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Sample records for bit-error rate ber

  1. The sensitivity of bit error rate (BER) performance in multi-carrier (OFDM) and single-carrier

    Science.gov (United States)

    Albdran, Saleh; Alshammari, Ahmed; Matin, Mohammad

    2012-10-01

    Recently, the single-carrier and multi-carrier transmissions have grabbed the attention of industrial systems. Theoretically, OFDM as a Multicarrier has more advantages over the Single-Carrier especially for high data rate. In this paper we will show which one of the two techniques outperforms the other. We will study and compare the performance of BER for both techniques for a given channel. As a function of signal to noise ratio SNR, the BER will be measure and studied. Also, Peak-to-Average Power Ratio (PAPR) is going to be examined and presented as a drawback of using OFDM. To make a reasonable comparison between the both techniques, we will use additive white Gaussian noise (AWGN) as a communication channel.

  2. Bit Error Rate Minimizing Channel Shortening Equalizers for Single Carrier Cyclic Prefixed Systems

    National Research Council Canada - National Science Library

    Martin, Richard K; Vanbleu, Koen; Ysebaert, Geert

    2007-01-01

    .... Previous work on channel shortening has largely been in the context of digital subscriber lines, a wireline system that allows bit allocation, thus it has focused on maximizing the bit rate for a given bit error rate (BER...

  3. A Fast Soft Bit Error Rate Estimation Method

    Directory of Open Access Journals (Sweden)

    Ait-Idir Tarik

    2010-01-01

    Full Text Available We have suggested in a previous publication a method to estimate the Bit Error Rate (BER of a digital communications system instead of using the famous Monte Carlo (MC simulation. This method was based on the estimation of the probability density function (pdf of soft observed samples. The kernel method was used for the pdf estimation. In this paper, we suggest to use a Gaussian Mixture (GM model. The Expectation Maximisation algorithm is used to estimate the parameters of this mixture. The optimal number of Gaussians is computed by using Mutual Information Theory. The analytical expression of the BER is therefore simply given by using the different estimated parameters of the Gaussian Mixture. Simulation results are presented to compare the three mentioned methods: Monte Carlo, Kernel and Gaussian Mixture. We analyze the performance of the proposed BER estimator in the framework of a multiuser code division multiple access system and show that attractive performance is achieved compared with conventional MC or Kernel aided techniques. The results show that the GM method can drastically reduce the needed number of samples to estimate the BER in order to reduce the required simulation run-time, even at very low BER.

  4. FPGA-based Bit-Error-Rate Tester for SEU-hardened Optical Links

    CERN Document Server

    Detraz, S; Moreira, P; Papadopoulos, S; Papakonstantinou, I; Seif El Nasr, S; Sigaud, C; Soos, C; Stejskal, P; Troska, J; Versmissen, H

    2009-01-01

    The next generation of optical links for future High-Energy Physics experiments will require components qualified for use in radiation-hard environments. To cope with radiation induced single-event upsets, the physical layer protocol will include Forward Error Correction (FEC). Bit-Error-Rate (BER) testing is a widely used method to characterize digital transmission systems. In order to measure the BER with and without the proposed FEC, simultaneously on several devices, a multi-channel BER tester has been developed. This paper describes the architecture of the tester, its implementation in a Xilinx Virtex-5 FPGA device and discusses the experimental results.

  5. A minimum bit error-rate detector for amplify and forward relaying systems

    KAUST Repository

    Ahmed, Qasim Zeeshan; Alouini, Mohamed-Slim; Aissa, Sonia

    2012-01-01

    In this paper, a new detector is being proposed for amplify-and-forward (AF) relaying system when communicating with the assistance of L number of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the system. The complexity of the system is further reduced by implementing this detector adaptively. The proposed detector is free from channel estimation. Our results demonstrate that the proposed detector is capable of achieving a gain of more than 1-dB at a BER of 10 -5 as compared to the conventional minimum mean square error detector when communicating over a correlated Rayleigh fading channel. © 2012 IEEE.

  6. A minimum bit error-rate detector for amplify and forward relaying systems

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2012-05-01

    In this paper, a new detector is being proposed for amplify-and-forward (AF) relaying system when communicating with the assistance of L number of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the system. The complexity of the system is further reduced by implementing this detector adaptively. The proposed detector is free from channel estimation. Our results demonstrate that the proposed detector is capable of achieving a gain of more than 1-dB at a BER of 10 -5 as compared to the conventional minimum mean square error detector when communicating over a correlated Rayleigh fading channel. © 2012 IEEE.

  7. Modeling of Bit Error Rate in Cascaded 2R Regenerators

    DEFF Research Database (Denmark)

    Öhman, Filip; Mørk, Jesper

    2006-01-01

    and the regenerating nonlinearity is investigated. It is shown that an increase in nonlinearity can compensate for an increase in noise figure or decrease in signal power. Furthermore, the influence of the improvement in signal extinction ratio along the cascade and the importance of choosing the proper threshold......This paper presents a simple and efficient model for estimating the bit error rate in a cascade of optical 2R-regenerators. The model includes the influences of of amplifier noise, finite extinction ratio and nonlinear reshaping. The interplay between the different signal impairments...

  8. Bit error rate testing of fiber optic data links for MMIC-based phased array antennas

    Science.gov (United States)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-01-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  9. Comparison of Bit Error Rate of Line Codes in NG-PON2

    Directory of Open Access Journals (Sweden)

    Tomas Horvath

    2016-05-01

    Full Text Available This article focuses on simulation and comparison of line codes NRZ (Non Return to Zero, RZ (Return to Zero and Miller’s code for NG-PON2 (Next-Generation Passive Optical Network Stage 2 using. Our article provides solutions with Q-factor, BER (Bit Error Rate, and bandwidth comparison. Line codes are the most important part of communication over the optical fibre. The main role of these codes is digital signal representation. NG-PON2 networks use optical fibres for communication that is the reason why OptSim v5.2 is used for simulation.

  10. Inclusive bit error rate analysis for coherent optical code-division multiple-access system

    Science.gov (United States)

    Katz, Gilad; Sadot, Dan

    2002-06-01

    Inclusive noise and bit error rate (BER) analysis for optical code-division multiplexing (OCDM) using coherence techniques is presented. The analysis contains crosstalk calculation of the mutual field variance for different number of users. It is shown that the crosstalk noise depends deeply on the receiver integration time, the laser coherence time, and the number of users. In addition, analytical results of the power fluctuation at the received channel due to the data modulation at the rejected channels are presented. The analysis also includes amplified spontaneous emission (ASE)-related noise effects of in-line amplifiers in a long-distance communication link.

  11. Linear transceiver design for nonorthogonal amplify-and-forward protocol using a bit error rate criterion

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2014-04-01

    The ever growing demand of higher data rates can now be addressed by exploiting cooperative diversity. This form of diversity has become a fundamental technique for achieving spatial diversity by exploiting the presence of idle users in the network. This has led to new challenges in terms of designing new protocols and detectors for cooperative communications. Among various amplify-and-forward (AF) protocols, the half duplex non-orthogonal amplify-and-forward (NAF) protocol is superior to other AF schemes in terms of error performance and capacity. However, this superiority is achieved at the cost of higher receiver complexity. Furthermore, in order to exploit the full diversity of the system an optimal precoder is required. In this paper, an optimal joint linear transceiver is proposed for the NAF protocol. This transceiver operates on the principles of minimum bit error rate (BER), and is referred as joint bit error rate (JBER) detector. The BER performance of JBER detector is superior to all the proposed linear detectors such as channel inversion, the maximal ratio combining, the biased maximum likelihood detectors, and the minimum mean square error. The proposed transceiver also outperforms previous precoders designed for the NAF protocol. © 2002-2012 IEEE.

  12. Bit Error Rate Analysis for MC-CDMA Systems in Nakagami- Fading Channels

    Directory of Open Access Journals (Sweden)

    Li Zexian

    2004-01-01

    Full Text Available Multicarrier code division multiple access (MC-CDMA is a promising technique that combines orthogonal frequency division multiplexing (OFDM with CDMA. In this paper, based on an alternative expression for the -function, characteristic function and Gaussian approximation, we present a new practical technique for determining the bit error rate (BER of multiuser MC-CDMA systems in frequency-selective Nakagami- fading channels. The results are applicable to systems employing coherent demodulation with maximal ratio combining (MRC or equal gain combining (EGC. The analysis assumes that different subcarriers experience independent fading channels, which are not necessarily identically distributed. The final average BER is expressed in the form of a single finite range integral and an integrand composed of tabulated functions which can be easily computed numerically. The accuracy of the proposed approach is demonstrated with computer simulations.

  13. Performance analysis for the bit-error rate of SAC-OCDMA systems

    Science.gov (United States)

    Feng, Gang; Cheng, Wenqing; Chen, Fujun

    2015-09-01

    Under low power, Gaussian statistics by invoking the central limit theorem is feasible to predict the upper bound in the spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system. However, this case severely underestimates the bit-error rate (BER) performance of the system under high power assumption. Fortunately, the exact negative binomial (NB) model is a perfect replacement for the Gaussian model in the prediction and evaluation. Based on NB statistics, a more accurate closed-form expression is analyzed and derived for the SAC-OCDMA system. The experiment shows that the obtained expression provides a more precise prediction of the BER performance under the low and high power assumptions.

  14. Power penalties for multi-level PAM modulation formats at arbitrary bit error rates

    Science.gov (United States)

    Kaliteevskiy, Nikolay A.; Wood, William A.; Downie, John D.; Hurley, Jason; Sterlingov, Petr

    2016-03-01

    There is considerable interest in combining multi-level pulsed amplitude modulation formats (PAM-L) and forward error correction (FEC) in next-generation, short-range optical communications links for increased capacity. In this paper we derive new formulas for the optical power penalties due to modulation format complexity relative to PAM-2 and due to inter-symbol interference (ISI). We show that these penalties depend on the required system bit-error rate (BER) and that the conventional formulas overestimate link penalties. Our corrections to the standard formulas are very small at conventional BER levels (typically 1×10-12) but become significant at the higher BER levels enabled by FEC technology, especially for signal distortions due to ISI. The standard formula for format complexity, P = 10log(L-1), is shown to overestimate the actual penalty for PAM-4 and PAM-8 by approximately 0.1 and 0.25 dB respectively at 1×10-3 BER. Then we extend the well-known PAM-2 ISI penalty estimation formula from the IEEE 802.3 standard 10G link modeling spreadsheet to the large BER case and generalize it for arbitrary PAM-L formats. To demonstrate and verify the BER dependence of the ISI penalty, a set of PAM-2 experiments and Monte-Carlo modeling simulations are reported. The experimental results and simulations confirm that the conventional formulas can significantly overestimate ISI penalties at relatively high BER levels. In the experiments, overestimates up to 2 dB are observed at 1×10-3 BER.

  15. Symbol and Bit Error Rates Analysis of Hybrid PIM-CDMA

    Directory of Open Access Journals (Sweden)

    Ghassemlooy Z

    2005-01-01

    Full Text Available A hybrid pulse interval modulation code-division multiple-access (hPIM-CDMA scheme employing the strict optical orthogonal code (SOCC with unity and auto- and cross-correlation constraints for indoor optical wireless communications is proposed. In this paper, we analyse the symbol error rate (SER and bit error rate (BER of hPIM-CDMA. In the analysis, we consider multiple access interference (MAI, self-interference, and the hybrid nature of the hPIM-CDMA signal detection, which is based on the matched filter (MF. It is shown that the BER/SER performance can only be evaluated if the bit resolution conforms to the condition set by the number of consecutive false alarm pulses that might occur and be detected, so that one symbol being divided into two is unlikely to occur. Otherwise, the probability of SER and BER becomes extremely high and indeterminable. We show that for a large number of users, the BER improves when increasing the code weight . The results presented are compared with other modulation schemes.

  16. Time Domain Equalizer Design Using Bit Error Rate Minimization for UWB Systems

    Directory of Open Access Journals (Sweden)

    Syed Imtiaz Husain

    2009-01-01

    Full Text Available Ultra-wideband (UWB communication systems occupy huge bandwidths with very low power spectral densities. This feature makes the UWB channels highly rich in resolvable multipaths. To exploit the temporal diversity, the receiver is commonly implemented through a Rake. The aim to capture enough signal energy to maintain an acceptable output signal-to-noise ratio (SNR dictates a very complicated Rake structure with a large number of fingers. Channel shortening or time domain equalizer (TEQ can simplify the Rake receiver design by reducing the number of significant taps in the effective channel. In this paper, we first derive the bit error rate (BER of a multiuser and multipath UWB system in the presence of a TEQ at the receiver front end. This BER is then written in a form suitable for traditional optimization. We then present a TEQ design which minimizes the BER of the system to perform efficient channel shortening. The performance of the proposed algorithm is compared with some generic TEQ designs and other Rake structures in UWB channels. It is shown that the proposed algorithm maintains a lower BER along with efficiently shortening the channel.

  17. Two-dimensional optoelectronic interconnect-processor and its operational bit error rate

    Science.gov (United States)

    Liu, J. Jiang; Gollsneider, Brian; Chang, Wayne H.; Carhart, Gary W.; Vorontsov, Mikhail A.; Simonis, George J.; Shoop, Barry L.

    2004-10-01

    Two-dimensional (2-D) multi-channel 8x8 optical interconnect and processor system were designed and developed using complementary metal-oxide-semiconductor (CMOS) driven 850-nm vertical-cavity surface-emitting laser (VCSEL) arrays and the photodetector (PD) arrays with corresponding wavelengths. We performed operation and bit-error-rate (BER) analysis on this free-space integrated 8x8 VCSEL optical interconnects driven by silicon-on-sapphire (SOS) circuits. Pseudo-random bit stream (PRBS) data sequence was used in operation of the interconnects. Eye diagrams were measured from individual channels and analyzed using a digital oscilloscope at data rates from 155 Mb/s to 1.5 Gb/s. Using a statistical model of Gaussian distribution for the random noise in the transmission, we developed a method to compute the BER instantaneously with the digital eye-diagrams. Direct measurements on this interconnects were also taken on a standard BER tester for verification. We found that the results of two methods were in the same order and within 50% accuracy. The integrated interconnects were investigated in an optoelectronic processing architecture of digital halftoning image processor. Error diffusion networks implemented by the inherently parallel nature of photonics promise to provide high quality digital halftoned images.

  18. PERBANDINGAN BIT ERROR RATE KODE REED-SOLOMON DENGAN KODE BOSE-CHAUDHURI-HOCQUENGHEM MENGGUNAKAN MODULASI 32-FSK

    Directory of Open Access Journals (Sweden)

    Eva Yovita Dwi Utami

    2016-11-01

    Full Text Available Kode Reed-Solomon (RS dan kode Bose-Chaudhuri-Hocquenghem (BCH merupakan kode pengoreksi error yang termasuk dalam jenis kode blok siklis. Kode pengoreksi error diperlukan pada sistem komunikasi untuk memperkecil error pada informasi yang dikirimkan. Dalam makalah ini, disajikan hasil penelitian kinerja BER sistem komunikasi yang menggunakan kode RS, kode BCH, dan sistem yang tidak menggunakan kode RS dan kode BCH, menggunakan modulasi 32-FSK pada kanal Additive White Gaussian Noise (AWGN, Rayleigh dan Rician. Kemampuan memperkecil error diukur menggunakan nilai Bit Error Rate (BER yang dihasilkan. Hasil penelitian menunjukkan bahwa kode RS seiring dengan penambahan nilai SNR, menurunkan nilai BER yang lebih curam bila dibandingkan sistem dengan kode BCH. Sedangkan kode BCH memberikan keunggulan saat SNR bernilai kecil, memiliki BER lebih baik daripada sistem dengan kode RS.

  19. Student laboratory experiments exploring optical fibre communication systems, eye diagrams, and bit error rates

    Science.gov (United States)

    Walsh, Douglas; Moodie, David; Mauchline, Iain; Conner, Steve; Johnstone, Walter; Culshaw, Brian

    2005-06-01

    Optical fibre communications has proved to be one of the key application areas, which created, and ultimately propelled the global growth of the photonics industry over the last twenty years. Consequently the teaching of the principles of optical fibre communications has become integral to many university courses covering photonics technology. However to reinforce the fundamental principles and key technical issues students examine in their lecture courses and to develop their experimental skills, it is critical that the students also obtain hands-on practical experience of photonics components, instruments and systems in an associated teaching laboratory. In recognition of this need OptoSci, in collaboration with university academics, commercially developed a fibre optic communications based educational package (ED-COM). This educator kit enables students to; investigate the characteristics of the individual communications system components (sources, transmitters, fibre, receiver), examine and interpret the overall system performance limitations imposed by attenuation and dispersion, conduct system design and performance analysis. To further enhance the experimental programme examined in the fibre optic communications kit, an extension module to ED-COM has recently been introduced examining one of the most significant performance parameters of digital communications systems, the bit error rate (BER). This add-on module, BER(COM), enables students to generate, evaluate and investigate signal quality trends by examining eye patterns, and explore the bit-rate limitations imposed on communication systems by noise, attenuation and dispersion. This paper will examine the educational objectives, background theory, and typical results for these educator kits, with particular emphasis on BER(COM).

  20. Bit-error-rate performance analysis of self-heterodyne detected radio-over-fiber links using phase and intensity modulation

    DEFF Research Database (Denmark)

    Yin, Xiaoli; Yu, Xianbin; Tafur Monroy, Idelfonso

    2010-01-01

    We theoretically and experimentally investigate the performance of two self-heterodyne detected radio-over-fiber (RoF) links employing phase modulation (PM) and quadrature biased intensity modulation (IM), in term of bit-error-rate (BER) and optical signal-to-noise-ratio (OSNR). In both links, self...

  1. Bit-error-rate testing of fiber optic data links for MMIC-based phased array antennas

    Science.gov (United States)

    Shalkhauser, K. A.; Kunath, R. R.; Daryoush, A. S.

    1990-01-01

    The measured bit-error-rate (BER) performance of a fiber optic data link to be used in satellite communications systems is presented and discussed. In the testing, the link was measured for its ability to carry high burst rate, serial-minimum shift keyed (SMSK) digital data similar to those used in actual space communications systems. The fiber optic data link, as part of a dual-segment injection-locked RF fiber optic link system, offers a means to distribute these signals to the many radiating elements of a phased array antenna. Test procedures, experimental arrangements, and test results are presented.

  2. Bit error rate analysis of free-space optical communication over general Malaga turbulence channels with pointing error

    KAUST Repository

    Alheadary, Wael Ghazy

    2016-12-24

    In this work, we present a bit error rate (BER) and achievable spectral efficiency (ASE) performance of a freespace optical (FSO) link with pointing errors based on intensity modulation/direct detection (IM/DD) and heterodyne detection over general Malaga turbulence channel. More specifically, we present exact closed-form expressions for adaptive and non-adaptive transmission. The closed form expressions are presented in terms of generalized power series of the Meijer\\'s G-function. Moreover, asymptotic closed form expressions are provided to validate our work. In addition, all the presented analytical results are illustrated using a selected set of numerical results.

  3. Invariance of the bit error rate in the ancilla-assisted homodyne detection

    International Nuclear Information System (INIS)

    Yoshida, Yuhsuke; Takeoka, Masahiro; Sasaki, Masahide

    2010-01-01

    We investigate the minimum achievable bit error rate of the discrimination of binary coherent states with the help of arbitrary ancillary states. We adopt homodyne measurement with a common phase of the local oscillator and classical feedforward control. After one ancillary state is measured, its outcome is referred to the preparation of the next ancillary state and the tuning of the next mixing with the signal. It is shown that the minimum bit error rate of the system is invariant under the following operations: feedforward control, deformations, and introduction of any ancillary state. We also discuss the possible generalization of the homodyne detection scheme.

  4. Analytical expression for the bit error rate of cascaded all-optical regenerators

    DEFF Research Database (Denmark)

    Mørk, Jesper; Öhman, Filip; Bischoff, S.

    2003-01-01

    We derive an approximate analytical expression for the bit error rate of cascaded fiber links containing all-optical 2R-regenerators. A general analysis of the interplay between noise due to amplification and the degree of reshaping (nonlinearity) of the regenerator is performed.......We derive an approximate analytical expression for the bit error rate of cascaded fiber links containing all-optical 2R-regenerators. A general analysis of the interplay between noise due to amplification and the degree of reshaping (nonlinearity) of the regenerator is performed....

  5. Framed bit error rate testing for 100G ethernet equipment

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Ruepp, Sarah Renée; Berger, Michael Stübert

    2010-01-01

    rate. As the need for 100 Gigabit Ethernet equipment rises, so does the need for equipment, which can properly test these systems during development, deployment and use. This paper presents early results from a work-in-progress academia-industry collaboration project and elaborates on the challenges...

  6. Bit Error-Rate Minimizing Detector for Amplify-and-Forward Relaying Systems Using Generalized Gaussian Kernel

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2013-01-01

    In this letter, a new detector is proposed for amplifyand- forward (AF) relaying system when communicating with the assistance of relays. The major goal of this detector is to improve the bit error rate (BER) performance of the receiver. The probability density function is estimated with the help of kernel density technique. A generalized Gaussian kernel is proposed. This new kernel provides more flexibility and encompasses Gaussian and uniform kernels as special cases. The optimal window width of the kernel is calculated. Simulations results show that a gain of more than 1 dB can be achieved in terms of BER performance as compared to the minimum mean square error (MMSE) receiver when communicating over Rayleigh fading channels.

  7. Novel relations between the ergodic capacity and the average bit error rate

    KAUST Repository

    Yilmaz, Ferkan

    2011-11-01

    Ergodic capacity and average bit error rate have been widely used to compare the performance of different wireless communication systems. As such recent scientific research and studies revealed strong impact of designing and implementing wireless technologies based on these two performance indicators. However and to the best of our knowledge, the direct links between these two performance indicators have not been explicitly proposed in the literature so far. In this paper, we propose novel relations between the ergodic capacity and the average bit error rate of an overall communication system using binary modulation schemes for signaling with a limited bandwidth and operating over generalized fading channels. More specifically, we show that these two performance measures can be represented in terms of each other, without the need to know the exact end-to-end statistical characterization of the communication channel. We validate the correctness and accuracy of our newly proposed relations and illustrated their usefulness by considering some classical examples. © 2011 IEEE.

  8. Accurate Bit Error Rate Calculation for Asynchronous Chaos-Based DS-CDMA over Multipath Channel

    Science.gov (United States)

    Kaddoum, Georges; Roviras, Daniel; Chargé, Pascal; Fournier-Prunaret, Daniele

    2009-12-01

    An accurate approach to compute the bit error rate expression for multiuser chaosbased DS-CDMA system is presented in this paper. For more realistic communication system a slow fading multipath channel is considered. A simple RAKE receiver structure is considered. Based on the bit energy distribution, this approach compared to others computation methods existing in literature gives accurate results with low computation charge. Perfect estimation of the channel coefficients with the associated delays and chaos synchronization is assumed. The bit error rate is derived in terms of the bit energy distribution, the number of paths, the noise variance, and the number of users. Results are illustrated by theoretical calculations and numerical simulations which point out the accuracy of our approach.

  9. Performance Analysis for Bit Error Rate of DS- CDMA Sensor Network Systems with Source Coding

    Directory of Open Access Journals (Sweden)

    Haider M. AlSabbagh

    2012-03-01

    Full Text Available The minimum energy (ME coding combined with DS-CDMA wireless sensor network is analyzed in order to reduce energy consumed and multiple access interference (MAI with related to number of user(receiver. Also, the minimum energy coding which exploits redundant bits for saving power with utilizing RF link and On-Off-Keying modulation. The relations are presented and discussed for several levels of errors expected in the employed channel via amount of bit error rates and amount of the SNR for number of users (receivers.

  10. Correct mutual information, quantum bit error rate and secure transmission efficiency in Wojcik's eavesdropping scheme on ping-pong protocol

    OpenAIRE

    Zhang, Zhanjun

    2004-01-01

    Comment: The wrong mutual information, quantum bit error rate and secure transmission efficiency in Wojcik's eavesdropping scheme [PRL90(03)157901]on ping-pong protocol have been pointed out and corrected

  11. Bit Error Rate Performance of a MIMO-CDMA System Employing Parity-Bit-Selected Spreading in Frequency Nonselective Rayleigh Fading

    Directory of Open Access Journals (Sweden)

    Claude D'Amours

    2011-01-01

    Full Text Available We analytically derive the upper bound for the bit error rate (BER performance of a single user multiple input multiple output code division multiple access (MIMO-CDMA system employing parity-bit-selected spreading in slowly varying, flat Rayleigh fading. The analysis is done for spatially uncorrelated links. The analysis presented demonstrates that parity-bit-selected spreading provides an asymptotic gain of 10log(Nt dB over conventional MIMO-CDMA when the receiver has perfect channel estimates. This analytical result concurs with previous works where the (BER is determined by simulation methods and provides insight into why the different techniques provide improvement over conventional MIMO-CDMA systems.

