensive simulation runs based on Monte Carlo simulation trials. We have exhibited the flexibility and robustness provided by MIMO-IDMA. Conclusion/Recommendations: It has been proved from the results that IDMA principle can be applied to realize many potential performance gains highlighted by information theory, including coding gain multiplexing gain and multiuser gain. Simulation results presented to demonstrate the benefits of IDMA with MUD and iterative decoding. It is discerned that IDMA performs better than CDMA in frequency selective channel for high load conditions which is assessed through computer simulation results.

  1. Design of Scheduling System of Dual Channel Data Communication Based on IP%基于IP的调度系统双通道数据通信设计

    Institute of Scientific and Technical Information of China (English)

    张野; 郭黎利

    2012-01-01

    In order to improve the stability and reliability of the digital voice scheduling system based on TDM and reduce the interrupt rate resulting from line failures, this paper emphasizes on a method of dual-channel data communication scheduling based on IP. Which can make mutual backups in 2B+D digital channel and IP channel of the same exchange platform. At last, the article introduces a specific design project.%为提高原有基于TDM的数字语音调度系统的稳定性和可靠性,降低因线路故障导致调度中断的几率,提出了基于IP的调度系统双通道数据通信的观点,实现在同一交换平台上2B+D数字通道与IP通道的互为备份,并给出具体设计方案.

  2. Digital Communication and Modulation

    DEFF Research Database (Denmark)

    Sørensen, John Aasted

    2010-01-01

    Fundamental principles in modern digital communication system like modems and wire- and wireless transmission over physical channels. Class room sessions and projects. Semester: Spring 2010 Extent: 7.5 ects Class size: 9......Fundamental principles in modern digital communication system like modems and wire- and wireless transmission over physical channels. Class room sessions and projects. Semester: Spring 2010 Extent: 7.5 ects Class size: 9...

  3. Digital Communication and Modulation

    DEFF Research Database (Denmark)

    Sørensen, John Aasted

    2010-01-01

    Fundamental principles in modern digital communication system like modems and wire- and wireless transmission over physical channels. Class room sessions and projects. Semester: Autumn 2010 Extent: 7.5 ects Class size: 18......Fundamental principles in modern digital communication system like modems and wire- and wireless transmission over physical channels. Class room sessions and projects. Semester: Autumn 2010 Extent: 7.5 ects Class size: 18...

  4. Design of Transport Layer Based Hybrid Covert Channel Detection Engine

    CERN Document Server

    K, Anjan; Jadhav, Mamatha; 10.5121/ijasuc.2010.1409

    2011-01-01

    Computer network is unpredictable due to information warfare and is prone to various attacks. Such attacks on network compromise the most important attribute, the privacy. Most of such attacks are devised using special communication channel called "Covert Channel". The word "Covert" stands for hidden or non-transparent. Network Covert Channel is a concealed communication path within legitimate network communication that clearly violates security policies laid down. The non-transparency in covert channel is also referred to as trapdoor. A trapdoor is unintended design within legitimate communication whose motto is to leak information. Subliminal channel, a variant of covert channel works similarly except that the trapdoor is set in a cryptographic algorithm. A composition of covert channel with subliminal channel is the "Hybrid Covert Channel". Hybrid covert channel is homogenous or heterogeneous mixture of two or more variants of covert channels either active at same instance or at different instances of time...

  5. 安稳通道在宁夏电力通信系统的配置应用%Configuration and application of secure channel in Ningxia electric power communication system

    Institute of Scientific and Technical Information of China (English)

    马润; 李亚鹏; 吴宁生

    2014-01-01

    Aiming at the problem of “double equipment,dual router”of secure channel in Ningxia power communication system,combining with the configuration status of Ningxia power communication system and the business access requirement of secure control,puts forward 3 kinds of improvement method for the secure control. The application result shows that:the improvement scheme effectively solve the problem of “double equipment,dual router”,and comprehensively improve the reliability and validity of automatization devices of secure control in Ningxia electric power communication system.%为了解决宁夏电力通信系统安稳业务的“双设备、双路由”配置问题,结合宁夏电力通信系统安稳通道配置现状以及通道业务接入需求,提出3种安稳通道改进方法。应用结果表明:改进方法有效解决了安稳通道的“双设备、双路由”问题,全面提高了宁夏电力通信系统安稳通道自动化装置的可靠性和有效性。

  6. Development of Communication Software for LMC Ultrasonic Open-channel Flowmeter Monitor System%LMC型超声波明渠流量计监控系统通信软件的开发

    Institute of Scientific and Technical Information of China (English)

    张戟; 钱敬荣; 沈昱明

    2001-01-01

    论述了专门用于工矿企业自然管道(明渠)污水排放量计量的一种新型明渠流量计量仪表--LMC型超声波明渠流量计--的后续研发工作,重点介绍了该流量计的监控系统通信技术,还详细介绍了如何利用VC++6.0的MSCOMM控件来开发上位机与8051单片机的串行通信,并给出了通信程序设计的部分流程图.%This paper describes the later R&D of a new-typed flow measuringmeter-LMC ultrasonic open-channel flowmeter specially designed for the measurement of the waste descharge from factory open-pipes. Introduces mainly the communication technology of monitor system, and introduces details of how to develop serial communication program by MSCOMM control of VC++6.0 as well as the partial flow chart of the communication programming.

  7. 传播学视野下的大众武术%Mass Media:The Communication Channels of Martial Art

    Institute of Scientific and Technical Information of China (English)

    谭吟月

    2013-01-01

      媒介是传承人类文明的最重要的物质载体。社会已经被纳入了大众媒介之中,大众武术当然也不可避免地受其影响。文章运用文献资料法,从传播学的视角分析了大众媒介在大众武术传播中的重要作用。研究表明:社会传播是大众武术传播的基础;社会传播是促进大众武术传播的推动力;社会传播影响着大众武术流行现象的兴衰。%Media are the most important material carriers of human civilization. The society has been included in the mass media, the public Wushu also inevitably affected by them. This article utilizes the method of literature, from the perspective of communication to analyzes the important role of mass media in mass Wushu dissemination. The research shows that:social communication is the basis of mass Wushu dissemination;social communication is the driving force to promote the spread of mass Wushu;social communication affects the rise and fall phenomena of public Wushu popular.

