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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. Downsampling of DFT Precoded Signals for the AWGN Channel

    DEFF Research Database (Denmark)

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

    2012-01-01

    , 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...

  3. Comparative Study of Different Guard Time Intervals to Improve the BER Performance of Wimax Systems to Minimize the Effects of ISI and ICI under Adaptive Modulation Techniques over SUI1 and AWGN Communication Channels

    CERN Document Server

    Hasan, Md Zahid; Islam, Md Ashraful; Hossain, Riaz

    2009-01-01

    The WIMAX technology based on air interface standard 802.16 wireless MAN is configured in the same way as a traditional cellular network with base stations using point to multipoint architecture to drive a service over a radius up to several kilometers. The range and the Non Line of Sight (NLOS) ability of WIMAX make the system very attractive for users, but there will be slightly higher BER at low SNR. The aim of this paper is the comparative study of different guard time intervals effect for improving BER at different SNR under digital modulation (QPSK, 16QAM and 64QAM) techniques and different communication channels AWGN and fading channels Stanford University Interim (SUI 1) of an WIMAX system. The comparison between these effects with Reed-Solomon (RS) encoder with Convolutional encoder (half) rated codes in FEC channel coding will be investigated. The simulation results of estimated Bit Error Rate (BER) displays that the implementation of interleaved RS code (255,239,8) with (half) rated Convolutional c...

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. AWGN Channel under Time-Varying Amplitude Constraints with Causal Information at the Transmitter

    CERN Document Server

    Ozel, Omur

    2011-01-01

    We consider the classical AWGN channel where the channel input is constrained to an amplitude constraint that stochastically varies at each channel use, independent of the message. This is an abstraction of an energy harvesting transmitter where the code symbol energy at each channel use is determined by an exogenous energy arrival process and there is no battery for energy storage. At each channel use, an independent realization of the amplitude constraint process is observed by the transmitter causally. This scenario is a state-dependent channel with perfect causal state information at the transmitter. We derive the capacity of this channel using Shannon's coding scheme with causal state information. We prove that the code symbols must be selected from a finite set in the capacity achieving scheme, as in the case of Smith. We numerically study the binary on-off energy arrivals where the amplitude constraint is either zero or a non-zero constant.

  9. Effects Of Filters on DVB-T Receiver Performance Under AWGN, RAYLEIGH and RICEAN Fading Channels

    Directory of Open Access Journals (Sweden)

    AKM Arifuzzaman

    2013-07-01

    Full Text Available Digital Video Broadcasting–Terrestrial(DVB-Thas become a very popular technologyforterrestrialdigital television services.DVB-T is based onOrthogonal Frequency Division Multiplexing (OFDMtechnique. OFDM is considered suitable forDVB-T system because of its low Inter-Symbol Interference(ISI.DVB-Thassomelimitationstooincluding large dynamicsignalrange and sensitivity to frequencyerror.To overcome these limitationsagoodDVB-Treceiveris amust.In this paperwe address theseissues. This paper hastwo-foldobjectives(itoinvestigatethe performances ofDVB-Tsystem underdifferent channel conditions, and (iito improveperformance ofDVB-Tsystembyselectingsuitable filtersin receiver.To investigate the performanceof DVB-Tsystemwe have consideredsome popular channelmodelsnamelyAWGN, Rayleigh, andRicean.In order to improvethe systemperformancesomeclassicfilters likeButterworth, Chebyshev, and elliptichavebeenincludedin the receiver. The simulation resultsshow thata careful selection offilteris a must foraDVB-Tsystem. It is also shown that the filter selectionshould bebasedon the underlying channel conditions

  10. 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.

  11. Comparison of FEC types to optimise the efficiency of TCP connections over AWGN satellite channels

    OpenAIRE

    Celandroni, Nedo

    2004-01-01

    The optimization of the end-to-end throughput of a TCP connection over geostationary satellite links is a challenging research topic. This is because the high delay-bandwidth product, together with a non-negligible random loss of packets, are conditions which differ considerably from the original environment for which TCP was originally designed. As a result TCP performance is significantly impaired by the channel bit error rate. The literature is full of suggestions for improving TCP goodput...

  12. Comparison of FEC Types with Regard to the Efficiency of TCP Connections over AWGN Satellite Channels

    OpenAIRE

    Celandroni, Nedo

    2006-01-01

    Optimizing the end-to-end throughput of a TCP connection (goodput) over geostationary satellite links is a challenging research topic. This is because the high delay-bandwidth product, together with a non-negligible random loss of packets, is a condition that considerably differs from the environments TCP was originally designed for. As a result, TCP performance is significantly impaired by the channel bit error rate. The literature is full of suggestions for improving TCP goodput, most based...

  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. 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

  16. 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.

  17. 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.

  18. 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

  19. 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...

  20. 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.

  1. 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.

  2. Quantum communication under channel uncertainty

    International Nuclear Information System (INIS)

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  3. 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...

  4. Lattice Codes for the Wiretap Gaussian Channel: Construction and Analysis

    CERN Document Server

    Oggier, Frédérique; Belfiore, Jean-Claude

    2011-01-01

    We consider the Gaussian wiretap channel, where two legitimate players Alice and Bob communicate over an AWGN channel, while Eve is eavesdropping, also through an AWGN channel. We propose a coding strategy based on lattice coset encoding. We analyze Eve's probability of decoding, from which we define the secrecy gain as a design criterion for lattice codes, expressed in terms of the lattice theta series, which characterizes Eve's confusion as a function of the channel parameters. The secrecy gain is studied for even unimodular lattices, and an asymptotic analysis shows that it grows exponentially in the dimension of the lattice. Examples of wiretap lattice codes are given.

  5. 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

  6. Quantum channel capacities: Multiparty communication

    Science.gov (United States)

    Demianowicz, Maciej; Horodecki, Paweł

    2006-10-01

    We analyze different aspects of multiparty communication over quantum memoryless channels and generalize some of the key results known from bipartite channels to the multiparty scenario. In particular, we introduce multiparty versions of subspace and entanglement transmission fidelities. We also provide alternative, local, versions of fidelities and show their equivalence to the global ones in context of capacity regions defined. An equivalence of two different capacity notions with respect to two types of fidelities is proven. In analogy to the 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 a multiple access channel [M. Horodecki , Nature 436, 673 (2005); J. Yard , e-print quant-ph/0501045], is optimal also in a scenario of an additional support of forward classical communication.

  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. SSC high speed communication channel and interconnects

    International Nuclear Information System (INIS)

    This paper investigates potential metallic and optical technology applications in SSC high speed interconnects and/or communication channels. Primary focus will be placed on evaluating several metallic and optical interconnect structures. 7 refs., 3 figs

  12. 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

  13. Quantum Communication With Zero-Capacity Channels

    OpenAIRE

    Smith, Graeme; Yard, Jon

    2008-01-01

    Communication over a noisy quantum channel introduces errors in the transmission that must be corrected. A fundamental bound on quantum error correction is the quantum capacity, which quantifies the amount of quantum data that can be protected. We show theoretically that two quantum channels, each with a transmission capacity of zero, can have a nonzero capacity when used together. This unveils a rich structure in the theory of quantum communications, implying that the quantum capacity does n...

  14. 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.

  15. 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.

  16. 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.

  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. Communication channels between SKI and parliamentarians

    International Nuclear Information System (INIS)

    This document deals with the communication channels between SKI (Swedish Nuclear Power Inspectorate) and parliamentarians. SKI is meant to supervise the safety of Swedish nuclear installations and is legally required to report to the public with openness. They do not take part in the Nuclear debate and their only contact with parliamentarians consists in giving them background material on nuclear safety, the channels used being yearly Status Reports on this subject. Contacts between SKI and municipalities concerning nuclear utilities are close and include information materials, meetings, seminars and so on. (TEC)

  20. 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...

  1. 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...

  2. 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

  3. Quantum communication using a multiqubit entangled channel

    Science.gov (United States)

    Ghose, Shohini; Hamel, Angele

    2015-12-01

    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.

  4. Channels, propagation and antennas for mobile communications

    CERN Document Server

    Vaughan, Rodney; Bach Andersen, J

    2003-01-01

    This exceptional text introduces the reader to the theory and basis of antennas and propagation in the rapidly developing field of mobile communications. Topics covered include basic multipath mechanisms and propagation, and propagation modelling as well as short term channel behavior from two path and many path models and scenarios. Also, the basics of antenna design and operation are discussed including array antennas. This book promises to be a valuable reference work for many years to come, and will be an important addition to the bookshelves of telecommunications engineers and researcher

  5. 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.

  6. 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.

  7. 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...

  8. Information-Theoretic Analysis of an Energy Harvesting Communication System

    CERN Document Server

    Ozel, Omur

    2010-01-01

    In energy harvesting communication systems, an exogenous recharge process supplies energy for the data transmission and arriving energy can be buffered in a battery before consumption. Transmission is interrupted if there is not sufficient energy. We address communication with such random energy arrivals in an information-theoretic setting. Based on the classical additive white Gaussian noise (AWGN) channel model, we study the coding problem with random energy arrivals at the transmitter. We show that the capacity of the AWGN channel with stochastic energy arrivals is equal to the capacity with an average power constraint equal to the average recharge rate. We provide two different capacity achieving schemes: {\\it save-and-transmit} and {\\it best-effort-transmit}. Next, we consider the case where energy arrivals have time-varying average in a larger time scale. We derive the optimal offline power allocation for maximum average throughput and provide an algorithm that finds the optimal power allocation.

  9. Reliable quantum communication over a quantum relay channel

    International Nuclear Information System (INIS)

    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. 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.

  11. Average energy efficiency contours for single carrier AWGN MAC

    OpenAIRE

    Akbari A; Imran M.A.; Hoshyar R.; Tafazolli R.

    2011-01-01

    Energy efficiency has become increasingly important in wireless communications, with significant environmental and financial benefits. This paper studies the achievable capacity region of a single carrier uplink channel consisting of two transmitters and a single receiver, and uses average energy efficiency contours to find the optimal rate pair based on four different targets: Maximum energy efficiency, a trade-off between maximum energy efficiency and rate fairness, achieving energy efficie...

  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. 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.

  14. 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.

  15. Capacity of very noisy communication channels based on Fisher information

    Science.gov (United States)

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2016-06-01

    We generalize the asymptotic capacity expression for very noisy communication channels to now include coloured noise. For the practical scenario of a non-optimal receiver, we consider the common case of a correlation receiver. Due to the central limit theorem and the cumulative characteristic of a correlation receiver, we model this channel noise as additive Gaussian noise. Then, the channel capacity proves to be directly related to the Fisher information of the noise distribution and the weak signal energy. The conditions for occurrence of a noise-enhanced capacity effect are discussed, and the capacity difference between this noisy communication channel and other nonlinear channels is clarified.

  16. Corporate blog as a channel for crisis communication: Case Talvivaara

    OpenAIRE

    Norros, Eeva

    2012-01-01

    The objective of this thesis was to study Talvivaara's corporate blog as a channel for crisis communication. The research conducted was two-fold: firstly the media coverage during the crisis was studied, after which Talvivaara's communications through their corporate blog were evaluated. By researching the case from two different aspects, the thesis aimed to uncover how the corporate blog functioned as a communication channel in this particular case study. The data of this study consisted...

  17. 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.

  18. Quantum Communication Scheme Using Non-symmetric Quantum Channel

    International Nuclear Information System (INIS)

    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

  19. Acoustic MIMO communications in a very shallow water channel

    Science.gov (United States)

    Zhou, Yuehai; Cao, Xiuling; Tong, Feng

    2015-12-01

    Underwater acoustic channels pose significant 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.

  20. 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.

  1. 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

  2. On Quantum Communication Channels with Constrained Inputs

    CERN Document Server

    Holevo, A S

    1997-01-01

    The purpose of this work is to extend the result of previous papers quant-ph/9611023, quant-ph/9703013 to quantum channels with additive constraints onto the input signal, by showing that the capacity of such channel is equal to the supremum of the entropy bound with respect to all apriori distributions satisfying the constraint. We also make an extension to channels with continuous alphabet. As an application we prove the formula for the capacity of the quantum Gaussian channel with constrained energy of the signal, establishing the asymptotic equivalence of this channel to the semiclassical photon channel. We also study the lower bounds for the reliability function of the pure-state Gaussian channel.

  3. 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.

  4. 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

  5. Latvian Language as a Code in Different Communication Channels

    OpenAIRE

    Bajarune, L; Ozols, A

    2015-01-01

    This paper is dedicated to analyze of Latvian language as a code in such literary communication channels like press, poet, prose, legal literature. There have been calculations for zero-order, first-order, second-order and third-order Shannon entropy made and also appropriate redundancy and coefficient of compression have been determined. All the calculus is done with self-made program. Different communication channels of Latvian language are compared mutually and also Latvian language is com...

  6. Latvian language as a code in different communication channels

    OpenAIRE

    Bajarune, Linda; Ozols, Andris

    2015-01-01

    This paper is dedicated to analyze of Latvian language as a code in such literary communication channels like press, poet, prose, legal literature. Calculations for zero-order, first-order, second-order and third-order Shannon entropy have been made and also corresponding values of redundancy and compression coefficients have been determined. All the calculations are done with a self-made computer program. Different communication channels of Latvian language are compared mutually and also Lat...

  7. Performance analysis of replication ALOHA for fading mobile communications channels

    Science.gov (United States)

    Yan, Tsun-Yee; Clare, Loren P.

    1986-01-01

    This paper describes an ALOHA random access protocol for fading communications channels. A two-state Markov model is used for the channel error process to account for the channel fading memory. The ALOHA protocol is modified to send multiple contiguous copies of a message at each transmission attempt. Both pure and slotted ALOHA channels are considered. The analysis is applicable to fading environments where the channel memory is short compared to the propagation delay. It is shown that smaller delay may be achieved using replications and, in noisy conditions, can also improve throughput.

  8. 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.

  9. 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...

  10. 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...

  11. 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.

  12. Channel Estimation for Wireless OFDM Communications

    OpenAIRE

    Lin, Jia-Chin

    2010-01-01

    In this chapter, a variety of CE techniques on OFDM communications were investigated. This author does not attempt to present this topic in detail nor provide theoretical derivations and rigorous statistical analysis, though they are thought of as the most crucial for a journal publication. Insightful and reader-friendly descriptions are presented to attract readers of any level, including practicing communication engineers and beginning and professional researchers. All interested readers ca...