  12. Analyzing the propagation behavior of scintillation index and bit error rate of a partially coherent flat-topped laser beam in oceanic turbulence.

    Science.gov (United States)

    Yousefi, Masoud; Golmohammady, Shole; Mashal, Ahmad; Kashani, Fatemeh Dabbagh

    2015-11-01

    In this paper, on the basis of the extended Huygens-Fresnel principle, a semianalytical expression for describing on-axis scintillation index of a partially coherent flat-topped (PCFT) laser beam of weak to moderate oceanic turbulence is derived; consequently, by using the log-normal intensity probability density function, the bit error rate (BER) is evaluated. The effects of source factors (such as wavelength, order of flatness, and beam width) and turbulent ocean parameters (such as Kolmogorov microscale, relative strengths of temperature and salinity fluctuations, rate of dissipation of the mean squared temperature, and rate of dissipation of the turbulent kinetic energy per unit mass of fluid) on propagation behavior of scintillation index, and, hence, on BER, are studied in detail. Results indicate that, in comparison with a Gaussian beam, a PCFT laser beam with a higher order of flatness is found to have lower scintillations. In addition, the scintillation index and BER are most affected when salinity fluctuations in the ocean dominate temperature fluctuations.

  13. Capacity Versus Bit Error Rate Trade-Off in the DVB-S2 Forward Link

    Directory of Open Access Journals (Sweden)

    Berioli Matteo

    2007-01-01

    Full Text Available The paper presents an approach to optimize the use of satellite capacity in DVB-S2 forward links. By reducing the so-called safety margins, in the adaptive coding and modulation technique, it is possible to increase the spectral efficiency at expenses of an increased BER on the transmission. The work shows how a system can be tuned to operate at different degrees of this trade-off, and also the performance which can be achieved in terms of BER/PER, spectral efficiency, and interarrival, duration, strength of the error bursts. The paper also describes how a Markov chain can be used to model the ModCod transitions in a DVB-S2 system, and it presents results for the calculation of the transition probabilities in two cases.

  14. Capacity Versus Bit Error Rate Trade-Off in the DVB-S2 Forward Link

    Directory of Open Access Journals (Sweden)

    Matteo Berioli

    2007-05-01

    Full Text Available The paper presents an approach to optimize the use of satellite capacity in DVB-S2 forward links. By reducing the so-called safety margins, in the adaptive coding and modulation technique, it is possible to increase the spectral efficiency at expenses of an increased BER on the transmission. The work shows how a system can be tuned to operate at different degrees of this trade-off, and also the performance which can be achieved in terms of BER/PER, spectral efficiency, and interarrival, duration, strength of the error bursts. The paper also describes how a Markov chain can be used to model the ModCod transitions in a DVB-S2 system, and it presents results for the calculation of the transition probabilities in two cases.

  15. Scintillation and bit error rate analysis of a phase-locked partially coherent flat-topped array laser beam in oceanic turbulence.

    Science.gov (United States)

    Yousefi, Masoud; Kashani, Fatemeh Dabbagh; Golmohammady, Shole; Mashal, Ahmad

    2017-12-01

    In this paper, the performance of underwater wireless optical communication (UWOC) links, which is made up of the partially coherent flat-topped (PCFT) array laser beam, has been investigated in detail. Providing high power, array laser beams are employed to increase the range of UWOC links. For characterization of the effects of oceanic turbulence on the propagation behavior of the considered beam, using the extended Huygens-Fresnel principle, an analytical expression for cross-spectral density matrix elements and a semi-analytical one for fourth-order statistical moment have been derived. Then, based on these expressions, the on-axis scintillation index of the mentioned beam propagating through weak oceanic turbulence has been calculated. Furthermore, in order to quantify the performance of the UWOC link, the average bit error rate (BER) has also been evaluated. The effects of some source factors and turbulent ocean parameters on the propagation behavior of the scintillation index and the BER have been studied in detail. The results of this investigation indicate that in comparison with the Gaussian array beam, when the source size of beamlets is larger than the first Fresnel zone, the PCFT array laser beam with the higher flatness order is found to have a lower scintillation index and hence lower BER. Specifically, in the sense of scintillation index reduction, using the PCFT array laser beams has a considerable benefit in comparison with the single PCFT or Gaussian laser beams and also Gaussian array beams. All the simulation results of this paper have been shown by graphs and they have been analyzed in detail.

  16. Practical scheme to share a secret key through a quantum channel with a 27.6% bit error rate

    International Nuclear Information System (INIS)

    Chau, H.F.

    2002-01-01

    A secret key shared through quantum key distribution between two cooperative players is secure against any eavesdropping attack allowed by the laws of physics. Yet, such a key can be established only when the quantum channel error rate due to eavesdropping or imperfect apparatus is low. Here, a practical quantum key distribution scheme by making use of an adaptive privacy amplification procedure with two-way classical communication is reported. Then, it is proven that the scheme generates a secret key whenever the bit error rate of the quantum channel is less than 0.5-0.1√(5)≅27.6%, thereby making it the most error resistant scheme known to date

  17. Linear transceiver design for nonorthogonal amplify-and-forward protocol using a bit error rate criterion

    KAUST Repository

    Ahmed, Qasim Zeeshan; Park, Kihong; Alouini, Mohamed-Slim; Aï ssa, Sonia

    2014-01-01

    The ever growing demand of higher data rates can now be addressed by exploiting cooperative diversity. This form of diversity has become a fundamental technique for achieving spatial diversity by exploiting the presence of idle users in the network

  18. Bit Error Rate Performance Analysis of a Threshold-Based Generalized Selection Combining Scheme in Nakagami Fading Channels

    Directory of Open Access Journals (Sweden)

    Kousa Maan

    2005-01-01

    Full Text Available The severity of fading on mobile communication channels calls for the combining of multiple diversity sources to achieve acceptable error rate performance. Traditional approaches perform the combining of the different diversity sources using either the conventional selective diversity combining (CSC, equal-gain combining (EGC, or maximal-ratio combining (MRC schemes. CSC and MRC are the two extremes of compromise between performance quality and complexity. Some researches have proposed a generalized selection combining scheme (GSC that combines the best branches out of the available diversity resources ( . In this paper, we analyze a generalized selection combining scheme based on a threshold criterion rather than a fixed-size subset of the best channels. In this scheme, only those diversity branches whose energy levels are above a specified threshold are combined. Closed-form analytical solutions for the BER performances of this scheme over Nakagami fading channels are derived. We also discuss the merits of this scheme over GSC.

  19. Latency and bit-error-rate evaluation for radio-over-ethernet in optical fiber front-haul networks

    DEFF Research Database (Denmark)

    Sayadi, Mohammadjavad; Rodríguez, Sebastián; Olmos, Juan José Vegas

    2018-01-01

    evaluate this Ethernet packet as a case of study for RoE applications. The packet is transmitted through different fiber spans, measuring the BER and latency on each case. The system achieves BER values below the FEC limit and a manageable latency. These results serve as a guideline and proof of concept...

  20. Novel ultra-wideband photonic signal generation and transmission featuring digital signal processing bit error rate measurements

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Yu, Xianbin; Tafur Monroy, Idelfonso

    2009-01-01

    We propose the novel generation of photonic ultra-wideband signals using an uncooled DFB laser. For the first time we experimentally demonstrate bit-for-bit DSP BER measurements for transmission of a 781.25 Mbit/s photonic UWB signal.......We propose the novel generation of photonic ultra-wideband signals using an uncooled DFB laser. For the first time we experimentally demonstrate bit-for-bit DSP BER measurements for transmission of a 781.25 Mbit/s photonic UWB signal....

  1. BER of subcarrier MPSK/MDPSK modulated OWC systems in Gamma-Gamma turbulence

    KAUST Repository

    Song, Xuegui

    2013-12-01

    Bit-error rate (BER) performance of subcarrier Mary phase-shift keying (MPSK) and M-ary differential PSK (MDPSK) is analyzed for optical wireless communications in Gamma-Gamma turbulence. We study the relation between the exact BER and the approximate BER, which is obtained by dividing the symbol error rate by the number of bits per symbol, for subcarrier MPSK and MDPSK modulations. The asymptotic performance gap between the exact and the approximate BERs is quantified analytically through our asymptotic analyses. The accuracy of the approximate BER of both MPSK and MDPSK depends on the channel conditions. Under weak turbulence conditions, the approximate BER expression can be used to predict the system performance with high accuracy, while under strong turbulence conditions the approximate BER becomes inaccurate and can only serve as a loose lower bound of the exact BER. The asymptotic BER performance loss of MDPSK with respect to MPSK is also quantified analytically. © 2013 IEEE.

  2. On the BER and capacity analysis of MIMO MRC systems with channel estimation error

    KAUST Repository

    Yang, Liang; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate the effect of channel estimation error on the capacity and bit-error rate (BER) of a multiple-input multiple-output (MIMO) transmit maximal ratio transmission (MRT) and receive maximal ratio combining (MRC) systems over

  3. Outage and BER analysis for ultrawideband-based WPAN in Nakagami-m fading channels

    KAUST Repository

    Mehbodniya, Abolfazl; Aissa, Sonia

    2011-01-01

    layer. Approximate expressions for the outage probability and average bit error rate (BER) are derived in closed form for the MB-OFDM target receiver, taking into account multi-user interference (MUI), as well as external interference in the form of time

  4. BER analysis of DS-UWB system employing a laplace distribution model

    KAUST Repository

    Mehbodniya, Abolfazl; Aissa, Sonia; Adachi, Fumiyuki

    2011-01-01

    This letter takes a new approach to extract a closed-form expression for the bit error rate (BER) of direct-sequence ultra wideband (DS-UWB) system. In the analysis, the main signal is impaired by multi-user interference (MUI) and an external source

  5. Analysis Of Impact Of Various Parameters On BER Performance For IEEE 802.11b

    Directory of Open Access Journals (Sweden)

    Nilesh B. Kalani

    2015-08-01

    Full Text Available Abstract This paper discusses about IEEE 802.11b simulation model implemented using LabVIEW software and its analyses for impact on bit error rate BER for different parameters as channel type channel number data transmission rate and packet size. Audio file is being transmitted processed and analyzed using the model for various parameters. This paper gives analysis of BER verses ESN0 for various parameter like data rate packet size and communication channel for the IEEE 802.11b simulation model generated using LabVIEW. It is proved that BER can be optimized by tweaking different parameters of wireless communication system.

  6. BER estimation for all-optical regenerators influenced by pattern effects

    DEFF Research Database (Denmark)

    Bischoff, Svend; Lading, B.; Mørk, Jesper

    2002-01-01

    An efficient method is presented for the estimation of the bit-error rate (BER) of a system employing all-optical regenerators influenced by pattern effects. We theoretically study noise accumulation and noise redistribution in long distance transmission systems employing a delayed interference...... signal wavelength converter for all-optical regeneration. The BER is studied for return-to-zero signals at bit rates of 2.5 Gb/s (no patterning) up to 40 Gb/s (strong patterning). The calculation of the BER is based on pattern dependent transfer functions, which may be obtained numerically or measured....

  7. BER of subcarrier MPSK and MDPSK systems in atmospheric turbulence

    KAUST Repository

    Song, Xuegui

    2015-01-01

    Bit-error rate (BER) performance of subcarrier $M$-ary phase-shift keying (MPSK) and $M$-ary differential PSK (MDPSK) is analyzed for optical wireless communications over Gamma-Gamma and lognormal turbulence channels. We study the relation between the exact BER and the approximate BER, which is obtained by dividing the symbol-error rate by the number of bits per symbol, for subcarrier MPSK and MDPSK modulations. The asymptotic BER performance gap between the exact and the approximate BERs is quantified analytically through our asymptotic analyses. The accuracy of the approximate BER of both MPSK and MDPSK depends on the channel conditions. Under weak turbulence conditions, the approximate BER expression can be used to predict the system performance with high accuracy, while under strong turbulence conditions the approximate BER becomes inaccurate and can only serve as a loose lower bound of the exact BER. The asymptotic BER performance loss of MDPSK with respect to MPSK is also quantified analytically.

  8. A New Closed Form Approximation for BER for Optical Wireless Systems in Weak Atmospheric Turbulence

    Science.gov (United States)

    Kaushik, Rahul; Khandelwal, Vineet; Jain, R. C.

    2018-04-01

    Weak atmospheric turbulence condition in an optical wireless communication (OWC) is captured by log-normal distribution. The analytical evaluation of average bit error rate (BER) of an OWC system under weak turbulence is intractable as it involves the statistical averaging of Gaussian Q-function over log-normal distribution. In this paper, a simple closed form approximation for BER of OWC system under weak turbulence is given. Computation of BER for various modulation schemes is carried out using proposed expression. The results obtained using proposed expression compare favorably with those obtained using Gauss-Hermite quadrature approximation and Monte Carlo Simulations.

  9. Impact of Mutual Coupling and Polarization of Antennas on BER Performances of Spatial Multiplexing MIMO Systems

    Directory of Open Access Journals (Sweden)

    Jianfeng Zheng

    2012-01-01

    Full Text Available This paper is aimed at studying the impacts of mutual coupling, matching networks, and polarization of antennas on performances of Multiple-Input Multiple-Output (MIMO systems employing Spatial Multiplexing (SM. In particular, the uncoded average Bit Error Rate (BER of MIMO systems is investigated. An accurate signal analysis framework based on circuit network parameters is presented to describe the transmit/receive characteristics of the matched/unmatched antenna array. The studied arrays consist of matched/unmatched compact copolarization and polarization diversity antenna array. Monte-Carlo numerical simulations are used to study the BER performances of the SM MIMO systems using maximum-likelihood and/or zero-forcing detection schemes. The simulation results demonstrate that the use of matching networks can improve the BER performance of SM MIMO systems significantly, and the BER performance deterioration due to antenna orientation randomness can be compensated by use of polarization diversity antenna arrays.

  10. Minimum BER Receiver Filters with Block Memory for Uplink DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Mérouane Debbah

    2008-05-01

    Full Text Available The problem of synchronous multiuser receiver design in the case of direct-sequence single-antenna code division multiple access (DS-CDMA uplink networks is studied over frequency selective fading channels. An exact expression for the bit error rate (BER is derived in the case of BPSK signaling. Moreover, an algorithm is proposed for finding the finite impulse response (FIR receiver filters with block memory such that the exact BER of the active users is minimized. Several properties of the minimum BER FIR filters with block memory are identified. The algorithm performance is found for scenarios with different channel qualities, spreading code lengths, receiver block memory size, near-far effects, and channel mismatch. For the BPSK constellation, the proposed FIR receiver structure with block memory has significant better BER with respect to Eb/N0 and near-far resistance than the corresponding minimum mean square error (MMSE filters with block memory.

  11. Minimum BER Receiver Filters with Block Memory for Uplink DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Debbah Mérouane

    2008-01-01

    Full Text Available Abstract The problem of synchronous multiuser receiver design in the case of direct-sequence single-antenna code division multiple access (DS-CDMA uplink networks is studied over frequency selective fading channels. An exact expression for the bit error rate (BER is derived in the case of BPSK signaling. Moreover, an algorithm is proposed for finding the finite impulse response (FIR receiver filters with block memory such that the exact BER of the active users is minimized. Several properties of the minimum BER FIR filters with block memory are identified. The algorithm performance is found for scenarios with different channel qualities, spreading code lengths, receiver block memory size, near-far effects, and channel mismatch. For the BPSK constellation, the proposed FIR receiver structure with block memory has significant better BER with respect to and near-far resistance than the corresponding minimum mean square error (MMSE filters with block memory.

  12. BER Analysis of Coherent Free-Space Optical Communication Systems with a Focal-Plane-Based Wavefront Sensor

    Science.gov (United States)

    Cao, Jingtai; Zhao, Xiaohui; Liu, Wei; Gu, Haijun

    2018-03-01

    A wavefront sensor is one of most important units for an adaptive optics system. Based on our previous works, in this paper, we discuss the bit-error-rate (BER) performance of coherent free space optical communication systems with a focal-plane-based wavefront sensor. Firstly, the theory of a focal-plane-based wavefront sensor is given. Then the relationship between the BER and the mixing efficiency with a homodyne receiver is discussed on the basis of binary-phase-shift-keying (BPSK) modulation. Finally, the numerical simulation results are shown that the BER will be decreased obviously after aberrations correction with the focal-plane-based wavefront sensor. In addition, the BER will decrease along with increasing number of photons received within a single bit. These analysis results will provide a reference for the design of the coherent Free space optical communication (FSOC) system.

  13. On the BER and capacity analysis of MIMO MRC systems with channel estimation error

    KAUST Repository

    Yang, Liang

    2011-10-01

    In this paper, we investigate the effect of channel estimation error on the capacity and bit-error rate (BER) of a multiple-input multiple-output (MIMO) transmit maximal ratio transmission (MRT) and receive maximal ratio combining (MRC) systems over uncorrelated Rayleigh fading channels. We first derive the ergodic (average) capacity expressions for such systems when power adaptation is applied at the transmitter. The exact capacity expression for the uniform power allocation case is also presented. Furthermore, to investigate the diversity order of MIMO MRT-MRC scheme, we derive the BER performance under a uniform power allocation policy. We also present an asymptotic BER performance analysis for the MIMO MRT-MRC system with multiuser diversity. The numerical results are given to illustrate the sensitivity of the main performance to the channel estimation error and the tightness of the approximate cutoff value. © 2011 IEEE.

  14. Outage and BER analysis for ultrawideband-based WPAN in Nakagami-m fading channels

    KAUST Repository

    Mehbodniya, Abolfazl

    2011-09-01

    This paper presents a performance analysis of multiband orthogonal frequency-division multiplexing (MB-OFDM) in ultra wideband (UWB)-based personal area networks (UPANs). A UPAN consists of devices with different UWB technologies at the physical layer. Approximate expressions for the outage probability and average bit error rate (BER) are derived in closed form for the MB-OFDM target receiver, taking into account multi-user interference (MUI), as well as external interference in the form of time-hopping (TH) and direct-sequence (DS) UWB signals. © 2010 IEEE.

  15. GFDM performance in terms of BER, PAPR and OOB and comparison to OFDM system

    Energy Technology Data Exchange (ETDEWEB)

    Antapurkar, Shwetal K., E-mail: h2014077@pilani.bits-pilani.ac.in; Pandey, Avinash, E-mail: h2014083@pilani.bits-pilani.ac.in [P G student, Dept. of EEE, Birla Institute of Technology and Science, Pilani, Rajasthan, India-333031 (India); Gupta, K. K., E-mail: kgupta@pilani.bits-pilani.ac.in [Asst Prof, Dept. of EEE, Birla Institute of Technology and Science, Pilani, Rajasthan, India-333031 (India)

    2016-03-09

    Generalized frequency division multiplexing is a multicarrier modulation technique which can be foreseen as a potential alternative for upcoming wireless networks. GFDM attractive features include reduced out-of-band radiation(OOB) and low peak-to-average ratio(PAPR), which are the crucial shortcomings of OFDM used in present day wireless communication networks. This paper gives detailed description of GFDM system model and further studies and validates through simulations, the performance of GFDM in terms of OOB, PAPR and Bit Error Rate (BER) and compares the results obtained with OFDM system.

  16. GFDM performance in terms of BER, PAPR and OOB and comparison to OFDM system

    International Nuclear Information System (INIS)

    Antapurkar, Shwetal K.; Pandey, Avinash; Gupta, K. K.

    2016-01-01

    Generalized frequency division multiplexing is a multicarrier modulation technique which can be foreseen as a potential alternative for upcoming wireless networks. GFDM attractive features include reduced out-of-band radiation(OOB) and low peak-to-average ratio(PAPR), which are the crucial shortcomings of OFDM used in present day wireless communication networks. This paper gives detailed description of GFDM system model and further studies and validates through simulations, the performance of GFDM in terms of OOB, PAPR and Bit Error Rate (BER) and compares the results obtained with OFDM system.

  17. BER analysis of DS-UWB system employing a laplace distribution model

    KAUST Repository

    Mehbodniya, Abolfazl

    2011-01-01

    This letter takes a new approach to extract a closed-form expression for the bit error rate (BER) of direct-sequence ultra wideband (DS-UWB) system. In the analysis, the main signal is impaired by multi-user interference (MUI) and an external source of interference originated by simultanously transmitting multiband orthogonal frequency division multiplexing (MB-OFDM) systems which are located in the vicinity of the DS-UWB receiver. All the transmission channels are affected by Nakagami-m fading. A Laplacian distribution is considered for MUI to comply more with real statistical behaviors of this kind of interference. © IEICE 2011.

  18. Particle-induced bit errors in high performance fiber optic data links for satellite data management

    International Nuclear Information System (INIS)

    Marshall, P.W.; Carts, M.A.; Dale, C.J.; LaBel, K.A.

    1994-01-01

    Experimental test methods and analysis tools are demonstrated to assess particle-induced bit errors on fiber optic link receivers for satellites. Susceptibility to direct ionization from low LET particles is quantified by analyzing proton and helium ion data as a function of particle LET. Existing single event analysis approaches are shown to apply, with appropriate modifications, to the regime of temporally (rather than spatially) distributed bits, even though the sensitivity to single events exceeds conventional memory technologies by orders of magnitude. The cross-section LET dependence follows a Weibull distribution at data rates from 200 to 1,000 Mbps and at various incident optical power levels. The LET threshold for errors is shown, through both experiment and modeling, to be 0 in all cases. The error cross-section exhibits a strong inverse dependence on received optical power in the LET range where most orbital single events would occur, thus indicating that errors can be minimized by operating links with higher incident optical power. Also, an analytic model is described which incorporates the appropriate physical characteristics of the link as well as the optical and receiver electrical characteristics. Results indicate appropriate steps to assure suitable link performance even in severe particle orbits

  19. SNR and BER Models and the Simulation for BER Performance of Selected Spectral Amplitude Codes for OCDMA

    Directory of Open Access Journals (Sweden)

    Abdul Latif Memon

    2014-01-01

    Full Text Available Many encoding schemes are used in OCDMA (Optical Code Division Multiple Access Network but SAC (Spectral Amplitude Codes is widely used. It is considered an effective arrangement to eliminate dominant noise called MAI (Multi Access Interference. Various codes are studied for evaluation with respect to their performance against three noises namely shot noise, thermal noise and PIIN (Phase Induced Intensity Noise. Various Mathematical models for SNR (Signal to Noise Ratios and BER (Bit Error Rates are discussed where the SNRs are calculated and BERs are computed using Gaussian distribution assumption. After analyzing the results mathematically, it is concluded that ZCC (Zero Cross Correlation Code performs better than the other selected SAC codes and can serve larger number of active users than the other codes do. At various receiver power levels, analysis points out that RDC (Random Diagonal Code also performs better than the other codes. For the power interval between -10 and -20 dBm performance of RDC is better ZCC. Their lowest BER values suggest that these codes should be part of an efficient and cost effective OCDM access network in the future.

  20. Average BER analysis of SCM-based free-space optical systems by considering the effect of IM3 with OSSB signals under turbulence channels.

    Science.gov (United States)

    Lim, Wansu; Cho, Tae-Sik; Yun, Changho; Kim, Kiseon

    2009-11-09

    In this paper, we derive the average bit error rate (BER) of subcarrier multiplexing (SCM)-based free space optics (FSO) systems using a dual-drive Mach-Zehnder modulator (DD-MZM) for optical single-sideband (OSSB) signals under atmospheric turbulence channels. In particular, we consider the third-order intermodulation (IM3), a significant performance degradation factor, in the case of high input signal power systems. The derived average BER, as a function of the input signal power and the scintillation index, is employed to determine the optimum number of SCM users upon the designing FSO systems. For instance, when the user number doubles, the input signal power decreases by almost 2 dBm under the log-normal and exponential turbulence channels at a given average BER.