  8. Mass Media:The Communication Channels of Martial Art%传播学视野下的大众武术

    Institute of Scientific and Technical Information of China (English)

    谭吟月

    2013-01-01

    Media are the most important material carriers of human civilization. The society has been included in the mass media, the public Wushu also inevitably affected by them. This article utilizes the method of literature, from the perspective of communication to analyzes the important role of mass media in mass Wushu dissemination. The research shows that:social communication is the basis of mass Wushu dissemination;social communication is the driving force to promote the spread of mass Wushu;social communication affects the rise and fall phenomena of public Wushu popular.%  媒介是传承人类文明的最重要的物质载体。社会已经被纳入了大众媒介之中,大众武术当然也不可避免地受其影响。文章运用文献资料法,从传播学的视角分析了大众媒介在大众武术传播中的重要作用。研究表明:社会传播是大众武术传播的基础;社会传播是促进大众武术传播的推动力;社会传播影响着大众武术流行现象的兴衰。

  9. 基于FPGA的多通道SSI通信控制器设计%Design of multi-channel SSI communication controller based on FPGA

    Institute of Scientific and Technical Information of China (English)

    张鹏飞; 王玮; 赵哲

    2011-01-01

    采用VHDL硬件描述语言,以Xilinx公司的FPGA为设计平台,设计实现了以开源软核MC8051为核心的控制单元,控制4路SSI协议模块的SoPC架构的通信控制器,并对通信控制器进行了功能仿真与验证.该控制器可灵活进行IP核模块扩展,并可作为外围处理机与TI公司TMS320C6000系列DSP进行互连通信,将慢速串行通信任务进行分离,从而减轻DSP的负担,提高系统的整体性能.%The article designs and implements typical communication controller based on SoPC architecture in VHDL on the platform of FPGA of Xilinx corporation with the open source code MC8051 IP core as the central control unit,which manages four same SSI modules,and the controller has been functionally simulated and verfied.The communication controller may flexibly add other IP core modules, and be used as a peripheral communication process unit and interconnect with TMS320C6000 series DSP of TI. It can separate the slow serial communication tasks, relieve the burdens of main controlling DSP,and improve the overall performance of system.

  10. Quantum channels with a finite memory

    OpenAIRE

    Bowen, Garry; Mancini, Stefano

    2003-01-01

    In this paper we study quantum communication channels with correlated noise effects, i.e., quantum channels with memory. We derive a model for correlated noise channels that includes a channel memory state. We examine the case where the memory is finite, and derive bounds on the classical and quantum capacities. For the entanglement-assisted and unassisted classical capacities it is shown that these bounds are attainable for certain classes of channel. Also, we show that the structure of any ...

  11. CAPACITY AND WEIGHT COEFFICIENTS IN MIMO WIRELESS COMMUNICATION CHANNELS BASED ON ADAPTIVE MULTI-BEAM ANTENNAS IN URBAN ENVIRONMENT WITH FADING

    OpenAIRE

    Blaunstein, N.; Cristodoulou, Ch; Sergeev, M.

    2014-01-01

    Purpose: Long-Term Evolution (LTE) system has had as many as 12 implementations, the later ones using multi-beam adaptive antennas. LTE development and usage have demonstrated that such systems cannot be adapted to environmental changes, to different locations of every subscriber in the service areas, either open or close for connection, or to the acknowledgement from every wireless channel of a Multiple Input Multiple Output (MIMO) system which goes through an environment with different fadi...

  12. Securing underwater wireless communication networks

    OpenAIRE

    Domingo Aladrén, Mari Carmen

    2011-01-01

    Underwater wireless communication networks are particularly vulnerable to malicious attacks due to the high bit error rates, large and variable propagation delays, and low bandwidth of acoustic channels. The unique characteristics of the underwater acoustic communication channel, and the differences between underwater sensor networks and their ground-based counterparts require the development of efficient and reliable security mechanisms. In this article, a compl...

  13. A simulation study of the performance of the NASA (2,1,6) convolutional code on RFI/burst channels

    Science.gov (United States)

    Perez, Lance C.; Costello, Daniel J., Jr.

    1993-01-01

    In an earlier report, the LINKABIT Corporation studied the performance of the (2,1,6) convolutional code on the radio frequency interference (RFI)/burst channel using analytical methods. Using an R(sub 0) analysis, the report concluded that channel interleaving was essential to achieving reliable performance. In this report, Monte Carlo simulation techniques are used to study the performance of the convolutional code on the RFI/burst channel in more depth. The basic system model under consideration is shown. The convolutional code is the NASA standard code with generators g(exp 1) = 1+D(exp 2)+D(exp 3)+D(exp 5)+D(exp 6) and g(exp 2) = 1+D+D(exp 2)+D(exp 3)+D(exp 6) and d(sub free) = 10. The channel interleaver is of the convolutional or periodic type. The binary output of the channel interleaver is transmitted across the channel using binary phase shift keying (BPSK) modulation. The transmitted symbols are corrupted by an RFI/burst channel consisting of a combination of additive white Gaussian noise (AWGN) and RFI pulses. At the receiver, a soft-decision Viterbi decoder with no quantization and variable truncation length is used to decode the deinterleaved sequence.

  14. DOCUMENT COMMUNICATION AS A FORM OF SOCIAL COMMUNICATION

    OpenAIRE

    Saidgasanova Elnara Umalatovna

    2014-01-01

    The article considers the notion of document communication in its relation to the notions of communication and social communication. The author analyses the approaches to the classification of communication types, to identification of its components – subjects, object, channel, etc. – and to construction of its models, to establishing the status and functions of document in the communication process. The author shares the interpretation of the document as the information, fixed on the materia...

  15. Democratizing HIV Communication

    OpenAIRE

    Thomas Scalway

    2005-01-01

    Information and communication are the key assets within the global knowledge economy. Economic growth, market access, and the ability to manage risk correlate directly with the rapidity and breadth of information access and the availability of appropriate communication channels. This article makes a start at showing how the media can democratize, illuminate and energize the response to the...

  16. Wideband Parameters Analysis and Validation for Indoor radio Channel at 60/70/80GHz for Gigabit Wireless Communication employing Isotropic, Horn and Omni directional Antenna

    Directory of Open Access Journals (Sweden)

    E. Affum

    2013-07-01

    Full Text Available recently, applications of millimeter (mm waves for high-speed broadband wireless local area network communication systems in indoor environment are increasingly gaining recognition as it provides gigabit-speed wireless communications with carrier-class performances over distances of a mile or more due to spectrum availability and wider bandwidth requirements. Collectively referred to as E-Band, the millimeter wave wireless technology present the potential to offer bandwidth delivery comparable to that of fiber optic, but without the financial and logistic challenges of deploying fiber. This paper investigates the wideband parameters using the ray tracing technique for indoor propagation systems with rms delay spread for Omni-directional and Horn Antennas for Bent Tunnel at 80GHz. The results obtained were 2.03and 1.95 respectively, besides, the normalized received power with 0.55×?10?^8excess delay at 70GHz for Isotropic Antenna which was at 0.97.