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. Information transmission and recovery in neural communications channels

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  20. 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

  1. 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...

  2. Transitions in the Communication Capacity of Dissipative Qubit Channels

    Science.gov (United States)

    Daems, D.

    2009-05-01

    The information transmission is studied for quantum channels in which the noise includes dissipative effects, more specifically, nonunitality. Noise is usually a nuisance but can sometimes be helpful. For these channels, the communication capacity is shown to increase with the dissipative component of the noise and may exhibit transitions beyond which it increases faster. The optimal states are constructed analytically as well as the pertaining “phase” diagram.

  3. Transitions in the communication capacity of dissipative qubit channels.

    Science.gov (United States)

    Daems, D

    2009-05-01

    The information transmission is studied for quantum channels in which the noise includes dissipative effects, more specifically, nonunitality. Noise is usually a nuisance but can sometimes be helpful. For these channels, the communication capacity is shown to increase with the dissipative component of the noise and may exhibit transitions beyond which it increases faster. The optimal states are constructed analytically as well as the pertaining "phase" diagram. PMID:19518853

  4. Using Uncensored Communication Channels to Divert Spam Traffic

    OpenAIRE

    Benjamin Chiao; Jeffrey MacKie-Mason

    2006-01-01

    We offer a microeconomic model of the two-sided market for the dominant form of spam: bulk, unsolicited, and commercial advertising email. We adopt an incentive-centered design approach to develop a simple, feasible improvement to the current email system using an uncensored communication channel. Such a channel could be an email folder or account, to which properly tagged commercial solicitations are routed. We characterize the circumstances under which spammers would voluntarily move much o...

  5. Optimized Compressed Sensing Matrix Design for Noisy Communication Channels

    OpenAIRE

    Shirazinia, Amirpasha; Dey, Subhrakanti

    2014-01-01

    We investigate a power-constrained sensing matrix design problem for a compressed sensing framework. We adopt a mean square error (MSE) performance criterion for sparse source reconstruction in a system where the source-to-sensor channel and the sensor-to-decoder communication channel are noisy. Our proposed sensing matrix design procedure relies upon minimizing a lower-bound on the MSE. Under certain conditions, we derive closed-form solutions to the optimization problem. Through numerical e...

  6. Partial synchronization in stochastic dynamical networks with switching communication channels

    Science.gov (United States)

    Huang, Chi; Ho, Daniel W. C.; Lu, Jianquan; Kurths, Jürgen

    2012-06-01

    In this paper, the partial synchronization problem of stochastic dynamical networks (SDNs) is investigated. Unlike the existing models, the SDN considered in this paper suffers from a class of communication constraint—only part of nodes' states can be transmitted. Thus, less nodes' states can be used to synchronize the SDN, which makes the analysis of the synchronization problem much harder. A set of channel matrices are introduced to reflect such kind of constraint. Furthermore, due to unpredictable environmental changes, the channel matrices can switch among some communication modes. The switching considered here is governed by a Markov process. To overcome the difficulty, a regrouping method is employed to derive our main results. The obtained conditions guarantee that partial synchronization can be achieved for SDNs under switching communication constraint. Finally, numerical examples are given to illustrate the effectiveness of the theoretical results and how the communication constraint influences synchronization result.

  7. 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...

  8. 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...

  9. 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.

  10. Strongly Secure Communications Over the Two-Way Wiretap Channel

    CERN Document Server

    Pierrot, Alexandre J

    2010-01-01

    We consider the problem of secure communications over the two-way wiretap channel under a strong secrecy criterion. We improve existing results by developing an achievable region based on strategies that exploit both the interference at the eavesdropper's terminal and cooperation between legitimate users. We leverage the notion of channel resolvability for the multiple-access channel to analyze cooperative jamming and we show that the artificial noise created by cooperative jamming induces a source of common randomness that can be used for secret-key agreement. We illustrate the gain provided by this coding technique in the case of the Gaussian two-way wiretap channel, and we show significant improvements for some channel configurations.

  11. Communication Through Jamming over a Slotted ALOHA Channel

    CERN Document Server

    Bhadra, Sandeep; Shakkottai, Sanjay; Vishwanath, Sriram

    2008-01-01

    This work derives bounds on the jamming capacity of a slotted ALOHA system. A system with n legitimate users, each with a Bernoulli arrival process is considered. Packets are temporarily stored at the corresponding user queues, and a slotted ALOHA strategy is used for packet transmissions over the shared channel. The scenario considered is that of a pair of illegitimate users that jam legitimate transmissions in order to communicate over the slotted ALOHA channel. Jamming leads to binary signaling between the illegitimate users, with packet collisions due to legitimate users treated as (multiplicative) noise in this channel. Further, the queueing dynamics at the legitimate users stochastically couples the jamming strategy used by the illegitimate users and the channel evolution. By considering various i.i.d. jamming strategies, achievable jamming rates over the slotted ALOHA channel are derived. Further, an upper bound on the jamming capacity over the class of all ergodic jamming policies is derived. These bo...

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. An adaptive chaotic secure communication scheme with channel noises

    International Nuclear Information System (INIS)

    In this Letter, an adaptive secure communication scheme with channel noises is proposed. Based on the idea of chaotic masking-modulation, the message is encrypted by a chaotic signal. By using adaptive feedback control techniques, the transmitter and the receiver are synchronized, so the masked signal can be perfectly recovered by the receiver in the presence of channel noises. In light of the Lyapunov stability theory for stochastic differential equations, several theoretical results are rigorously established. Finally, the famous Chua's circuits is used to illustrate the possible applications of the obtained theoretical results, and the computer simulations show that the proposed scheme is feasible and efficient

  18. 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.

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

    DEFF Research Database (Denmark)

    Iversen, Villy Bæk

    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...... protection mechanisms for protecting services and subscriber groups.We study cellular systems with overlaid cells, and the effect of overlapping cells, and we show that by dynamic channel allocation we obtain a high utilization.The models are generalizations of the Erlang-B formula, and can be evaluated...

  20. Long distance quantum communication over a noisy channel

    International Nuclear Information System (INIS)

    The creation of a quantum network is an important goal of quantum information processing. Long distance quantum communication with high fidelity is the main obstacle in achieving this goal. A scheme to transmit qubits without fidelity decrease over the noisy channel is presented. Using the idea of 'time-bin entanglement', the scheme works without any auxiliary particles and there is no resources increase with the length of the channel. A protocol proposed by Kalamidas is suitable to realize our scheme with the current experimental technology

  1. 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.

  2. Security of direct communication quantum channel with feedback

    Science.gov (United States)

    Usenko, Constantin V.

    2015-01-01

    In the direct communication quantum channels, the authorized recipient (Bob) and the non-authorized recipient (Eve) have different abilities for verification of received information. Bob can apply the feedback to commit the sender (Alice) to perform verification. Eve has to use for verification an indirect method based on the measurement of a set of incompatible observables enough for determination of the coding basis used by Alice. In the protocol of direct communication, regular modification of coding basis and masking it with an equilibrium in average information carrier density matrix prevents reconstruction of coding basis by the results of Eve’s measurements of an arbitrary set of observables. This provides unconditional security of the channel.

  3. Residential Noise Control Requirements for Powerline Communications Channel

    OpenAIRE

    Guillen, Edward; Lopez, Julian; Padilla, Daniel

    2010-01-01

    Noises on powerline communication channels such as coloured noise, narrow band noise, periodic impulsive noise and asynchronous impulsive noise affect PLC network throughput. However, these noises can be successfully controlled by band-pass and bandstop filters installed on strategic PLC network connection points. It's necessary to establish a model to probe if the noise measurements on this work can be applied on industrial environments and if the noise can affect PLC networks installed on n...

  4. 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...

  5. Convolutional/Single Parity Check Turbo Codes for Wireless Multimedia Communications

    Directory of Open Access Journals (Sweden)

    N. Kostov

    2004-12-01

    Full Text Available Error correction codes are widely used in digital communications toimprove the Quality of Service. The Quality of Service is typicallyexpressed in terms of maximum acceptable frame error rate and bit errorrate. The key implementation issues for most powerful error correctioncodes are the complexity and overall encoding/decoding latency. In thispaper, short-frame turbo product codes for real-time wirelessmultimedia communications are proposed. Performance of the proposedturbo codes is studied through simulations on an additive whiteGaussian noise (AWGN channel. The obtained results indicate that theperformance of these codes is quite exceptional given their decodingcomplexity.

  6. 2-D sensor position perturbation analysis: Equivalence to AWGN on array outputs

    OpenAIRE

    McClellan, J. H.; Cevher, Volkan

    2002-01-01

    In this paper, the performance of a subspace beamformer, namely the multiple signal classification algorithm (MUSIC), is scrutinized in the presence of sensor position errors. Based on a perturbation model, a relationship between the array autocorrelation matrix and the source autocorrelation matrix is established. It is shown that under certain assumptions on the source signals, the Gaussian sensor perturbation errors can be modelled as additive white Gaussian noise (AWGN) for an array where...

  7. Concatenated Coding Using Linear Schemes for Gaussian Broadcast Channels with Noisy Channel Output Feedback

    OpenAIRE

    Ahmad, Ziad; Chance, Zachary; Love, David J.

    2013-01-01

    Linear coding schemes have been the main choice of coding for the additive white Gaussian noise broadcast channel (AWGN-BC) with noiseless feedback in the literature. The achievable rate regions of these schemes go well beyond the capacity region of the AWGN-BC without feedback. In this paper, a concatenating coding design for the $K$-user AWGN-BC with noisy feedback is proposed that relies on linear feedback schemes to achieve rate tuples outside the no-feedback capacity region. Specifically...

  8. 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...

  9. SSC high-speed communication channel and interconnects

    International Nuclear Information System (INIS)

    The three types of interconnect technology available are the following: (1) Metallic (the most mature of the technologies): Many of the simulation tools have been developed. However, metallic interconnects have relatively large bulk volume and mass (i.e., metal cables and transmission lines) that require high-powered terminated drivers and have low channel capacity, when compared with optics. (2) Dielectric guided optics: Dielectric guides (fiber optics) have high channel capacity (1-10 THz). Although they are available commercially, technology is still at the development stage, and they require optical drivers/receivers made from materials that may not be compatible with silicon. The required simulation tools are still under development. (3) Free-space optics: Free-space optics have very high channel capacity and small mass/volume requirements. Potential problems are the same as those of dielectric guides. In addition, one needs to consider optical alignment. This paper investigates potential metallic and optical technology applications in Superconducting Super Collider (SSC) high-speed interconnects and/or communication channels. Primary focus will be placed on evaluating several metallic and optical interconnect structures

  10. 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

  11. 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.

  12. On quantum capacity of erasure channel assisted by back classical communication

    OpenAIRE

    Leung, Debbie; Lim, Joungkeun; Shor, Peter

    2007-01-01

    We present a communication protocol for the erasure channel assisted by backward classical communication, which achieves a significantly better rate than the best prior result. In addition, we prove an upper bound for the capacity of the channel. The upper bound is smaller than the capacity of the erasure channel when it is assisted by two-way classical communication. Thus, we prove the separation between quantum capacities assisted by backward classical communication and two-way classical co...

  13. 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.

  14. 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.

  15. 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.

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

    CERN Document Server

    Narimanov, E E; 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.

  18. 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.

  19. 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

  20. 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...

  1. 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

  2. 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

  3. 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…

  4. 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.

  5. Disappearance and revival of squeezing in quantum communication with squeezed state over a noisy channel

    Science.gov (United States)

    Deng, Xiaowei; Hao, Shuhong; Tian, Caixing; Su, Xiaolong; Xie, Changde; Peng, Kunchi

    2016-02-01

    Squeezed state can increase the signal-to-noise ratio in quantum communication and quantum measurement. However, losses and noises existing in real communication channels will reduce or even totally destroy the squeezing. The phenomenon of disappearance of the squeezing will result in the failure of quantum communication. In this letter, we present the experimental demonstrations on the disappearance and revival of the squeezing in quantum communication with squeezed state. The experimental results show that the squeezed light is robust (squeezing never disappears) in a pure lossy but noiseless channel. While in a noisy channel, the excess noise will lead to the disappearance of the squeezing, and the squeezing can be revived by the use of a correlated noisy channel (non-Markovian environment). The channel capacity of quantum communication is increased after the squeezing is revived. The presented results provide useful technical references for quantum communication with squeezed light.

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

    Science.gov (United States)

    Herceg, Marijan; Švedek, Tomislav; Matić, Tomislav

    2010-12-01

    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. 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.

  8. 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.

  9. Effects Of Filters on DVB-T Receiver Performance Under AWGN, RAYLEIGH and RICEAN Fading Channels

    OpenAIRE

    AKM Arifuzzaman; Mussab Saleh; Mohammed Tarique; Rumana Islam

    2013-01-01

    Digital Video Broadcasting–Terrestrial(DVB-T)has become a very popular technologyforterrestrialdigital television services.DVB-T is based onOrthogonal Frequency Division Multiplexing (OFDM)technique. OFDM is considered suitable forDVB-T system because of its low Inter-Symbol Interference(ISI).DVB-Thassomelimitationstooincluding large dynamicsignalrange and sensitivity to frequencyerror.To overcome these limitationsagoodDVB-Treceiveris amust.In this paperwe address theseissues. This paper hast...

  10. 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...

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. Composability of partially entanglement breaking channels via entanglement assisted local operations and classical communication

    OpenAIRE

    Namiki, Ryo

    2013-01-01

    We consider composability of quantum channels from a limited amount of entanglement via local operations and classical communication (LOCC). We show that any $k$-partially entanglement breaking channel can be composed from an entangled state with Schmidt number of $k$ via one-way LOCC. From the entanglement assisted construction we can reach an alternative definition of partially entanglement breaking channels.

  17. Symmetric and asymmetric quantum channels in quantum communication systems

    International Nuclear Information System (INIS)

    Symmetric and asymmetric quantum channels which act on bipartite bosonic states are considered. The linear dissipative channel and the quantum teleportation channel are applied. The influences of the symmetric and asymmetric quantum channels on bipartite Gaussian states are investigated by means of the inseparability condition. Furthermore, quantum teleportation and quantum dense coding of continuous variables performed by means of two-mode squeezed-vacuum states under the influence of the noisy quantum channels are discussed

  18. 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.