  1. On Bit Error Probability and Power Optimization in Multihop Millimeter Wave Relay Systems

    KAUST Repository

    Chelli, Ali

    2018-01-15

    5G networks are expected to provide gigabit data rate to users via millimeter-wave (mmWave) communication technology. One of the major problem faced by mmWaves is that they cannot penetrate buildings. In this paper, we utilize multihop relaying to overcome the signal blockage problem in mmWave band. The multihop relay network comprises a source device, several relay devices and a destination device and uses device-todevice communication. Relay devices redirect the source signal to avoid the obstacles existing in the propagation environment. Each device amplifies and forwards the signal to the next device, such that a multihop link ensures the connectivity between the source device and the destination device. We consider that the relay devices and the destination device are affected by external interference and investigate the bit error probability (BEP) of this multihop mmWave system. Note that the study of the BEP allows quantifying the quality of communication and identifying the impact of different parameters on the system reliability. In this way, the system parameters, such as the powers allocated to different devices, can be tuned to maximize the link reliability. We derive exact expressions for the BEP of M-ary quadrature amplitude modulation (M-QAM) and M-ary phase-shift keying (M-PSK) in terms of multivariate Meijer’s G-function. Due to the complicated expression of the exact BEP, a tight lower-bound expression for the BEP is derived using a novel Mellin-approach. Moreover, an asymptotic expression for the BEP at high SIR regime is derived and used to determine the diversity and the coding gain of the system. Additionally, we optimize the power allocation at different devices subject to a sum power constraint such that the BEP is minimized. Our analysis reveals that optimal power allocation allows achieving more than 3 dB gain compared to the equal power allocation.This research work can serve as a framework for designing and optimizing mmWave multihop

  2. BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

    Directory of Open Access Journals (Sweden)

    I. Develi

    2010-09-01

    Full Text Available Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature.

  3. BER and Availability Measured on FSO Link

    Czech Academy of Sciences Publication Activity Database

    Kvíčala, R.; Kvičera, V.; Grábner, M.; Fišer, Ondřej

    2007-01-01

    Roč. 16, č. 3 (2007), s. 7-12 ISSN 1210-2512 Grant - others:Ministry of research and technology(DE) 17050531 Institutional research plan: CEZ:AV0Z30420517 Keywords : free space optical links * quality of service * meteorological optical range * link unavailability * bit error rate Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. An Alternative Method to Compute the Bit Error Probability of Modulation Schemes Subject to Nakagami- Fading

    Directory of Open Access Journals (Sweden)

    Madeiro Francisco

    2010-01-01

    Full Text Available Abstract This paper presents an alternative method for determining exact expressions for the bit error probability (BEP of modulation schemes subject to Nakagami- fading. In this method, the Nakagami- fading channel is seen as an additive noise channel whose noise is modeled as the ratio between Gaussian and Nakagami- random variables. The method consists of using the cumulative density function of the resulting noise to obtain closed-form expressions for the BEP of modulation schemes subject to Nakagami- fading. In particular, the proposed method is used to obtain closed-form expressions for the BEP of -ary quadrature amplitude modulation ( -QAM, -ary pulse amplitude modulation ( -PAM, and rectangular quadrature amplitude modulation ( -QAM under Nakagami- fading. The main contribution of this paper is to show that this alternative method can be used to reduce the computational complexity for detecting signals in the presence of fading.

  5. Computing in the presence of soft bit errors. [caused by single event upset on spacecraft

    Science.gov (United States)

    Rasmussen, R. D.

    1984-01-01

    It is shown that single-event-upsets (SEUs) due to cosmic rays are a significant source of single bit error in spacecraft computers. The physical mechanism of SEU, electron hole generation by means of Linear Energy Transfer (LET), it discussed with reference made to the results of a study of the environmental effects on computer systems of the Galileo spacecraft. Techniques for making software more tolerant of cosmic ray effects are considered, including: reducing the number of registers used by the software; continuity testing of variables; redundant execution of major procedures for error detection; and encoding state variables to detect single-bit changes. Attention is also given to design modifications which may reduce the cosmic ray exposure of on-board hardware. These modifications include: shielding components operating in LEO; removing low-power Schottky parts; and the use of CMOS diodes. The SEU parameters of different electronic components are listed in a table.

  6. Upper Bounds on the BER Performance of MTCM-STBC Schemes over Shadowed Rician Fading Channels

    Directory of Open Access Journals (Sweden)

    M. Uysal

    2004-08-01

    Full Text Available Space-time block coding (STBC provides substantial diversity advantages with a low decoding complexity. However, these codes are not designed to achieve coding gains. Outer codes should be concatenated with STBC to provide additional coding gain. In this paper, we analyze the performance of concatenated trellis-coded STBC schemes over shadowed Rician frequency-flat fading channels. We derive an exact pairwise error probability (PEP expression that reveals the dominant factors affecting performance. Based on the derived PEP, in conjunction with the transfer function technique, we also present upper bounds on the bit error rate (BER, which are further shown to be tight through a Monte-Carlo simulation study.

  7. Effect of Pointing Error on the BER Performance of an Optical CDMA FSO Link with SIK Receiver

    Science.gov (United States)

    Nazrul Islam, A. K. M.; Majumder, S. P.

    2017-12-01

    An analytical approach is presented for an optical code division multiple access (OCDMA) system over free space optical (FSO) channel considering the effect of pointing error between the transmitter and the receiver. Analysis is carried out with an optical sequence inverse keying (SIK) correlator receiver with intensity modulation and direct detection (IM/DD) to find the bit error rate (BER) with pointing error. The results are evaluated numerically in terms of signal-to-noise plus multi-access interference (MAI) ratio, BER and power penalty due to pointing error. It is noticed that the OCDMA FSO system is highly affected by pointing error with significant power penalty at a BER of 10-6 and 10-9. For example, penalty at BER 10-9 is found to be 9 dB corresponding to normalized pointing error of 1.4 for 16 users with processing gain of 256 and is reduced to 6.9 dB when the processing gain is increased to 1,024.

  8. Multi-bits error detection and fast recovery in RISC cores

    International Nuclear Information System (INIS)

    Wang Jing; Yang Xing; Zhang Weigong; Shen Jiao; Qiu Keni; Zhao Yuanfu

    2015-01-01

    The particles-induced soft errors are a major threat to the reliability of microprocessors. Even worse, multi-bits upsets (MBUs) are ever-increased due to the rapidly shrinking feature size of the IC on a chip. Several architecture-level mechanisms have been proposed to protect microprocessors from soft errors, such as dual and triple modular redundancies (DMR and TMR). However, most of them are inefficient to combat the growing multi-bits errors or cannot well balance the critical paths delay, area and power penalty. This paper proposes a novel architecture, self-recovery dual-pipeline (SRDP), to effectively provide soft error detection and recovery with low cost for general RISC structures. We focus on the following three aspects. First, an advanced DMR pipeline is devised to detect soft error, especially MBU. Second, SEU/MBU errors can be located by enhancing self-checking logic into pipelines stage registers. Third, a recovery scheme is proposed with a recovery cost of 1 or 5 clock cycles. Our evaluation of a prototype implementation exhibits that the SRDP can successfully detect particle-induced soft errors up to 100% and recovery is nearly 95%, the other 5% will inter a specific trap. (paper)

  9. Multi-bits error detection and fast recovery in RISC cores

    Science.gov (United States)

    Jing, Wang; Xing, Yang; Yuanfu, Zhao; Weigong, Zhang; Jiao, Shen; Keni, Qiu

    2015-11-01

    The particles-induced soft errors are a major threat to the reliability of microprocessors. Even worse, multi-bits upsets (MBUs) are ever-increased due to the rapidly shrinking feature size of the IC on a chip. Several architecture-level mechanisms have been proposed to protect microprocessors from soft errors, such as dual and triple modular redundancies (DMR and TMR). However, most of them are inefficient to combat the growing multi-bits errors or cannot well balance the critical paths delay, area and power penalty. This paper proposes a novel architecture, self-recovery dual-pipeline (SRDP), to effectively provide soft error detection and recovery with low cost for general RISC structures. We focus on the following three aspects. First, an advanced DMR pipeline is devised to detect soft error, especially MBU. Second, SEU/MBU errors can be located by enhancing self-checking logic into pipelines stage registers. Third, a recovery scheme is proposed with a recovery cost of 1 or 5 clock cycles. Our evaluation of a prototype implementation exhibits that the SRDP can successfully detect particle-induced soft errors up to 100% and recovery is nearly 95%, the other 5% will inter a specific trap.

  10. Pulse shaping for high data rate ultra-wideband wireless transmission under the Russian spectral emission mask

    DEFF Research Database (Denmark)

    Rommel, Simon; Grakhova, Elizaveta P.; Jurado-Navas, Antonio

    2017-01-01

    This paper addresses impulse-radio ultra-wideband (IR-UWB) transmission under the Russian spectral emission mask for unlicensed UWB radio communications. Four pulse shapes are proposed and their bit error rate (BER) performance is both estimated analytically and evaluated experimentally. Well......-known shapes such as the Gaussian, root-raised cosine, hyperbolic secant, and the frequency B-spline wavelet are used to form linear combinations of component pulses, shaped to make efficient use of the spectral emission mask. Analytical BER values are derived using a Nakagami-m model, and good agreement......-UWB transmission under the strict regulations of the Russian spectral emission mask....

  11. Reducing BER of spectral-amplitude coding optical code-division multiple-access systems by single photodiode detection technique

    Science.gov (United States)

    Al-Khafaji, H. M. R.; Aljunid, S. A.; Amphawan, A.; Fadhil, H. A.; Safar, A. M.

    2013-03-01

    In this paper, we present a single photodiode detection (SPD) technique for spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems. The proposed technique eliminates both phase-induced intensity noise (PIIN) and multiple-access interference (MAI) in the optical domain. Analytical results show that for 35 simultaneous users transmitting at data rate of 622 Mbps, the bit-error rate (BER) = 1.4x10^-28 for SPD technique is much better compared to 9.3x10^-6 and 9.6x10^-3 for the modified-AND as well as the AND detection techniques, respectively. Moreover, we verified the improved performance afforded by the proposed technique using data transmission simulations.

  12. Novel relations between the ergodic capacity and the average bit error rate

    KAUST Repository

    Yilmaz, Ferkan; Alouini, Mohamed-Slim

    2011-01-01

    technologies based on these two performance indicators. However and to the best of our knowledge, the direct links between these two performance indicators have not been explicitly proposed in the literature so far. In this paper, we propose novel relations

  13. Near-minimum bit-error rate equalizer adaptation for PRML systems

    NARCIS (Netherlands)

    Riani, J.; Beneden, van S.J.L; Bergmans, J.W.M.; Immink, A.H.J.

    2007-01-01

    Receivers for partial response maximum-likelihood systems typically use a linear equalizer followed by a Viterbi detector. The equalizer tries to confine the channel intersymbol interference to a short span in order to limit the implementation complexity of the Viterbi detector. Equalization is

  14. Bit Error Rate Due to Misalignment of Earth Station Antenna Pointing to Satellite

    Directory of Open Access Journals (Sweden)

    Wahyu Pamungkas

    2010-04-01

    Full Text Available One problem causing reduction of energy in satellite communications system is the misalignment of earth station antenna pointing to satellite. Error in pointing would affect the quality of information signal to energy bit in earth station. In this research, error in pointing angle occurred only at receiver (Rx antenna, while the transmitter (Tx antennas precisely point to satellite. The research was conducted towards two satellites, namely TELKOM-1 and TELKOM-2. At first, measurement was made by directing Tx antenna precisely to satellite, resulting in an antenna pattern shown by spectrum analyzer. The output from spectrum analyzers is drawn with the right scale to describe swift of azimuth and elevation pointing angle towards satellite. Due to drifting from the precise pointing, it influenced the received link budget indicated by pattern antenna. This antenna pattern shows reduction of power level received as a result of pointing misalignment. As a conclusion, the increasing misalignment of pointing to satellite would affect in the reduction of received signal parameters link budget of down-link traffic.

  15. Transmission modulation system for mobile phone reduces battery consumption without increasing bit error rate

    NARCIS (Netherlands)

    Moretti, M.; Janssen, G.J.M.

    2000-01-01

    The transmission modulation system minimizes the wasted 'out of band' power. The digital data (1) to be transmitted is fed via a pulse response filter (2) to a mixer (4) where it modulates a carrier wave (4). The digital data is also fed via a delay circuit (5) and identical filter (6) to a second

  16. Improving 3D-Turbo Code's BER Performance with a BICM System over Rayleigh Fading Channel

    Directory of Open Access Journals (Sweden)

    R. Yao

    2016-12-01

    Full Text Available Classical Turbo code suffers from high error floor due to its small Minimum Hamming Distance (MHD. Newly-proposed 3D-Turbo code can effectively increase the MHD and achieve a lower error floor by adding a rate-1 post encoder. In 3D-Turbo codes, part of the parity bits from the classical Turbo encoder are further encoded through the post encoder. In this paper, a novel Bit-Interleaved Coded Modulation (BICM system is proposed by combining rotated mapping Quadrature Amplitude Modulation (QAM and 3D-Turbo code to improve the Bit Error Rate (BER performance of 3D-Turbo code over Raleigh fading channel. A key-bit protection scheme and a Two-Dimension (2D iterative soft demodulating-decoding algorithm are developed for the proposed BICM system. Simulation results show that the proposed system can obtain about 0.8-1.0 dB gain at BER of 10^{-6}, compared with the existing BICM system with Gray mapping QAM.

  17. BER and optimal power allocation for amplify-and-forward relaying using pilot-aided maximum likelihood estimation

    KAUST Repository

    Wang, Kezhi

    2014-10-01

    Bit error rate (BER) and outage probability for amplify-and-forward (AF) relaying systems with two different channel estimation methods, disintegrated channel estimation and cascaded channel estimation, using pilot-aided maximum likelihood method in slowly fading Rayleigh channels are derived. Based on the BERs, the optimal values of pilot power under the total transmitting power constraints at the source and the optimal values of pilot power under the total transmitting power constraints at the relay are obtained, separately. Moreover, the optimal power allocation between the pilot power at the source, the pilot power at the relay, the data power at the source and the data power at the relay are obtained when their total transmitting power is fixed. Numerical results show that the derived BER expressions match with the simulation results. They also show that the proposed systems with optimal power allocation outperform the conventional systems without power allocation under the same other conditions. In some cases, the gain could be as large as several dB\\'s in effective signal-to-noise ratio.

  18. BER and optimal power allocation for amplify-and-forward relaying using pilot-aided maximum likelihood estimation

    KAUST Repository

    Wang, Kezhi; Chen, Yunfei; Alouini, Mohamed-Slim; Xu, Feng

    2014-01-01

    Bit error rate (BER) and outage probability for amplify-and-forward (AF) relaying systems with two different channel estimation methods, disintegrated channel estimation and cascaded channel estimation, using pilot-aided maximum likelihood method in slowly fading Rayleigh channels are derived. Based on the BERs, the optimal values of pilot power under the total transmitting power constraints at the source and the optimal values of pilot power under the total transmitting power constraints at the relay are obtained, separately. Moreover, the optimal power allocation between the pilot power at the source, the pilot power at the relay, the data power at the source and the data power at the relay are obtained when their total transmitting power is fixed. Numerical results show that the derived BER expressions match with the simulation results. They also show that the proposed systems with optimal power allocation outperform the conventional systems without power allocation under the same other conditions. In some cases, the gain could be as large as several dB's in effective signal-to-noise ratio.

  19. Inter-symbol interference and beat noise in flexible data-rate coherent OCDMA and the BER improvement by using optical thresholding.

    Science.gov (United States)

    Wang, Xu; Wada, Naoya; Kitayama, Ken-Ichi

    2005-12-26

    Impairments of inter-symbol interference and beat noise in coherent time-spreading optical code-division-multiple-access are investigated theoretically and experimentally by sweeping the data-rate from 622 Mbps up to 10 Gbps with 511-chip superstructured fiber Bragg grating. The BER improvement by using optical thresholding technique has been verified in the experiment.

  20. Average bit error probability of binary coherent signaling over generalized fading channels subject to additive generalized gaussian noise

    KAUST Repository

    Soury, Hamza

    2012-06-01

    This letter considers the average bit error probability of binary coherent signaling over flat fading channels subject to additive generalized Gaussian noise. More specifically, a generic closed form expression in terms of the Fox\\'s H function is offered for the extended generalized-K fading case. Simplifications for some special fading distributions such as generalized-K fading and Nakagami-m fading and special additive noise distributions such as Gaussian and Laplacian noise are then presented. Finally, the mathematical formalism is illustrated by some numerical examples verified by computer based simulations for a variety of fading and additive noise parameters. © 2012 IEEE.

  1. Novel MGF-based expressions for the average bit error probability of binary signalling over generalized fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2014-04-01

    The main idea in the moment generating function (MGF) approach is to alternatively express the conditional bit error probability (BEP) in a desired exponential form so that possibly multi-fold performance averaging is readily converted into a computationally efficient single-fold averaging - sometimes into a closed-form - by means of using the MGF of the signal-to-noise ratio. However, as presented in [1] and specifically indicated in [2] and also to the best of our knowledge, there does not exist an MGF-based approach in the literature to represent Wojnar\\'s generic BEP expression in a desired exponential form. This paper presents novel MGF-based expressions for calculating the average BEP of binary signalling over generalized fading channels, specifically by expressing Wojnar\\'s generic BEP expression in a desirable exponential form. We also propose MGF-based expressions to explore the amount of dispersion in the BEP for binary signalling over generalized fading channels.

  2. On Bit Error Probability and Power Optimization in Multihop Millimeter Wave Relay Systems

    KAUST Repository

    Chelli, Ali; Kansanen, Kimmo; Alouini, Mohamed-Slim; Balasingham, Ilangko

    2018-01-01

    5G networks are expected to provide gigabit data rate to users via millimeter-wave (mmWave) communication technology. One of the major problem faced by mmWaves is that they cannot penetrate buildings. In this paper, we utilize multihop relaying

  3. Real-time minimal-bit-error probability decoding of convolutional codes

    Science.gov (United States)

    Lee, L.-N.

    1974-01-01

    A recursive procedure is derived for decoding of rate R = 1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit, subject to the constraint that the decoding delay be limited to Delta branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A real-time, i.e., fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications, such as in the inner coding system for concatenated coding.

  4. Real-time minimal bit error probability decoding of convolutional codes

    Science.gov (United States)

    Lee, L. N.

    1973-01-01

    A recursive procedure is derived for decoding of rate R=1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit subject to the constraint that the decoding delay be limited to Delta branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A real-time, i.e. fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications such as in the inner coding system for concatenated coding.

  5. BER Analysis Using Beat Probability Method of 3D Optical CDMA Networks with Double Balanced Detection

    Directory of Open Access Journals (Sweden)

    Chih-Ta Yen

    2015-01-01

    Full Text Available This study proposes novel three-dimensional (3D matrices of wavelength/time/spatial code for code-division multiple-access (OCDMA networks, with a double balanced detection mechanism. We construct 3D carrier-hopping prime/modified prime (CHP/MP codes by extending a two-dimensional (2D CHP code integrated with a one-dimensional (1D MP code. The corresponding coder/decoder pairs were based on fiber Bragg gratings (FBGs and tunable optical delay lines integrated with splitters/combiners. System performance was enhanced by the low cross correlation properties of the 3D code designed to avoid the beat noise phenomenon. The CHP/MP code cardinality increased significantly compared to the CHP code under the same bit error rate (BER. The results indicate that the 3D code method can enhance system performance because both the beating terms and multiple-access interference (MAI were reduced by the double balanced detection mechanism. Additionally, the optical component can also be relaxed for high transmission scenery.

  6. Influence of transmission bit rate on performance of optical fibre communication systems with direct modulation of laser diodes

    International Nuclear Information System (INIS)

    Ahmed, Moustafa F

    2009-01-01

    This paper reports on the influence of the transmission bit rate on the performance of optical fibre communication systems employing laser diodes subjected to high-speed direct modulation. The performance is evaluated in terms of the bit error rate (BER) and power penalty associated with increasing the transmission bit rate while keeping the transmission distance. The study is based on numerical analysis of the stochastic rate equations of the laser diode and takes into account noise mechanisms in the receiver. Correlation between BER and the Q-parameter of the received signal is presented. The relative contributions of the transmitter noise and the circuit and shot noises of the receiver to BER are quantified as functions of the transmission bit rate. The results show that the power penalty at BER = 10 -9 required to keep the transmission distance increases moderately with the increase in the bit rate near 1 Gbps and at high bias currents. In this regime, the shot noise is the main contributor to BER. At higher bit rates and lower bias currents, the power penalty increases remarkably, which comes mainly from laser noise induced by the pseudorandom bit-pattern effect.

  7. Wireless Powered Relaying Networks Under Imperfect Channel State Information: System Performance and Optimal Policy for Instantaneous Rate

    Directory of Open Access Journals (Sweden)

    D. T. Do

    2017-09-01

    Full Text Available In this investigation, we consider wireless powered relaying systems, where energy is scavenged by a relay via radio frequency (RF signals. We explore hybrid time switching-based and power splitting-based relaying protocol (HTPSR and compare performance of Amplify-and-Forward (AF with Decode-and-Forward (DF scheme under imperfect channel state information (CSI. Most importantly, the instantaneous rate, achievable bit error rate (BER are determined in the closed-form expressions under the impact of imperfect CSI. Through numerical analysis, we evaluate system insights via different parameters such as power splitting (PS and time switching (TS ratio of the considered HTPSR which affect outage performance and BER. It is noted that DF relaying networks outperform AF relaying networks. Besides that, the numerical results are given to prove the optimization problems of PS and TS ratio to obtain optimal instantaneous rate.

  8. Improved BER based on intensity noise alleviation using developed detection technique for incoherent SAC-OCDMA systems

    Science.gov (United States)

    Al-Khafaji, Hamza M. R.; Aljunid, S. A.; Fadhil, Hilal A.

    2012-06-01

    The major drawback of incoherent spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems is their inherent intensity noise originating due to the incoherency of the broadband light sources. In this paper, we propose a developed detection technique named the modified-AND subtraction detection for incoherent SAC-OCDMA systems. This detection technique is based upon decreasing the received signal strength during the decoding process by dividing the spectrum of the utilized code sequence. The proposed technique is capable of mitigating the intensity noise effect, as well as suppressing the multiple-access interference impact. Based on modified quadratic congruence (MQC) code, the analytical results reveal that the modified-AND detection offer best bit-error rate (BER) performance and enables MQC code to support higher transmission rate up to 1.25 Gb/s compared to conventional AND detection. Furthermore, we ascertained that the proposed technique enhances the system performance using a simulation experiment.

  9. BER analysis for MPAM signal constellations in the presence of fading and ADC quantization noise

    NARCIS (Netherlands)

    Rizvi, U.H.; Janssen, G.J.M.; Weber, J.H.

    2009-01-01

    In this letter, closed-form expressions for the bit error rate of M-ary pulse amplitude modulated signal constellations as a function of the analog-to-digital converter word length, the signal-to-noise ratio and the fading distribution, are derived. These results allow for a rapid and accurate

  10. BER Science Network Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Alapaty, Kiran; Allen, Ben; Bell, Greg; Benton, David; Brettin, Tom; Canon, Shane; Dart, Eli; Cotter, Steve; Crivelli, Silvia; Carlson, Rich; Dattoria, Vince; Desai, Narayan; Egan, Richard; Tierney, Brian; Goodwin, Ken; Gregurick, Susan; Hicks, Susan; Johnston, Bill; de Jong, Bert; Kleese van Dam, Kerstin; Livny, Miron; Markowitz, Victor; McGraw, Jim; McCord, Raymond; Oehmen, Chris; Regimbal, Kevin; Shipman, Galen; Strand, Gary; Flick, Jeff; Turnbull, Susan; Williams, Dean; Zurawski, Jason

    2010-11-01

    The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the US Department of Energy Office of Science, the single largest supporter of basic research in the physical sciences in the United States. In support of the Office of Science programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs that it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 20 years. In April 2010 ESnet and the Office of Biological and Environmental Research, of the DOE Office of Science, organized a workshop to characterize the networking requirements of the science programs funded by BER. The requirements identified at the workshop are summarized and described in more detail in the case studies and the Findings section. A number of common themes emerged from the case studies and workshop discussions. One is that BER science, like many other disciplines, is becoming more and more distributed and collaborative in nature. Another common theme is that data set sizes are exploding. Climate Science in particular is on the verge of needing to manage exabytes of data, and Genomics is on the verge of a huge paradigm shift in the number of sites with sequencers and the amount of sequencer data being generated.