  17. Conceptual Model for Communication

    CERN Document Server

    Fedaghi, Sabah Al; Fadel, Zahraa

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannons communication model and ending with the OSI model, this paper presents progressively more advanced forms of modeling of communication systems by tying communication models together based on the notion of flow. The basic communication process is divided into different spheres (sources, channels, and destinations), each with its own five interior stages, receiving, processing, creating, releasing, and transferring of information. The flow of information is ontologically distinguished from the flow of physical signals, accordingly, Shannons model, network based OSI models, and TCP IP are redesigned.

  18. MARKETING COMMUNICATION IN THE INTERNET

    OpenAIRE

    Simona Duhalm

    2008-01-01

    Currently, communication becomes more complex, faster and more dynamic every day. In this context, communication switches channels on traditional media to online applications. Thus, the electronic communication threatens, if not take the physical communication. We live in the era of information and the information they seek more ways than quick, cheap and accessible spread. Among the most common methods of electronic communication including website, electronic newsletter, blog and email custo...

  19. The multiparty coherent channel and its implementation with linear optics.

    Science.gov (United States)

    He, Guangqiang; Liu, Taizhi; Tao, Xin

    2013-08-26

    The continuous-variable coherent (conat) channel is a useful resource for coherent communication, supporting coherent teleportation and coherent superdense coding. We extend the conat channel to multiparty conditions by proposing definitions on multiparty position-quadrature and momentum-quadrature conat channel. We additionally provide two methods to implement this channel using linear optics. One method is the multiparty version of coherent communication assisted by entanglement and classical communication (CCAECC). The other is multiparty coherent superdense coding. PMID:24105527

  20. Optimal Encoding of Data in Data Transmission Channels

    OpenAIRE

    Silviu Draghici; Cornelia Anghel Drugarin; Chioncel Cristian Paul

    2013-01-01

    This paper aims to present the methods of achieving an optimal encoding in the data communication channels. After a short description of the communication channel and of the data communication channel types, follow briefly a few notions of the data channel enthropy, information, transinformation, with their properties, definitions and mathematical relations connecting them. Chapter 2 presents the concept of optimal code, following a detailed description (using two suggestive examples) of the ...

  1. Multimedia communications and networking

    CERN Document Server

    da Silva, Mario Marques

    2012-01-01

    The result of decades of research and international project experience, Multimedia Communications and Networking provides authoritative insight into recent developments in multimedia, digital communications, and networking services and technologies. Supplying you with the required foundation in these areas, it illustrates the means that will allow for improved digital communications and networks. The book starts with a review of the fundamental concepts, requirements, and constraints in networks and telecommunications. It describes channel disturbances that can hinder system performance--inclu

  2. Quantum channels with a finite memory

    CERN Document Server

    Bowen, G; Bowen, Garry; Mancini, Stefano

    2004-01-01

    In this paper we study quantum communication channels with correlated noise effects, i.e., quantum channels with memory. We derive a model for correlated noise channels that includes a channel memory state. We examine the case where the memory is finite, and derive bounds on the classical and quantum capacities. For the entanglement-assisted and unassisted classical capacities it is shown that these bounds are attainable for certain classes of channel. Also, we show that the structure of any finite memory state is unimportant in the asymptotic limit, and specifically, for a perfect finite-memory channel where no information is lost to the environment, the channel is asymptotically noiseless.

  3. 基于MIMO的可见光通信中的信道均衡%Channel equalization in the visible-light communication based on MIMO

    Institute of Scientific and Technical Information of China (English)

    张妥; 梁忠诚; 刘学明; 张琪; 居秋琦

    2015-01-01

    针对基于多输入多输出(MIMO)的室内可见光通信(Visible-Light Communication,VLC)系统中存在的码间串扰(ISI)问题进行了分析,并提出了适用于MIMO可见光通信系统的信道均衡方案及实现方法.仿真实验结果表明,该方法可以有效降低MIMO可见光通信系统中的码间串扰的影响.

  4. Channel Identification Machines

    Directory of Open Access Journals (Sweden)

    Aurel A. Lazar

    2012-01-01

    Full Text Available We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

  5. A father protocol for quantum broadcast channels

    CERN Document Server

    Dupuis, F; Dupuis, Fr\\'ed\\'eric; Hayden, Patrick

    2006-01-01

    We present a new protocol for quantum broadcast channels based on the fully quantum Slepian-Wolf protocol. The protocol yields an achievable rate region for entanglement-assisted transmission of quantum information through a quantum broadcast channel that can be considered the quantum analogue of Marton's region for classical broadcast channels. The protocol can be adapted to yield achievable rate regions for unassisted quantum communication and for entanglement-assisted classical communication. Regularized versions of all three rate regions are provably optimal.

  6. Communication theory

    CERN Document Server

    Goldie, Charles M

    1991-01-01

    This book is an introduction, for mathematics students, to the theories of information and codes. They are usually treated separately but, as both address the problem of communication through noisy channels (albeit from different directions), the authors have been able to exploit the connection to give a reasonably self-contained treatment, relating the probabilistic and algebraic viewpoints. The style is discursive and, as befits the subject, plenty of examples and exercises are provided. Some examples and exercises are provided. Some examples of computer codes are given to provide concrete illustrations of abstract ideas.

  7. Communications technology

    Science.gov (United States)

    Cuccia, C. Louis; Sivo, Joseph

    1986-01-01

    The technologies for optimized, i.e., state of the art, operation of satellite-based communications systems are surveyed. Features of spaceborne active repeater systems, low-noise signal amplifiers, power amplifiers, and high frequency switches are described. Design features and capabilities of various satellite antenna systems are discussed, including multiple beam, shaped reflector shaped beam, offset reflector multiple beam, and mm-wave and laser antenna systems. Attitude control systems used with the antenna systems are explored, along with multiplexers, filters, and power generation, conditioning and amplification systems. The operational significance and techniques for exploiting channel bandwidth, baseband and modulation technologies are described. Finally, interconnectivity among communications satellites by means of RF and laser links is examined, as are the roles to be played by the Space Station and future large space antenna systems.