  19. 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.

  20. 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.

  1. Performance Analysis of New Binary User Codes for DS-CDMA Communication

    Science.gov (United States)

    Usha, Kamle; Jaya Sankar, Kottareddygari

    2016-03-01

    This paper analyzes new binary spreading codes through correlation properties and also presents their performance over additive white Gaussian noise (AWGN) channel. The proposed codes are constructed using gray and inverse gray codes. In this paper, a n-bit gray code appended by its n-bit inverse gray code to construct the 2n-length binary user codes are discussed. Like Walsh codes, these binary user codes are available in sizes of power of two and additionally code sets of length 6 and their even multiples are also available. The simple construction technique and generation of code sets of different sizes are the salient features of the proposed codes. Walsh codes and gold codes are considered for comparison in this paper as these are popularly used for synchronous and asynchronous multi user communications respectively. In the current work the auto and cross correlation properties of the proposed codes are compared with those of Walsh codes and gold codes. Performance of the proposed binary user codes for both synchronous and asynchronous direct sequence CDMA communication over AWGN channel is also discussed in this paper. The proposed binary user codes are found to be suitable for both synchronous and asynchronous DS-CDMA communication.

  2. 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.

  3. 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

  4. 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)

  5. Performance analysis of multi-channel and multi-traffic on wireless communication networks

    CERN Document Server

    Yue, Wuyi

    2007-01-01

    List of Figures. List of Tables. Preface. Acknowledgments. 1: Introduction. 1. Overview of Multiple Access Communication Networks. 2. Packet Communication Networks 3. Wireless Communication Networks. 4. Multiple Access Protocols 5. Mobile Packet Radio Networks with Random Access Protocols. 6. Multichannel Networks with Random Access Protocols. 7. Multi-Hop Networks with Random Access Protocols. 8. Channel Assignment Schemes in Cellular Mobile Networks. 9. Performance Analysis of Wireless Communication Networks. 10. System Models and Performance Analyses in the Book. Part I: Multichannel and Mu

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Load-adaptive practical multi-channel communications in wireless sensor networks.

    Science.gov (United States)

    Islam, Md Shariful; Alam, Muhammad Mahbub; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    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. PMID:22163685

  12. 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.

  13. Technology of newspaper transmission over ground and satellite communications channels

    Science.gov (United States)

    Mel'Nik, Semen Osherovich

    The design principles of a facsimile newspaper transmission system are examined with emphasis on signal-conversion processes in the transmitting and receiving devices. The design of the comunications channels is considered along with newspaper transmission over cable, radio-relay, and satellite channels. The operation of the Gazeta-2 facsimile system is described as an example.

  14. 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...

  15. Channel Model for Train to Train Communication using the 400 MHz Band

    OpenAIRE

    Rico Garcia, Cristina; Lehner, Andreas; Strang, Thomas

    2008-01-01

    This paper presents a channel model for direct train-to-train communication appropriate for the 400 MHz band. Extrapolation of theoretical and experimental results obtained for the planning of other railway communication systems like GSM-R is not obvious due to the difference in frequencies, antenna height and absence of base stations. In this paper, the analysis of the channel model covers different radio phenomena including path loss, Doppler, fading, and delay spread. ...

  16. 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...

  17. 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...

  18. 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...

  19. 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.

  20. A Study on the Inter-Channel Communication Independence for SMART I and C System

    International Nuclear Information System (INIS)

    In nuclear power plants (NPP) the greatest concern is to ensure the safety goal, so it is designed with a protection conception using diversity and redundancy methods. Usually the I and C (Instrumentation and Control) system of NPP is composed of four channels to enhance the performance of the safety functions and performs the monitoring and control functions. In these redundant structures, the most important thing is that a malfunction in one channel cannot affect the safety functions of the redundant channels. The communication network of the digital I and C system is playing a role in intra-channel communication and inter-channel communication in four-channel I and C structure. Recent licensee experience indicates that companies planning to use the interchannel communication must perform a detailed analysis of all credible failure modes. In this paper, we propose some evaluation criteria to evaluate the inter-channel communication independence of SMART I and C system and preliminary design for mitigating methodologies of each credible failure

  1. Disseminating Information and Soliciting Input during Planned Organizational Change: Implementers' Targets, Sources, and Channels for Communicating.

    Science.gov (United States)

    Lewis, Laurie K.

    1999-01-01

    Examines implementers' use of channels to disseminate information to and solicit input from staff members during planned change. Assesses how communication was differently directed to paid and volunteer staff and the degree to which channel use is predictive of implementers' assessments of success of change efforts. Discusses potential…

  2. 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.

  3. A study of the effect of group delay distortion on an SMSK satellite communications channel

    Science.gov (United States)

    Kerczewski, Robert J.

    1987-01-01

    The effects of group delay distortion on an SMSK satellite communications channel have been investigated. Software and hardware simulations have been used to determine the effects of channel group delay variations with frequency on the bit error rate for a 220 Mbps SMSK channel. These simulations indicate that group delay distortions can significantly degrade the bit error rate performance. The severity of the degradation is dependent on the amount, type, and spectral location of the group delay distortion.

  4. 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

  5. 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

  6. 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…

  7. 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…

  8. 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…

  9. 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

  10. 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)…

  11. Propagation and Wireless Channel Modeling Development on Wide-Sense Vehicle-to-X Communications

    Directory of Open Access Journals (Sweden)

    Wenyi Jiang

    2013-01-01

    Full Text Available The need for improving the safety and the efficiency of transportation systems has become of extreme importance. In this regard, the concept of vehicle-to-X (V2X communication has been introduced with the purpose of providing wireless communication technology in vehicular networks. Not like the traditional views, the wide-sense V2X (WSV2X communications in this paper are defined by including not only vehicle-to-vehicle (V2V and vehicle-to-infrastructure (V2I communications but also train-to-X (T2X communications constituted of train-to-train (T2T and train-to-infrastructure (T2I communications. All the information related to the wide-sense V2X channels, such as the standardization, scenarios, characters, and modeling philosophies, is organized and summarized to form the comprehensive understanding of the development of the WSV2X channels.

  12. 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

  13. 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.

  14. Long Distance Non-Line-of-Sight Ultraviolet Communication Channel Analysis and Experimental Verification

    Science.gov (United States)

    Liao, Linchao

    In this thesis, the characteristics of long-distance non-line-of-sight (NLOS) ultraviolet (UV) communication channel are studied through experiment and theoretical analysis. The research focuses on the validation of different channel models, long distance NLOS link loss and received signal energy distribution based on outdoor experiment results and numerous simulations. All the previous research on NLOS UV only considered short communication range scenarios, in which turbulence effects were assumed to be negligible. In fact, with the increasing of communication distance, optical turbulence effects may degrade UV communication performance because the fading irradiance significantly deteriorates the received signal in two aspects: received energy fluctuation and extra path loss. In the beginning, the author conducts a comprehensive outdoor channel measurement from several hundreds meters up to four thousand meters. To the best of our knowledge, this experiment represents the most comprehensive examination of the NLOS UV communication channel at such distances. By reporting experimentally collected data, we illustrate two approaches to measuring path loss. In addition to highlighting practical issues, which is death time, that must be considered when performing such measurement , the data provide validation of a previously reported Monte Carlo multiple-scattering channel model. In addition, we examine the distribution of received photon counts for evidence of the effects of turbulence in the NLOS channel. In this case, however, there is less agreement with predictions from existing turbulence models, suggesting the need for additional research on the refinement of turbulence modeling. For this reason, we then propose a MC channel model to capture the multiple scattering channel behavior under turbulence condition. In addition, we present a serial experimental results and study the characteristic of NLOS UV turbulence channel with farthest distances up to 1 km. Through

  15. 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.

  16. MARKETING COMMUNICATION CHANNELS USED BY LOCAL GOVERNMENTS VS. TOURISTS` EXPECTATIONS

    OpenAIRE

    HERNIK JOANNA; SMALEC AGNIESZKA

    2013-01-01

    Marketing communication specialists in local governments have at their disposal a number of communication instruments. Significant that the most commonly they use printed materials, brochures and leaflets, web sites and walking maps. The question is: if this is sufficient for modern tourists? That’s why the article presents the results of study of secondary data on the development of tourism in the West Pomeranian Province (Poland), as well as the original findings relating to the expectation...

  17. 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.

  18. 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...

  19. 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.

  20. 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

  1. 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.

  2. 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....

  3. A Dynamic Wideband Directional Channel Model for Vehicle-to-Vehicle Communications

    OpenAIRE

    He, Ruisi; Renaudin, Olivier; Kolmonen, Veli-Matti; Haneda, Katsuyuki; Zhong, Zhangdui; Ai, Bo; Oestges, Claude

    2015-01-01

    Vehicle-to-vehicle (V2V) communications have received a lot of attention due to their numerous applications in traffic safety. The design, testing, and improvement of the V2V system hinge critically on the understanding of the propagation channels. An important feature of the V2V channel is the time variance. To statistically model the time-variant V2V channels, a dynamic wideband directional channel model is proposed in this paper, based on measurements conducted at 5.3 GHz in suburban, urba...

  4. 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.

  5. 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.

  6. Limits to clock synchronization induced by completely dephasing communication channels

    International Nuclear Information System (INIS)

    Clock synchronization procedures are analyzed in the presence of imperfect communications. In this context we show that there are physical limitations, which prevent one from synchronizing distant clocks when the intervening medium is completely dephasing, as in the case of a rapidly varying dispersive medium

  7. Whittle Communications and Channel One: Rhetorical Strategies of Innovation.

    Science.gov (United States)

    Adams, Scott

    A study examined the message features that influence an innovation's acceptance by a mass audience. The study looked at three strategies of innovational rhetoric (denial of controversy, subtle criticism of existing institutions, and projection of a rhetorical vision) used by a commercial broadcasting company, called Whittle Communications in 1989,…

  8. Some properties of quantum reiliablity function for quantum communication channel

    OpenAIRE

    Kurokawa, K; Sasaki, M; Osaki, M.; Hirota, O.

    1997-01-01

    This paper presents some examples of quantum reliability function for the quantum communication system in which classical information is transmitted by quantum states. In addition, the quantum Cut off rate is defined. They will be compared with Gallager's reliability function for the same system.

  9. Some properties of quantum reliablity function for quantum communication channel

    CERN Document Server

    Kurokawa, K; Sasaki, M; Osaki, M; Hirota, O

    1997-01-01

    This paper presents some examples of quantum reliability function for the quantum communication system in which classical information is transmitted by quantum states. In addition the quantum Cut off rate is defined. They will be compared with Gallager's reliability function for the same system.

  10. Dispensing with Channel Estimation: Differentially Modulated Cooperative Wireless Communications

    OpenAIRE

    Wang, Li; Hanzo, Lajos

    2012-01-01

    As a bene?t of bypassing the potentially excessive complexity and yet inaccurate channel estimation, differentially encoded modulation in conjunction with low-complexity noncoherent detection constitutes a viable candidate for user-cooperative systems, where estimating all the links by the relays is unrealistic. In order to stimulate further research on differentially modulated cooperative systems, a number of fundamental challenges encountered in their practical implementations are addressed...

  11. Safety assessment of inter-channel / inter-system digital communications: A defensive measures approach

    International Nuclear Information System (INIS)

    Inappropriately designed inter-channel and inter-system digital communications could initiate common cause failure of multiple channels or multiple systems. Defensive measures were introduced in EPRI report TR-1002835 (Guideline for Performing Defense-in-Depth and Diversity Assessments for Digital Upgrades) to assess, on a deterministic basis, the susceptibility of digital systems architectures to common-cause failures. This paper suggests how this approach could be applied to assess inter-channel and inter-system digital communications from a safety standpoint. The first step of the approach is to systematically identify the so called 'influence factors' that one end of the data communication path can have on the other. Potential factors to be considered would typically include data values, data volumes and data rates. The second step of the approach is to characterize the ways possible failures of a given end of the communication path could affect these influence factors (e.g., incorrect data values, excessive data rates, time-outs, incorrect data volumes). The third step is to analyze the designed-in measures taken to guarantee independence of the other end. In addition to classical error detection and correction codes, typical defensive measures are one-way data communication, fixed-rate data communication, fixed-volume data communication, validation of data values. (authors)

  12. 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.

  13. 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...

  14. 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...

  15. 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.

  16. Control channels with full galvanic isolation by the fiber optical communication line method

    International Nuclear Information System (INIS)

    Application of control channel with full galvanic insulation using the fiber optics communication line (FOCL) method was analyzed. The developed control systems provide full electrical insulation between the controlled facility and control center. Application of FOCL method excludes loops, occurring under conditions of coearthing of several pulse units, and background effects, occurring between control channels. The full insulation between the facility and control center assures the safety operation and high electric potential

  17. Effective capacity of communication systems over $\\kappa$-$\\mu$ shadowed fading channels

    OpenAIRE

    Zhang, Jiayi; Dai, Linglong; Gerstacker, Wolfgang H.; Wang, Zhaocheng

    2015-01-01

    The effective capacity of communication systems over generalized $\\kappa$-$\\mu$ shadowed fading channels is investigated in this letter. A novel and analytical expression for the exact effective capacity is derived in terms of extended generalized bivariate Meijer's-$G$ function. To intuitively reveal the impact of the system and channel parameters on the effective capacity, we also derive closed-form expressions for the effective capacity in the asymptotically high signal-to-noise ratio regi...

  18. 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.

  19. 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.

  20. Statistical entropy of a nuclear spectrometer vis-a-vis communication channel

    International Nuclear Information System (INIS)

    The aim of this paper is to present an esoteric model of a nuclear spectrometer e.g. a gamma ray spectrometer as a communication channel. The source entropy, receiver entropy, and joint entropy of a gamma ray spectrometer were estimated for an observed 1 K gamma spectrum containing a 662 keV peak from a 137Cs source. The information loss estimated for the observed gamma spectrum was of the order of 94.5%. In a typical communication engineering channel, the information loss is of the order of 30%. The information loss in a gamma spectrometer is far more than that in a communication channel. Hence the information extraction in a nuclear spectrometer is extremely challenging vis-a-vis communication channel. This also explains high redundancy of spectral channels, and justifies that a priori information required is much more than the a posteriori information extracted in nuclear spectrometers. Also the model amply justifies wide ranging results for the IAEA intercomparison of spectral analysis programs in which 212 results from 163 laboratories from 34 countries were compared

  1. 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.