  11. Error-rate performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2011-09-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path can be considered unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We first derive the exact statistics of each hop, in terms of probability density function (PDF). Then, the PDFs are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation where the detector may use maximum ration combining (MRC) or selection combining (SC). Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network (LN) architecture and considering Rayleigh fading channels. © 2011 IEEE.

  12. Analysis of the Tradeoff between Delay and Source Rate in Multiuser Wireless Systems

    Directory of Open Access Journals (Sweden)

    Soret Beatriz

    2010-01-01

    Full Text Available This work addresses the limits on the information that can be transmitted over the wireless channel under the conditions stated by the MAC layer: a selected scheduling discipline and an ensured level of QoS. Based on the effective bandwidth theory, the joint influence of the channel fading, the data outsourcing process, and the scheduling discipline in the QoS metrics are studied. We obtain a closed-form expression of the vector of attainable users' rates for several scheduling algorithms, representing the maximum constant rate that the uth user can transmit under the selected discipline and fulfilling a target Bit Error Rate (BER and the delay constraint given by the pair , where is the target delay and is the probability of exceeding .

  13. BER analysis of regularized least squares for BPSK recovery

    KAUST Repository

    Ben Atitallah, Ismail; Thrampoulidis, Christos; Kammoun, Abla; Al-Naffouri, Tareq Y.; Hassibi, Babak; Alouini, Mohamed-Slim

    2017-01-01

    This paper investigates the problem of recovering an n-dimensional BPSK signal x0 ∈ {−1, 1}n from m-dimensional measurement vector y = Ax+z, where A and z are assumed to be Gaussian with iid entries. We consider two variants of decoders based on the regularized least squares followed by hard-thresholding: the case where the convex relaxation is from {−1, 1}n to ℝn and the box constrained case where the relaxation is to [−1, 1]n. For both cases, we derive an exact expression of the bit error probability when n and m grow simultaneously large at a fixed ratio. For the box constrained case, we show that there exists a critical value of the SNR, above which the optimal regularizer is zero. On the other side, the regularization can further improve the performance of the box relaxation at low to moderate SNR regimes. We also prove that the optimal regularizer in the bit error rate sense for the unboxed case is nothing but the MMSE detector.

  14. BER analysis of regularized least squares for BPSK recovery

    KAUST Repository

    Ben Atitallah, Ismail

    2017-06-20

    This paper investigates the problem of recovering an n-dimensional BPSK signal x0 ∈ {−1, 1}n from m-dimensional measurement vector y = Ax+z, where A and z are assumed to be Gaussian with iid entries. We consider two variants of decoders based on the regularized least squares followed by hard-thresholding: the case where the convex relaxation is from {−1, 1}n to ℝn and the box constrained case where the relaxation is to [−1, 1]n. For both cases, we derive an exact expression of the bit error probability when n and m grow simultaneously large at a fixed ratio. For the box constrained case, we show that there exists a critical value of the SNR, above which the optimal regularizer is zero. On the other side, the regularization can further improve the performance of the box relaxation at low to moderate SNR regimes. We also prove that the optimal regularizer in the bit error rate sense for the unboxed case is nothing but the MMSE detector.

  15. High SNR BER comparison of coherent and differentially coherent modulation schemes in lognormal fading channels

    KAUST Repository

    Song, Xuegui; Cheng, Julian; Alouini, Mohamed-Slim

    2014-01-01

    Using an auxiliary random variable technique, we prove that binary differential phase-shift keying and binary phase-shift keying have the same asymptotic bit-error rate performance in lognormal fading channels. We also show that differential quaternary phase-shift keying is exactly 2.32 dB worse than quaternary phase-shift keying over the lognormal fading channels in high signal-to-noise ratio regimes.

  16. High SNR BER comparison of coherent and differentially coherent modulation schemes in lognormal fading channels

    KAUST Repository

    Song, Xuegui

    2014-09-01

    Using an auxiliary random variable technique, we prove that binary differential phase-shift keying and binary phase-shift keying have the same asymptotic bit-error rate performance in lognormal fading channels. We also show that differential quaternary phase-shift keying is exactly 2.32 dB worse than quaternary phase-shift keying over the lognormal fading channels in high signal-to-noise ratio regimes.

  17. 20-meter underwater wireless optical communication link with 1.5 Gbps data rate.

    Science.gov (United States)

    Shen, Chao; Guo, Yujian; Oubei, Hassan M; Ng, Tien Khee; Liu, Guangyu; Park, Ki-Hong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S

    2016-10-31

    The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (~10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion.

  18. 20-meter underwater wireless optical communication link with 15 Gbps data rate

    KAUST Repository

    Shen, Chao

    2016-10-24

    The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (∼10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion. © 2016 Optical Society of America.

  19. 20-meter underwater wireless optical communication link with 15 Gbps data rate

    KAUST Repository

    Shen, Chao; Guo, Yong; Oubei, Hassan M.; Ng, Tien Khee; Liu, Guangyu; Park, Kihong; Ho, Kang-Ting; Alouini, Mohamed-Slim; Ooi, Boon S.

    2016-01-01

    The video streaming, data transmission, and remote control in underwater call for high speed (Gbps) communication link with a long channel length (∼10 meters). We present a compact and low power consumption underwater wireless optical communication (UWOC) system utilizing a 450-nm laser diode (LD) and a Si avalanche photodetector. With the LD operating at a driving current of 80 mA with an optical power of 51.3 mW, we demonstrated a high-speed UWOC link offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5 Gbps over a record 20-meter-long underwater channel. The measured bit-error rate (BER) are 2.8 × 10-5, and 3.0 × 10-3, respectively, which pass well the forward error correction (FEC) criterion. © 2016 Optical Society of America.

  20. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

    2011-01-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

  1. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2011-06-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

  2. Test Methods for Telemetry Systems and Subsystems Volume 1: Test Methods for Vehicle Telemetry Systems

    Science.gov (United States)

    2012-05-01

    Noise Test .......................................................................... 5-106 5.29 Transmitter Bit Error Probability ( BEP ) versus Eb/N0...modulation BC Bus controller BCD Binary coded decimal BCM Bit code modulation BEP Bit error probability BER Bit error rate BPF Band-pass filter BW...5.29 Transmitter Phase Noise Test X X 5.30 Transmitter Bit Error Probability ( BEP ) versus Eb/N0 X (5) X (5) X X X X 5.31 Software

  3. Subcarrier MPSK/MDPSK modulated optical wireless communications in lognormal turbulence

    KAUST Repository

    Song, Xuegui; Yang, Fan; Cheng, Julian; Alouini, Mohamed-Slim

    2015-01-01

    Bit-error rate (BER) performance of subcarrier Mary phase-shift keying (MPSK) and M-ary differential phase-shift keying (MDPSK) is analyzed for optical wireless communications over the lognormal turbulence channels. Both exact BER and approximate

  4. Kultur als Ordnungshypothese über Raum?

    OpenAIRE

    Klüter, Helmut

    2009-01-01

    Inhalt: 1 Einleitung 2 Zur Attraktivität von Kultur 3 Kulturologische Methodik 4 Schnittmengen mit und Bindearme zur Kulturgeographie 5 Kritische Argumente gegen Kultur als Ordnungshypothese über Raum 6 Räumliche Abstraktion als Ordnungsstrategie über „Kultur“? 7 Zusammenfassung

  5. An Exact Closed-Form Expression for the BER of Binary Modulations with Dual-Branch Selection over Generalized-K Fading

    KAUST Repository

    Ansari, Imran Shafique

    2012-07-31

    Error performance is one of the main performance measures and the derivation of its closed-form expression has proved to be quite involved for certain systems. In this paper, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing independent but not necessarily identically distributed generalized-K fading is derived in terms of the extended generalized bivariate Meijer G-function.

  6. A New Formula for the BER of Binary Modulations with Dual-Branch Selection over Generalized-K

    KAUST Repository

    Ansari, Imran Shafique

    2012-09-08

    Error performance is one of the main performance measures and the derivation of its closed-form expression has proved to be quite involved for certain communication systems operating over composite fading channels. In this letter, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing independent but not necessarily identically distributed generalized-K fading is derived in terms of the extended generalized bivariate Meijer G-function.

  7. BER analysis of multi-hop heterodyne FSO systems with fixed gain relays over general Malaga turbulence channels

    KAUST Repository

    Alheadary, Wael Ghazy

    2017-07-20

    This work investigates the end-to-end performance of a free space optical amplify-and-forward (AF) fixed-gain relaying system using heterodyne detection over misaligned general Malaga turbulence channels. More specifically, we present exact closed-form expressions for average bit-error rate achievable spectral efficiency non-adaptive/adaptive modulation schemes by employing generalized power series identity of Meijer\\'s G-function. Moreover, asymptotic closed-form expressions are derived to validate our results at high signal-to-noise ratio. In addition, the analytical results have been presented with compare to range of numerical values.

  8. BER analysis of multi-hop heterodyne FSO systems with fixed gain relays over general Malaga turbulence channels

    KAUST Repository

    Alheadary, Wael Ghazy; Park, Kihong; Alouini, Mohamed-Slim

    2017-01-01

    This work investigates the end-to-end performance of a free space optical amplify-and-forward (AF) fixed-gain relaying system using heterodyne detection over misaligned general Malaga turbulence channels. More specifically, we present exact closed-form expressions for average bit-error rate achievable spectral efficiency non-adaptive/adaptive modulation schemes by employing generalized power series identity of Meijer's G-function. Moreover, asymptotic closed-form expressions are derived to validate our results at high signal-to-noise ratio. In addition, the analytical results have been presented with compare to range of numerical values.

  9. Aperture averaging and BER for Gaussian beam in underwater oceanic turbulence

    Science.gov (United States)

    Gökçe, Muhsin Caner; Baykal, Yahya

    2018-03-01

    In an underwater wireless optical communication (UWOC) link, power fluctuations over finite-sized collecting lens are investigated for a horizontally propagating Gaussian beam wave. The power scintillation index, also known as the irradiance flux variance, for the received irradiance is evaluated in weak oceanic turbulence by using the Rytov method. This lets us further quantify the associated performance indicators, namely, the aperture averaging factor and the average bit-error rate (). The effects on the UWOC link performance of the oceanic turbulence parameters, i.e., the rate of dissipation of kinetic energy per unit mass of fluid, the rate of dissipation of mean-squared temperature, Kolmogorov microscale, the ratio of temperature to salinity contributions to the refractive index spectrum as well as system parameters, i.e., the receiver aperture diameter, Gaussian source size, laser wavelength and the link distance are investigated.

  10. Mittheilungen über Scyphomedusen I

    NARCIS (Netherlands)

    Stiasny, G.

    1921-01-01

    Hiemit beabsichtige ich eine Reihe kleinerer Mittheilungen über Semaeostomeen und Rhizostomeen des Rijksmuseums van Natuurlijke Historie in Leiden zu veröffentlichen, welche die Systematik, Biologie, Entwicklungsgeschichte und Anatomie verschiedener Scyphomedusen behandeln. Die vorliegenden beiden

  11. Über dieses Heft

    Directory of Open Access Journals (Sweden)

    Editors / Herausgeber

    2013-06-01

    Full Text Available Bilder, audiovisuelle Medien, elektronische Medien, World Wide Web: Das Erzählen vollzieht sich mittlerweile in vielfältigen Formen. Der intensive Gebrauch von neuen Medien in unterschiedlichen Zusammenhängen begegnet, überlagert und vermischt sich mit der Rezeption traditioneller literarischer Medien, die nach wie vor weit verbreitet sind. Für die Erzählforschung ergibt sich aus der veränderten kulturellen Praxis eine Vielzahl von Folgen. Die vorliegende Ausgabe von DIEGESIS soll einen Eindruck davon vermitteln. So rückt etwa ein Korpus in den Vordergrund, das lange Zeit eine Randexistenz führte: Erzählungen, die nicht oder nicht ausschließlich durch Sprache vermittelt werden, und solche, die nicht mehr nur die Kulturtechnik des Lesens und Schreibens voraussetzen. Andere Techniken, andere Gesten begleiten den Umgang mit diesen Erzählungen, und diese Differenz wird an denjenigen Stellen besonders deutlich, wo unterschiedliche Medien ineinander verschachtelt sind. Die Erzeugung von Komplexität durch intermediale Relationen charakterisiert dieses neue Korpus und öffnet für die Erzählforschung neue Arbeitsfelder. Gerade die markanten Medienwechsel, die mit der Vermarktung erfolgreicher Stoffe – als Roman, als Film, als Computerspiel, als Comic, als YouTube-Parodie – einhergehen, werfen die doppelte Frage auf, was in diesen Varianten das gemeinsame narrative Substrat, und was hingegen medienspezifische Erzählverfahren sind. Der ersten Perspektive folgt in der vorliegenden Ausgabe Matthias Brütsch mit einer kritischen Prüfung transmedialer Narrativitätsvergleiche; die zweite entfalten Sebastian Armbrusts Beitrag über Komplexität in bekannten Fernsehserien wie House und The Wire und Markus Kuhns Analyse der narrativen Funktion der Handkamera als spezifischem Verfahren in Spielfilmen und fiktionalen Internetclips. Selbstverständlich haben sich auch bestehende Kategorien der Erzählforschung unter dem Eindruck gewandelt, dass

  12. Über dieses Heft

    Directory of Open Access Journals (Sweden)

    Editors / Herausgeber

    2013-12-01

    Full Text Available Das journalistische Erzählen ist nicht erst neu zu entdecken – es besitzt eine lange und prominente eigenständige Tradition, die von so unterschiedlichen Autoren wie Émile Zola, Egon Erwin Kisch, Gabriel García Márquez, Tom Wolfe u.v.a.m. geprägt wurde. Narratologische Zugänge haben jedoch in den letzten Jahren zu einer präziseren Beschreibung der besonderen Leistungen journalistischen Erzählens beigetragen. Das verdeutlichen auch die Beiträge dieses Heftes. Ethische Aspekte journalistischer Texte können eng mit den jeweils verwendeten Erzählverfahren zusammenhängen – so die These Friederike Herrmanns. Sie kritisiert den vermeintlich objektiven, quasi erzählerlosen Darstellungsstil von Nachrichten in Printmedien als einen weit verbreiteten, aber vergeblichen Versuch, mit Hilfe einer unsichtbar gemachten Erzählinstanz das Ideal einer reinen Faktenpräsentation zu erreichen. Stattdessen, so ihr Vorschlag, solle der Reporter die Standpunktgebundenheit seines Nachrichtentextes stilistisch und erzählerisch deutlich machen. Im interaktiven Online-Journalismus seien Ansätze zu einer derartigen Nachrichtenvermittlung auf Augenhöhe mit den Lesern erkennbar. Narrativer Journalismus, führt Marie Vanoost aus, sei als hybrides Genre zwischen fiktionaler Erzählliteratur und konventionellen Pressemeldungen angesiedelt. Er zeichne sich durch ebenso komplexe wie spezifische Plotkonstruktionen aus. In drei Fallanalysen untersucht Vanoost mit Hilfe von Begriffen Raphäel Baronis und Paul Ricoeurs das Zusammenspiel von intriguing function (fonction intriguante, in der die Dynamik des Leseprozesses im Vordergrund stehe, und configuring function (fonction configurante, die eher informativ und explikativ orientiert sei. Plotkonstruktionen stehen auch im Vordergrund von Valérie Roberts Beitrag über den journalistischen Umgang mit der „Wulff-Affäre“, die im Jahr 2012 zum Rücktritt des deutschen Bundespräsidenten Christian Wulff f

  13. A 750 MHz semi-digital clock and data recovery circuit with 10−12 BER

    International Nuclear Information System (INIS)

    Wei Xueming; Wang Yiwen; Li Ping; Luo Heping

    2011-01-01

    A semi-digital clock and data recovery (CDR) is presented. In order to lower CDR trace jitter and decrease loop latency, an average-based phase detection algorithm is adopted and realized with a novel circuit. Implemented in a 0.13 μm standard 1P8M CMOS process, our CDR is integrated into a high speed serial and de-serial (SERDES) chip. Measurement results of the chip show that the CDR can trace the phase of the input data well and the RMS jitter of the recovery clock in the observation pin is 122 ps at 75 MHz clock frequency, while the bit error rate of the recovery data is less than 10 × 10 −12 . (semiconductor integrated circuits)

  14. Analytic discrete cosine harmonic wavelet transform based OFDM ...

    Indian Academy of Sciences (India)

    in improving Bit Error Rate (BER) and Peak to Average Power Ratio (PAPR) per- ... as an alternative to Fourier basis has been suggested for multicarrier transmission ..... Ramjee Prasad 2004 OFDM for Wireless Communications Systems.

  15. An OFDM System Using Polyphase Filter and DFT Architecture for Very High Data Rate Applications

    Science.gov (United States)

    Kifle, Muli; Andro, Monty; Vanderaar, Mark J.

    2001-01-01

    This paper presents a conceptual architectural design of a four-channel Orthogonal Frequency Division Multiplexing (OFDM) system with an aggregate information throughput of 622 megabits per second (Mbps). Primary emphasis is placed on the generation and detection of the composite waveform using polyphase filter and Discrete Fourier Transform (DFT) approaches to digitally stack and bandlimit the individual carriers. The four-channel approach enables the implementation of a system that can be both power and bandwidth efficient, yet enough parallelism exists to meet higher data rate goals. It also enables a DC power efficient transmitter that is suitable for on-board satellite systems, and a moderately complex receiver that is suitable for low-cost ground terminals. The major advantage of the system as compared to a single channel system is lower complexity and DC power consumption. This is because the highest sample rate is half that of the single channel system and synchronization can occur at most, depending on the synchronization technique, a quarter of the rate of a single channel system. The major disadvantage is the increased peak-to-average power ratio over the single channel system. Simulation results in a form of bit-error-rate (BER) curves are presented in this paper.

  16. Rate adaptive multilevel coded modulation with high coding gain in intensity modulation direct detection optical communication

    Science.gov (United States)

    Xiao, Fei; Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Zhang, Qi; Tian, Qinghua; Tian, Feng; Wang, Yongjun; Rao, Lan; Ullah, Rahat; Zhao, Feng; Li, Deng'ao

    2018-02-01

    A rate-adaptive multilevel coded modulation (RA-MLC) scheme based on fixed code length and a corresponding decoding scheme is proposed. RA-MLC scheme combines the multilevel coded and modulation technology with the binary linear block code at the transmitter. Bits division, coding, optional interleaving, and modulation are carried out by the preset rule, then transmitted through standard single mode fiber span equal to 100 km. The receiver improves the accuracy of decoding by means of soft information passing through different layers, which enhances the performance. Simulations are carried out in an intensity modulation-direct detection optical communication system using MATLAB®. Results show that the RA-MLC scheme can achieve bit error rate of 1E-5 when optical signal-to-noise ratio is 20.7 dB. It also reduced the number of decoders by 72% and realized 22 rate adaptation without significantly increasing the computing time. The coding gain is increased by 7.3 dB at BER=1E-3.

  17. Neue Werkstoffe über additive Fertigung

    OpenAIRE

    Günther, Johannes; Niendorf, Thomas

    2016-01-01

    Über die additive Fertigung, oftmals bezeichnet als 3D-Druck, lassen sich Bauteile nahezu beliebiger geometrischer Komplexität herstellen. Gleichzeitig lassen die Prozessrandbedingungen die direkte Einstellung der Mikrostruktur in den verwendeten metallischen Werkstoffen zu. Hieraus ergeben sich weitreichende Möglichkeiten bezüglich der Eigenschaftsoptimierung aktueller Hochleistungswerkstoffe.

  18. Bemerkungen über Pedipalpi (Fortsetzung)

    NARCIS (Netherlands)

    Speijer, E.A.M.

    1931-01-01

    In meiner vorigen Mitteilung (Bemerkungen über Pedipalpi, Zoologische Mededeelingen 's Rijks Museum van Natuurlijke Historie te Leiden Deel XIV, Afl. 1—2, 1931, p. 79—88) habe ich schon darauf hingewiesen, dass man bei der Bearbeitung der Thelyphonidae auf eigentümliche Schwierigkeiten stösst. Diese

  19. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong

    2011-07-01

    Visible light communication (VLC) using optical sources which can be simultaneously utilized for illumination and communication is currently an attractive option for wireless personal area network. Improving the data rate in optical wireless communication system is challenging due to the limited bandwidth of the optical sources. In this paper, we design the singular value decomposition (SVD)- based multiplexing multiple-input multiple-output (MIMO) system to support two data streams in optical wireless channels. Noting that the conventional allocation method in radio frequency (RF) MIMO channels cannot be applied directly to the optical intensity channels, we propose a novel method to allocate the optical power, the offset value and the modulation size for maximum sum rate under the constraints of the nonnegativity of the modulated signals, the aggregate optical power and the bit error rate (BER) requirement. The simulation results show that the proposed allocation method gives the better performance than the method to allocate the optical power equally for each data stream. © 2011 IEEE.

  20. A software reconfigurable optical multiband UWB system utilizing a bit-loading combined with adaptive LDPC code rate scheme

    Science.gov (United States)

    He, Jing; Dai, Min; Chen, Qinghui; Deng, Rui; Xiang, Changqing; Chen, Lin

    2017-07-01

    In this paper, an effective bit-loading combined with adaptive LDPC code rate algorithm is proposed and investigated in software reconfigurable multiband UWB over fiber system. To compensate the power fading and chromatic dispersion for the high frequency of multiband OFDM UWB signal transmission over standard single mode fiber (SSMF), a Mach-Zehnder modulator (MZM) with negative chirp parameter is utilized. In addition, the negative power penalty of -1 dB for 128 QAM multiband OFDM UWB signal are measured at the hard-decision forward error correction (HD-FEC) limitation of 3.8 × 10-3 after 50 km SSMF transmission. The experimental results show that, compared to the fixed coding scheme with the code rate of 75%, the signal-to-noise (SNR) is improved by 2.79 dB for 128 QAM multiband OFDM UWB system after 100 km SSMF transmission using ALCR algorithm. Moreover, by employing bit-loading combined with ALCR algorithm, the bit error rate (BER) performance of system can be further promoted effectively. The simulation results present that, at the HD-FEC limitation, the value of Q factor is improved by 3.93 dB at the SNR of 19.5 dB over 100 km SSMF transmission, compared to the fixed modulation with uncoded scheme at the same spectrum efficiency (SE).

  1. Low dose rate gamma ray induced loss and data error rate of multimode silica fibre links

    International Nuclear Information System (INIS)

    Breuze, G.; Fanet, H.; Serre, J.

    1993-01-01

    Fiber optics data transmission from numerous multiplexed sensors, is potentially attractive for nuclear plant applications. Multimode silica fiber behaviour during steady state gamma ray exposure is studied as a joint programme between LETI CE/SACLAY and EDF Renardieres: transmitted optical power and bit error rate have been measured on a 100 m optical fiber

  2. Adaptive upstream rate adjustment by RSOA-ONU depending on different injection power of seeding light in standard-reach and long-reach PON systems

    Science.gov (United States)

    Yeh, C. H.; Chow, C. W.; Shih, F. Y.; Pan, C. L.

    2012-08-01

    The wavelength division multiplexing-time division multiplexing (WDM-TDM) passive optical network (PON) using reflective semiconductor optical amplifier (RSOA)-based colorless optical networking units (ONUs) is considered as a promising candidate for the realization of fiber-to-the-home (FTTH). And this architecture is actively considered by Industrial Technology Research Institute (ITRI) for the realization of FTTH in Taiwan. However, different fiber distances and optical components would introduce different power budgets to different ONUs in the PON. Besides, due to the aging of optical transmitter (Tx), the power decay of the distributed optical carrier from the central office (CO) could also reduce the injection power into each ONU. The situation will be more severe in the long-reach (LR) PON, which is considered as an option for the future access. In this work, we investigate a WDM-TDM PON using RSOA-based ONU for upstream data rate adjustment depending on different continuous wave (CW) injection powers. Both standard-reach (25 km) and LR (100 km) transmissions are evaluated. Moreover, a detail analysis of the upstream signal bit-error rate (BER) performances at different injection powers, upstream data rates, PON split-ratios under stand-reach and long-reach is presented.

  3. Gõtter, Grãber und Gelehrte

    Directory of Open Access Journals (Sweden)

    Pedro Moacyr Campos

    1953-09-01

    Full Text Available CERAM, (C. W.. — Gõtter, Grãber und Gelehrte, Rowohlt Verlag, Hamburg.,  1951, 494 págs. (Primeiro Parágrafo do Artigo Bem merecido foi o sucesso encontrado pelo livro de Ceram, Gotter, Graber und Gelehrte, ("Deuses, túmulos e eruditos", que alcançou a cifra de 106.000 exemplares entre novembro de 1949 e março de 1951, continuando a ser reimpresso após esta data.