  8. On Outage Probability and Diversity-Multiplexing Tradeoff in MIMO Relay Channels

    CERN Document Server

    Loyka, Sergey

    2011-01-01

    Fading MIMO relay channels are studied analytically, when the source and destination are equipped with multiple antennas and the relays have a single one. Compact closed-form expressions are obtained for the outage probability under i.i.d. and correlated Rayleigh-fading links. Low-outage approximations are derived, which reveal a number of insights, including the impact of correlation, of the number of antennas, of relay noise and of relaying protocol. The effect of correlation is shown to be negligible, unless the channel becomes almost fully correlated. The SNR loss of relay fading channels compared to the AWGN channel is quantified. The SNR-asymptotic diversity-multiplexing tradeoff (DMT) is obtained for a broad class of fading distributions, including, as special cases, Rayleigh, Rice, Nakagami, Weibull, which may be non-identical, spatially correlated and/or non-zero mean. The DMT is shown to depend not on a particular fading distribution, but rather on its polynomial behavior near zero, and is the same ...

  9. Fade-Free Mobile Communication

    Science.gov (United States)

    Stevenson, C. R.

    1986-01-01

    Scheme for mobile communication reduces multipath fading and interference between adjacent channels. Proposed communication system lends itself to almost completely digital implementation, eliminating costly and bulky crystal filters. Scheme suitable for satellite-aided or terrestrial mobile communication, including cellular mobile telephony, at frequencies in 150-to-900-MHz range.

  10. The Evolution of Communication Systems

    CERN Document Server

    Leydesdorff, Loet

    2010-01-01

    One can study communications by using Shannon's (1948) mathematical theory of communication. In social communications, however, the channels are not "fixed", but themselves subject to change. Communication systems change by communicating information to related communication systems; co-variation among systems if repeated over time, can lead to co-evolution. Conditions for stabilization of higher-order systems are specifiable: segmentation, stratification, differentiation, reflection, and self-organization can be distinguished in terms of developmental stages of increasingly complex networks. In addition to natural and cultural evolution, a condition for the artificial evolution of communication systems can be specified.

  11. 叠加导频的放大转发协作通信系统时变信道估计方法%Time-Variant Channel Estimation for AF Cooperative Communication System Based on Superimposed Pilot

    Institute of Scientific and Technical Information of China (English)

    陈艳杰; 曹威; 张士杰

    2015-01-01

    在基于正交频分复用技术的放大转发协作通信系统中,针对整体中继信道估计(S-R-D)辅助导频占用额外带宽使带宽利用率低的缺点以及传统叠加导频信道估计性能不高的缺点,提出了一种新的对角叠加导频方案.在不增加导频数量的前提下,将叠加导频的位置由传统的块状叠加变为对角叠加后,信道估计性能优于传统叠加导频方案和辅助导频方案,且与理想信道估计性能接近.仿真结果表明:和传统方法相比,采用对角叠加导频方案不仅提高了信道估计精度和带宽利用率,而且可以较好地跟踪信道的变化.%In amplify and forward cooperative communication system based on orthogonal frequency division multiplexing,auxiliary pilot has the defect for low bandwidth efficiency due to extra bandwidth occupied,superimposed pilot has the defect of low estimation accuracy. For these problems, a new diagonal superimposed pilot scheme is proposed for the overall relay channel (SRD)estimation in this paper. Without increasing the number of the pilots,the location of the superimposed pilots will overlay from the traditional block to a diagonal superposition,the channel estimation performance is superior to the traditional superimposed pilot scheme and the auxiliary pilot scheme,which is close to the ideal estimation performance. Simulation results show that,compared with the traditional methods, the proposed diagonal superimposed pilot scheme improves the accuracy of channel estimation and bandwidth utilization,and can better track channel change.

  12. Analysis of synchronous digital-modulation schemes for satellite communication

    Science.gov (United States)

    Takhar, G. S.; Gupta, S. C.

    1975-01-01

    The multipath communication channel for space communications is modeled as a multiplicative channel. This paper discusses the effects of multiplicative channel processes on the symbol error rate for quadrature modulation (QM) digital modulation schemes. An expression for the upper bound on the probability of error is derived and numerically evaluated. The results are compared with those obtained for additive channels.

  13. Radio propagation measurement and channel modelling

    CERN Document Server

    Salous, Sana

    2013-01-01

    While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

  14. Characterizing Nanoscale Transient Communication.

    Science.gov (United States)

    Chen, Yifan; Anwar, Putri Santi; Huang, Limin; Asvial, Muhamad

    2016-04-01

    We consider the novel paradigm of nanoscale transient communication (NTC), where certain components of the small-scale communication link are physically transient. As such, the transmitter and the receiver may change their properties over a prescribed lifespan due to their time-varying structures. The NTC systems may find important applications in the biomedical, environmental, and military fields, where system degradability allows for benign integration into life and environment. In this paper, we analyze the NTC systems from the channel-modeling and capacity-analysis perspectives and focus on the stochastically meaningful slow transience scenario, where the coherence time of degeneration Td is much longer than the coding delay Tc. We first develop novel and parsimonious models to characterize the NTC channels, where three types of physical layers are considered: electromagnetism-based terahertz (THz) communication, diffusion-based molecular communication (DMC), and nanobots-assisted touchable communication (TouchCom). We then revisit the classical performance measure of ϵ-outage channel capacity and take a fresh look at its formulations in the NTC context. Next, we present the notion of capacity degeneration profile (CDP), which describes the reduction of channel capacity with respect to the degeneration time. Finally, we provide numerical examples to demonstrate the features of CDP. To the best of our knowledge, the current work represents a first attempt to systematically evaluate the quality of nanoscale communication systems deteriorating with time.

  15. Wire communication engineering

    International Nuclear Information System (INIS)

    This book describes wire telecommunication engineering/ It is divided into eleven chapter, which deal with Introduction with development of telecommunication, voice and sound wave and communication network, Telegraphy with summary of telegraphy, code of telegraphy, communication speed, morse and telex, Telephone on structure, circuit and image telephone, Traffic on telecommunication traffic, transmission of line about theory, cable line and loaded cable, carrier communication with carrier telegraphy and carrier telephone, optical communication with types, structure, specialty, laser and equipment, DATA, Mobile telecommunication on summary, mobile telephone, radio paging and digital mobile telecommunication, ISDN with channel of ISDN, and service of ISDN, and design of telecommunication.