  2. Simulation of an Underwater Acoustic Communication Channel Characterized by Wind-Generated Surface Waves and Bubbles

    OpenAIRE

    Dol, H.S.; Colin, M.E.G.D.; Ainslie, M.A.; Walree, P.A. van; Janmaat, J.

    2012-01-01

    Sea surface scattering by wind-generated waves and bubbles is regarded to be the main non-platform related cause of the time variability of shallow acoustic communication channels. Simulations for predicting the quality of acoustic communication links in such channels thus require adequate modeling of these dynamic sea-surface effects. It is known that, for frequencies in the range 1-4 kHz, the main effect of bubbles on sea surface reflection loss is due to refraction, which can be modeled wi...

  3. 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...

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Interactive multimedia systems as communication channels in color workshops

    Science.gov (United States)

    Gaudio, Alejandra; De Ponti, Javier

    2002-06-01

    Great technological advances can help us to recover communication areas that might otherwise be lost. Media competition and visual contamination frequently appear in daily communication. A notable anonymity in human relationship has emerged as a consequence of this. Educational establishments receive an overflowing number of students. Schools and students are overwhelmed by this situation. Teachers don't know their students and students usually don't know their own classmates, with all the consequences that this implies. In front of this inadequate structure of educational institutions, technology has improved the possibilities of instant answers and the dialogue between teachers and students; the unilateral exposition pronounced by teachers in front of the anonymous mass finds an alternative in multimedia systems. The present work describes Interactive Multimedia System's utilization for teaching the chromatic circle as a system of color organization. The proposed method intends to devise a theoretical and conceptual frame and its production for multimedia systems oriented to elaborate, represent, store, interact with and access to knowledge Its relevance comes from the potential contribution to build up knowledge systems that value cultural codes and at the same time make creative and motivating interactive experiences. This work concerns the realization and understanding of the chromatic circle, selection of different color systems, logical strategies for playing and studying theory and multimedia. Levels of visualization: theory, practice, developing skills, works and evaluation. Levels to study: teaching chromatic circle, multimedia supports, quality, application and linking screens, help, theory, etc; without losing the interdisciplinary nature of the work, specialist participation, and Multimedia Systems in the steps of its realization.

  9. 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.

  10. End-to-End Throughput with Cooperative Communication in Multi-channel Wireless Networks

    OpenAIRE

    Huang, Zheng; Wang, Xin; Li, Baochum

    2010-01-01

    Although cooperative communication has been proposed at the physical layer to address multi-path fading e®ects, how physical layer gains with cooperative communication can translate to tangible perfor- mance bene¯ts in end-to-end °ows remains to be an open problem. This paper represents one step forward towards a deeper understanding of the interplay between end-to-end throughput and physical layer cooperative communication, in the general context of multi-hop multi-channel wire- less network...

  11. 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.

  12. 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.

  13. Quantum phase communication channels in the presence of static and dynamical phase diffusion

    Science.gov (United States)

    Trapani, Jacopo; Teklu, Berihu; Olivares, Stefano; Paris, Matteo G. A.

    2015-07-01

    We address quantum communication channels based on phase modulation of coherent states and analyze in detail the effects of static and dynamical (stochastic) phase diffusion. We evaluate mutual information for an ideal phase receiver and for a covariant phase-space-based receiver, and compare their performances by varying the number of symbols in the alphabet and/or the overall energy of the channel. Our results show that phase communication channels are generally robust against phase noise, especially for large alphabets in the low-energy regime. In the presence of dynamical (non-Markovian) noise the mutual information is preserved by the time correlation of the environment, and when the noise spectra are detuned with respect to the information carrier, revivals of mutual information appear.

  14. 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.

  15. What You Don't Know Won't Hurt Me: Impression Management Functions of Communication Channels in Relationships.

    Science.gov (United States)

    O'Sullivan, Patrick B.

    2000-01-01

    Addresses the implications of interpersonal communication technology use for personal relationships. Tests elements of an impression management model, which specifies the processes and outcomes of strategic uses of channel and message for self-presentational goals. Supports a functional perspective that views mediated communication channels as a…

  16. Channel equalization and synchronization in chaotic communications using a dual Kalman filtering scheme

    Science.gov (United States)

    Rigatos, Gerasimos; Zervos, Nikolaos

    2013-10-01

    A new nonlinear filtering method, the so-called Derivative-free nonlinear Kalman Filter, is used in the design of chaotic communication systems. In the transmitter's side the source of information undergoes modulation (encryption) in which a chaotic signal generated by the Duffing oscillator is the carrier. The modulated signal is transmitted through a communication channel and at the receiver's side demodulation takes place, by exploiting the estimation provided about the state vector of the chaotic oscillator by the Derivative-free nonlinear Kalman Filter. Moreover, it is shown that the proposed Derivative-free nonlinear Kalman Filter can work within a dual Kalman Filtering scheme, for performing simultaneously transmitter-receiver synchronization and estimation of unknown coefficients of the communication channel (equalization). Evaluation tests confirm that the proposed filtering method has improved performance over the Extended Kalman Filter and reduces significantly the rate of transmission errors.

  17. 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.

  18. 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.

  19. 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.

  20. Which verification qubits perform best for secure communication in noisy channel?

    Science.gov (United States)

    Sharma, Rishi Dutt; Thapliyal, Kishore; Pathak, Anirban; Pan, Alok Kumar; De, Asok

    2016-04-01

    In secure quantum communication protocols, a set of single qubits prepared using 2 or more mutually unbiased bases or a set of n-qubit (n≥ 2) entangled states of a particular form are usually used to form a verification string which is subsequently used to detect traces of eavesdropping. The qubits that form a verification string are referred to as decoy qubits, and there exists a large set of different quantum states that can be used as decoy qubits. In the absence of noise, any choice of decoy qubits provides equivalent security. In this paper, we examine such equivalence for noisy environment (e.g., in amplitude damping, phase damping, collective dephasing and collective rotation noise channels) by comparing the decoy-qubit-assisted schemes of secure quantum communication that use single-qubit states as decoy qubits with the schemes that use entangled states as decoy qubits. Our study reveals that the single- qubit-assisted scheme performs better in some noisy environments, while some entangled-qubit-assisted schemes perform better in other noisy environments. Specifically, single-qubit-assisted schemes perform better in amplitude damping and phase damping noisy channels, whereas a few Bell-state-based decoy schemes are found to perform better in the presence of the collective noise. Thus, if the kind of noise present in a communication channel (i.e., the characteristics of the channel) is known or measured, then the present study can provide the best choice of decoy qubits required for implementation of schemes of secure quantum communication through that channel.

  1. 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

  2. Novel control channel quality improvement in satellite communication systems employing high coding gain FEC

    Science.gov (United States)

    Morikura, Masahiro; Kubota, Shuji; Enomoto, Kiyoshi; Kato, Shuzo

    The authors propose a novel control channel quality improvement scheme for satellite communication systems using a majority decision method over convolutional coding and Viterbi decoding channels. To improve majority decision performance, which is degraded by burst errors due to Viterbi decoding in conventional serial transmission methods, a parallel transmission method is proposed. The performance of the parallel and serial transmission methods has been analyzed, and experiments have been carried out using rate-1/2 convolutional encoding and Viterbi decoding (constraint length 4 and 7). It is shown that the parallel transmission method has about 1010 times lower block-error performance at Pe = 1 x 10-4 than the conventional method.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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 number...... of sets of cochannel cells or allocation patterns and then assigning them to channels. This usually implies that only a subset of the feasible region is attainable. The approach suggested in this paper uses the concept of packed pattern, since all patterns in an optimal solution will be of that kind...... further advantage of flexibility when dealing with extensions to the problem. A neighbouring structure was used, that facilitated the calculations while still allowing for the search in the entire solution space. A summary of extensive numerical experiments is presented. The outcome is an improvement over...

  18. 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 number...... of sets of cochannel cells or allocation patterns and then assigning them to channels. This usually implies that only a subset of the feasible region is attainable. The approach suggested in this paper uses the concept of packed pattern, since all patterns in an optimal solution will be of that kind....... With a constructive method, the entire set of packed patterns is built and used in the optimisation process. The complexity (large-scale and nonlinearity) of the resulting problem suggested the use of general search procedures (local search, tabu search, simulated annealing, etc.), which have the...

  19. Energy-efficient Joint Power Allocation and Channel Selection for D2D Communications

    Directory of Open Access Journals (Sweden)

    Guifang Ma

    2015-08-01

    Full Text Available Device-to-device (D2D communications have gained great attentions due to the potential and numerous benefits for cellular networks. However,it also brings tremendous resource allocation challenges for the sake of the constraint of battery life. Up to now, there are limited works attempt to prolong the battery life by improving the energy efficiency (EE. In this paper, we study how to perform resource allocation to increase EE in a interference limited environment under a noncooperative game model. Each D2D pair can reuse all or part of the channel resources allocated to cellular users. An energy-efficient joint power allocation and channel selection is proposed by employing the nonlinear fractional programming. We obtain the optimal power allocation and channel selection through an iterative algorithm called Dinkelbach method. Finally, the algorithm proposed in this paper is verified by simulation.

  20. 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.

  1. 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.

  2. On Communication over Unknown Sparse Frequency-Selective Block-Fading Channels

    CERN Document Server

    Kannu, Arun Pachai

    2010-01-01

    The problem of reliable communication over unknown frequency-selective block-fading channels with sparse impulse responses is considered. In particular, discrete-time channels of length $L$ and sparsity $S\\leq L$, whose support and coefficients remain fixed over blocks of $N>L$ channel uses, but change independently from block to block, are considered in the high-SNR regime. Here, both the support and the coefficient realizations are apriori unknown. Assuming that the non-zero coefficients and noise are both Gaussian, it is first shown that the ergodic noncoherent channel capacity has pre-log factor $1-\\frac{S}{N}$ for any $L$. Next a pilot-aided transmission (PAT) scheme and noncoherent decoder are proposed which are capable of communicating with arbitrarily small error probability using only $S$ pilots per fading block. Furthermore, the achievable rate of this scheme is shown to have the optimal pre-log factor, i.e., $1-\\frac{S}{N}$. The proposed approach, which requires only $S$ pilots, can be contrasted w...

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Random matrix theory of multi-antenna communications: the Ricean channel

    International Nuclear Information System (INIS)

    The use of multi-antenna arrays in wireless communications through disordered media promises huge increases in the information transmission rate. It is therefore important to analyse the information capacity of such systems in realistic situations of microwave transmission, where the statistics of the transmission amplitudes (channel) may be coloured. Here, we present an approach that provides analytic expressions for the statistics, i.e. the moments of the distribution, of the mutual information for general Gaussian channel statistics. The mathematical method applies tools developed originally in the context of coherent wave propagation in disordered media, such as random matrix theory and replicas. Although it is valid formally for large antenna numbers, this approach produces extremely accurate results even for arrays with as few as two antennas. We also develop a method to analytically optimize over the input signal distribution, which enables us to calculate analytic capacities when the transmitter has knowledge of the statistics of the channel. The emphasis of this paper is on elucidating the novel mathematical methods used. We do this by analysing a specific case when the channel matrix is a complex Gaussian with arbitrary mean and unit covariance, which is usually called the Ricean channel

  8. Intercellular Odontoblast Communication via ATP Mediated by Pannexin-1 Channel and Phospholipase C-coupled Receptor Activation

    OpenAIRE

    Sato, Masaki; Furuya, Tadashi; Kimura, Maki; Kojima, Yuki; Tazaki, Masakazu; Sato, Toru; Shibukawa, Yoshiyuki

    2015-01-01

    Extracellular ATP released via pannexin-1 channels, in response to the activation of mechanosensitive-TRP channels during odontoblast mechanical stimulation, mediates intercellular communication among odontoblasts in dental pulp slice preparation dissected from rat incisor. Recently, odontoblast cell lines, such as mouse odontoblast lineage cells, have been widely used to investigate physiological/pathological cellular functions. To clarify whether the odontoblast cell lines also communicate ...

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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…

  17. Relay Assisted Cooperative OSTBC Communication with SNR Imbalance and Channel Estimation Errors

    CERN Document Server

    Niu, Bo; Lin, Zinan; Chitrapu, Prabhakar

    2010-01-01

    In this paper, a two-hop relay assisted cooperative Orthogonal Space-Time Block Codes (OSTBC) transmission scheme is considered for the downlink communication of a cellular system, where the base station (BS) and the relay station (RS) cooperate and transmit data to the user equipment (UE) in a distributed fashion. We analyze the impact of the SNR imbalance between the BS-UE and RS-UE links, as well as the imperfect channel estimation at the UE receiver. The performance is analyzed in the presence of Rayleigh flat fading and our results show that the SNR imbalance does not impact the spatial diversity order. On the other hand, channel estimation errors have a larger impact on the system performance. Simulation results are then provided to confirm the analysis.

  18. 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.

  19. 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.

  20. 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.

  1. Fault-tolerant controlled quantum secure direct communication over a collective quantum noise channel

    International Nuclear Information System (INIS)

    This work proposes controlled quantum secure direct communication (CQSDC) over an ideal channel. Based on the proposed CQSDC, two fault-tolerant CQSDC protocols that are robust under two kinds of collective noises, collective-dephasing noise and collective-rotation noise, respectively, are constructed. Due to the use of quantum entanglement of the Bell state (or logical Bell state) as well as dense coding, the proposed protocols provide easier implementation as well as better qubit efficiency than other CQSDC protocols. Furthermore, the proposed protocols are also free from correlation-elicitation attack and other well-known attacks. (paper)

  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. Fundamental dispersion limit for spectrally bounded On-Off-Keying communication channels

    CERN Document Server

    Granot, Er'el

    2012-01-01

    The fundamental dispersion limit for optical communication based the On-Off-Keying format is calculated. It is shown both analytically and with numerical simulations that an OOK optical sequence, which passes through spectrally narrow noncompensated dispersive channel cannot exceed the limit 1/{\\pi} > {\\beta_2} L B^2, where {\\beta_2}, L and B are the dispersion coefficient, the fiber's length and the bit-rate respectively. To the best of our knowledge, this is the first time that such a fundamental limit was formulated. In the literature, only approximation evaluations were developed yielding much smaller limiting values.