  4. Lipman Bers, a life in mathematics

    CERN Document Server

    Keen, Linda; Rodríguez, Rubí E

    2015-01-01

    The book is part biography and part collection of mathematical essays that gives the reader a perspective on the evolution of an interesting mathematical life. It is all about Lipman Bers, a giant in the mathematical world who lived in turbulent and exciting times. It captures the essence of his mathematics, a development and transition from applied mathematics to complex analysis-quasiconformal mappings and moduli of Riemann surfaces-and the essence of his personality, a progression from a young revolutionary refugee to an elder statesman in the world of mathematics and a fighter for global h

  5. Adaptive Modulation with Best User Selection over Non-Identical Nakagami Fading Channels

    KAUST Repository

    Rao, Anlei; Alouini, Mohamed-Slim

    2012-01-01

    capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER

  6. Effect of Post-Harvest Treatments on Enzyme Activity and Quality of Cold Stored Ber Fruit

    Directory of Open Access Journals (Sweden)

    Sukhjit K. JAWANDHA

    2012-11-01

    Full Text Available Ber (Zizyphus mauritiana Lamk fruits are perishable in nature and have poor shelf- life. To extend the storage life of ber fruits different post-harvest treatments, like CaCl2 (0.5, 1.0 and 2.0%, Ca(NO32 (0.5, 1.0 and 2.0%, gibberellic acid (GA3 (20, 40 and 60 ppm and Bavistin (0.1% were given to fruits and their effect was studied on the storage life and quality of Umran ber (Zizyphus mauritiana Lamk fruits under cold storage conditions. Fruits of uniform size and colour were harvested, from healthy plants, and subjected to post harvest dip of different chemicals, before packing in CFB boxes and placed in cold storage (3-5C and 85-90% RH They have been evaluated after 10, 20 and 30 days of storage for physiological loss in weight (PLW, firmness, pectin methyl esterase (PME activity and palatability rating. The PLW increased and fruit firmness decreased during storage at each treatment. The sensory rating increased up to 10 days at all treatments, except control but subsequently it decreased during storage. The increase rate in PME activity was faster, up to 10 days, in untreated fruits, while treated fruits showed slower rise in PME activity, up to 20 days with a decline afterwards. It can be concluded that ber fruits can be stored up to 20 days by post-harvest treatment using GA3 at 60 ppm, with acceptable quality.

  7. Optical fiber communication — An overview

    Indian Academy of Sciences (India)

    This paper deals with the historical development of optical communication systems and their failures initially. Then the different generations in optical fiber communication along with their features are discussed. Some aspects of total internal reflection, different types of fibers along with their size and refractive index profile, ...

  8. Multiscale Computation. Needs and Opportunities for BER Science

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Timothy D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smith, Jeremy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-01-01

    The Environmental Molecular Sciences Laboratory (EMSL), a scientific user facility managed by Pacific Northwest National Laboratory for the U.S. Department of Energy, Office of Biological and Environmental Research (BER), conducted a one-day workshop on August 26, 2014 on the topic of “Multiscale Computation: Needs and Opportunities for BER Science.” Twenty invited participants, from various computational disciplines within the BER program research areas, were charged with the following objectives; Identify BER-relevant models and their potential cross-scale linkages that could be exploited to better connect molecular-scale research to BER research at larger scales and; Identify critical science directions that will motivate EMSL decisions regarding future computational (hardware and software) architectures.

  9. BER EVALUATION OF LDPC CODES WITH GMSK IN NAKAGAMI FADING CHANNEL

    Directory of Open Access Journals (Sweden)

    Surbhi Sharma

    2010-06-01

    Full Text Available LDPC codes (Low Density Parity Check Codes have already proved its efficacy while showing its performance near to the Shannon limit. Channel coding schemes are spectrally inefficient as using an unfiltered binary data stream to modulate an RF carrier that will produce an RF spectrum of considerable bandwidth. Techniques have been developed to improve this bandwidth inefficiency or spectral efficiency, and ease detection. GMSK or Gaussian-filtered Minimum Shift Keying uses a Gaussian Filter of an appropriate bandwidth so as to make system spectrally efficient. A Nakagami model provides a better explanation to less and more severe conditions than the Rayleigh and Rician model and provide a better fit to the mobile communication channel data. In this paper we have demonstrated the performance of Low Density Parity Check codes with GMSK modulation (BT product=0.25 technique in Nakagami fading channel. In results it is shown that average bit error rate decreases as the ‘m’ parameter increases (Less fading.

  10. Optimal linear detectors for nonorthogonal amplify-and-forward protocol

    KAUST Repository

    Ahmed, Qasim Zeeshan; Park, Kihong; Alouini, Mohamed-Slim; Aissa, Sonia

    2013-01-01

    In this paper, we propose optimal linear detectors for non-orthogonal amplify-and-forward cooperative protocol when considering a single-relay scenario. Two types of detectors are proposed based on the principles of minimum mean square error (MMSE) and minimum bit error rate (MBER). The MMSE detector minimizes the mean square error, while the MBER minimizes the system bit error rate (BER). Both detectors exhibit excellent BER performance with relatively low complexity as compared to the maximal likelihood (ML) detector. The BER performance of both detectors is superior to the channel inversion, the maximal ratio combining, and the biased ML detectors. © 2013 IEEE.

  11. Optimal linear detectors for nonorthogonal amplify-and-forward protocol

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2013-06-01

    In this paper, we propose optimal linear detectors for non-orthogonal amplify-and-forward cooperative protocol when considering a single-relay scenario. Two types of detectors are proposed based on the principles of minimum mean square error (MMSE) and minimum bit error rate (MBER). The MMSE detector minimizes the mean square error, while the MBER minimizes the system bit error rate (BER). Both detectors exhibit excellent BER performance with relatively low complexity as compared to the maximal likelihood (ML) detector. The BER performance of both detectors is superior to the channel inversion, the maximal ratio combining, and the biased ML detectors. © 2013 IEEE.

  12. Replacing the soft-decision FEC limit paradigm in the design of optical communication systems

    NARCIS (Netherlands)

    Alvarado, A.; Agrell, E.; Lavery, D.; Maher, R.; Bayvel, P.

    2016-01-01

    The FEC limit paradigm is the prevalent practice for designing optical communication systems to attain a certain bit error rate (BER) without forward error correction (FEC). This practice assumes that there is an FEC code that will reduce the BER after decoding to the desired level. In this paper,

  13. A novel technique to increase the capacity of code division multiple ...

    African Journals Online (AJOL)

    linear parallel interference cancellation (WLPIC) technique for N = 64 at a Bit Error Rate (BER) of 10-3 and 75% overloading at a BER of 10-2. The three-stage WLPIC scheme clearly outperforms matched filter detector, Conventional LPIC and the twostage WLPIC on Additive White Gaussian Noise (AWGN) channel.

  14. Alfredo Häberli ja Iittala : Senta / Piret Veigel

    Index Scriptorium Estoniae

    Veigel, Piret, 1961-

    2004-01-01

    Jaanuaris Pariisi messil Maison & Objet aasta disaineriks kuulutatud Alfredo Häberli esitles veebruaris Frankfurdi messil Ambiente oma neljandat ühisprojekti Soome Iittalaga: Senta-nimelisi valge, punase ja vahuveini klaase

  15. Subcarrier MPSK/MDPSK modulated optical wireless communications in lognormal turbulence

    KAUST Repository

    Song, Xuegui

    2015-03-01

    Bit-error rate (BER) performance of subcarrier Mary phase-shift keying (MPSK) and M-ary differential phase-shift keying (MDPSK) is analyzed for optical wireless communications over the lognormal turbulence channels. Both exact BER and approximate BER expressions are presented. We demonstrate that the approximate BER, which is obtained by dividing the symbol error rate by the number of bits per symbol, can be used to estimate the BER performance with acceptable accuracy. Through our asymptotic analysis, we derive closed-form asymptotic BER performance loss expression for MDPSK with respect to MPSK in the lognormal turbulence channels. © 2015 IEEE.

  16. Effect of Post-Harvest Treatments on Enzyme Activity and Quality of Cold Stored Ber Fruit

    Directory of Open Access Journals (Sweden)

    Sukhjit K. JAWANDHA

    2012-11-01

    Full Text Available Ber (Zizyphus mauritiana Lamk fruits are perishable in nature and have poor shelf- life. To extend the storage life of ber fruits different post-harvest treatments, like CaCl2 (0.5, 1.0 and 2.0%, Ca(NO32 (0.5, 1.0 and 2.0%, gibberellic acid (GA3 (20, 40 and 60 ppm and Bavistin (0.1% were given to fruits and their effect was studied on the storage life and quality of �Umran� ber (Zizyphus mauritiana Lamk fruits under cold storage conditions. Fruits of uniform size and colour were harvested, from healthy plants, and subjected to post harvest dip of different chemicals, before packing in CFB boxes and placed in cold storage (3-5�C and 85-90% RH They have been evaluated after 10, 20 and 30 days of storage for physiological loss in weight (PLW, firmness, pectin methyl esterase (PME activity and palatability rating. The PLW increased and fruit firmness decreased during storage at each treatment. The sensory rating increased up to 10 days at all treatments, except control but subsequently it decreased during storage. The increase rate in PME activity was faster, up to 10 days, in untreated fruits, while treated fruits showed slower rise in PME activity, up to 20 days with a decline afterwards. It can be concluded that ber fruits can be stored up to 20 days by post-harvest treatment using GA3 at 60 ppm, with acceptable quality.

  17. Risk of the research reactor BER II in Berlin; Risiken des Berliner Experimentierreaktors BER II

    Energy Technology Data Exchange (ETDEWEB)

    Paulitz, Henrik; Hoevener, Barbara; Rosen, Alex

    2015-04-20

    The research reactor BER II is sited at the periphery of Berlin in the neighborhood of residential areas. The operational license is limited until December 31, 2019. The reactor is funded by the Federal Government (90%) and the city of Berlin (10%). The stress test has shown that the reactor is not secured against an aircraft crash (airliner or fast flying military jet), meltdown with remarkable radiological consequences to the public would be the consequence. Further hazards result from the radioactive waste transport, explosions and fires. The emergency measures cannot be considered to be sufficient. The city of Berlin would not be able to fulfill the required measures in case of a radiation accident.

  18. HEU/LEU-conversion of BER II successfully finished

    International Nuclear Information System (INIS)

    Haas, K.; Fischer, C.-O.; Krohn, H.

    2000-01-01

    The BER II (Berliner Experimental Reactor) research reactor is a swimming pool type reactor located in Berlin, Germany. The reactor operates with a thermal power of 10 MW and is primarily used to produce neutrons for neutron scattering experiments. The conversion from HEU- to LEU-fuel elements began in August, 1997. At the last RERTR Meeting 1999 in Budapest, Hungary, Hahn-Meitner-Institut (HMI) presented a 'Status Report' on the conversion of 10 HEU/LEU mixed cores. In February 2000, HMI finished the HEU/LEU-conversion. Hereby, the first pure LEU-standard-core went into operation. Our second LEU-core just ends its operation at the end of July. The third LEU-core will be built up in the beginning of August. The average burn-up rate was improved from 50 - 55% (HEU) to 60 - 65% (LEU). Therefore, only 14 elements/year are now used instead of 28/year. The following report describes our first steps in building pure LEU-cores from mixed HEU/LEU-cores, as well as our initial experience using the pure LEU-cores. (author)

  19. Experimental Analysis of 60-GHz VCSEL and ECL Photonic Generation and Transmission of Impulse-Radio Ultra-Wideband Signals

    DEFF Research Database (Denmark)

    Beltran, Marta; Jensen, Jesper Bevensee; Llorente, Roberto

    2011-01-01

    for comparison purposes. Real-time bit-error-rate (BER) performance of generated signals at 3.125 Gb/s is evaluated combining fiber and 2-m wireless transmission. Different optical fiber types including 1-km bend-insensitive single-mode fiber and 20-km nonzero dispersion-shifted fiber is evaluated. $\\hbox......{BER} for the ECL and $\\hbox{BER} for the VCSEL requiring higher received optical power than the ECL is demonstrated employing electrical power detection....

  20. Performance analysis of bi-directional broadband passive optical network using erbium-doped fiber amplifier

    Science.gov (United States)

    Almalaq, Yasser; Matin, Mohammad A.

    2014-09-01

    The broadband passive optical network (BPON) has the ability to support high-speed data, voice, and video services to home and small businesses customers. In this work, the performance of bi-directional BPON is analyzed for both down and up streams traffic cases by the help of erbium doped fiber amplifier (EDFA). The importance of BPON is reduced cost. Because PBON uses a splitter the cost of the maintenance between the providers and the customers side is suitable. In the proposed research, BPON has been tested by the use of bit error rate (BER) analyzer. BER analyzer realizes maximum Q factor, minimum bit error rate, and eye height.

  1. Storage temperature affects fruit quality attributes of Ber ( Ziziphus ...

    African Journals Online (AJOL)

    Fruit utilization is affected by quality attributes and shelf life. The quality of Jujube or Ber (Ziziphus mauritiana Lamk.) fruits after harvest depends on storage conditions used. In this study, different storage temperatures and durations were evaluated to determine the appropriate storage conditions of fresh fruits of Z.

  2. High Data Rate Optical Wireless Communications Based on Ultraviolet Band

    KAUST Repository

    Sun, Xiaobin

    2017-10-01

    . The measured bit-error rate (BER) of 2.8 × 10−4 and 2.4 × 10−4, respectively, are well below the forward error correction (FEC) criterion of 3.8 × 10−3. The demonstrated high data-rate OFDM-based UVB communication link paves the way for realizing high-speed non-line-of-sight free-space optical (FSO) communications.

  3. A Qualidade Observada em Salas de Berçário

    OpenAIRE

    Tadeu, Bárbara; Aguiar, Cecília

    2017-01-01

    RESUMO Este estudo teve como objetivo investigar a qualidade de estruturas formais de educação para crianças com menos de 12 meses de idade. Participaram 30 salas de berçário de Setúbal e Palmela, no sul de Portugal. A qualidade global das salas foi avaliada com base na Infant/Toddler Environment Rating Scale - Revised Edition e as práticas de socialização, com base na Caregiver Interaction Scale. Os resultados revelam qualidade global média moderada das salas e elevada qualidade nas práticas...

  4. Untersuchungen über Veronica triloba (Opiz) Kerner in Rheinhessen

    OpenAIRE

    Oesau, Albert

    1981-01-01

    Untersuchungen in den Jahren 1977-1979 ergaben, daß Veronica triloba (Opiz) Kerner, eine Sippe aus dem Veronica hederifolia-Aggregat, in Rheinhessen überraschenderweise weit verbreitet ist und bisher übersehen wurde. Sie siedelt vor allem in Ackerunkraut- und Felsgrus-Gesellschaften sowie lückigen Trockenrasen, ohne eine gesellschaftsspezifische Bindung zu zeigen. Gut ausgeprägte morphologische Merkmale gestatten eine sichere Differenzierung gegenüber den übrigen Sippenvertretern V. hederifol...

  5. Discrete polyphase matched filtering-based soft timing estimation for mobile wireless systems

    CSIR Research Space (South Africa)

    Olwal, TO

    2009-01-01

    Full Text Available of the communication system is conserved. However, the computational complexity of ideal turbo synchronization is increased by 50%. Several simulation tests on bit error rate (BER) and block error rate (BLER) versus low SNR reveal that the proposed iterative soft...

  6. Irradiation devices at the upgraded research reactor BER II

    International Nuclear Information System (INIS)

    Gawlik, D.; Robertson, T.

    1992-06-01

    An overview is given of those properties of the BER II research reactor which are important for carrying out irradiation experiments. The subsequent section describes the irradiation devices currently installed in the reactor, or which are under construction, and some of the experiments which can be conducted using them. The field of application of these experiments extends from the study of the metabolism of trace elements in man, employing a highly sensitive element analysis, via radiation damage of high-tech materials, to the identification of paintings of the old masters. The report concludes with a review of the technical details of the irradiation devices, giving information of interest for potential users. (orig.)

  7. Richard Wollheim über die Metapher in der Malerei

    OpenAIRE

    Heinrich, Richard

    1993-01-01

    Es handelt sich um den Text eines Vortrages, den ich Jänner 1993 im Rahmen einer Vortragsreihe am Institut für Kunstgeschichte der Universität Wien gehalten habe. Er ist bisher unpubliziert und nicht redigiert. Das worüber ich spreche ist ein Artikel von Richard Wollheim mit dem Titel "Die Metapher in der Malerei". Diesen Artikel habe ich herausgegeben, gemeinsam mit meinem Kollegen Helmuth Vetter, 1991 in dem Band "Bilder der Philosophie". Ursprünglich handelt es sich um einen Vortrag, d...

  8. Experimental analysis of THz receiver performance in 80 Gbit/s communication system

    DEFF Research Database (Denmark)

    Jia, Shi; Yu, Xianbin; Hu, Hao

    2016-01-01

    –450 GHz band with 4×10 GBaud/s QPSK modulation, reaching an overall capacity of 80 Gbit/s. The bit error rate (BER) performance for all the channels reaches below the forward error correction (FEC) threshold of 3.8∗10−3, and the experimental results indicate that the existence of harmonics spurs...

  9. Binary palmprint representation for feature template protection

    NARCIS (Netherlands)

    Mu, Meiru; Ruan, Qiuqi; Shao, X.; Spreeuwers, Lieuwe Jan; Veldhuis, Raymond N.J.

    2012-01-01

    The major challenge of biometric template protection comes from the intraclass variations of biometric data. The helper data scheme aims to solve this problem by employing the Error Correction Codes (ECC). However, many reported biometric binary features from the same user reach bit error rate (BER)

  10. Physically Protected Spread Spectrum Communications

    Science.gov (United States)

    2016-04-14

    c) it shows bit error rate (BER) performance with negligible degradation in SNR, compared to that of a coherent FH system. These advantages of the...Advanced),” IEEE International Conference on Communication Systems (ICCS), Singapore , pp. 146–150, Nov. 2010. [4] K.S. Gong, “Performance of Diversity

  11. Interferometric crosstalk reduction by phase scrambling

    NARCIS (Netherlands)

    Tafur Monroy, I.; Tangdiongga, E.; Jonker, R.J.W.; Waardt, de H.

    2000-01-01

    Interferometric crosstalk, arising from the detection of undesired signals at the same nominal wavelength, may introduce large power penalties and bit-error rate (BER) floor significantly restricting the scalability of optical networks. In this paper, interferometric crosstalk reduction in optical

  12. Throughput Performance Evaluation of Multiservice Multirate OCDMA in Flexible Networks

    DEFF Research Database (Denmark)

    Raddo, Thiago R.; Sanches, Anderson L.; Tafur Monroy, Idelfonso

    2016-01-01

    in the system. The bit error rate (BER) and packet correct probability expressions are derived, considering the multiple-access interference as binomially distributed. Packet throughput expressions, on the other hand, are derived considering Poisson, binomial, and Markov chain approaches for the composite......, the binomial approach proved to be more straightforward, computationally more efficient, and just as accurate as the Markov chain approach....

  13. COMOPTEVFOR Acronym and Abbreviation List (CAAL).

    Science.gov (United States)

    1981-10-01

    Control AFCS Automatic Flight Control System AD Acoustic Firing Device AFEWC Air Force Electronic Warfare Center * AFETR Air Force Eastern Test Range...Dressing Station * BE Bearing Error BER Bit Effectiveness Report Bit Error Rate BETA Battlefield Exploitation and Target Acquisition BFDL Blue Force...System Command Destruct System CDSS Command Decision Subsystem CE Cost Effectiveness Critical Examination CEB CNO Executive Board CEI Communications

  14. 47 CFR 27.1252 - Involuntary Relocation Procedures.

    Science.gov (United States)

    2010-10-01

    ... costs, including all engineering, equipment, site and FCC fees, as well as any legitimate and prudent... measured by the percent of time the bit error rate (BER) exceeds a desired value, and for analog or digital video transmissions, it is measured by whether the end-to-end transmission delay is within the required...

  15. 47 CFR 27.1251 - Mandatory Negotiations.

    Science.gov (United States)

    2010-10-01

    ... incumbent. In evaluating claims that a party has not negotiated in good faith, the FCC will consider, inter..., reliability is measured by the percent of time the bit error rate (BER) exceeds a desired value, and for analog or digital video transmission, it is measured by whether the end-to-end transmission delay is...

  16. 47 CFR 101.91 - Involuntary relocation procedures.

    Science.gov (United States)

    2010-10-01

    ... engineering, equipment, site and FCC fees, as well as any legitimate and prudent transaction expenses incurred..., reliability is measured by the percent of time the bit error rate (BER) exceeds a desired value, and for analog or digital voice transmissions, it is measured by the percent of time that audio signal quality...

  17. 47 CFR 101.75 - Involuntary relocation procedures.

    Science.gov (United States)

    2010-10-01

    ... engineering, equipment, site and FCC fees, as well as any legitimate and prudent transaction expenses incurred... reliability of their system. For digital data systems, reliability is measured by the percent of time the bit error rate (BER) exceeds a desired value, and for analog or digital voice transmissions, it is measured...

  18. 47 CFR 22.602 - Transition of the 2110-2130 and 2160-2180 MHz channels to emerging technologies.

    Science.gov (United States)

    2010-10-01

    ... process. In evaluating claims that a party has not negotiated in good faith, the FCC will consider, inter... relocation costs, including all engineering, equipment, site and FCC fees, as well as any legitimate and..., reliability is measured by the percent of time the bit error rate (BER) exceeds a desired value, and for...

  19. Exact performance analysis of decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel; Alouini, Mohamed-Slim; Yang, Hongchuan

    2010-01-01

    the decision to cooperate takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive an exact closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation

  20. Wavelet based multicarrier code division multiple access ...

    African Journals Online (AJOL)

    This paper presents the study on Wavelet transform based Multicarrier Code Division Multiple Access (MC-CDMA) system for a downlink wireless channel. The performance of the system is studied for Additive White Gaussian Noise Channel (AWGN) and slowly varying multipath channels. The bit error rate (BER) versus ...

  1. An Importance Sampling Simulation Method for Bayesian Decision Feedback Equalizers

    OpenAIRE

    Chen, S.; Hanzo, L.

    2000-01-01

    An importance sampling (IS) simulation technique is presented for evaluating the lower-bound bit error rate (BER) of the Bayesian decision feedback equalizer (DFE) under the assumption of correct decisions being fed back. A design procedure is developed, which chooses appropriate bias vectors for the simulation density to ensure asymptotic efficiency of the IS simulation.

  2. Low-Power and Reliable Communications for UWB-Based Wireless Monitoring Sensor Networks in Underground Mine Tunnels

    OpenAIRE

    Abou El-Nasr, Mohamad; Shaban, Heba

    2015-01-01

    This paper investigates the bit-error-rate (BER) and maximum allowable data throughput (MADTh) performance of a novel low-power mismatched Rake receiver structure for ultra wideband (UWB) wireless monitoring sensor networks in underground mine tunnels. This receive node structure provides a promising solution for low-power and reliable communications in underground mine tunnels with more than 90% reduction in power consumption. The BER and MADTh of the proposed receive nodes are investigated ...

  3. BER Science Network Requirements Workshop -- July 26-27,2007

    Energy Technology Data Exchange (ETDEWEB)

    Tierney, Brian L.; Dart, Eli

    2008-02-01

    The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the US Department of Energy Office of Science, the single largest supporter of basic research in the physical sciences in the United States of America. In support of the Office of Science programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs that it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 20 years. In July 2007, ESnet and the Biological and Environmental Research (BER) Program Office of the DOE Office of Science organized a workshop to characterize the networking requirements of the science programs funded by the BER Program Office. These included several large programs and facilities, including Atmospheric Radiation Measurement (ARM) Program and the ARM Climate Research Facility (ACRF), Bioinformatics and Life Sciences Programs, Climate Sciences Programs, the Environmental Molecular Sciences Laboratory at PNNL, the Joint Genome Institute (JGI). National Center for Atmospheric Research (NCAR) also participated in the workshop and contributed a section to this report due to the fact that a large distributed data repository for climate data will be established at NERSC, ORNL and NCAR, and this will have an effect on ESnet. Workshop participants were asked to codify their requirements in a 'case study' format, which summarizes the instruments and facilities necessary for the science and the process by which the science is done, with emphasis on the network services needed and the way in which the network is used. Participants were asked to consider three time scales in their case studies--the near term (immediately and up to 12 months in the future), the medium term (3-5 years in the future), and the long term (greater than 5 years in the future). In addition to achieving its goal of collecting and

  4. Risk of the research reactor BER II in Berlin

    International Nuclear Information System (INIS)

    Paulitz, Henrik; Hoevener, Barbara; Rosen, Alex

    2015-01-01

    The research reactor BER II is sited at the periphery of Berlin in the neighborhood of residential areas. The operational license is limited until December 31, 2019. The reactor is funded by the Federal Government (90%) and the city of Berlin (10%). The stress test has shown that the reactor is not secured against an aircraft crash (airliner or fast flying military jet), meltdown with remarkable radiological consequences to the public would be the consequence. Further hazards result from the radioactive waste transport, explosions and fires. The emergency measures cannot be considered to be sufficient. The city of Berlin would not be able to fulfill the required measures in case of a radiation accident.