  16. Mobile communication and intermediality

    DEFF Research Database (Denmark)

    Helles, Rasmus

    2013-01-01

    The article argues the importance of intermediality as a concept for research in mobile communication and media. The constant availability of several, partially overlapping channels for communication (texting, calls, email, Facebook, etc.) requires that we adopt an integrated view of the various...... communicative affordances of mobile devices in order to understand how people choose between them for different purposes. It is argued that mobile communication makes intermediality especially central, as the choice of medium is detached from the location of stationary media and begins to follow the user across...

  17. Electromagnetic channel capacity for practical purposes

    CERN Document Server

    Giovannetti, Vittorio; Maccone, Lorenzo; Shapiro, Jeffrey H

    2012-01-01

    We give analytic upper bounds to the channel capacity C for transmission of classical information in electromagnetic channels (bosonic channels with thermal noise). In the practically relevant regimes of high noise and low transmissivity, by comparison with know lower bounds on C, our inequalities determine the value of the capacity up to corrections which are irrelevant for all practical purposes. Examples of such channels are radio communication, infrared or visible-wavelength free space channels. We also provide bounds to active channels that include amplification.

  18. Evaporation duct communication: Test Plan

    Science.gov (United States)

    Anderson, K. D.

    1991-02-01

    The Evaporation Duct Communication (EDCOM) project is an effort to provide an alternative ship-to-ship communications channel using the natural environment. A microwave communication link can be used on an over-the-water, over-the-horizon path through the evaporation duct. This report shows how a microwave communication link, operating at a range separation of more than twice the line-of-sight range, can be constructed. This link can achieve about 80-percent availability at a transmission frequency of 14.5 GHz and can be constructed using off-the-shelf RF equipment. Operation of this link will provide the first set of measurements of channel capacity that can be critically dependent on the existence of an oceanic evaporation duct. Construction of this link presents a unique opportunity to study and evaluate an alternative communications channel that can be used to alleviate naval battlegroup communications load.

  19. 物联网无线通信传输层动态通道保障机制%Networking Wireless Communication Transport Layer Security Mechanism of Dynamic Channel

    Institute of Scientific and Technical Information of China (English)

    陈家迁

    2014-01-01

    With the rapid development of our economy and the construction of socialist modernization is gradually perfect, the national electric power industry has been hitherto unknown progress, application of smart grid building and grid advanced mea⁃suring system has become represent the general trend, the key technology is to realize the user side of reliable information access. Wireless communication to multiple access technology and self organization network theory as the core link, is the foundation of Internet of things system can run effectively, an important means to solve the technical difficulties and. But in the actual operation of the process, because of the variety and complexity of the user side environment, often make the wireless channel is impeded, re transmission rate significantly increased. In this regard, China's relevant technical units of transport layer protocol and design a new technical facilities, namely dynamic additional transmission channel security mechanism. It can appear in the transmission congestion problem, arouse the second generation agent, determine the best parameter transfer direction, and carry out to travel alone, to achieve rapid change additional channels. In view of this phenomenon, we must combine with actual situation of IOT wireless communication transmission layer operation, using theoretical formula are deduced to it, thus effectively avoid TCP a long time in the slow start phase, do the security mechanism of the dynamic channel.%随着我国经济的飞速发展以及社会主义现代化建设的逐步完善,国家电力行业得到了前所未有的进步,智能电网的建立和电网高级量测系统的应用已经成为了大势所趋,其中的关键技术就是实现用户侧信息可靠接入。以无线通信多址接入技术和自组织网络理论为核心的环节,是物联网体系基础能够有效运行,并解决技术难点的重要手段。但是在实际运行过

  20. Interdisciplinary Communication

    Directory of Open Access Journals (Sweden)

    Nagib Callaos

    2013-12-01

    Full Text Available Communication is fundamental in scientific practice and an integral part of academic work. The practice of communication cannot be neglected by those who are trying to advance scientific research. Effective means should continuously be identified in order to open channels of communication within and among disciplines, among scientists and between scientists and the general public.[1]The increasing importance of interdisciplinary communication has been pointed out by an increasing number of researchers and scholars, as well as in conferences and roundtables on the subject. Some authors even estimate that "interdisciplinary study represents the future of the university."[2] Since interdisciplinary study is "the most underthought critical, pedagogical and institutional concept in modern academy"[3] it is important to think and reflect, and even do some research, on this concept or notion. Research and practice based reflections with regards to this issue are important especially because the increasing complexity and proliferation of scientific research is generating countless specialties, sub-specialties and sub-sub-specialties, with their respective special languages; which were "created for discrete local areas of research based upon the disconnected branches of science."[4] On the other hand, scientific, technical and societal problems are requiring multi- or inter-disciplinary consideration. Consequently, interdisciplinary communication channels are being needed with urgency, and scientific research should be integrated, not just in the context of its discipline, but also in the context of related disciplines. Much more reflection and research should be done on this issue. Research on adequate research integration and communication is urgently required, i.e. meta-research efforts should be done in order to relate research results in an adequate and more useful way. This meta-research effort might be done in the context of each particular

  1. Performance analysis of a finite radon transform in OFDM system under different channel models

    Energy Technology Data Exchange (ETDEWEB)

    Dawood, Sameer A.; Anuar, M. S.; Fayadh, Rashid A. [School of Computer and Communication Engineering, Universiti Malaysia Perlis (UniMAP) Pauh Putra, 02000 Arau, Parlis (Malaysia); Malek, F.; Abdullah, Farrah Salwani [School of Electrical System Engineering, Universiti Malaysia Perlis (UniMAP) Pauh Putra, 02000 Arau, Parlis (Malaysia)

    2015-05-15

    In this paper, a class of discrete Radon transforms namely Finite Radon Transform (FRAT) was proposed as a modulation technique in the realization of Orthogonal Frequency Division Multiplexing (OFDM). The proposed FRAT operates as a data mapper in the OFDM transceiver instead of the conventional phase shift mapping and quadrature amplitude mapping that are usually used with the standard OFDM based on Fast Fourier Transform (FFT), by the way that ensure increasing the orthogonality of the system. The Fourier domain approach was found here to be the more suitable way for obtaining the forward and inverse FRAT. This structure resulted in a more suitable realization of conventional FFT- OFDM. It was shown that this application increases the orthogonality significantly in this case due to the use of Inverse Fast Fourier Transform (IFFT) twice, namely, in the data mapping and in the sub-carrier modulation also due to the use of an efficient algorithm in determining the FRAT coefficients called the optimal ordering method. The proposed approach was tested and compared with conventional OFDM, for additive white Gaussian noise (AWGN) channel, flat fading channel, and multi-path frequency selective fading channel. The obtained results showed that the proposed system has improved the bit error rate (BER) performance by reducing inter-symbol interference (ISI) and inter-carrier interference (ICI), comparing with conventional OFDM system.