  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. Free-space quantum cryptography with quantum and telecom communication channels

    Science.gov (United States)

    Toyoshima, Morio; Takayama, Yoshihisa; Klaus, Werner; Kunimori, Hiroo; Fujiwara, Mikio; Sasaki, Masahide

    2008-07-01

    Quantum cryptography is a new technique that uses the laws of physics to transmit information securely. In such systems, the vehicle to transfer quantum information is a single photon. However, the transmission distance is limited by the absorption of photons in an optical fiber in which the maximum demonstrated range is about 100 km. Free-space quantum cryptography between a ground station and a satellite is a way of sending the quantum information further distances than that with optical fibers since there is no birefringence effect in the atmosphere. At the National Institute of Information and Communications Technology (NICT), the laser communication demonstration between the NICT optical ground station and a low earth orbit satellite was successfully conducted in 2006. For such space communication links, free-space quantum cryptography is considered to be an important application in the future. We have developed a prototype system for free-space quantum cryptography using a weak coherent light and a telecom communication channel. The preliminary results are presented.

  9. 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.

  10. 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

  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. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Modulation of metabolic communication through gap junction channels by transjunctional voltage; synergistic and antagonistic effects of gating and ionophoresis

    OpenAIRE

    Palacios-Prado, Nicolás; Bukauskas, Feliksas F.

    2011-01-01

    Gap junction (GJ) channels assembled from connexin (Cx) proteins provide a structural basis for direct electrical and metabolic cell-cell communication. Here, we focus on gating and permeability properties of Cx43/Cx45 heterotypic GJs exhibiting asymmetries of both voltage-gating and transjunctional flux (Jj) of fluorescent dyes depending on transjunctional voltage (Vj). Relatively small differences in the resting potential of communicating cells can substantially reduce or enhance this flux ...

  19. 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.

  20. 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.

  1. 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…

  2. 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.

  3. Networking remote control of nuclear instruments based on multi-channel serial communication in ARM-linux

    International Nuclear Information System (INIS)

    Measurement and control of nuclear instruments in particular environment is not suitable for on-site direct operation. In addition, monitor of nuclear instruments should be multi-point binding and continuous monitoring. With those characteristics, the solution for remote control and nuclear instruments networking by multi-channel serial communication interface under ARM-Linux is proposed. On the basis of practical application, mode of hardware connection for multi-channel serial interface is analyzed. Moreover, the paper also describes in detail serial port initialization and multi-port serial programming. Finally experiments prove that multi-channel serial communication can improve data transmission rate of nuclear instruments, but also achieve remote monitor and centralized management of nuclear instruments networking. (authors)

  4. 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...

  5. 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.

  6. Managing Brand Equity in an Integrated Marketing Communication Strategy : - A Case Study in the FMCG industry of the effectiveness and synergies of digital marketing channels.

    OpenAIRE

    Rashid, Paola

    2014-01-01

    Purpose: The purpose of this thesis is to add empirical findings of IMC strategies utilizing digital- and traditional marketing communication channels to build and maintain brand equity in the FMCG industry. More specifically awareness, associations/image and sales that are said to be critically affected by communication are the focus of the study. Research Question: Are digital marketing communication channels in an IMC strategy effective in creating awareness, associations and sales within ...

  7. 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.

  8. 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.

  9. 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....

  10. 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.

  11. 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.

  12. Approximate symbol error rate of cooperative communication over generalised κ−μ and η−μ fading channels

    Directory of Open Access Journals (Sweden)

    Brijesh Kumbhani

    2014-01-01

    Full Text Available Closed form expressions for approximate symbol error rate are obtained using moment generating function for a two branch cooperative communication system over generalised κ−μ and η−μ i.i.d. fading channels for BPSK and QAM modulation schemes. Selective decode and forward protocol is used at the relay transmitter. At the destination maximal-ratio combining is used. Monte Carlo simulations are performed to verify the analytical results.

  13. SOCIAL NETWORKING SITES AS A TYPE OF VIRTUAL COMMUNITIES – PROCESSING AS A MARKETING COMMUNICATION CHANNEL

    OpenAIRE

    Erkan Akar

    2010-01-01

    “Socializing†environments has created an important and critical potential power in virtual world. Recent trends in this field are social networking sites such as MySpace, Facebook, Twitter etc. Social networking sites are a very huge marketing environment. This marketing environment has functioned as a new marketing communication channel. The aim of this study is to reveal how the social networks affect the decision of purchasing and the processing of social networking sites as a marketin...

  14. Comparison of Digisonde and CDSS measurement for the monitoring of the existence of the Ionospheric communication channel

    Czech Academy of Sciences Publication Activity Database

    Rejfek, Luboš; Mošna, Zbyšek; Beran, L.; Chmelař, P.; Chmelařová, N.; Dobrovolný, P.; Rozsíval, P.

    2015-01-01

    Roč. 2, č. 12 (2015), s. 67-71. ISSN 2313-626X R&D Projects: GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : Ionospheric communication channel * Digisonde * Continuous Doppler Sounding System Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.science-gate.com/IJAAS/Articles/2015-2-12/12%202015-2-12-pp.67-71.pdf

  15. Performance of a Coded Non-Square Quadrature Amplitude Modulation Scheme over Fading Channels

    Science.gov (United States)

    Li, L.; Divsalar, D.; Dolinar, S.

    2004-02-01

    It is shown that a non-square (NS) 2^(2n+1)-ary quadrature amplitude modulation (QAM) can be decomposed into a single-parity-check (SPC) block encoder and a memoryless modulator with independent in-phase (I) and quadrature (Q) symbol mapping. When NS-2^(2n+1)-QAM is concatenated with a forward-error-correcting (FEC) code, iterative demodulation and decoding of the FEC code and the inherent SPC code of NS-2^(2n+1)-QAM exploits the modulation's inherent memory and its independent I- and Q-channel mapping and demapping. The capacity and the bit-/symbol-error-rate (BER/SER) performance of coded and uncoded NS-2^(2n+1)-QAM systems are given for both additive white Gaussian noise (AWGN) channels and Rayleigh fading channels and are compared to those of other conventional 2^(2n+1)-ary systems. Simulation results show that, with iterative demodulation and decoding, coded NS-8QAM outperforms three conventional 8-ary systems by at least 0.65 dB on AWGN channels and by at least 0.57 dB on Rayleigh fading channels at BER = 10^(-5), when the FEC code is a concatenation of (15,11) Hamming codes with rate-1 accumulator codes, while coded NS-32QAM outperforms standard 32QAM by about 0.45 dB on AWGN channels and by about 0.27 dB on Rayleigh fading channels.

  16. 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

  17. 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.

  18. 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...

  19. 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.

  20. 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.

  1. Impact of 4D Channel Distribution on the Achievable Rates in Coherent Optical Communication Experiments

    Science.gov (United States)

    Eriksson, Tobias A.; Fehenberger, Tobias; Andrekson, Peter A.; Karlsson, Magnus; Hanik, Norbert; Agrell, Erik

    2016-05-01

    We experimentally investigate mutual information and generalized mutual information for coherent optical transmission systems. The impact of the assumed channel distribution on the achievable rate is investigated for distributions in up to four dimensions. Single channel and wavelength division multiplexing (WDM) transmission over transmission links with and without inline dispersion compensation are studied. We show that for conventional WDM systems without inline dispersion compensation, a circularly symmetric complex Gaussian distribution is a good approximation of the channel. For other channels, such as with inline dispersion compensation, this is no longer true and gains in the achievable information rate are obtained by considering more sophisticated four-dimensional (4D) distributions. We also show that for nonlinear channels, gains in the achievable information rate can also be achieved by estimating the mean values of the received constellation in four dimensions. The highest gain for such channels is seen for a 4D correlated Gaussian distribution.

  2. Time Reversal UWB Communication System: A Novel Modulation Scheme with Experimental Validation

    Directory of Open Access Journals (Sweden)

    Khaleghi A

    2010-01-01

    Full Text Available A new modulation scheme is proposed for a time reversal (TR ultra wide-band (UWB communication system. The new modulation scheme uses the binary pulse amplitude modulation (BPAM and adds a new level of modulation to increase the data rate of a TR UWB communication system. Multiple data bits can be transmitted simultaneously with a cost of little added interference. Bit error rate (BER performance and the maximum achievable data rate of the new modulation scheme are theoretically analyzed. Two separate measurement campaigns are carried out to analyze the proposed modulation scheme. In the first campaign, the frequency responses of a typical indoor channel are measured and the performance is studied by the simulations using the measured frequency responses. Theoretical and the simulative performances are in strong agreement with each other. Furthermore, the BER performance of the proposed modulation scheme is compared with the performance of existing modulation schemes. It is shown that the proposed modulation scheme outperforms QAM and PAM for in an AWGN channel. In the second campaign, an experimental validation of the proposed modulation scheme is done. It is shown that the performances with the two measurement campaigns are in good agreement.

  3. Time Reversal UWB Communication System: A Novel Modulation Scheme with Experimental Validation

    Directory of Open Access Journals (Sweden)

    I. H. Naqvi

    2010-01-01

    Full Text Available A new modulation scheme is proposed for a time reversal (TR ultra wide-band (UWB communication system. The new modulation scheme uses the binary pulse amplitude modulation (BPAM and adds a new level of modulation to increase the data rate of a TR UWB communication system. Multiple data bits can be transmitted simultaneously with a cost of little added interference. Bit error rate (BER performance and the maximum achievable data rate of the new modulation scheme are theoretically analyzed. Two separate measurement campaigns are carried out to analyze the proposed modulation scheme. In the first campaign, the frequency responses of a typical indoor channel are measured and the performance is studied by the simulations using the measured frequency responses. Theoretical and the simulative performances are in strong agreement with each other. Furthermore, the BER performance of the proposed modulation scheme is compared with the performance of existing modulation schemes. It is shown that the proposed modulation scheme outperforms QAM and PAM for M≥4 in an AWGN channel. In the second campaign, an experimental validation of the proposed modulation scheme is done. It is shown that the performances with the two measurement campaigns are in good agreement.

  4. Maximum noise-immunity of a digital communications channel with binary coding

    Science.gov (United States)

    Senderskii, V. A.; Strokov, V. V.

    1987-07-01

    The maximum noise-immunity of a digital comunications channel with binary coding is analyzed as a function of the coding rate. The investigation is carried out for two limiting cases: binary-continuous and binary symmetric channels. It is concluded that the results obtained can be used to estimate the degree to which the noise-immunity values of actual digital channels approximate the maximally possible values.

  5. An improved Channel Estimation Algorithm for Ultra- Wideband Wireless Communication Systems

    Directory of Open Access Journals (Sweden)

    Liu Jinhu

    2013-07-01

    Full Text Available Traditional DFT channel estimation algorithm is relatively balanced in terms of complexity and estimation performance, but compared with the four typical channels of UWB, especially in terms of CM1 and CM2 channel with a small number of the diameter, the cyclic prefix length is relatively much larger than the length of their delay, so the back part is still noise. Aimed at this problem, an improved DFT channel estimation algorithm is brought up in this paper, and this algorithm adds the appropriate threshold threshold in the CP to further eliminate noise, and simulation results show that the improved algorithm is better than the original algorithm.  

  6. 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.

  7. Distributed Generalized Low-Density Codes for Multiple Relay Cooperative Communications

    Directory of Open Access Journals (Sweden)

    Han Changcai

    2008-01-01

    Full Text Available As a class of pseudorandom error correcting codes, generalized low-density (GLD codes exhibit excellent performance over both additive white Gaussian noise (AWGN and Rayleigh fading channels. In this paper, distributed GLD codes are proposed for multiple relay cooperative communications. Specifically, using the partial error detecting and error correcting capabilities of the GLD code, each relay node decodes and forwards some of the constituent codes of the GLD code to cooperatively form a distributed GLD code, which can work effectively and keep a fixed overall code rate when the number of relay nodes varies. Also, at relay nodes, a progressive processing procedure is proposed to reduce the complexity and adapt to the source-relay channel variations. At the destination, the soft information from different paths is combined for the GLD decoder thus diversity gain and coding gain are achieved simultaneously. Simulation results verify that distributed GLD codes with various number of relay nodes can obtain significant performance gains in quasistatic fading channels compared with the strategy without relays and the performance is further improved when more relays are employed.

  8. 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...

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    Anita Papić

    2012-11-01

    Full Text Available 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 'toolshed' (now called 'home', and the Information Highway. The paper presents the basic media in each of the revolutions, questions the very current issues of convergence (as some modern scholars consider the term convergence to be more appropriate than the term revolution, and divergence of media, and special attention is paid to the social context that lead to particular revolutions. The central conclusion is that information revolutions were not the time of replacing the old media with the new, but the times of condensation of communication possibilities. During those times the new media joined the existing types, not replacing them but co-existing. They faded out gradually or disappeared only over extended periods of time. Key-words: information revolutions, media, convergence, divergence, communication.

  11. Characterization of a Class of Error Correcting Frames for Robust Signal Transmission over Wireless Communication Channels

    Directory of Open Access Journals (Sweden)

    Rath Gagan

    2005-01-01

    Full Text Available Joint source-channel coding has been introduced recently as an element of QoS support for IP-based wired and wireless multimedia. Indeed, QoS provisioning in a global mobility context with highly varying channel characteristics is all the most challenging and requires a loosening of the layer and source-channel separation principle. Overcomplete frame expansions have been introduced as joint source-channel codes for erasure channels, that is, to allow for a signal representation that would be resilient to erasures in wired and wireless channels. In this paper, we characterize a class of frames for error correction besides erasure recovery in such channels. We associate the frames with complex number codes and characterize them based on the BCH-like property of the parity check matrices of the associated codes. We show that, in addition to the BCH-type decoding, subspace-based algorithms can also be used to localize errors over such frame expansion coefficients. When the frame expansion coefficients are quantized, we modify these algorithms suitably and compare their performances in terms of the accuracy of error localization and the signal-to-noise ratio of the reconstructed signal. In particular, we compare the frames associated with lowpass DFT, DCT, and DST codes, which belong to the defined class, in terms of their error correction efficiency.