  5. Workshop on instrumentation of the disassembled BER II

    International Nuclear Information System (INIS)

    Jauch, W.; Steiner, M.

    1982-01-01

    A workshop on the instrumentation of a disassembled BER II-reactor took place in the Hahn-Meitner-Institute in Berlin on April 19 and 20, 1982. Invited were all groups that are promoted by the associations 'Neutron Scattering for Investigation of Condensed Substance' and 'Neutron Scattering and Complementary Methods in Chemistry and Biology', along with experts for neutron spectrometers. 40 foreign scientists from 22 different institutes had accepted the invitation. The actual questions were treated in 13 presentations and a certain number of posters, with the latter also comprising activation analysis. The present report contains the presentations submitted, the final discussion minutes and a summary from HMI-view. (orig./RW) [de

  6. Neutron scattering-instrumentation at the upgraded research reactor BER II

    International Nuclear Information System (INIS)

    1991-01-01

    The Berlin Neutron Scattering Centre (BENSC) is a newly created special department of the Hahn-Meitner-Institut, in the framework of which the BER II neutron beam reactor is made available to external users. BENSC is devoted to development, continuous modernisation and maintenance of the scientific instrumets at the BER II and to the support of their users. (orig./HSI)

  7. Transmission of Voice Signal: BER Performance Analysis of Different FEC Schemes Based OFDM System over Various Channels

    OpenAIRE

    Rashed, Md. Golam; Kabir, M. Hasnat; Reza, Md. Selim; Islam, Md. Matiqul; Shams, Rifat Ara; Masum, Saleh; Ullah, Sheikh Enayet

    2012-01-01

    In this paper, we investigate the impact of Forward Error Correction (FEC) codes namely Cyclic Redundancy Code and Convolution Code on the performance of OFDM wireless communication system for speech signal transmission over both AWGN and fading (Rayleigh and Rician) channels in term of Bit Error Probability. The simulation has been done in conjunction with QPSK digital modulation and compared with uncoded resultstal modulation. In the fading channels, it is found via computer simulation that...

  8. BER IMPROVEMENT OF WIRELESS LAN IEEE 802.11 STANDARD USING WAVELET PACKET TRANSFORMS

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar

    2012-09-01

    Full Text Available High data rates and spectral efficiency is the main requirements for wireless communication systems. Orthogonal Frequency Division Multiplexing (OFDM is a special form of multi carrier transmission used to achieve high data rates of the various WLAN standards. WLAN uses an Inverse Fast Fourier Transform (IFFT at the transmitter to modulate a high bit-rate signal onto a number of carriers and ensure orthogonality between the carriers. The FFT-OFDM has a disadvantage that it is inherently inflexible and requires a complex IFFT core. Recently, Wavelet Packet Transform is proposed as an alternate to FFT. It is a multiplexing method in which data is assigned to wavelet sub bands having different time and frequency resolutions. This paper presents a BER analysis of Fourier-based OFDM (FFT-OFDM and Wavelet Packet based OFDM (WPT-OFDM in WLAN standard (IEEE 802.11a. The performance of FFT and WPT OFDM for various modulation techniques such as PSK, DPSK and QAM for varying values of M was evaluated in AWGN Channel.

  9. Effect of gamma irradiation on antioxidant properties of ber (Zizyphus mauritiana) fruit

    International Nuclear Information System (INIS)

    Kavitha, C.; Kuna, Aparna; Sagar, S.B.; Padmavati, T.V.N.; Supraja, T.; Prabhakar, N.

    2015-01-01

    Effect of gamma irradiation (0.25 to 1.0kGy) on antioxidant properties of ber fruit was studied. Antioxidant properties of ber fruits were determined by scavenging DPPH radical activity, reducing power assay, super oxide anion radical activity, TBARS, total phenolic content and total flavonoid content. Gamma irradiation treatment up to 1.0 kGy elevated the scavenging DPPH radical activity (9 %), super oxide anion radical activity (26 %) and total flavonoid content (208 %) compared to fresh ber fruit. On the other hand it brought down the reducing power activity (65 %) and total phenolic content (18 %) as compared to raw fruit. The TBARS activity statistically increased upon irradiation of ber fruit. It indicated that total antioxidant activity decreased as TBARS value increased. Therefore 0.25 to 0.5kGy is better dose to retain the natural antioxidant in fruit. (author)

  10. Bulgarian Emergency Response System (BERS) in case of nuclear accident with exposure doses’estimation

    Energy Technology Data Exchange (ETDEWEB)

    Syrakov, M.; Prodanova, M.; Slavov, K.; Veleva, B.

    2015-07-01

    A PC-oriented Emergency Response System in case of nuclear accident (BERS) is developed and works operationally in the National Institute of Meteorology and Hydrology (NIMH). The creation and development of BERS was highly stimulated by the ETEX (European Tracer Experiment) project. BERS comprises two main parts - the operational and the accidental ones. The operational part, run automatically every 12 hours, prepares the input meteorological file used by both trajectory and dispersion models, runs the trajectory models, visualizes the results and uploads the maps of trajectories to a dedicated web-site. The accidental part is activated manually when a real radioactive releases occur or during emergency exercises. Its core is the Bulgarian dispersion models EMAP. Outputs are concentration, accumulated deposition and selected doses fields. In the paper, the BERS overall structure is described and examples of its products are presented. (Author)

  11. Bulgarian Emergency Response System (BERS) in case of nuclear accident with exposure doses estimation

    Energy Technology Data Exchange (ETDEWEB)

    Syrakov, D.; Prodanova, M.; Slavov, K.; Veleva, B.

    2015-07-01

    A PC-oriented Emergency Response System in case of nuclear accident (BERS) is developed and works operationally in the National Institute of Meteorology and Hydrology (NIMH). The creation and development of BERS was highly stimulated by the ETEX (European Tracer Experiment) project. BERS comprises two main parts - the operational and the accidental ones. The operational part, run automatically every 12 hours, prepares the input meteorological file used by both trajectory and dispersion models, runs the trajectory models, visualizes the results and uploads the maps of trajectories to a dedicated web-site. The accidental part is activated manually when a real radioactive releases occur or during emergency exercises. Its core is the Bulgarian dispersion models EMAP. Outputs are concentration, accumulated deposition and selected doses fields. In the paper, the BERS overall structure is described and examples of its products are presented. Key words: nuclear accident, emergency response, early warning system, air dispersion models, radioactive exposure dose. (Author)

  12. Linewidth-tolerant 10-Gbit/s 16-QAM transmission using a pilot-carrier based phase-noise cancelling technique.

    Science.gov (United States)

    Nakamura, Moriya; Kamio, Yukiyoshi; Miyazaki, Tetsuya

    2008-07-07

    We experimentally demonstrated linewidth-tolerant 10-Gbit/s (2.5-Gsymbol/s) 16-quadrature amplitude modulation (QAM) by using a distributed-feedback laser diode (DFB-LD) with a linewidth of 30 MHz. Error-free operation, a bit-error rate (BER) of noise canceling capability provided by a pilot-carrier and standard electronic pre-equalization to suppress inter-symbol interference (ISI) gave clear 16-QAM constellations and floor-less BER characteristics. We evaluated the BER characteristics by real-time measurement of six (three different thresholds for each I- and Q-component) symbol error rates (SERs) with simultaneous constellation observation.

  13. Germanismen im epilinguistischen Diskurs über die Zagreber Umgangssprache und in der Reflexion über den eigenen Sprachgebrauch

    Directory of Open Access Journals (Sweden)

    Goranka Rocco

    2014-03-01

    Full Text Available Abstract – This paper sheds light on the epilinguistic discourse on germanisms in themetropolitan dialect of Zagreb. The empirical study is based on two methods: 1 the qualitative analysis of the internet forum discussion on what the dialectof Zagreb is, what the germanisms "purger" and "purgerski" mean, to what extent germanisms and elements from other languages should beused and why they are used; 2 the written questionnaire assessing theself-perception of the use of germanisms. The results of both inquiries arecompared and contrasted in order to gain a more complete picture of languageattitudes and language use in a given situation and the way of expressing themin the epilinguistic discourse.Keywords:epilinguisticdiscourse, germanisms, self-perception, language attitudes, language useAbstract –  Die Studie wendet sich dem epilinguistischen Diskursüber die Germanismen in der Stadtsprache von Zagreb zu. Sie setzt sich zumZiel, anhand der qualitätiven Analyse der Internetforum-Beiträge und der schriftlichenBefragung herauszufinden, um welche Themen der epilinguistische Diskurs überdie Germanismen kreist, wie lebendig diese in der Sprache zweier verschiedenenGenerationen der gebürtiger Zagreber sind, inweiweit die Sprecher Veränderungenim eigenen Sprachgebruch wahrnehmen, ob und welche Ausdrücke von den ihnen alstypisch für die Zagreber Umgangssprache (purgerski betrachtet werden und,damit verbunden, wie die Bedeutung der auf die Stadtsprache und -mentalitätbezogenen Germanismen „purger" und "purgerski" definiert wird.Schlüsselwörter:epilinguistischerDiskurs, Germanismus, Selbstwahrnehmung, Spracheinstellungen, Sprachgebrauch.

  14. A atualidade da visão de Ab’Sáber / The current view of Ab’Sáber

    Directory of Open Access Journals (Sweden)

    Claudio Antonio Di Mauro

    2012-04-01

    Full Text Available A produção científica⃰ pela lavra do Professor Aziz Nacib Ab´Sáber é revisitada em, pelo menos, três aspectos considerados fundamentais: 1 a geomorfologia e a evolução paleoclimática no terciário e quaternário, quando o autor reconhece que os estudos de fisiologia de paisagens, ainda que essenciais para os objetivos dos geomorfologistas, somente podem ser esclarecidos à custa de pesquisas marcadamente interdisciplinares; 2 as mudanças climáticas em processos, que são ignoradas nos conhecimentos sobre o presente, e as heranças obtidas ao longo da história do Planeta Terra, para planejar, com cuidados, as ações que as sociedades promoveriam em busca do “desenvolvimento”; 3 o sítio urbano de São Paulo, em meados do século passado, quando, em menos de 15 anos, a cidade que nasceu e cresceu sobre colinas, e que elegeu as colinas como seu tipo ideal de sítio topográfico, desceu para as várzeas, ocupando setores e glebas importantes das planícies recém enxugadas pelas obras da Companhia Light. As contribuições, inicialmente elaboradas sob a perspectiva geomorfológica, tinham, em suas essências, a visão geográfica do cidadão do mundo.

  15. Das Volkslied in Deutschland, Frankreich, Belgien und Holland. Untersuchungen über die Auffassung des Begriffes; Über die traditionellen Zeilen, die Zahlen-, Blumen- und Farbensymbolik

    NARCIS (Netherlands)

    Brouwer, Cornelis

    1930-01-01

    Wenn man die gewaltige Menge Publikationen über das Volkslied, die im Laufe des 19. und 20. Jahrhunderts in Deutschland, Frankreich, Belgien und Holland erschienen sind, vergleicht, springen zwei Punkte sofort ins Auge: 1. der Unterschied zwischen den verschiedenen Auffassungen vom Begriff Volkslied

  16. Optimal power allocation for SM-OFDM systems with imperfect channel estimation

    International Nuclear Information System (INIS)

    Yu, Feng; Song, Lijun; Lei, Xia; Xiao, Yue; Jiang, Zhao Xiang; Jin, Maozhu

    2016-01-01

    This paper analyses the bit error rate (BER) of the spatial modulation orthogonal frequency division multiplex (SM-OFDM) system and derives the optimal power allocation between the data and the pilot symbols by minimizing the upper bound for the BER operating with imperfect channel estimation. Furthermore, we prove the proposed optimal power allocation scheme applies to all generalized linear interpolation techniques with the minimum mean square error (MMSE) channel estimation . Simulation results show that employing the proposed optimal power allocation provides a substantial gain in terms of the average BER performance for the SM-OFDM system compared to its equal-power-allocation counterpart.

  17. BER PERFORMANCE COMPARISON OF MIMO SYSTEMS USING OSTBC WITH ZF AND ML DECODING

    Directory of Open Access Journals (Sweden)

    Zenitha Rehman

    2014-12-01

    Full Text Available Multiple Input Multiple Output (MIMO systems with multiple antenna elements at both transmitter and receiver ends are an efficient solution for wireless communication systems. They provide high data rates by exploiting the spatial domain under the constraints of limited bandwidth and transmit power. Space-Time Block Coding (STBC is a MIMO transmit strategy which exploits transmit diversity and provides high reliability. Implementation of orthogonal space-time block codes (OSTBCs for a two transmitter–two receiver system under AWGN (Additive White Gaussian Noise channel and flat fading channel is performed. Alamouti code is employed for the STBC. The modulation techniques used are BPSK, QPSK and 16-QAM. Decoding is done using the Zero Forcing (ZF algorithm and Maximum Likelihood (ML algorithm. The BER Performance of each modulation scheme is compared with the un-coded version of the same. Performance comparison between the two decoding techniques is also done. It is found that ML detection offers a slightly better performance for BPSK and QPSK system than ZF detection.

  18. Monitoring artificial radioactivity in the Nordic countries. BER-2 final report

    International Nuclear Information System (INIS)

    Bennerstedt, T.; Rantanen, H.; Mortensen, B.N.

    1994-05-01

    This final report of the Nordic Nuclear Safety Research Project BER-2 gives detailed information on the monitoring of artificial radioactivity in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden). A comparison shows that for early warning the Nordic countries use a mix of stations measuring external gamma radiation and stations measuring airborne radioactivity. There is a trade-off between fast alarms and the sensitivity threshold. Total gamma measuring stations cannot detect increases smaller than the variations of normal background. Some stations, notably all Danish stations, are equipped with sodium iodide (NaI) type detectors, and operated in such a way that stray peaks due to an increase in the natural radon background can be subtracted. A Nordic Radiation Data Exchange System has been set up and tested on a trial basis. This system focuses on dose rate data from the automatic gamma monitoring stations. An important goal achieved in the project was to determine which data is essential, and to specify a common format for the data exchange. Various telecommunication methods have been tested, and the actual transfer of monitoring results between the Nordic countries was started. It is recommended as a future approach that every country appoint one organization with the responsibility of operating a national information data base, which can be commonly accessed from all the Nordic countries. A procedure for establishing a system of this type has been outlined

  19. Comparative analyses of ber (zizyphus) honey with other types of honey

    International Nuclear Information System (INIS)

    Iftikhar, F.; Mehmood, R.

    2007-01-01

    Eight different honey samples were collected from different ecological areas of Pakistan and analyzed for various physico-chemical parameters. The aim was to evaluate the quality, difference in the composition and comparison of Ber/Sidder (Zizyphus spp.) honey with other types of honey. The two samples of Ber honey and six other floral honey i.e., Citrus, mixed (citrus + Justicia), Acacia modesta, multi-flora and mixed (zizyphus + sesamum) were collected from Apis mellifera colonies. The colonies of Apis mellifera foraged on the above-mentioned flora in different ecological areas i.e. ber honey from Bannu and Karak, Citrus and mixed (citrus + Justicia) honey from Mandi Bahauddin, Acacia honey from Peshawar + Islamabad and multi-flora from Lahore. Nine legal parameters of honey quality control were followed. All honey samples were well within the limits of Codex Alimentarius Commission except ber and citrus. The ber honey showed high pH (6.85) and low reducing sugars (67.66%), sucrose (1.0%), free acidity (6.09 meq/kg) and total acidity (7.68 meq/kg). Mixed honey (zizyphus + sesamum) exhibited highest pH (6.88), lowest free acidity (2.80 meq/kg) and total acidity (5.50 meq/kg). Citrus honey was also found high in Hydroxy-methyl-furfural (HMF, 22.75 meql kg). (author)

  20. Purification, crystallization and initial crystallographic characterization of brazil-nut allergen Ber e 2

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Feng; Jin, Tengchuan; Howard, Andrew; Zhang, Yu-Zhu, E-mail: zhangy@iit.edu [Department of Biology, Illinois Institute of Technology, Chicago, IL 60616 (United States)

    2007-11-01

    The crystallization of the brazil nut allergen Ber e 2 is reported. Peanut and tree-nut allergies have attracted considerable attention because of their frequency and their lifelong persistence. Brazil-nut (Bertholletia excelsa) allergies have been well documented and the 11S legumin-like seed storage protein Ber e 2 (excelsin) is one of the two known brazil-nut allergens. In this study, Ber e 2 was extracted from brazil-nut kernels and purified to high purity by crystalline precipitation and gel-filtration chromatography. Well diffracting single crystals were obtained using the hanging-drop vapour-diffusion method. A molecular-replacement structural solution has been obtained. Refinement of the structure is currently under way.

  1. BER performance comparison of optical CDMA systems with/without turbo codes

    Science.gov (United States)

    Kulkarni, Muralidhar; Chauhan, Vijender S.; Dutta, Yashpal; Sinha, Ravindra K.

    2002-08-01

    In this paper, we have analyzed and simulated the BER performance of a turbo coded optical code-division multiple-access (TC-OCDMA) system. A performance comparison has been made between uncoded OCDMA and TC-OCDMA systems employing various OCDMA address codes (optical orthogonal codes (OOCs), Generalized Multiwavelength Prime codes (GMWPC's), and Generalized Multiwavelength Reed Solomon code (GMWRSC's)). The BER performance of TC-OCDMA systems has been analyzed and simulated by varying the code weight of address code employed by the system. From the simulation results, it is observed that lower weight address codes can be employed for TC-OCDMA systems that can have the equivalent BER performance of uncoded systems employing higher weight address codes for a fixed number of active users.

  2. Do berço ao berçário: a instituição como morada e lugar de contato

    Directory of Open Access Journals (Sweden)

    Marta Nörnberg

    2013-12-01

    Full Text Available Este ensaio aborda o sentido da instituição infantil a partir de uma perspectiva ético-estético-afetiva do viver humano. A abordagem ampara-se em perspectivas filosóficas sobre a existência humana. Os argumentos apresentam o berçário como morada, lugar do viver juntos, instituição que se faz em coletividade, nela e com ela, decorrente do encontro de bebês e adultos. Ao constituir-se como morada dos bebês, o berçário ritualiza e reatualiza a prática pedagógica como lugar de relação entre bebês e adultos, requerendo uma pedagogia do contato.

  3. Cooperative MIMO Communication at Wireless Sensor Network: An Error Correcting Code Approach

    Science.gov (United States)

    Islam, Mohammad Rakibul; Han, Young Shin

    2011-01-01

    Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error pb. It is observed that C-MIMO performs more efficiently when the targeted pb is smaller. Also the lower encoding rate for LDPC code offers better error characteristics. PMID:22163732

  4. Lebensdauer von Stahlseilen beim kombinierten Lauf über Treib- und Ablenkscheiben unterschiedlicher Rillenform

    OpenAIRE

    Berner, Oliver Roger

    2011-01-01

    Die Lebensdauer von Stahldrahtseilen in Treibscheibenaufzügen wird von unterschiedlichen Faktoren beeinflusst. Bei allen Anwendungen, bei denen Seile über Rollen laufen, erfahren die Seile eine Zug- und Biegebeanspruchung, die zu einer Materialermüdung und zu einem Verschleiß der Drähte an der Seiloberfläche und im Inneren der Seile führt. Darüber hinaus findet man bei Treibscheibenaufzügen systembedingt weitere anwendungsspezifische Beanspruchungen, die zu einer zusätzlichen Lebensdauerminde...

  5. Simulasi Teknik Pengkodean Regular Low Density Parity Check Code Pada Sistem MC-CDMA

    OpenAIRE

    Tonny Juliandy

    2009-01-01

    Sebagai efek dari perkembangan jaman, teknologi telekomunikasi khususnya dalam sistem komunikasi wireless, dituntut untuk dapat menyediakan layanan data yang berkecepatan tinggi (high data rate) dengan Quality of Service (QoS) yang reliable dengan kata lain memiliki Bit Error Rate (BER) yang kecil dengan daya sekecil mungkin). Masalah yang timbul dalam komunikasi bergerak adalah adanya multipath fading, yang mengakibatkan adanya kesalahan data yang diterima pada Receiver menjadi meningkat.Sis...

  6. Efficient TTI for 3G Multimedia Applications

    Directory of Open Access Journals (Sweden)

    Costas Chaikalis

    2007-01-01

    investigated using the maximum UMTS frame length, and simulation results are presented for the four possible outer block interleaver configurations in the case of flat Rayleigh fading channel. It is shown that different operating environments require an appropriate TTI in terms of bit error rate (BER performance for the following data rates: 28.8 kbps, 64 kbps, 144 kbps, 384 kbps, and 2 Mbps.

  7. Grossforschung in neuen Dimensionen : Denker unserer Zeit über die aktuelle Elementarteilchenphysik am CERN

    CERN Document Server

    Blanchard, Philippe; Kommer, Christoph; ZiF-Konferenz 2013; CERN : Large-scale Research in New Dimension

    2015-01-01

    Der 4. Juli 2012 stellt ein historisches Datum für das Europäische Kernforschungszentrum CERN in Genf dar: die Verkündung der Entdeckung des letzten, vorhergesagten, noch fehlenden und lange gesuchten Elementarteilchens, des Higgs-Bosons. Ein Jahr später kommen im Rahmen der Konferenz des Zentrums für interdisziplinäre Forschung (ZiF) in Bielefeld eine Vielzahl der mit dem Großprojekt am CERN verbundenen Wissenschaftler zusammen, um nicht nur über die Entdeckung des Teilchens, sondern vor allem über die Realisierung und Bedeutung eines derart ungeheuren Unterfangens für solch ein wissenschaftliches Großprojekt zu berichten. Der Generaldirektor des CERN, Prof. Dr. Rolf-Dieter Heuer, liefert in seinem Eröffnungsvortrag die Grundlage für die Diskussion der vielerlei Aspekte, die dabei ins Spiel kommen. So finden sich im vorliegenden Band zum einen Berichte über die Großforschung selbst: von der Entdeckung des Higgs-Teilchens über die Erforschung des Quark-Gluon-Plasmas und die Bedeutung von Th...

  8. BER Reduction for mQAM High-Speed Tranmission in Optical Fiber ...

    African Journals Online (AJOL)

    The study was conducted in a software cosimulation environment with VPITransmissionMaker and Matlab software. The simulation results showed that error correcting codes and particularly LDPC codes are effective and provide satisfactory solutions to reduce the BER by fighting against optical transmission channel ...

  9. BER and total throughput of asynchronous DS-OCDMA/WDM systems with multiple user interference

    OpenAIRE

    Ghiringhelli, F.; Zervas, M.N.

    2003-01-01

    The BER and throughput of Direct-Sequence OCDMA/WDM systems based on quadripolar codes and superstructured fiber Bragg gratings are statistically derived under asynchronous operation, intensity detection, and Multiple User Interference. Performance improvements with Forward Error Correction are included.

  10. Ein Lehrbuch über Psychiatrie und Psychotherapie – Geschlechtsunterschiede unter der Lupe?

    Directory of Open Access Journals (Sweden)

    Isabella Heuser

    2007-07-01

    Full Text Available Anke Rohde und Andreas Marneros haben sich ein hohes Ziel gesetzt: ein übersichtliches Lehrbuch für Psychiatrie und Psychotherapie, das erstmals eine systematische Zusammenstellung des Wissens über geschlechtsspezifische Aspekte von Symptomatologie, Epidemiologie, Diagnostik, Pharmakotherapie und Psychotherapie psychischer Störungen enthält. Bemerkenswert ist dabei zweierlei: Erstens werden bei der Betrachtung geschlechtsspezifischer Unterschiede im Sinne der Genderforschung Frauen und Männer berücksichtigt, zweitens wird ein vollständiger Überblick sowohl über die häufigen und bekannten psychischen Störungen als auch die äußerst seltenen psychiatrischen Erkrankungen der gesamten Altersspanne gegeben. Wenngleich die Qualität der einzelnen Beiträge deutlich zwischen sehr differenzierter und leider auch für ein Handbuch eindeutig zu oberflächlicher Betrachtung variiert, liegt in dem Band ein weitgehend informatives Nachschlagewerk vor, das einen ersten Überblick über die geschlechtsspezifische Psychiatrie gibt.