  2. Performance analysis of a finite radon transform in OFDM system under different channel models

    International Nuclear Information System (INIS)

    In this paper, a class of discrete Radon transforms namely Finite Radon Transform (FRAT) was proposed as a modulation technique in the realization of Orthogonal Frequency Division Multiplexing (OFDM). The proposed FRAT operates as a data mapper in the OFDM transceiver instead of the conventional phase shift mapping and quadrature amplitude mapping that are usually used with the standard OFDM based on Fast Fourier Transform (FFT), by the way that ensure increasing the orthogonality of the system. The Fourier domain approach was found here to be the more suitable way for obtaining the forward and inverse FRAT. This structure resulted in a more suitable realization of conventional FFT- OFDM. It was shown that this application increases the orthogonality significantly in this case due to the use of Inverse Fast Fourier Transform (IFFT) twice, namely, in the data mapping and in the sub-carrier modulation also due to the use of an efficient algorithm in determining the FRAT coefficients called the optimal ordering method. The proposed approach was tested and compared with conventional OFDM, for additive white Gaussian noise (AWGN) channel, flat fading channel, and multi-path frequency selective fading channel. The obtained results showed that the proposed system has improved the bit error rate (BER) performance by reducing inter-symbol interference (ISI) and inter-carrier interference (ICI), comparing with conventional OFDM system

  3. 一种海洋蒸发波导通信带限信道建模方法%A Bandwidth Channel Modeling Method for Sea Evaporation Duct Communication

    Institute of Scientific and Technical Information of China (English)

    肖金光; 周新力; 张烨

    2015-01-01

    To compute the field and estimate the time delay of multi-path signal in sea evaporation duct ( SED) ,a method of modeling communication bandwidth channel is presented. Algorithm of ray tracing in subsections is proposed. A method of separating arriving multi-path signal and computing field is put for﹣ward,considering space wave diffusion, rough surface reflection and reception sphere. Characteristics of time delay estimation,system design and strategies of usage are studied. Feasibility of the constructed meth﹣od is verified by numerical experiments. The new method provides an effective way of link budget and per﹣formance analysis in SED communication to get expectable performances,with proper selection of signal fre﹣quency,bandwidth and energy surplus.%针对海洋蒸发波导中多径信号场强计算和时延估计问题,提出了一种通信带限信道建模方法。给出了一种分段的射线追踪算法,提出了多径到达信号分离和场强计算的方法,考虑了电波空间扩散、粗糙海面反射和接收球;研究了时延估计规律、系统设计和使用策略。数值试验验证了建立的带限冲激响应建模方法的可行性,为海洋蒸发波导通信的链路预算和性能分析提供了有效的途径,通过控制信号频率、带宽和能量正余量可达到预期系统性能。

  4. The Analysis on the Factors Which Affecting Price Dispersion between Traditional Retail Channel and Internet Retail Channel

    OpenAIRE

    Xujin Pu

    2009-01-01

    With network economy springing up and communication technology expanding fast, the retailing channels composed of Internet retail channel become the choice of many traditional retailers. Price dispersion always exists between traditional retail channel and Internet retail channel. In this text, we bring forward the model about traditional retail channel and internet retail channel based on classical hotelling linear city model. We find the price dispersion will be different when the parameter...

  5. Congestion Control Strategy of Random Access Channel in Machine Type Communication%机器类型通信中随机接入信道的拥塞控制策略

    Institute of Scientific and Technical Information of China (English)

    周伟; 谭小彬; 季海波

    2015-01-01

    在基于3GPP长期演进技术的机器类型通信( MTC)应用背景下,针对无线接入网络中随机接入信道的拥塞问题,提出一种改进的拥塞控制策略,MTC器件利用基站广播信息自适应调整各自的接入时间,避免由于大量MTC器件同时发起随机接入而引起接入碰撞的问题,实现基站的负载均衡及信道资源的合理分配。基于最大熵原理证明各MTC器件接入时间的均匀分布是最优分布。仿真实验结果表明,与接入类别限制策略相比,该策略可缓解随机接入信道的拥塞状况,提高MTC器件的随机接入成功率,降低接入时延,从而提升网络整体性能及服务质量。%This paper proposes an improved congestion control strategy to alleviate the congestion of random access channel in radio access network of Machine Type Communication(MTC) based on 3GPP-Long Term Evolution(LTE). In order to reach the base-station’ s load balancing in the time interval and allocate the channel resources rationally,it schedules the access time of MTC devices through the base-station’ s broadcasted information,and thereby avoids access collisions caused by massive number of MTC devices access the base-station simultaneously. It also proofs that uniform distribution of the access time is the optimal choice by maximum entropy principle. Simulation experimental results show that the strategy can alleviate the channel congestion significantly and increase the random access success rate of MTC devices,reduce the delay,and thus improve the network’ s performance and guarantee the network’ s Quality of Service ( QoS) compared with Access Class Barring( ACB) strategy.

  6. Variable Step Closed Loop Power Control with Space Diversity for Low Elevation Angle High Altitude Platforms Communication Channel [Langkah Variabel Kontrol Daya Loop Tertutup dengan Keragaman Ruang untuk Sudut Elevasi Rendah pada Kanal Komunikasi HAPs

    Directory of Open Access Journals (Sweden)

    Iskandar Iskandar

    2016-07-01

    Full Text Available This paper proposes variable step closed loop power control algorithm combined with space diversity to improve the performance of High Altitude Platforms (HAPs communication at low elevation angle using Code Division Multiple Access (CDMA. In this contribution, we first develop HAPs channel model which is derived from experimental measurement. From our experiment, we found HAPs channel characteristic can be modeled as a Ricean distribution because the presence of line of sight path. Different elevation angle resulting different K factor value.  This value is then used in Signal to Interference Ratio (SIR based closed loop power control evaluation. The variable step algorithm is simulated under various elevation angles with different speed of mobile user. The performance is presented in terms of user elevation angle, user speed, step size and space diversity order. We found that the performance of variable step closed-loop power control less effective at low elevation angle. However our simulation shows that space diversity is able to improve the performance of closed loop power control for HAPs channel at low elevation angle.*****Kajian ini mengusulkan suatu algoritma kontrol daya langkah variabel loop tertutup dikombinasikan dengan keragaman ruang untuk meningkatkan kinerja komunikasi High Altitude Platforms(HAPs pada sudut elevasi rendah menggunakan Code Division Multiple Access (CDMA. Kami berkontribusi untuk mengembangkan model kanal HAPs yang berasal dari pengukuran eksperimental sebelumnya. Dari percobaan tersebut, kami menemukan karakteristik kanal HAPs yang dapat dimodelkan sebagai distribusi Ricean karena kehadiran jalur tanpa penghalang. Eksperimen menunjukkan bahwa perbedaan sudut elevasi menghasilkan perbedaan nilai factor K. Nilai ini kemudian digunakan dalam Signal to Interference Ratio (SIR berbasiskan evaluasi kontrol daya loop tertutup. Algoritma langkah variabel disimulasikan dibawah sudut elevasi yang berbeda dengan kecepatan