  12. 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.

  13. Enhanced UWB Radio Channel Model for Short-Range Communication Scenarios Including User Dynamics

    DEFF Research Database (Denmark)

    Kovacs, Istvan Zsolt; Nguyen, Tuan Hung; Eggers, Patrick Claus F.; Olesen, Kim

    2005-01-01

    including realistic device and user terminal antenna configurations. The radio channel measurements have been performed in the lower UWB frequency band of 3GHz to 5GHz with a 2x4 MIMO antenna configuration. Several environments, user scenarios and two types of user terminals have been used. The developed......In this paper we propose a SISO UWB radio channel model for short-range radio link scenarios between a fixed device and a dynamic user hand-held device. The channel model is derived based on novel experimental UWB radio propagation investigations carried out in typical indoor PAN scenarios...

  14. 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.

  15. OFDM based PHY Performance of IEEE 802.11a Using Various practical channel models

    Directory of Open Access Journals (Sweden)

    Narendra Giradkar

    2011-09-01

    Full Text Available Today with the advent of wireless communication and need for greater bandwidth and speed requirement with noise free reception, research has opened up a whole new market for wireless solutions. The IEEE 802.11a standards using orthogonal frequency division multiplexing (OFDM can provide data rates up to 54 Mbps which makes good for high speed communications in wireless local area networks. In this paper, We evaluated the OFDM based PHY performance of IEEE 802.11a using various practical channel models such as Rician Fading, Rayleigh multipath Fading & AWGN. The effects of different transmission modes define in PHY on IEEE 802.11a system performance are studied using MATLAB SIMULINK. The performance is characterized in terms of 802.11a receivers bit error rates and signal to noise ratio for various modulation schemes such as 16 QAM, 64 QAM, BPSK and QPSK for different code rates as defined by the IEEE Standards 802.11a. All the Simulink models were studied using convolutional coder and Viterbi Decoder and standard OFDM format with 48 carriers, 4 pilots and a zero insertion in the middle.

  16. 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.

  17. 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.

  18. Asymmetry and decoherence of a quantum channel in the quantum communication system of continuous variables

    International Nuclear Information System (INIS)

    Influences of an asymmetric noisy quantum channel on continuous variable entanglement and quantum teleportation are investigated. It is shown that when the resource of entanglement is a two-mode squeezed-vacuum state, the amount of the shared entanglement and the performance of the quantum teleportation are greater (smaller) in the symmetric quantum channel than in the asymmetric one if n-bar >n-barth (n-bar th) , where n-bar and n-barth are the average photon numbers of the two-mode squeezed-vacuum state and the thermal noise. When the quantum teleportation is carried out in the asymmetric quantum channel, introducing an additional loss makes better the performance of the quantum teleportation under certain conditions. The introduction of an additional loss makes smaller not only the shared entanglement but also the degree of the channel asymmetry

  19. 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.

  20. Intercellular odontoblast communication via ATP mediated by pannexin-1 channel and phospholipase C-coupled receptor activation.

    Directory of Open Access Journals (Sweden)

    Masaki Sato

    2015-11-01

    Full Text Available Extracellular ATP released via pannexin-1 channels, in response to the activation of mechanosensitive-TRP channels during odontoblast mechanical stimulation, mediates intercellular communication among odontoblasts in dental pulp slice preparation dissected form rat incisor. Recently, odontoblast cell lines, such as mouse odontoblast lineage cells, have been widely used to investigate physiological/pathological cellular functions. To clarify whether the odontoblast cell lines also communicate with each other by diffusible chemical substance(s, we investigated the chemical intercellular communication among cells from mouse odontoblast cell lines following mechanical stimulation. A single cell was stimulated using a glass pipette filled with standard extracellular solution. We measured intracellular free Ca2+ concentration ([Ca2+]i by fura-2 in stimulated cells, as well as in cells located nearby. Direct mechanical stimulation to a single odontoblast increased [Ca2+]i, which showed sensitivity to capsazepine. In addition, we observed increases in [Ca2+]i not only in the mechanically stimulated odontoblast, but also in nearby odontoblasts. We could observe mechanical stimulation-induced increase in [Ca2+]i in a stimulated human embryo kidney (HEK 293 cell, but not in nearby HEK293 cells. The increase in [Ca2+]i in nearby odontoblasts, but not in the stimulated odontoblast, was inhibited by adenosine triphosphate (ATP release channel (pannexin-1 inhibitor in a concentration- and spatial-dependent manner. Moreover, in the presence of phospholipase C (PLC inhibitor, the increase in [Ca2+]i in nearby odontoblasts, following mechanical stimulation of a single odontoblast, was abolished. We could record some inward currents evoked from odontoblasts near the stimulated odontoblast, but the currents were observed in only 4.8% of the recorded odontoblasts. The results of this study showed that ATP is released via pannexin-1, from a mechanically stimulated

  1. 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 ...

  2. 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.

  3. 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...

  4. 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.

  5. Research on Satellite Communication Channel Estimation and Adaptive Modulation Decision Technology

    Directory of Open Access Journals (Sweden)

    Zhendong Yin

    2013-01-01

    Full Text Available Satellite communication has become a modern indispensable means of communication. In order to reduce the BER in a maximum limit, the transmitting terminal of adaptive satellite communication technology can automatic select working frequency, data transmission rate and modulation mode. In this study, a simple and practical design of system based on the Signal-to-noise Ratio (SNR estimation scheme with adaptive modulation for satellite communication is presented. This system applies Maximum-likelihood (ML algorithm to estimate SNR. Simulation deduces the modulation mode switching threshold. In addition, the adaptive modulation switching threshold is the trade off between spectral efficiency and Bit Error Rate (BER. Furthermore, the modulation mode decision strategy should be considered to achieve the highest spectral efficiency and to maintain constant average BER. The design of an integrated SNR estimation and adaptive modulation mode decision system is highly challenging. Numerical results show that the design fulfills superior performance.

  6. Network Coded Multi-Hop Wireless Communication Networks: Channel Estimation and Training Design

    OpenAIRE

    Peng, Mugen; Hu, Qiang; Xie, Xinqian; Zhao, Zhongyuan; Poor, H. Vincent

    2014-01-01

    User cooperation based multi-hop wireless communication networks (MH-WCNs) as the key communication technological component of mobile social networks (MSNs) should be exploited to enhance the capability of accumulating data rates and extending coverage flexibly. As one of the most promising and efficient user cooperation techniques, network coding can increase the potential cooperation performance gains among selfishly driven users in MSNs. To take full advantages of network coding in MH-WCNs...

  7. 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.

  8. 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.

  9. 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...

  10. 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.

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

    DEFF Research Database (Denmark)

    Rodes Lopez, Roberto; Yu, Xianbin; Caballero Jambrina, Antonio; Jensen, Jesper Bevensee; Gibbon, Timothy Braidwood; Guerrero Gonzalez, Neil; Tafur Monroy, Idelfonso

    2010-01-01

    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 and...

  12. Controlled quantum secure direct communication using a non-symmetric quantum channel with quantum superdense coding

    International Nuclear Information System (INIS)

    We present a controlled quantum secure direct communication protocol that uses a 2-dimensional Greenberger-Horne-Zeilinger (GHZ) entangled state and a 3-dimensional Bell-basis state and employs the high-dimensional quantum superdense coding, local collective unitary operations and entanglement swapping. The proposed protocol is secure and of high source capacity. It can effectively protect the communication against a destroying-travel-qubit-type attack. With this protocol, the information transmission is greatly increased. This protocol can also be modified, so that it can be used in a multi-party control system

  13. 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。

  14. 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.

  15. 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.

  16. 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.

  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)

    Rinne Mika

    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. 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.

  20. 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

  1. Satellite channel modelling using a Ray-tracing Tool for train communication

    OpenAIRE

    Berbineau, M.; Masson, E; Chennaoui, M.; Marais, J

    2006-01-01

    Pushed by international trends to develop Intelligent Transport Systems, railways operators rely more and more on the new information and communication technology to optimize exploitation and maintenance costs but also to enhance the friendliness, comfort and security feeling of public transport by offering new services to passengers while traveling. There is not a lot of study dealing with this problem of high data rate services both in uplink and downlink directions in the case of high-spee...

  2. 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.

  3. 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.

  4. 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......-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...

  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. 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

  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. Experimental confirmation and physical understanding of ultra-high bit rate impulse radio in the THz digital communication channels of the atmosphere

    International Nuclear Information System (INIS)

    We have performed highly accurate numerical calculations of high bit rate impulse propagation through the seven digital communication channels of the atmosphere at RH 58% (10 g m−3). These calculations maximized bit rates for pathlengths equal to or longer than 100 m. We have experimentally verified our calculations for three channels with a propagation pathlength of 137 m and RH 65% (11.2 g m−3). Excellent agreement between measurement and theory was obtained for Channel 3 at 252 GHz, bit rate 84 Gb s−1, FWHM bandwidth (BW) 180 GHz; Channel 6 at 672 GHz, 45 Gb s−1, BW 84 GHz; and Channel 7 at 852 GHz, 56.8 Gb s−1, BW 108 GHz. (special issue article)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. The Yoruba farm market as a communication channel in guinea worm disease surveillance.

    Science.gov (United States)

    Brieger, W R; Kendall, C

    1996-01-01

    Disease eradication programmes are by definition time bound and require strategies that facilitate timely intervention. Surveillance, which undergirds eradication, also requires timely strategies. Finding such strategies is especially challenging when the target disease is endemic in remote areas, e.g. guinea worm disease, the focus of this study. A strategy of market based surveillance was pilot tested in Ifeloju Local Government Area (LGA) of Oyo State, Nigeria. The project goal was to design a surveillance system that both fit into the natural communication network of rural people, and also enlisted their active involvement. Ethnographic research methods were employed to learn about market location, structure, catchment area and attendance pattern. Four larger farm markets (serving 164 hamlets with 17,000 population) were chosen. Each hamlet was visited and a volunteer 'reporter' was recruited. Reporters were trained on case recognition and detection, first aid and prevention, with a sensitivity to distinguishing indigenous and clinical perceptions of guinea worm. The market cycle was based on the traditional four-day week. Field workers visited every second market 16 times between October 1990 and February 1991. The reporter was expected to identify correctly the first case of the season and thus label the village as endemic for the season. Reporters gave oral reports, and positive indications were followed up within 48 hr by field workers, who verified the case and administered first aid. All hamlets were visited once a month to verify negative reports. Reporter attendance was monitored. Those who had a formal role in the market, e.g. sales agents, had better attendance than ordinary farmers who came only to sell their own produce. Knowledge of market structure and attender roles offers a guide for adapting this surveillance approach to other cultural systems and health issues. PMID:8928032

  14. 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。

  15. 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.

  16. 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...

  17. 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.

  18. 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…

  19. 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)

  20. 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 ...

  1. Joint Source-Channel Coding with Correlated Interference

    CERN Document Server

    Huang, Yu-Chih

    2010-01-01

    In this paper, we study the joint source-channel coding problem of transmitting a discrete-time analog source over an AWGN channel with interference known at transmitter. We consider the case when the source and the interference may not be uncorrelated. We first derive an outer bound on the achievable distortion and then, we propose two joint source-channel coding schemes to make use of the correlation between the source and the interference. The first scheme is the superposition of the uncoded signal and a digital part which is the concatenation of a Wyner-Ziv encoder and a dirty paper encoder. In the second scheme, the digital part is replaced by a hybrid digital and analog scheme so that the proposed scheme can provide graceful degradation in the presence of SNR mismatch. We then extend this coding scheme to the generalized cognitive radio channels and analyze the achievable distortion regions for several cases.

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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-...

  7. 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.

  8. 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.

  9. 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.

  10. Forward Error Correcting Codes for 100 Gbit/s Optical Communication Systems

    DEFF Research Database (Denmark)

    Li, Bomin

    demonstrated in a dual polarization (DP) 16-ary quadrature amplitude modulation (16QAM) and coherent detection based WDM transmission over 741 km at a raw data rate of 88.8 Gb/s. FEC can compensate in both regimes, but the channel analysis does not show an additive white Gaussian noise (AWGN) channel. Besides...... FEC codes and their associated experimental demonstration and hardware implementation. The demonstrated high CG, flexibility, robustness and scalability reveal the important role of FEC techniques in the next generation high-speed, high-capacity, high performance and energy-efficient fiber-optic data...

  11. Maximal Ratio Combining Diversity Analysis of Underwater Wireless Communications Subject to {\\kappa}-{\\mu} Shadowed Fading Channels

    OpenAIRE

    Salahat, Ehab; Hakam, Ali

    2016-01-01

    In this paper, a novel unified analytical expression for average bit error rates (ABER) and average channel capacity (ACC) is presented for the {\\kappa}-{\\mu} shadowed fading model. This new shadowed fading model has shown to be suitable for underwater wireless channel modeling for the measurements conducted by the Naval Research Laboratory, and is not so well covered in the public literature. Deploying the Maximal Ratio Combining (MRC) receiver, a new simple analytical expression for the pro...

  12. 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.

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

    Institute of Scientific and Technical Information of China (English)

    张高境

    2015-01-01

    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.%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。

  14. 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。

  15. 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 ...).

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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。

  1. Analysis of Communication and Dissemination Channels Influencing the Adoption of Integrated Soil Fertility Management in Western Kenya

    Science.gov (United States)

    Adolwa, Ivan S.; Okoth, Peter F.; Mulwa, Richard M.; Esilaba, Anthony O.; Mairura, Franklin S.; Nambiro, Elizabeth

    2012-01-01

    Purpose: The following study was carried out to evaluate the socio-economic factors influencing access to Integrated Soil Fertility Management (ISFM) information and knowledge among farmers in western Kenya, and subsequent ISFM uptake with a view to assessing communication gaps. Design/Methodology/Approach: Structured questionnaires were…

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. CSR reports and communication channels from the stakeholder point of view. Do the reports have an effect on consumers?

    OpenAIRE

    Cervantes, Rodrigo

    2010-01-01

    The objective of the current research project was to find out if consumers actually know what social and environmental activities companies are involved in and if they do actually perform consumption decisions based on the information given by the company in their CSR and sustainability reports. In order to achieve the previously stated objective, three main research questions were drafted. Question one is how can CSR be communicated in a way in which consumers can understand and use ...