  11. Notizen über Thatcheria Angas, Clinura Bellardi und Clinuropsis Vincent

    NARCIS (Netherlands)

    Beets, C.

    1942-01-01

    1. Es sind bisher über die merkwürdige rezente marine Gastropoden-Gruppe Thatcheria Angas, 1877 sehr wenige Gegebenheiten bekannt, vergleichende Untersuchungen mit fossilen Arten fehlen (fast) vollkommen und auch die Frage ihrer systematischen Stellung ist nie in befriedigender Weise gelöst worden.

  12. The research of atmospheric 2D optical PPM CDMA system with turbo coding

    Science.gov (United States)

    Zhou, Xiuli; Li, Zaoxia

    2007-11-01

    The atmospheric two-dimensional optical code-division multiple-access (CDMA) systems using pulse-position modulation (PPM) and Turbo-coded were presented. We analyzed the bit-error rate (BER) of the proposed system using pulse-position modulation (PPM) with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference. We showed that the atmospheric two dimensional (2D) optical PPM CDMA systems can realize high-speed communications when the logarithm variance of the scintillation is less than 0.1, and the turbo-coded atmospheric optical CDMA system has better bit error rate(BER) performance than the atmospheric optical PPM CDMA systems without turbo-coded. We also showed that the turbo-coded system has better performance than the multi-user detection system.

  13. Information rates and post-FEC BER prediction in optical fiber communications

    NARCIS (Netherlands)

    Alvarado, Alex

    2017-01-01

    Information-theoretic metrics to analyze optical fiber communications systems with binary and nonbinary soft-decision FEC are reviewed. The numerical evaluation of these metrics in both simulations and experiments is also discussed. Ready-to-use closed-form approximations are presented.

  14. Quantum mean-field decoding algorithm for error-correcting codes

    International Nuclear Information System (INIS)

    Inoue, Jun-ichi; Saika, Yohei; Okada, Masato

    2009-01-01

    We numerically examine a quantum version of TAP (Thouless-Anderson-Palmer)-like mean-field algorithm for the problem of error-correcting codes. For a class of the so-called Sourlas error-correcting codes, we check the usefulness to retrieve the original bit-sequence (message) with a finite length. The decoding dynamics is derived explicitly and we evaluate the average-case performance through the bit-error rate (BER).

  15. The Signal and Noise Analysis of Direct Conversion EHM Transceivers

    Directory of Open Access Journals (Sweden)

    Shayegh

    2006-01-01

    Full Text Available A direct conversion modulator-demodulator with even harmonic mixers with emphasis on noise analysis is presented. The circuits consist of even harmonic mixers (EHMs realized with antiparallel diode pairs (APDPs. We evaluate the different levels of I/Q imbalances and DC offsets and use signal space concepts to analyze the bit error rate (BER of the proposed transceiver using M-ary QAM schemes. Moreover, the simultaneous analysis of the signal and noise has been presented.

  16. Implementation of LTE SC-FDMA on the USRP2 Software Defined Radio Platform

    DEFF Research Database (Denmark)

    Jørgensen, Peter Bjørn; Hansen, Thomas Lundgaard; Sørensen, Troels Bundgaard

    2011-01-01

    In this paper we discuss the implementation of a Single Carrier Frequency Division Multiple Access (SC-FDMA) transceiver running over the Universal Software Radio Peripheral 2 (USRP2). SC-FDMA is the air interface which has been selected for the uplink in the latest Long Term Evolution (LTE....../s. Experimental results on the Bit Error Rate (BER) versus Signal-to-Noise Ratio (SNR) are presented and compared to theoretical and simulated performance....

  17. 160 Gb/s OFDM transmission utilizing an all-optical symbol generator based on PLC

    Science.gov (United States)

    Liang, Xiaojun; Qiao, Yaojun; Li, Wei; Mei, Junyao; Qin, Yi

    2009-11-01

    We demonstrate a 160 Gb/s orthogonal frequency division multiplexing (OFDM) system using an all-optical symbol generator based on planar light circuit (PLC) technology. Excellent bit error rate (BER) is observed after long-distance transmission. The proposed symbol generator fundamentally eliminates the processing speed limits introduced by electronics and is suitable for high integration, making it physically realizable to build high-speed all-optical OFDM systems with a large number of subcarriers.

  18. Comparison of equalisation strategies for multi-carrier CDMA

    OpenAIRE

    Cooper, MA; Armour, SMD; Bian, YQ; McGeehan, JP

    2003-01-01

    This paper focuses on the bit error rate (BER) performance of equalisation strategies for a downlink MC-CDMA based system. Simulation results utilising maximal ratio combining (MRC), orthogonal restoring combining (ORC), equal gain combining (EGC) and minimum mean square error combining (MMSEC) for a multiuser scenario are presented. In addition, we analyse the relative complexities of each scheme and discuss their suitability for implementation in future consumer products

  19. An OTDM-To-WDM Converter Using Optical Fourier Transformation

    OpenAIRE

    Khin Su Myat Min; Zaw Myo Lwin; Hla Myo Tun

    2015-01-01

    We demonstrate serial-to-parallel conversion of 40 Gbps optical time division multiplexed OTDM signal to 4x10 Gbps wavelength division-multiplexed WDM individual channels by using Optical Fourier Transformation OFT method. OFT is also called time lens technique and it is implemented by the combination of dispersive fiber and phase modulation. In this research electro-optic phase modulator EOM is used as time lens. As our investigations simulation results and bit error rate BER measurements ar...

  20. Efficient demodulation scheme for rolling-shutter-patterning of CMOS image sensor based visible light communications.

    Science.gov (United States)

    Chen, Chia-Wei; Chow, Chi-Wai; Liu, Yang; Yeh, Chien-Hung

    2017-10-02

    Recently even the low-end mobile-phones are equipped with a high-resolution complementary-metal-oxide-semiconductor (CMOS) image sensor. This motivates using a CMOS image sensor for visible light communication (VLC). Here we propose and demonstrate an efficient demodulation scheme to synchronize and demodulate the rolling shutter pattern in image sensor based VLC. The implementation algorithm is discussed. The bit-error-rate (BER) performance and processing latency are evaluated and compared with other thresholding schemes.

  1. Impact of Different Spreading Codes Using FEC on DWT Based MC-CDMA System

    OpenAIRE

    Masum, Saleh; Kabir, M. Hasnat; Islam, Md. Matiqul; Shams, Rifat Ara; Ullah, Shaikh Enayet

    2012-01-01

    The effect of different spreading codes in DWT based MC-CDMA wireless communication system is investigated. In this paper, we present the Bit Error Rate (BER) performance of different spreading codes (Walsh-Hadamard code, Orthogonal gold code and Golay complementary sequences) using Forward Error Correction (FEC) of the proposed system. The data is analyzed and is compared among different spreading codes in both coded and uncoded cases. It is found via computer simulation that the performance...

  2. Experimental Demonstration of an Electro-Absorption Modulated Laser for High-Speed Transmissions at 1.55-μm Window Using Digital Signal Processing

    Directory of Open Access Journals (Sweden)

    Fotini Karinou

    2017-02-01

    Full Text Available We experimentally investigate the transmission performance of 56 Gb/s four-level pulse amplitude modulation (PAM-4 over 30-km standard single mode fiber (SMF using a C-band EML for low-cost metro and short-reach wavelength division multiplexing (WDM applications. Bit error rate (BER performance below the HD-FEC threshold is achieved for up to 30-km maximum reported distance without employing dispersion compensation fiber (DCF in the link.

  3. Joint Frequency-Domain Equalization and Despreading for Multi-Code DS-CDMA Using Cyclic Delay Transmit Diversity

    Science.gov (United States)

    Yamamoto, Tetsuya; Takeda, Kazuki; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide a better bit error rate (BER) performance than rake combining. To further improve the BER performance, cyclic delay transmit diversity (CDTD) can be used. CDTD simultaneously transmits the same signal from different antennas after adding different cyclic delays to increase the number of equivalent propagation paths. Although a joint use of CDTD and MMSE-FDE for direct sequence code division multiple access (DS-CDMA) achieves larger frequency diversity gain, the BER performance improvement is limited by the residual inter-chip interference (ICI) after FDE. In this paper, we propose joint FDE and despreading for DS-CDMA using CDTD. Equalization and despreading are simultaneously performed in the frequency-domain to suppress the residual ICI after FDE. A theoretical conditional BER analysis is presented for the given channel condition. The BER analysis is confirmed by computer simulation.

  4. The BER necessities: the repair of DNA damage in human-adapted bacterial pathogens.

    Science.gov (United States)

    van der Veen, Stijn; Tang, Christoph M

    2015-02-01

    During colonization and disease, bacterial pathogens must survive the onslaught of the host immune system. A key component of the innate immune response is the generation of reactive oxygen and nitrogen species by phagocytic cells, which target and disrupt pathogen molecules, particularly DNA, and the base excision repair (BER) pathway is the most important mechanism for the repair of such oxidative DNA damage. In this Review, we discuss how the human-specific pathogens Mycobacterium tuberculosis, Helicobacter pylori and Neisseria meningitidis have evolved specialized mechanisms of DNA repair, particularly their BER pathways, compared with model organisms such as Escherichia coli. This specialization in DNA repair is likely to reflect the distinct niches occupied by these important human pathogens in the host.

  5. Categorization of ber varieties in relation to blooming period, fruit setting and harvesting time

    International Nuclear Information System (INIS)

    Sharif, N.; Abbas, M.M.; Ishfaq, M.; Memon, N.U.N.

    2013-01-01

    Thirty four local Ber varieties were evaluated at Horticultural Research Institute AARI, Faisalabad, Horticultural Research Station Bahawalpur (Punjab) and Jujube Research Station, Tandojam (Sindh). Traits viz. total period of blooming (dates), peak period of blooming (dates), total period of fruit set (dates), peak period of fruit set (dates), total period of fruit harvest (dates), peak period of fruit harvest (dates), total flowering days, peak flowering days, total fruit setting days, peak fruit setting days, total harvesting days and peak harvesting days were studied. The results revealed significant differences in parameters studied except total period of blooming under Tandojam, Sindh conditions. Varieties were classified as early, mid and late season for both provinces. Local varieties had potential for further manipulation in terms of variety improvement to attract growers for extensive ber cultivations under changing global climatic scenario. (author)

  6. The research reactor BER II at the Helmholtz-Center Berlin

    Energy Technology Data Exchange (ETDEWEB)

    Krohn, Herbert [Helmholtz-Zentrum Berlin (HZB), Berlin (Germany)

    2012-10-15

    For basic and application-oriented research assignments the Helmholtz-Center Berlin (Helmholtz Zentrum Berlin - HZB) runs a research reactor that operates as a source of neutron beams for a wide range of scientific investigations. At the end of the 1980{sup th} the BER II was completed renewed and fitted with new experimental facilities. The BER II is a light water cooled and moderated swimming pool type reactor to be operated at 10 MW thermal power. Six neutron guides deliver cold neutrons from the cold moderator cell to a neutron guide hall adjacent to the experiment hall. With its 24 experimental stations, experimenters at HZB have practically all neutron scattering or neutron radiography techniques at their disposal. (orig.)

  7. Natural biostimulants reduce the incidence of BER in sweet yellow pepper plants (Capsicum annuum L.

    Directory of Open Access Journals (Sweden)

    Nada Parađiković

    2013-06-01

    Full Text Available Modern greenhouse pepper production should evolve towards more sustainable systems. The growing technique which combines soilless culture and biostimulants may reduce nutrient and water use with beneficial impact on the environment. Therefore, this work aimed to investigate effects of biostimulants application on hydroponically produced pepper plants (Capsicum annuum L. in conditions of reduced fertilization. Positive influence of biostimulant treatment on yield parameters was observed along with significant decrease in incidence of blossom-end rot (BER in two pepper cultivars. Biostimulants application resulted in overall increase in macro- and microelement content in fruits of treated pepper cultivars. Generally, biostimulants improved the yield of pepper plants grown hydroponically by increasing the nutrient uptake and decreasing the occurrence of BER. Thus, the application of biostimulants could be considered as a good production strategy for obtaining high yields of nutritionally valuable vegetables with lower impact on the environment.

  8. The research reactor BER II at the Helmholtz-Center Berlin

    International Nuclear Information System (INIS)

    Krohn, Herbert

    2012-01-01

    For basic and application-oriented research assignments the Helmholtz-Center Berlin (Helmholtz Zentrum Berlin - HZB) runs a research reactor that operates as a source of neutron beams for a wide range of scientific investigations. At the end of the 1980 th the BER II was completed renewed and fitted with new experimental facilities. The BER II is a light water cooled and moderated swimming pool type reactor to be operated at 10 MW thermal power. Six neutron guides deliver cold neutrons from the cold moderator cell to a neutron guide hall adjacent to the experiment hall. With its 24 experimental stations, experimenters at HZB have practically all neutron scattering or neutron radiography techniques at their disposal. (orig.)

  9. Performance Analysis of DPSK-OCDMA System for Optical Access Network

    Science.gov (United States)

    Islam, Monirul; Ahmed, N.; Aljunid, S. A.; Ali, Sharafat; Sayeed, S.; Sabri, Naseer

    2016-03-01

    In this research, the performance of optical code division multiple access (OCDMA) using differential phase shift keying (DPSK) has been compared with OCDMA On-Off Keying (OOK). This comparison took place in terms of bit error rate (BER) and receiver power where two bit rates (155 Mbps and 622 Mbps) have been used for this analysis. Using of OptiSystem 7.0 simulation, comparing eye diagram and optical spectrum alongside with BER and Rx power. It is found that OCDMA-DPSK performs better in comparison to OCDMA-OOK. The performance analysis also provides parameter for designing and development of an OCDMA system for optical access network using DPSK.

  10. Impact of optical hard limiter on the performance of an optical overlapped-code division multiple access system

    Science.gov (United States)

    Inaty, Elie; Raad, Robert; Tablieh, Nicole

    2011-08-01

    Throughout this paper, a closed form expression of the multiple access interference (MAI) limited bit error rate (BER) is provided for the multiwavelength optical code-division multiple-access system when the system is working above the nominal transmission rate limit imposed by the passive encoding-decoding operation. This system is known in literature as the optical overlapped code division multiple access (OV-CDMA) system. A unified analytical framework is presented emphasizing the impact of optical hard limiter (OHL) on the BER performance of such a system. Results show that the performance of the OV-CDMA system may be highly improved when using OHL preprocessing at the receiver side.

  11. Briti teadlane: kübersõda ei tule / Thomas Rid ; intervjueerinud Raimo Poom

    Index Scriptorium Estoniae

    Rid, Thomas

    2013-01-01

    Sõjauuringute õppejõud Thomas Rid leiab, et internetis on palju ohte, kuid kübersõda ei ole üks neist. Ridi arvates on äärmiselt ebatõenäoline, et NATO käivitaks kunagi küberrünnaku tõttu 5. artikli. Interneti kõige suuremaks ohustajaks pole NSA, vaid vabadust piirata soovivad autoritaarsed riigid

  12. Rehabilitierungs-Szenarien, Geschichten über Hexen, Verdingkinder, Flüchtlingshelfer usw.

    OpenAIRE

    Rüegger, Vanessa

    2015-01-01

    In den vergangenen Jahren haben Parlamente, Regierungen und Gerichte unterschiedliche Personen und Personengruppen rehabilitiert. Der vorliegende Beitrag bietet einen Überblick über die jüngst in der Schweiz ausgesprochenen Rehabilitierungen, ordnet diese rechtsdogmatisch ein und zeigt weiter die Funktionen und Grenzen der Rehabilitierung als Form staatlicher ,Vergangenheitsbewältigung‘ auf. Der Beitrag schliesst mit der Erkenntnis, dass Flüchtlingshelfer, Spanienkämpfer, administrativ Versor...

  13. Neural Network based Minimization of BER in Multi-User Detection in SDMA

    OpenAIRE

    VENKATA REDDY METTU; KRISHAN KUMAR,; SRIKANTH PULLABHATLA

    2011-01-01

    In this paper we investigate the use of neural network based minimization of BER in MUD. Neural networks can be used for linear design, Adaptive prediction, Amplitude detection, Character Recognition and many other applications. Adaptive prediction is used in detecting the errors caused in AWGN channel. These errors are rectified by using Widrow-Hoff algorithm by updating their weights andAdaptive prediction methods. Both Widrow-Hoff and Adaptive prediction have been used for rectifying the e...

  14. Clustered DNA lesions containing 5-formyluracil and AP site: repair via the BER system.

    Directory of Open Access Journals (Sweden)

    Ekaterina A Belousova

    Full Text Available Lesions in the DNA arise under ionizing irradiation conditions or various chemical oxidants as a single damage or as part of a multiply damaged site within 1-2 helical turns (clustered lesion. Here, we explored the repair opportunity of the apurinic/apyrimidinic site (AP site composed of the clustered lesion with 5-formyluracil (5-foU by the base excision repair (BER proteins. We found, that if the AP site is shifted relative to the 5-foU of the opposite strand, it could be repaired primarily via the short-patch BER pathway. In this case, the cleavage efficiency of the AP site-containing DNA strand catalyzed by human apurinic/apyrimidinic endonuclease 1 (hAPE1 decreased under AP site excursion to the 3'-side relative to the lesion in the other DNA strand. DNA synthesis catalyzed by DNA polymerase lambda was more accurate in comparison to the one catalyzed by DNA polymerase beta. If the AP site was located exactly opposite 5-foU it was expected to switch the repair to the long-patch BER pathway. In this situation, human processivity factor hPCNA stimulates the process.

  15. Nachrichtenberichterstattung über Terrorismus. Eine Analyse der TV-Nachrichten über die Terroranschläge in Kenia 2002

    Directory of Open Access Journals (Sweden)

    Nicole Haußecker

    2007-04-01

    Full Text Available Nach der starken Kritik der Medienberichterstattung über Terrorismus, besonders nach dem 11.09.2001, werden die theoretischen Hintergründe ausgewählter Kritikpunkte betrachtet und ein weiteres terroristisches Ereignis, die Anschläge in Kenia am 28.11.2002, inhaltsanalytisch untersucht. Ziel dabei ist es, Aussagen bezüglich inhaltlicher und formaler Merkmale der Fernseh-berichterstattung über ein terroristisches Ereignis zu treffen. Deshalb liegt der Fokus auf den folgenden drei Forschungsfragen: 1. Welche Nachrichtenfaktoren spielen für die Selektion und Intensität der Berichterstattung über das terroristische Ereignis eine Rolle? 2. Wird mit Emotionalisierung gearbeitet? 3. Liegen negative Stereotype und/oder Feindbilder bezüglich der islamischen und arabischen Welt vor? Die Ergebnisse der Untersuchung zeigen erwartete Tendenzen sowohl die Merkmale der Terrorismusberichterstattung als auch die Senderkonvergenzen und -divergenzen im dualen System betreffend. Der Nachrichtenwert eines terroristischen Ereignisses ist anfänglich sehr hoch, jedoch verliert das Ereignis ab dem dritten Tag aufgrund diverser Nachrichtenfaktoren deutlich an Beachtung in der Berichterstattung. Das Vorkommen emotionalisierender Mittel wird empirisch bestätigt. Nicht nur emotionale Sprache und Sprechweise, sondern vor allem Formen der expliziten Emotionalisierung sind vertreten. Damit wird die Vermutung bekräftigt, dass die Medien die mit den terroristischen Ereignissen verbundene beängstigende Stimmung senderabhängig unterschiedlich stark aufgreifen. Ein direkter islamischer Feindbildaufbau ist in der Berichterstattung nicht zu verzeichnen. Allerdings liegen latente negative Bewertungstendenzen sowie negative Stereotype bezüglich der arabischen und islamischen Welt vor, die das seit dem 11.09.2001 negativ geprägte Bild festigen. Die meist narrativ inszenierte Fixierung auf Bin Laden und al Qaida erfolgt oberflächlich und vernachlässigt m

  16. Neuronale Korrelate sozialer Interaktion beim Menschen und deren genetische Modulation unter besonderer Berücksichtigung des Spiegelneuronensystems

    OpenAIRE

    Cordes, Andrea

    2013-01-01

    Die in vielen Lebenssituationen über Erfolg und Misserfolg, Sympathie und Antipathie entscheidende, unterschiedlich ausgeprägte Fähigkeit zur sozialen Interaktion ist Gegenstand neurowissenschaftlicher Untersuchungen. Die Versuche einer kortikalen Lokalisierung führten zur Beschreibung des Spiegelneuronensystems (SNS) in Hirnregionen, die sowohl beim Ausführen einer Aktion Aktivität zeigten als auch beim Beobachten derselben beim Gegenüber. Die stärkste Aktivierung dieser Areale wurde bei sch...

  17. Paradigmenwechsel in der politischen Ökologie? Zur deutschen Diskussion über die Lokale Agenda 21

    OpenAIRE

    Pettenkofer, Andreas

    2001-01-01

    Der Text berichtet über die in Deutschland geführte sozialwissenschaftliche Diskussion über das umweltpolitische Programm Lokale Agenda 21; er versucht eine vorläufige Rekonstruktion der spezifischen Gestalt der Agenda-Prozesse und ihrer Abweichungen von der westdeutschen Tradition der Politischen Ökologie, und diskutiert die theoretischen Fragen, die sich angesichts dieser neuartigen Phänomene stellen. Dabei geht es vor allem um die Angemessenheit der modernisierungstheoretischen Perspektive...

  18. Erstellung eines multimedialen Lernprogramms über die Grundlagen der EKG-Aufzeichnung und Auswertung bei Hund und Katze

    OpenAIRE

    Weigel-Ossiander, Fiona Sarah

    2016-01-01

    Mit EKG Basics wurde ein detailliertes multimediales Lernprogramm über die Grundlagen der Elektrokardiographie bei Hund und Katze erstellt unter besonderer Berücksichtigung von didaktischen und ergonomischen Gesichtspunkten. Da vielen Veterinärmedizinerinnen/Veterinärmedizinern das Erlernen, Verstehen und Interpretieren der Elektrokardiographie schwer fällt, war das Ziel der vorliegenden Arbeit, sowohl Studierenden der Tiermedizin als auch interessierten Tierärztinnen/Tierärzten die Thema...

  19. Decreased expression level of BER genes in Alzheimer's disease patients is not derivative of their DNA methylation status.

    Science.gov (United States)

    Sliwinska, Agnieszka; Sitarek, Przemysław; Toma, Monika; Czarny, Piotr; Synowiec, Ewelina; Krupa, Renata; Wigner, Paulina; Bialek, Katarzyna; Kwiatkowski, Dominik; Korycinska, Anna; Majsterek, Ireneusz; Szemraj, Janusz; Galecki, Piotr; Sliwinski, Tomasz

    2017-10-03

    Neurodegeneration in Alzheimer's disease can be caused by accumulation of oxidative DNA damage resulting from altered expression of genes involved in the base excision repair system (BER). Promoter methylation can affect the profile of BER genes expression. Decreased expression of BER genes was observed in the brains of AD patients. The aim of our study was to compare the expression and methylation profiles of six genes coding for proteins involved in BER, namely: hOGG1, APE1, MUTYH, NEIL1, PARP1 and XRCC1, in the peripheral blood cells of AD patients and healthy volunteers. The study consisted of 100 persons diagnosed with Alzheimer's disease according to DSM-IV criteria, and 110 healthy volunteers. DNA and total RNA were isolated from venous blood cells. Promoter methylation profiles were obtained by High Resolution Melting (HRM) analysis of bisulfide converted DNA samples. Real-time PCR with TaqMan probes was employed for gene expression analysis. APE1, hOGG1, MUTYH, PARP1 and NEIL1 were significantly (pgenes. The methylation status of promoters is not associated with downregulation of BER genes. Our results show that downregulation of BER genes detected in peripheral blood samples could reflect the changes occurring in the brain of patients with AD, and may be a useful biomarker of this disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Statistical-mechanics approach to wide-band digital communication.