  7. IMPROVING COMMUNICATION BETWEEN DOCTORS AND PATIENTS

    OpenAIRE

    Stremtan Filimon; Radoviciu Ruxandra

    2010-01-01

    Communication is the key factor necessary to improve the relation between doctors and patients. The communication is the method used to transmit or collect information using different types of channels. The communication process should provide useful information for doctors and patients. In order to establish a good communication system, both parts must fulfil some obligations. The present paper presents direct communication methods and indirect methods of communication.

  8. Improving communication between doctors and patients

    OpenAIRE

    Radoviciu Ruxandra; Stremtan Filimon

    1999-01-01

    Communication is the key factor necessary to improve the relation between doctors and patients. The communication is the method used to transmit or collect information using different types of channels. The communication process should provide useful information for doctors and patients. In order to establish a good communication system, both parts must fulfil some obligations. The present paper presents direct communication methods and indirect methods of communication.

  9. Cognitive Radio Channel Selection Strategy Based on Experience-Weighted Attraction Learning

    OpenAIRE

    Qian Jiansheng; Sun Yong

    2013-01-01

    In this paper, an innovative proposed channel selection algorithm based on Experience-Weighted Attraction (EWA) learning allows Cognitive Radio (CR) to learn radio environment communication channel characteristics online. By accumulating the history channel experience, it can predict, select and change the current optimal communication channel, dynamic ensure the quality of communication links and finally reduce system communication outage probability. Validation and reliability have been str...

  10. Estimation over MIMO Fading Channels: Outage and Diversity Analysis

    OpenAIRE

    Parseh, Reza

    2016-01-01

    In this thesis, estimation of signals over fading channels for analog uncoded transmission is considered. In communication settings with tight delay requirements, e.g. in real-time control over wireless fading channels and vehicle-to-vehicle communication, the use of efficient and therefore long channel codes for reliability is not possible. Without channel codes, one needs to seek out alternative techniques. One such technique is to send uncompressed discrete-time source samples ...

  11. Channel estimation in TDD mode

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi; GU Jian; YANG Da-cheng

    2006-01-01

    An efficient solution is proposed in this article for the channel estimation in time division duplex (TDD) mode wireless communication systems. In the proposed solution, the characteristics of fading channels in TDD mode systems are fully exploited to estimate the path delay of the fading channel.The corresponding amplitude is estimated using the minimum mean square error (MMSE) criterion. As a result, it is shown that the proposed novel solution is more accurate and efficient than the traditional solution, and the improvement is beneficial to the performance of Joint Detection.

  12. Experimental Results and Issues on Equalization for Nonlinear Memory Channel: Pre-Cursor Enhanced Ram-DFE Canceler

    Science.gov (United States)

    Yuan, Lu; LeBlanc, James

    1998-01-01

    This thesis investigates the effects of the High Power Amplifier (HPA) and the filters over a satellite or telemetry channel. The Volterra series expression is presented for the nonlinear channel with memory, and the algorithm is based on the finite-state machine model. A RAM-based algorithm operating on the receiver side, Pre-cursor Enhanced RAM-FSE Canceler (PERC) is developed. A high order modulation scheme , 16-QAM is used for simulation, the results show that PERC provides an efficient and reliable method to transmit data on the bandlimited nonlinear channel. The contribution of PERC algorithm is that it includes both pre-cursors and post-cursors as the RAM address lines, and suggests a new way to make decision on the pre-addresses. Compared with the RAM-DFE structure that only includes post- addresses, the BER versus Eb/NO performance of PERC is substantially enhanced. Experiments are performed for PERC algorithms with different parameters on AWGN channels, and the results are compared and analyzed. The investigation of this thesis includes software simulation and hardware verification. Hardware is setup to collect actual TWT data. Simulation on both the software-generated data and the real-world data are performed. Practical limitations are considered for the hardware collected data. Simulation results verified the reliability of the PERC algorithm. This work was conducted at NMSU in the Center for Space Telemetering and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department.

  13. Aerosol optical properties derived from the DRAGON-NE Asia campaign, and implications for a single-channel algorithm to retrieve aerosol optical depth in spring from Meteorological Imager (MI) on-board the Communication, Ocean, and Meteorological Satellite (COMS)

    Science.gov (United States)

    Kim, M.; Kim, J.; Jeong, U.; Kim, W.; Hong, H.; Holben, B.; Eck, T. F.; Lim, J. H.; Song, C. K.; Lee, S.; Chung, C.-Y.

    2016-02-01

    An aerosol model optimized for northeast Asia is updated with the inversion data from the Distributed Regional Aerosol Gridded Observation Networks (DRAGON)-northeast (NE) Asia campaign which was conducted during spring from March to May 2012. This updated aerosol model was then applied to a single visible channel algorithm to retrieve aerosol optical depth (AOD) from a Meteorological Imager (MI) on-board the geostationary meteorological satellite, Communication, Ocean, and Meteorological Satellite (COMS). This model plays an important role in retrieving accurate AOD from a single visible channel measurement. For the single-channel retrieval, sensitivity tests showed that perturbations by 4 % (0.926 ± 0.04) in the assumed single scattering albedo (SSA) can result in the retrieval error in AOD by over 20 %. Since the measured reflectance at the top of the atmosphere depends on both AOD and SSA, the overestimation of assumed SSA in the aerosol model leads to an underestimation of AOD. Based on the AErosol RObotic NETwork (AERONET) inversion data sets obtained over East Asia before 2011, seasonally analyzed aerosol optical properties (AOPs) were categorized by SSAs at 675 nm of 0.92 ± 0.035 for spring (March, April, and May). After the DRAGON-NE Asia campaign in 2012, the SSA during spring showed a slight increase to 0.93 ± 0.035. In terms of the volume size distribution, the mode radius of coarse particles was increased from 2.08 ± 0.40 to 2.14 ± 0.40. While the original aerosol model consists of volume size distribution and refractive indices obtained before 2011, the new model is constructed by using a total data set after the DRAGON-NE Asia campaign. The large volume of data in high spatial resolution from this intensive campaign can be used to improve the representative aerosol model for East Asia. Accordingly, the new AOD data sets retrieved from a single-channel algorithm, which uses a precalculated look-up table (LUT) with the new aerosol model, show an