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. Characterization of on-body communication channel and energy efficient topology design for wireless body area networks.

    Science.gov (United States)

    Reusens, Elisabeth; Joseph, Wout; Latré, Benoît; Braem, Bart; Vermeeren, Günter; Tanghe, Emmeric; Martens, Luc; Moerman, Ingrid; Blondia, Chris

    2009-11-01

    Wireless body area networks (WBANs) offer many promising new applications in the area of remote health monitoring. An important element in the development of a WBAN is the characterization of the physical layer of the network, including an estimation of the delay spread and the path loss between two nodes on the body. This paper discusses the propagation channel between two half-wavelength dipoles at 2.45 GHz, placed near a human body and presents an application for cross-layer design in order to optimize the energy consumption of different topologies. Propagation measurements are performed on real humans in a multipath environment, considering different parts of the body separately. In addition, path loss has been numerically investigated with an anatomically correct model of the human body in free space using a 3-D electromagnetic solver. Path loss parameters and time-domain channel characteristics are extracted from the measurement and simulation data. A semi-empirical path loss model is presented for an antenna height above the body of 5 mm and antenna separations from 5 cm up to 40 cm. A time-domain analysis is performed and models are presented for the mean excess delay and the delay spread. As a cross-layer application, the proposed path loss models are used to evaluate the energy efficiency of single-hop and multihop network topologies. PMID:19789118

  14. Revisiting Controlled Quantum Secure Direct Communication Using a Non-symmetric Quantum Channel with Quantum Superdense Coding

    International Nuclear Information System (INIS)

    Recently Xia and Song [Phys. Lett. A 364 (2007) 117] have proposed a controlled quantum secure direct communication (CQSDC) protocol. They claimed that in their protocol only with the help of the controller Charlie, the receiver Alice can successfully extract the secret message from the sender Bob. In this letter, first we will show that within their protocol the controller Charlie's role could have been excluded if it were not for their unreasonable design. We then revise the Xia-Song CQSDC protocol such that its original advantages are retained and the CQSDC can be really realized

  15. Power Line Communications over Power Distribution Networks of Microprocessors - Feasibility Study, Channel Modeling, and a Circuit Design Approach

    OpenAIRE

    Thirugnanam, Rajesh

    2008-01-01

    Power line communications (PLC) has been considered by utility companies for over a half century and for home networking in recent years. However, PLC at the IC level, or even at the PCB level, has not been investigated outside Dr. Haâ s research group. This thesis investigates the feasibility of PLC over power distribution networks (PDNs) of advanced microprocessors. A PDN in an integrated circuit (IC) is ubiquitous as seen by the internal logic, i.e., a power line is accessible to any inte...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. The Performance of a Dual Header Pulse Interval Modulation in the Presence of Artificial Light Interferences in an Indoor Optical Wireless Communications Channel with Wavelet Denoising

    Directory of Open Access Journals (Sweden)

    S. Rajbhandari

    2011-01-01

    Full Text Available Problem statement: Similar to other baseband modulation schemes, the performance of the Dual Header Pulse Interval Modulation (DH-PIM is adversely affected by Artificial Light Interferences (ALI in an indoor Optical Wireless Communications (OWC channel. Approach: The Discrete Wavelet Transform (DWT based denoising is studied for reducing the effect of the ALI. Computer simulation is carried out to demonstrate the effectiveness of the proposed system. The Baseline Wander (BLW affects for a range of bit resolutions is also analyzed. Results: The normalized optical power requirement in the presence of ALI is high in the range of 9-15 dB depending upon the bit resolution. A significant reduction in the optical power penalty is observed with the DWT denoising scheme. Conclusion: The DWT based denoising scheme is effective in reducing the consequence of the ALI. The optical power penalty decreases with an increase in the data rate and the bit resolution, which is due to reduction of the DC values and low frequency spectrum.

  1. 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.

  2. 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...

  3. 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。

  4. 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。

  5. 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

  6. 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.

  7. Conceptual Model for Communication

    OpenAIRE

    Zahra'a Fadel; Ala'a Alsaqa; Sabah Al-Fedaghi

    2009-01-01

    A variety of idealized models of communication systems exist, and all may have something in common. Starting with Shannon’s 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, process...

  8. 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。

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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 ...

  17. 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...

  18. Quantum communication, reference frames, and gauge theory

    International Nuclear Information System (INIS)

    We consider quantum communication in the case that the communicating parties not only do not share a reference frame but use imperfect quantum communication channels, in that each channel applies some fixed but unknown unitary rotation to each qubit. We discuss similarities and differences between reference frames within that quantum communication model and gauge fields in gauge theory. We generalize the concept of refbits and analyze various quantum communication protocols within the communication model

  19. Communication: Determining the structure of the N2Ar van der Waals complex with laser-based channel-selected Coulomb explosion

    International Nuclear Information System (INIS)

    We experimentally reconstructed the structure of the N2Ar van der Waals complex with the technique of laser-based channel-selected Coulomb explosion imaging. The internuclear distance between the N2 center of mass and the Ar atom, i.e., the length of the van der Waals bond, was determined to be 3.88 Å from the two-body explosion channels. The angle between the van der Waals bond and the N2 principal axis was determined to be 90° from the three-body explosion channels. The reconstructed structure was contrasted with our high level ab initio calculations. The agreement demonstrated the potential application of laser-based Coulomb explosion in imaging transient molecular structure, particularly for floppy van der Waals complexes, whose structures remain difficult to be determined by conventional spectroscopic methods

  20. 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...

  1. 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...

  2. 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.

  3. 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...

  4. Complete Quantum Communication with Security

    OpenAIRE

    Mitra, Arindam

    1998-01-01

    The long-standing problem of quantum information processing is to remove the classical channel from quantum communication. Introducing a new information processing technique, it is discussed that both insecure and secure quantum communications are possible without the requirement of classical channel.

  5. 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.

  6. 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.

  7. 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...

  8. 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...

  9. 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.

  10. 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...

  11. 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...

  12. 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.

  13. 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

  14. 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 ...

  15. Quantum communication, reference frames and gauge theory

    OpenAIRE

    van Enk, S. J.

    2006-01-01

    We consider quantum communication in the case that the communicating parties not only do not share a reference frame but use imperfect quantum communication channels, in that each channel applies some fixed but unknown unitary rotation to each qubit. We discuss similarities and differences between reference frames within that quantum communication model and gauge fields in gauge theory. We generalize the concept of refbits and analyze various quantum communication protocols within the communi...

  16. 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

  17. 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 ...

  18. MIMO Wiretap Channels with Arbitrarily Varying Eavesdropper Channel States

    CERN Document Server

    He, Xiang

    2010-01-01

    In this work, a class of information theoretic secrecy problems is addressed where the eavesdropper channel states are completely unknown to the legitimate parties. In particular, MIMO wiretap channel models are considered where the channel of the eavesdropper is arbitrarily varying over time. Assuming that the number of antennas of the eavesdropper is limited, the secrecy rate of the MIMO wiretap channel in the sense of strong secrecy is derived, and shown to match with the converse in secure degrees of freedom. It is proved that there exists a universal coding scheme that secures the confidential message against any sequence of channel states experienced by the eavesdropper. This yields the conclusion that secure communication is possible regardless of the location or channel states of (potentially infinite number of) eavesdroppers. Additionally, it is observed that, the present setting renders the secrecy capacity problems for multi-terminal wiretap-type channels more tractable as compared the case with fu...

  19. The private classical capacity of a partially degradable quantum channel

    International Nuclear Information System (INIS)

    For a partially degradable (PD) channel, the channel output state can be used to simulate the degraded environment state. The quantum capacity of a PD channel has been proven to be additive. Here, we show that the private classical capacity of arbitrary dimensional PD channels is equal to the quantum capacity of the channel, and it also single-letterizes. We prove that higher rates of private classical communication can be achieved over a PD channel in comparison to standard degradable channels. (paper)

  20. 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.

  1. Communicating Quantum Processes

    CERN Document Server

    Gay, S; Gay, Simon; Nagarajan, Rajagopal

    2004-01-01

    We define a language CQP (Communicating Quantum Processes) for modelling systems which combine quantum and classical communication and computation. CQP combines the communication primitives of the pi-calculus with primitives for measurement and transformation of quantum state; in particular, quantum bits (qubits) can be transmitted from process to process along communication channels. CQP has a static type system which classifies channels, distinguishes between quantum and classical data, and controls the use of quantum state. We formally define the syntax, operational semantics and type system of CQP, prove that the semantics preserves typing, and prove that typing guarantees that each qubit is owned by a unique process within a system. We illustrate CQP by defining models of several quantum communication systems, and outline our plans for using CQP as the foundation for formal analysis and verification of combined quantum and classical systems.

  2. 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 ...

  3. 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.

  4. Exclusive quantum channels in quantum networks

    OpenAIRE

    Chen, Xi; Wang, He-Ming; Mu, Liang-Zhu; Fan, Heng

    2014-01-01

    Quantum state can be teleported to a remote site by only local measurement and classical communication if the prior Einstein-Podolsky-Rosen quantum channel is available between the sender and the receiver. Those quantum channels shared by multiple nodes can constitute a quantum network. Yet, studies on the efficiency of quantum communication between nodes of quantum networks remain limited, which differs from classical case in that the quantum channel will be consumed if teleportation is perf...

  5. Restricciones en el canal de comunicación y representación de influencia en situación de toma de decisión Restrictions in the communication channel and influence representation in taking up decisions

    Directory of Open Access Journals (Sweden)

    Jorge R. Vivas

    2001-06-01

    Full Text Available La comunicación mediada por computadora ha tenido un efecto de alto impacto social en la última década. Los efectos psicosociales de la utilización de estos medios tecnológicos en la comunicación humana son observados con creciente interés. Este trabajo reporta las variaciones de la percepción de influencia durante una tarea de toma de decisión colaborativa al modificar las restricciones del canal de comunicación (presencial o mediado por computadora. Se trabajó con cien sujetos repartidos en ambas condiciones de tarea sobre un problema de decisión múltiple. Los análisis muestran una diferencia notable en los aspectos considerados por los individuos para la construcción de la representación de influencia en una y otra modalidad. Estas diferencias son interpretadas como producto de que la magnitud de la presencia social esta modulada por las restricciones inherentes al canal mediador, dificultando y hasta impidiendo, la percepción de los mecanismos de influencia social que permiten la construcción de una representación de influencia ajustada a los efectivos intercambios realizados en torno al producto generado colaborativamente.Computer mediated communication had a high social impact in the last decade. The psychosocial effects of the use of these technological media on human communication are observed with growing interest. This work reports the differences of influence perception during the collaborative making decision task when varying the communicational channel restrictions (Face To Face or computer mediated. The design included a hundred students in both task conditions on a multiple decision problem. The outcomes show a great differences in how individuals remarks different aspects for the representational construction of the influence in each modality. These results suggest that the amount of social presence is modulated by the channel restrictions, which make it difficult and even constrain, the perception of the

  6. 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.

  7. 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...

  8. 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.

  9. Quantum secure direct communication network with hyperentanglement

    International Nuclear Information System (INIS)

    We propose a quantum secure direct communication protocol with entanglement swapping and hyperentanglement. Any two users, Alice and Bob, can communicate with each other in a quantum network, even though there is no direct quantum channel between them. The trust center, Trent, who provides a quantum channel to link them by performing entanglement swapping, cannot eavesdrop on their communication. This protocol provides a high channel capacity because it uses hyperentanglement, which can be generated using a beta barium borate crystal. (general)

  10. Sequence Selection and Performance in DS/CDMA Systems

    Directory of Open Access Journals (Sweden)

    Jefferson Santos Ambrosio

    2016-03-01

    Full Text Available In this work key concepts on coding division multiple access (CDMA communication systems have been discussed. The sequence selection impact on the performance and capacity of direct sequence CDMA (DS/CDMA systems under AWGN and increasing system loading, as well as under multiple antennas channels was investigated.

  11. Sequence Selection and Performance in DS/CDMA Systems

    OpenAIRE

    Jefferson Santos Ambrosio; Franscisco de Assis Scannavino Junior; Taufik Abrão

    2016-01-01

    In this work key concepts on coding division multiple access (CDMA) communication systems have been discussed. The sequence selection impact on the performance and capacity of direct sequence CDMA (DS/CDMA) systems under AWGN and increasing system loading, as well as under multiple antennas channels was investigated.

  12. 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.

  13. Joint-source-channel coding scheme for scalable video-coding-based digital video broadcasting, second generation satellite broadcasting system

    Science.gov (United States)

    Seo, Kwang-Deok; Chi, Won Sup; Lee, In Ki; Chang, Dae-Ig

    2010-10-01

    We propose a joint-source-channel coding (JSCC) scheme that can provide and sustain high-quality video service in spite of deteriorated transmission channel conditions of the second generation of the digital video broadcasting (DVB-S2) satellite broadcasting service. Especially by combining the layered characteristics of the SVC (scalable video coding) video and the robust channel coding capability of LDPC (low-density parity check) employed for DVB-S2, a new concept of JSCC for digital satellite broadcasting service is developed. Rain attenuation in high-frequency bands such as the Ka band is a major factor for lowering the link capacity in satellite broadcasting service. Therefore, it is necessary to devise a new technology to dynamically manage the rain attenuation by adopting a JSCC scheme that can apply variable code rates for both source and channel coding. For this purpose, we develop a JSCC scheme by combining SVC and LDPC, and prove the performance of the proposed JSCC scheme by extensive simulations where SVC coded video is transmitted over various error-prone channels with AWGN (additive white Gaussian noise) patterns in DVB-S2 broadcasting service.

  14. 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.

  15. 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.

  16. 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

  17. Detecting Lower Bounds to Quantum Channel Capacities

    Science.gov (United States)

    Macchiavello, Chiara; Sacchi, Massimiliano F.

    2016-04-01

    We propose a method to detect lower bounds to quantum capacities of a noisy quantum communication channel by means of a few measurements. The method is easily implementable and does not require any knowledge about the channel. We test its efficiency by studying its performance for most well-known single-qubit noisy channels and for the generalized Pauli channel in an arbitrary finite dimension.