  14. Preface for the book: Antennas And Propagation for Body-Centric Wireless Communications

    DEFF Research Database (Denmark)

    Frederiksen, Flemming Bjerge; Prasad, Ramjee

    2006-01-01

    The book address the following subjects: Body Centric Wireless Communications possibilities, Electromagnetic properties of the body, On-body Communication Channels at high and low frequency bands, Body Centric UWB Communications, Wearable Antennas for cellular and WLAN communications, Body...

  15. A Perspective on the MIMO Wiretap Channel

    KAUST Repository

    Oggier, Frederique

    2015-10-01

    A wiretap channel is a communication channel between a transmitter Alice and a legitimate receiver Bob, in the presence of an eavesdropper Eve. The goal of communication is to achieve reliability between Alice and Bob, but also confidentiality despite Eve’s presence. Wiretap channels are declined in all kinds of flavors, depending on the underlying channels used by the three players: discrete memoryless channels, additive Gaussian noise channels, or fading channels, to name a few. In this survey, we focus on the case where the three players use multiple-antenna channels with Gaussian noise to communicate. After summarizing known results for multiple-input–multiple-output (MIMO) channels, both in terms of achievable reliable data rate (capacity) and code design, we introduce the MIMO wiretap channel. We then state the MIMO wiretap capacity, summarize the idea of the proof(s) behind this result, and comment on the insights given by the proofs on the physical meaning of the secrecy capacity. We finally discuss design criteria for MIMO wiretap codes.

  16. Quantum cryptography communication technology

    International Nuclear Information System (INIS)

    Quantum cryptography communication based on quantum mechanics provides and unconditional security between two users. Even though huge advance has been done since the 1984, having a complete system is still far away. In the case of real quantum cryptography communication systems, an unconditional security level is lowered by the imperfection of the communication unit. It is important to investigate the unconditional security of quantum communication protocols based on these experimental results and implementation examples for the advanced spread all over the world. The Japanese report, titled, 'Investigation report on the worldwide trends of quantum cryptography communications systems' was translated and summarized in this report. An unconditional security theory of the quantum cryptography and real implementation examples in the domestic area are investigated also. The goal of the report is to make quantum cryptography communication more useful and reliable alternative telecommunication infrastructure as the one of the cyber security program of the class 1-E communication system of nuclear power plant. Also another goal of this report is to provide the quantitative decision basis on the quantum cryptography communication when this secure communication system will be used in class 1-E communication channel of the nuclear power plant

  17. Quantum cryptography communication technology

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Wan; Choi, Young Soo; Lee, Jae Chul; Choi, Yu Rak; Jung, Gwang Il; Jung, Jong Eun; Hong, Seok Boong; Koo, In Soo

    2007-09-15

    Quantum cryptography communication based on quantum mechanics provides and unconditional security between two users. Even though huge advance has been done since the 1984, having a complete system is still far away. In the case of real quantum cryptography communication systems, an unconditional security level is lowered by the imperfection of the communication unit. It is important to investigate the unconditional security of quantum communication protocols based on these experimental results and implementation examples for the advanced spread all over the world. The Japanese report, titled, 'Investigation report on the worldwide trends of quantum cryptography communications systems' was translated and summarized in this report. An unconditional security theory of the quantum cryptography and real implementation examples in the domestic area are investigated also. The goal of the report is to make quantum cryptography communication more useful and reliable alternative telecommunication infrastructure as the one of the cyber security program of the class 1-E communication system of nuclear power plant. Also another goal of this report is to provide the quantitative decision basis on the quantum cryptography communication when this secure communication system will be used in class 1-E communication channel of the nuclear power plant.

  18. Visualizing multi-channel networks

    DEFF Research Database (Denmark)

    Antemijczuk, Paweł; Magiera, Marta; Jørgensen, Sune Lehmann;

    2014-01-01

    In this paper, we propose a visualization to illustrate social interactions, built from multiple distinct channels of communication. The visualization displays a summary of dense personal information in a compact graphical notation. The starting point is an abstract drawing of a spider’s web. Bel...

  19. The quantum capacity with symmetric side channels

    CERN Document Server

    Smith, G; Winter, A; Smith, Graeme; Smolin, John A.; Winter, Andreas

    2006-01-01

    We present an upper bound for the quantum channel capacity that is both additive and convex. Our bound can be interpreted as the capacity of a channel for high-fidelity communication when assisted by the family of all channels mapping symmetrically to their output and environment. The bound seems to be quite tight, and for degradable quantum channels it coincides with the unassisted channel capacity. Using this symmetric side channel capacity, we find new upper bounds on the capacity of the depolarizing channel. We also briefly indicate an analogous notion for distilling entanglement using the same class of (one-way) channels, yielding one of the few genuinely 1-LOCC monotonic entanglement measures.

  20. Joint Symbol Timing and CFO Estimation for OFDM/OQAM Systems in Multipath Channels

    Directory of Open Access Journals (Sweden)

    Angelo Petrella

    2010-01-01

    Full Text Available The problem of data-aided synchronization for orthogonal frequency division multiplexing (OFDM systems based on offset quadrature amplitude modulation (OQAM in multipath channels is considered. In particular, the joint maximum-likelihood (ML estimator for carrier-frequency offset (CFO, amplitudes, phases, and delays, exploiting a short known preamble, is derived. The ML estimators for phases and amplitudes are in closed form. Moreover, under the assumption that the CFO is sufficiently small, a closed form approximate ML (AML CFO estimator is obtained. By exploiting the obtained closed form solutions a cost function whose peaks provide an estimate of the delays is derived. In particular, the symbol timing (i.e., the delay of the first multipath component is obtained by considering the smallest estimated delay. The performance of the proposed joint AML estimator is assessed via computer simulations and compared with that achieved by the joint AML estimator designed for AWGN channel and that achieved by a previously derived joint estimator for OFDM systems.