  18. 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

  19. Evaluating the Effectiveness of Your Organization's Communications.

    Science.gov (United States)

    St. John, Walter

    1989-01-01

    Outlines 8 essential components of the communication process and defines 10 categories of questions covered by a communications evaluation instrument, including communications ethics, climate, channels, methods, timing, message content, feedback, information sources, types of information needed, and supervisor-subordinate communication. Provides…

  20. 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

  1. 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.

  2. 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。

  3. 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.

  4. Wiretap Channel with Action-Dependent Channel State Information

    Directory of Open Access Journals (Sweden)

    Bin Dai

    2013-01-01

    Full Text Available In this paper, we investigate the model of wiretap channel with action-dependent channel state information. Given the message to be communicated, the transmitter chooses an action sequence that affects the formation of the channel states, and then generates the channel input sequence based on the state sequence and the message. The main channel and the wiretap channel are two discrete memoryless channels (DMCs, and they are connected with the legitimate receiver and the wiretapper, respectively. Moreover, the transition probability distribution of the main channel depends on the channel state. Measuring wiretapper’s uncertainty about the message by equivocation, inner and outer bounds on the capacity-equivocation region are provided both for the case where the channel inputs are allowed to depend non-causally on the state sequence and the case where they are restricted to causal dependence. Furthermore, the secrecy capacities for both cases are bounded, which provide the best transmission rate with perfect secrecy. The result is further explained via a binary example.

  5. 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...

  6. 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...

  7. Robust Timing Synchronization for Aviation Communications, and Efficient Modulation and Coding Study for Quantum Communication

    Science.gov (United States)

    Xiong, Fugin

    2003-01-01

    One half of Professor Xiong's effort will investigate robust timing synchronization schemes for dynamically varying characteristics of aviation communication channels. The other half of his time will focus on efficient modulation and coding study for the emerging quantum communications.

  8. 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

  9. 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.

  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. 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

  12. Culturally Aware Agent Communication

    DEFF Research Database (Denmark)

    Rehm, Matthias; Nakano, Yukiko; Koda, Tomoko;

    2012-01-01

    Agent based interaction in the form of Embodied Conversational Agents (ECAs) has matured over the last decade and agents have become more and more sophisticated in terms of their verbal and nonverbal behavior like facial expressions or gestures. Having such “natural” communication channels...

  13. Proximity Communication 2

    OpenAIRE

    Massarenti, CA

    2010-01-01

    Proximity Communication involves all access devices used in mobility and requires that contents be designed for specific contexts, both temporal and spatial. Locations based services can be deployed to enhance attention gathering. New marketing methods can be developed by combining different channels and media.

  14. Digital and analog communication systems

    Science.gov (United States)

    Shanmugam, K. S.

    1979-01-01

    The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

  15. Communications: Roots of the problem

    International Nuclear Information System (INIS)

    This paper examines the role of communications in the public and political acceptance of nuclear power programs. The authors demonstrate communication principles that can be useful to any technical sector where there is a need to get facts before the public, the legislators, regulators, and the media. The topics of the paper include an examination of the dimensions of the problem, the nuclear industry's communications shortcomings, a brief chronology of events, communications illustrated, suggestions for a nuclear power public image program, and communication channels

  16. A Novel Uncoded SER/BER Estimation Method

    Directory of Open Access Journals (Sweden)

    Mahesh Patel

    2015-06-01

    Full Text Available Due to the rapidly increasing data speed requirement, it has become essential to smartly utilize the available frequency spectrum. In wireless communications systems, channel quality parameters are often used to enable resource allocation techniques that improve system capacity and user quality. The uncoded bit or symbol error rate (SER is specified as an important parameter in the second and third generation partnership project (3GPP. Nonetheless, techniques to estimate the uncoded SER are usually not much published. This paper introduces a novel uncoded bit error rate (BER estimation method using the accurate-bits sequence of the new channel codes over the AWGN channel. Here, we have used the new channel codes as a forward error correction coding scheme for our communication system. This paper also presents the simulation results to demonstrate and compare the estimation accuracy of the proposed method over the AWGN channel.

  17. Quantum broadcast communication

    Institute of Scientific and Technical Information of China (English)

    Wang Jian; Zhang Quan; Tang Chao-Jing

    2007-01-01

    Broadcast encryption allows the sender to securely distribute his/her secret to a dynamically changing group of users over a broadcast channel. In this paper, we just take account of a simple broadcast communication task in quantum scenario, in which the central party broadcasts his secret to multi-receiver via quantum channel. We present three quantum broadcast communication schemes. The first scheme utilizes entanglement swapping and GreenbergerHorne-Zeilinger state to fulfil a task that the central party broadcasts the secret to a group of receivers who share a group key with him. In the second scheme, based on dense coding, the central party broadcasts the secret to multi-receiver,each of which shares an authentication key with him. The third scheme is a quantum broadcast communication scheme with quantum encryption, in which the central party can broadcast the secret to any subset of the legal receivers.

  18. Communication: I like

    CERN Multimedia

    Staff Association

    2015-01-01

    To fulfill its mission to represent CERN personnel with the Management and the Member States, the Staff Council has set up a series of Commissions: employment conditions, pensions, legal matters, social protection, health and safety, InformAction, CAPA (individual cases) and, more recently, Media-Com. As its name suggests the Media-Com Commission deals with all matters of communication. The mandate of the new Commission is to implement and optimize the communication channels that the Staff Association uses to keep you informed. To attract the greatest number of people, Media-Com operates through multiple communication channels, such as articles in the Echo, the Staff Association information bulletin, the Staff Association website (http://staff- association.web.cern.ch/), Facebook, and, more recently, the intra-CERN Social platform. The Social platform is a discussion forum, for exchanging ideas, expressing views, reacting to, and commenting on current events of the Staff Association. To participa...

  19. 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.

  20. Quantum Entanglement and Communication Complexity

    OpenAIRE

    Buhrman, Harry; Cleve, Richard; Van Dam

    1997-01-01

    We consider a variation of the multi-party communication complexity scenario where the parties are supplied with an extra resource: particles in an entangled quantum state. We show that, although a prior quantum entanglement cannot be used to simulate a communication channel, it can reduce the communication complexity of functions in some cases. Specifically, we show that, for a particular function among three parties (each of which possesses part of the function's input), a prior quantum ent...

  1. 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.

  2. Signal processing for mobile communications handbook

    CERN Document Server

    Ibnkahla, Mohamed

    2004-01-01

    INTRODUCTIONSignal Processing for Future Mobile Communications Systems: Challenges and Perspectives; Quazi Mehbubar Rahman and Mohamed IbnkahlaCHANNEL MODELING AND ESTIMATIONMultipath Propagation Models for Broadband Wireless Systems; Andreas F. Molisch and Fredrik TufvessonModeling and Estimation of Mobile Channels; Jitendra K. TugnaitMobile Satellite Channels: Statistical Models and Performance Analysis; Giovanni E. Corazza, Alessandro Vanelli-Coralli, Raffaella Pedone, and Massimo NeriMobile Velocity Estimation for Wireless Communications; Bouchra Senadji, Ghazem Azemi, and Boualem Boashash

  3. Advanced relay selection schemes for cooperative communications

    OpenAIRE

    Seyfi, Mehdi

    2013-01-01

    It is widely considered that cooperative diversity, in idealized conditions, can provide dramatic performance improvements in capacity and error probability. But non-ideal phenomena, such as fast time variations of the channel, channel estimation errors (CEE), feedback delay (FD) and co-channel interference, degrade the performance of the cooperative communication networks. This thesis studies the impact of these phenomena on advanced relay selection techniques in cooperative communication ne...

  4. 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...

  5. INTELLIGENT WIRELESS COMMUNICATION SYSTEM USING COGNITIVE RADIO

    OpenAIRE

    Asma Amraoui; Badr Benmammar; Fethi Tarik Bendimerad; Francine Krief

    2012-01-01

    The increasing demand for wireless communication introduces efficient spectrum utilization challenge. To address this challenge, cognitive radio (CR) is emerged as the key technology; which enables opportunistic access to the spectrum. CR is a form of wireless communication in which a transceiver can intelligently detect which communication channels are in use and which are not, and instantly move into vacant channels while avoiding occupied ones. This optimizes the use of available ...

  6. 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.

  7. 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

  8. The interaction between digital marketing communication and customer loyalty

    OpenAIRE

    Merisavo, Marko

    2008-01-01

    Digital channels and information technology are changing the way that companies communicate and maintain relationships with their customers. The Internet, email, mobile phones, digital TV, and other evolving channels offer opportunities for frequent, costeffective, personalized, and interactive communication between the company and their customers. In addition to traditional offers and persuasion, customers can be provided with relational communication like newsletters, usage tips, maintenanc...

  9. Principles and Limitations of Ultra-Wideband FM Communications Systems

    Directory of Open Access Journals (Sweden)

    Kouwenhoven Michiel HL

    2005-01-01

    Full Text Available This paper presents a novel UWB communications system using double FM: a low-modulation index digital FSK followed by a high-modulation index analog FM to create a constant-envelope UWB signal. FDMA techniques at the subcarrier level are exploited to accommodate multiple users. The system is intended for low (1–10 kbps and medium (100–1000 kbps bit rate, and short-range WPAN systems. A wideband delay-line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the UWBFM receiver. This unusual approach permits multiple users to share the same RF bandwidth. Multipath, however, may limit the useful subcarrier bandwidth to one octave. This paper addresses the performance with AWGN and multipath, the resistance to narrowband interference, as well as the simultaneous detection of multiple FM signals at the same carrier frequency. SPICE and Matlab simulation results illustrate the principles and limitations of this new technology. A hardware demonstrator has been realized and has allowed the confirmation of theory with practical results.

  10. A father protocol for quantum broadcast channels

    OpenAIRE

    Dupuis, Frédéric; Hayden, Patrick; Li, Ke

    2006-01-01

    A new protocol for quantum broadcast channels based on the fully quantum Slepian-Wolf protocol is presented. 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 communica...

  11. Globalstar communications payload for global mobile communications

    Science.gov (United States)

    Louie, Ming; Monte, Paul; Tyner, Randy; Rouffet, Denis; Gilhousen, Klein S.

    1992-03-01

    The Globalstar LEO satellite-based mobile-communications system is evaluated with respect to its potential for global digital communications and for radio-determination satellite service. The significant novel attributes of the Globalsat payload are examined including code-division multiple-access technologies, beam-hopping and time-domain-duplexing (TDD) capabilities, and six elliptical spot-beam L/S-band antennas. The antennas are designed to address the 'near-far' problem associated with mobile systems through the use of the Isoflux design. The Isoflux beams provide gain contours that compensate for differences in the spacecraft/earth slant range and that provide low spillover illumination. Two candidate payloads are presented - one which incorporates TDD and beam hopping - and found to provide efficient global mobile-communications services for the Globalstar system. A single satellite can provide up to 2800 full-duplex voice channels, and TDD allows uplink and downlink signals to share the same frequency.

  12. Fiber Optic Communications Technology. A Status Report.

    Science.gov (United States)

    Hull, Joseph A.

    Fiber optic communications (communications over very pure glass transmission channels of diameter comparable to a human hair) is an emerging technology which promises most improvements in communications capacity at reasonable cost. The fiber transmission system offers many desirable characteristics representing improvements over conventional…

  13. Early Communication in Dyads with Visual Impairment

    Science.gov (United States)

    Rattray, Julie; Zeedyk, M. Suzanne

    2005-01-01

    The ability of dyads with restricted access to the visual channel of communication to establish a reliable pre-linguistic communicative signalling system has traditionally been viewed as problematic. Such a conclusion is due in part to the emphasis that has been placed on vision as central to communication by traditional theory. The data presented…

  14. Planning to Communicate: A Budget Companion

    Science.gov (United States)

    Dereef, Marvin

    2011-01-01

    Failing to have a plan to communicate with stakeholders during the budget process is a plan to fail. Without community support, getting budget approval can be difficult. Thus, school business officials must have a plan to ensure the appropriate budget message is conveyed throughout all communication channels. In fact, a communication plan is the…

  15. A Formulation of the Potential for Communication Condition using C2KA

    OpenAIRE

    Jaskolka, Jason; Khedri, Ridha

    2014-01-01

    An integral part of safeguarding systems of communicating agents from covert channel communication is having the ability to identify when a covert channel may exist in a given system and which agents are more prone to covert channels than others. In this paper, we propose a formulation of one of the necessary conditions for the existence of covert channels: the potential for communication condition. Then, we discuss when the potential for communication is preserved after the modification of s...

  16. Coherent communication with continuous quantum variables

    International Nuclear Information System (INIS)

    The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding

  17. Coherent Communication with Continuous Quantum Variables

    OpenAIRE

    Wilde, Mark M.; Krovi, Hari; Brun, Todd A.

    2006-01-01

    The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through su...

  18. Reachability problems for communicating finite state machines

    OpenAIRE

    Pachl, Jan

    2003-01-01

    The paper deals with the verification of reachability properties in a commonly used state transition model of communication protocols, which consists of finite state machines connected by potentially unbounded FIFO channels. Although simple reachability problems are undecidable for general protocols with unbounded channels, they are decidable for the protocols with the recognizable channel property. The decidability question is open for the protocols with the rational channel property.

  19. The Correlation Conversion Property of Quantum Channels

    OpenAIRE

    Gyongyosi, Laszlo

    2013-01-01

    Transmission of quantum entanglement will play a crucial role in future networks and long-distance quantum communications. Quantum Key Distribution, the working mechanism of quantum repeaters and the various quantum communication protocols are all based on quantum entanglement. On the other hand, quantum entanglement is extremely fragile and sensitive to the noise of the communication channel over which it has been transmitted. To share entanglement between distant points, high fidelity quant...

  20. Wireless communications algorithmic techniques

    CERN Document Server

    Vitetta, Giorgio; Colavolpe, Giulio; Pancaldi, Fabrizio; Martin, Philippa A

    2013-01-01

    This book introduces the theoretical elements at the basis of various classes of algorithms commonly employed in the physical layer (and, in part, in MAC layer) of wireless communications systems. It focuses on single user systems, so ignoring multiple access techniques. Moreover, emphasis is put on single-input single-output (SISO) systems, although some relevant topics about multiple-input multiple-output (MIMO) systems are also illustrated.Comprehensive wireless specific guide to algorithmic techniquesProvides a detailed analysis of channel equalization and channel coding for wi