    Science.gov (United States)

    Efraim, Hadar; Peleg, Yitzhak; Kanter, Ido; Shental, Ori; Kabashima, Yoshiyuki

    2010-12-01

    The emerging popular scheme of fourth generation wireless communication, orthogonal frequency-division multiplexing, is mapped onto a variant of a random field Ising Hamiltonian and results in an efficient physical intercarrier interference (ICI) cancellation decoding scheme. This scheme is based on Monte Carlo (MC) dynamics at zero temperature as well as at the Nishimori temperature and demonstrates improved bit error rate (BER) and robust convergence time compared to the state of the art ICI cancellation decoding scheme. An optimal BER performance is achieved with MC dynamics at the Nishimori temperature but with a substantial computational cost overhead. The suggested ICI cancellation scheme also supports the transmission of biased signals.

  1. Pilot power optimization for AF relaying using maximum likelihood channel estimation

    KAUST Repository

    Wang, Kezhi

    2014-09-01

    Bit error rates (BERs) for amplify-and-forward (AF) relaying systems with two different pilot-symbol-aided channel estimation methods, disintegrated channel estimation (DCE) and cascaded channel estimation (CCE), are derived in Rayleigh fading channels. Based on these BERs, the pilot powers at the source and at the relay are optimized when their total transmitting powers are fixed. Numerical results show that the optimized system has a better performance than other conventional nonoptimized allocation systems. They also show that the optimal pilot power in variable gain is nearly the same as that in fixed gain for similar system settings. andcopy; 2014 IEEE.

  2. A new LDPC decoding scheme for PDM-8QAM BICM coherent optical communication system

    Science.gov (United States)

    Liu, Yi; Zhang, Wen-bo; Xi, Li-xia; Tang, Xian-feng; Zhang, Xiao-guang

    2015-11-01

    A new log-likelihood ratio (LLR) message estimation method is proposed for polarization-division multiplexing eight quadrature amplitude modulation (PDM-8QAM) bit-interleaved coded modulation (BICM) optical communication system. The formulation of the posterior probability is theoretically analyzed, and the way to reduce the pre-decoding bit error rate ( BER) of the low density parity check (LDPC) decoder for PDM-8QAM constellations is presented. Simulation results show that it outperforms the traditional scheme, i.e., the new post-decoding BER is decreased down to 50% of that of the traditional post-decoding algorithm.

  3. An optical CDMA system based on chaotic sequences

    Science.gov (United States)

    Liu, Xiao-lei; En, De; Wang, Li-guo

    2014-03-01

    In this paper, a coherent asynchronous optical code division multiple access (OCDMA) system is proposed, whose encoder/decoder is an all-optical generator. This all-optical generator can generate analog and bipolar chaotic sequences satisfying the logistic maps. The formula of bit error rate (BER) is derived, and the relationship of BER and the number of simultaneous transmissions is analyzed. Due to the good property of correlation, this coherent OCDMA system based on these bipolar chaotic sequences can support a large number of simultaneous users, which shows that these chaotic sequences are suitable for asynchronous OCDMA system.

  4. Demonstration of two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded longperiod fiber gratings formed in dispersion-compensating fiber with inner-cladding structure

    DEFF Research Database (Denmark)

    Kim, Sun-Jong; Eom, T.J.; Kim, T.Y.

    2005-01-01

    A two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in a dispersion-compensating fiber (DCF) is demonstrated. Our results show that the sensitivity of cladding modes to the refractive index change on the cladding...... surface is greatly reduced by utilizing the inner-cladding mode of the DCF. Two pairs of encoder/decoder are constructed and the performance is evaluated by measuring bit error rate (BER). With an interferer, a BER of 1.5 X 10(-12) is measured at a received optical power of -6 dBm....

  5. Spectral-Amplitude-Coded OCDMA Optimized for a Realistic FBG Frequency Response

    Science.gov (United States)

    Penon, Julien; El-Sahn, Ziad A.; Rusch, Leslie A.; Larochelle, Sophie

    2007-05-01

    We develop a methodology for numerical optimization of fiber Bragg grating frequency response to maximize the achievable capacity of a spectral-amplitude-coded optical code-division multiple-access (SAC-OCDMA) system. The optimal encoders are realized, and we experimentally demonstrate an incoherent SAC-OCDMA system with seven simultaneous users. We report a bit error rate (BER) of 2.7 x 10-8 at 622 Mb/s for a fully loaded network (seven users) using a 9.6-nm optical band. We achieve error-free transmission (BER < 1 x 10-9) for up to five simultaneous users.

  6. Demonstration of two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in dispersion-compensating fiber with inner-cladding structure

    Science.gov (United States)

    Kim, Sun-Jong; Eom, Tae-Jung; Kim, Tae-Young; Lee, Byeong Ha; Park, Chang-Soo

    2005-09-01

    A two-user, 10-Gbits/s optical code-division multiple-access system implemented by using cascaded long-period fiber gratings formed in a dispersion-compensating fiber (DCF) is demonstrated. Our results show that the sensitivity of cladding modes to the refractive index change on the cladding surface is greatly reduced by utilizing the inner-cladding mode of the DCF. Two pairs of encoder/decoder are constructed and the performance is evaluated by measuring bit error rate (BER). With an interferer, a BER of 1.5×10-12 is measured at a received optical power of -6 dBm.

  7. Effect of the Primary User Traffic on Cognitive Relaying with Adaptive Transmission

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive-relay system, the secondary user is permitted to transmit data via a relay when the spectrum bands are detected to be free. The miss detection of spectrum sensing and the primary user traffic will affect the data transmission performance of the secondary user. In this paper, we investigate the impact of the status change of the primary user on the bit error rate (BER) of the adaptive transmission of the secondary user in a cognitive-relay system. Numerical results show that the primary user traffic can significantly degrade the BER of the secondary user transmission.

  8. Energy detection UWB system based on pulse width modulation

    Directory of Open Access Journals (Sweden)

    Song Cui

    2014-05-01

    Full Text Available A new energy detection ultra-wideband system based on pulse width modulation is proposed. The bit error rate (BER performance of this new system is slightly worst than that of a pulse position modulation (PPM system in additive white Gaussian noise channels. In multipath channels, this system does not suffer from cross-modulation interference as PPM, so it can achieve better BER performance than PPM when cross-modulation interference occurs. In addition, when synchronisation errors occur, this system is more robust than PPM.

  9. Solution structure, copper binding and backbone dynamics of recombinant Ber e 1-the major allergen from Brazil nut.

    Directory of Open Access Journals (Sweden)

    Louise Rundqvist

    Full Text Available BACKGROUND: The 2S albumin Ber e 1 is the major allergen in Brazil nuts. Previous findings indicated that the protein alone does not cause an allergenic response in mice, but the addition of components from a Brazil nut lipid fraction were required. Structural details of Ber e 1 may contribute to the understanding of the allergenic properties of the protein and its potential interaction partners. METHODOLOGY/PRINCIPAL FINDINGS: The solution structure of recombinant Ber e 1 was solved using NMR spectroscopy and measurements of the protein back bone dynamics at a residue-specific level were extracted using (15N-spin relaxation. A hydrophobic cavity was identified in the structure of Ber e 1. Using the paramagnetic relaxation enhancement property of Cu(2+ in conjunction with NMR, it was shown that Ber e 1 is able to specifically interact with the divalent copper ion and the binding site was modeled into the structure. The IgE binding region as well as the copper binding site show increased dynamics on both fast ps-ns timescale as well as slower µs-ms timescale. CONCLUSIONS/SIGNIFICANCE: The overall fold of Ber e 1 is similar to other 2S albumins, but the hydrophobic cavity resembles that of a homologous non-specific lipid transfer protein. Ber e 1 is the first 2S albumin shown to interact with Cu(2+ ions. This Cu(2+ binding has minimal effect on the electrostatic potential on the surface of the protein, but the charge distribution within the hydrophobic cavity is significantly altered. As the hydrophobic cavity is likely to be involved in a putative lipid interaction the Cu(2+ can in turn affect the interaction that is essential to provoke an allergenic response.

  10. Blinde Mimesis. Über Ordo und Kontingenz in der literaturgeschichtlichen Traditionsbildung (Horaz und Petron

    Directory of Open Access Journals (Sweden)

    Jürgen Paul Schwindt

    2010-11-01

    Full Text Available me truncus illapsus cerebro / sustulerat, nisi Faunus ictum / dextra levasset, Mercurialium / custos virorum.(Hor. carm. 2, 17, 27–30... et ipse Trimalchio capillatus caduceum tenebat Minervaque ducente Romam intrabat.(Petron. 29, 3Es ist zuweilen das Schicksal besonders gut erforschter Texte, daß sie im System der Bezüge, der Quellen und Verweise, das die gelehrte Erklärung über, neben und unter ihnen errichtet hat (Hyper-, Para-, Prae- oder Subtext, zu verschwimmen, konturlos zu werden, ...

  11. EMI and BER/PER Analysis of Wi-Fi and Bluetooth Communication for CRIP Platform

    DEFF Research Database (Denmark)

    Ravelo, Blaise; Cabral, Jorge; Wagner, Stefan Rahr

    This paper is devoted to the characterization of the electromagnetic interference (EMI) effects on wireless communication devices for telemedicine healthcare application. The proposed wireless system operates at the 2.4GHz ISM band with a hardware interface communicating by Wi-Fi and BLE (Bluetooth...... path loss model is investigated for the indoor RF link budget. The quality of the EM coverage and SNR and SINR on QoS with transmitted data BER and PER is analysed. It was examined that the QoS can be degraded according to the distance between the Wi-Fi and BLE device sensitivity and also...

  12. On the average capacity and bit error probability of wireless communication systems

    KAUST Repository

    Yilmaz, Ferkan; Alouini, Mohamed-Slim

    2011-01-01

    Analysis of the average binary error probabilities and average capacity of wireless communications systems over generalized fading channels have been considered separately in the past. This paper introduces a novel moment generating function

  13. On the average capacity and bit error probability of wireless communication systems

    KAUST Repository

    Yilmaz, Ferkan

    2011-12-01

    Analysis of the average binary error probabilities and average capacity of wireless communications systems over generalized fading channels have been considered separately in the past. This paper introduces a novel moment generating function-based unified expression for both average binary error probabilities and average capacity of single and multiple link communication with maximal ratio combining. It is a matter to note that the generic unified expression offered in this paper can be easily calculated and that is applicable to a wide variety of fading scenarios, and the mathematical formalism is illustrated with the generalized Gamma fading distribution in order to validate the correctness of our newly derived results. © 2011 IEEE.

  14. 16-bit error detection and correction (EDAC) controller design using FPGA for critical memory applications

    International Nuclear Information System (INIS)

    Misra, M.K.; Sridhar, N.; Krishnakumar, B.; Ilango Sambasivan, S.

    2002-01-01

    Full text: Complex electronic systems require the utmost reliability, especially when the storage and retrieval of critical data demands faultless operation, the system designer must strive for the highest reliability possible. Extra effort must be expended to achieve this reliability. Fortunately, not all systems must operate with these ultra reliability requirements. The majority of systems operate in an area where system failure is not hazardous. But the applications like nuclear reactors, medical and avionics are the areas where system failure may prove to have harsh consequences. High-density memories generate errors in their stored data due to external disturbances like power supply surges, system noise, natural radiation etc. These errors are called soft errors or transient errors, since they don't cause permanent damage to the memory cell. Hard errors may also occur on system memory boards. These hard errors occur if one RAM component or RAM cell fails and is stuck at either 0 or 1. Although less frequent, hard errors may cause a complete system failure. These are the major problems associated with memories

  15. Binary Biometrics: An Analytic Framework to Estimate the Bit Error Probability under Gaussian Assumption

    NARCIS (Netherlands)

    Kelkboom, E.J.C.; Molina, G.; Kevenaar, T.A.M.; Veldhuis, Raymond N.J.; Jonker, Willem

    2008-01-01

    In recent years the protection of biometric data has gained increased interest from the scientific community. Methods such as the helper data system, fuzzy extractors, fuzzy vault and cancellable biometrics have been proposed for protecting biometric data. Most of these methods use cryptographic

  16. Hilfe oder Hindernis? Meinungen finnischer Sprachstudierender über Mehrsprachigkeit als Ressource beim Deutschlernen

    Directory of Open Access Journals (Sweden)

    Sabine Grasz

    2017-10-01

    Full Text Available Der Fremdsprachenunterricht in Finnland befindet sich gerade in einer Umbruchphase, denn mit der Einführung neuer Lehrpläne im Jahr 2016 werden Verfahren der Mehrsprachigkeitsdidaktik in Zukunft eine zentrale Rolle spielen. In diesem Beitrag wird untersucht, ob und wie finnische Universitätsstudierende, die selbst von einer eher monolingual ausgerichteten Lerntradition geprägt sind, ihr mehrsprachiges Repertoire als Ressource beim Lernen weiterer Fremdsprachen sehen. Zu diesem Zweck wurde eine Befragung unter Lehramtsstudierenden der Fächer Anglistik und Skandinavistik, die Germanistik als Nebenfach studieren möchten, durchgeführt. Die Analyse zeigt, dass die Studierenden zwar mehrheitlich positive Einstellungen gegenüber Mehrsprachigkeit aufweisen, dass es aber Entwicklungsbedarf im Hinblick auf Sprachbewusstheit, multilinguale Fähigkeiten und bei den Einstellungen gegenüber Sprachmischungen gibt. Foreign language education in Finland is currently undergoing a period of change, as the introduction of new curricula in 2016 will lead to a central role of multilingualism in teaching. This article examines whether and how Finnish university students, who themselves were influenced by a more monolingual learning tradition, consider their multilingual repertoire as a resource for learning other foreign languages. For this purpose, a survey was conducted among teacher students of English and Swedish, who would like to study German as a minor. The analysis shows that while the majority of students have positive attitudes towards multilingualism, there is a need for development in terms of language awareness, multilingual skills, and attitudes towards language mixes.

  17. Shuttle bit rate synchronizer. [signal to noise ratios and error analysis

    Science.gov (United States)

    Huey, D. C.; Fultz, G. L.

    1974-01-01

    A shuttle bit rate synchronizer brassboard unit was designed, fabricated, and tested, which meets or exceeds the contractual specifications. The bit rate synchronizer operates at signal-to-noise ratios (in a bit rate bandwidth) down to -5 dB while exhibiting less than 0.6 dB bit error rate degradation. The mean acquisition time was measured to be less than 2 seconds. The synchronizer is designed around a digital data transition tracking loop whose phase and data detectors are integrate-and-dump filters matched to the Manchester encoded bits specified. It meets the reliability (no adjustments or tweaking) and versatility (multiple bit rates) of the shuttle S-band communication system through an implementation which is all digital after the initial stage of analog AGC and A/D conversion.

  18. Low-sampling-rate ultra-wideband digital receiver using equivalent-time sampling

    KAUST Repository

    Ballal, Tarig

    2014-09-01

    In this paper, we propose an all-digital scheme for ultra-wideband symbol detection. In the proposed scheme, the received symbols are sampled many times below the Nyquist rate. It is shown that when the number of symbol repetitions, P, is co-prime with the symbol duration given in Nyquist samples, the receiver can sample the received data P times below the Nyquist rate, without loss of fidelity. The proposed scheme is applied to perform channel estimation and binary pulse position modulation (BPPM) detection. Results are presented for two receivers operating at two different sampling rates that are 10 and 20 times below the Nyquist rate. The feasibility of the proposed scheme is demonstrated in different scenarios, with reasonable bit error rates obtained in most of the cases.

  19. Low-sampling-rate ultra-wideband digital receiver using equivalent-time sampling

    KAUST Repository

    Ballal, Tarig; Al-Naffouri, Tareq Y.

    2014-01-01

    In this paper, we propose an all-digital scheme for ultra-wideband symbol detection. In the proposed scheme, the received symbols are sampled many times below the Nyquist rate. It is shown that when the number of symbol repetitions, P, is co-prime with the symbol duration given in Nyquist samples, the receiver can sample the received data P times below the Nyquist rate, without loss of fidelity. The proposed scheme is applied to perform channel estimation and binary pulse position modulation (BPPM) detection. Results are presented for two receivers operating at two different sampling rates that are 10 and 20 times below the Nyquist rate. The feasibility of the proposed scheme is demonstrated in different scenarios, with reasonable bit error rates obtained in most of the cases.

  20. Selection combining for noncoherent decode-and-forward relay networks

    Directory of Open Access Journals (Sweden)

    Nguyen Ha

    2011-01-01

    Full Text Available Abstract This paper studies a new decode-and-forward relaying scheme for a cooperative wireless network composed of one source, K relays, and one destination and with binary frequency-shift keying modulation. A single threshold is employed to select retransmitting relays as follows: a relay retransmits to the destination if its decision variable is larger than the threshold; otherwise, it remains silent. The destination then performs selection combining for the detection of transmitted information. The average end-to-end bit-error-rate (BER is analytically determined in a closed-form expression. Based on the derived BER, the problem of choosing an optimal threshold or jointly optimal threshold and power allocation to minimize the end-to-end BER is also investigated. Both analytical and simulation results reveal that the obtained optimal threshold scheme or jointly optimal threshold and power-allocation scheme can significantly improve the BER performance compared to a previously proposed scheme.

  1. Construction and performance analysis of variable-weight optical orthogonal codes for asynchronous OCDMA systems

    Science.gov (United States)

    Li, Chuan-qi; Yang, Meng-jie; Zhang, Xiu-rong; Chen, Mei-juan; He, Dong-dong; Fan, Qing-bin

    2014-07-01

    A construction scheme of variable-weight optical orthogonal codes (VW-OOCs) for asynchronous optical code division multiple access (OCDMA) system is proposed. According to the actual situation, the code family can be obtained by programming in Matlab with the given code weight and corresponding capacity. The formula of bit error rate (BER) is derived by taking account of the effects of shot noise, avalanche photodiode (APD) bulk, thermal noise and surface leakage currents. The OCDMA system with the VW-OOCs is designed and improved. The study shows that the VW-OOCs have excellent performance of BER. Despite of coming from the same code family or not, the codes with larger weight have lower BER compared with the other codes in the same conditions. By taking simulation, the conclusion is consistent with the analysis of BER in theory. And the ideal eye diagrams are obtained by the optical hard limiter.

  2. Dual branch transmit switch-and-stay diversity for underlay cognitive networks

    KAUST Repository

    Sayed, Mostafa M.; Abdallah, Mohamed M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

    2011-01-01

    In this paper, we study applying dual branch transmit switch-and-stay combining (SSC) technique for underlay cognitive radio (UCR) networks. In UCR, the secondary user is allowed to share the spectrum with the primary (licensed) user under the condition that interference at the primary receiver is below a predetermined threshold. Assuming binary phaseshift keying (BPSK) modulation and Rayleigh fading channels, we develop a closed form expression for the average bit error rate (BER) of the secondary link as a function of the switching threshold. We then find a closed form expression for the optimal switching threshold in the sense of minimizing the average BER. For the sake of comparison we derive an expression for the average BER of the dual branch transmit selection combining (SC) technique. We finally investigate the effect of correlation between secondary and interference channels on the average BER and the associated optimal switching threshold. © 2011 IEEE.

  3. Dual branch transmit switch-and-stay diversity for underlay cognitive networks

    KAUST Repository

    Sayed, Mostafa M.

    2011-05-01

    In this paper, we study applying dual branch transmit switch-and-stay combining (SSC) technique for underlay cognitive radio (UCR) networks. In UCR, the secondary user is allowed to share the spectrum with the primary (licensed) user under the condition that interference at the primary receiver is below a predetermined threshold. Assuming binary phaseshift keying (BPSK) modulation and Rayleigh fading channels, we develop a closed form expression for the average bit error rate (BER) of the secondary link as a function of the switching threshold. We then find a closed form expression for the optimal switching threshold in the sense of minimizing the average BER. For the sake of comparison we derive an expression for the average BER of the dual branch transmit selection combining (SC) technique. We finally investigate the effect of correlation between secondary and interference channels on the average BER and the associated optimal switching threshold. © 2011 IEEE.

  4. The new 'BerSANS-PC' software for reduction and treatment of small angle neutron scattering data

    International Nuclear Information System (INIS)

    Keiderling, U.

    2002-01-01

    Measurements on small angle neutron scattering (SANS) instruments are typically characterized by a large number of samples, short measurement times for the individual samples, and a frequent change of visiting scientist groups. Besides this, recent advances in instrumentation have led to more frequent measurements of kinetic sequences and a growing interest in analyzing two-dimensional scattering data, these requiring special software tools that enable the users to extract physically relevant information from the scattering data with a minimum of effort. The new 'BerSANS-PC' data-processing software has been developed at the Hahn-Meitner-Institut (HMI) in Berlin, Germany, to meet these requirements and to support an efficiently working guest-user service. Comprising some basic functions of the 'BerSANS' program available at the HMI and other institutes in the past, BerSANS-PC is a completely new development for network-independent use on local PCs with a full-feature graphical interface. (orig.)

  5. Implementation of Layered Decoding Architecture for LDPC Code using Layered Min-Sum Algorithm

    Directory of Open Access Journals (Sweden)

    Sandeep Kakde

    2017-12-01

    Full Text Available For binary field and long code lengths, Low Density Parity Check (LDPC code approaches Shannon limit performance. LDPC codes provide remarkable error correction performance and therefore enlarge the design space for communication systems.In this paper, we have compare different digital modulation techniques and found that BPSK modulation technique is better than other modulation techniques in terms of BER. It also gives error performance of LDPC decoder over AWGN channel using Min-Sum algorithm. VLSI Architecture is proposed which uses the value re-use property of min-sum algorithm and gives high throughput. The proposed work has been implemented and tested on Xilinx Virtex 5 FPGA. The MATLAB result of LDPC decoder for low bit error rate (BER gives bit error rate in the range of 10-1 to 10-3.5 at SNR=1 to 2 for 20 no of iterations. So it gives good bit error rate performance. The latency of the parallel design of LDPC decoder has also reduced. It has accomplished 141.22 MHz maximum frequency and throughput of 2.02 Gbps while consuming less area of the design.

  6. Berührt sein – Ein Fallbericht zur Rolle von WATSU (WasserShiatsu) in der Rehabilitation nach Polytrauma

    OpenAIRE

    Schitter, Agnes Maria; Fleckenstein, Johannes

    2017-01-01

    Hintergrund: Die herausragende Bedeutung von Körperkontakt für den Menschen ist bekannt und nachgewiesen. Während aber intensiver Körperkontakt in der medizinischen Versorgung von Frühgeborenen etabliert ist, wird Berührung in schulmedizinische Therapiekonzepte für Erwachsene bisher nur marginal integriert. Massnahmen aus der Komplementärmedizin berücksichtigen den individuellen Bedarf an körperlicher Nähe und leisten einen klinischen Mehrwert für den Gesundungsprozess. In besonderer Weise...

  7. BER and FER Prediction of Control and Traffic Channels for a GSM type of interface

    DEFF Research Database (Denmark)

    Wigard, Jeroen; Nielsen, Thomas Toftegaard; Michaelsen, Per Henrik

    1998-01-01

    in a network simulator, but without having to simulate every single link, since this would be to time consuming. In this paper a method is presented to find the BER and FER from the signal to interference (C/I) values for a GSM type of air-interface, which can be used for integration of link aspects...... in a network simulator. The accuracy is within 0.2 dB in case of the BER and 0.5 for the FER. Both traffic and control channels are studied and the method is independent of hopping sequences and speed...

  8. NB-PLC channel modelling with cyclostationary noise addition & OFDM implementation for smart grid

    Science.gov (United States)

    Thomas, Togis; Gupta, K. K.

    2016-03-01

    Power line communication (PLC) technology can be a viable solution for the future ubiquitous networks because it provides a cheaper alternative to other wired technology currently being used for communication. In smart grid Power Line Communication (PLC) is used to support communication with low rate on low voltage (LV) distribution network. In this paper, we propose the channel modelling of narrowband (NB) PLC in the frequency range 5 KHz to 500 KHz by using ABCD parameter with cyclostationary noise addition. Behaviour of the channel was studied by the addition of 11KV/230V transformer, by varying load location and load. Bit error rate (BER) Vs signal to noise ratio SNR) was plotted for the proposed model by employing OFDM. Our simulation results based on the proposed channel model show an acceptable performance in terms of bit error rate versus signal to noise ratio, which enables communication required for smart grid applications.

  9. A CBPR partnership increases HIV testing among men who have sex with men (MSM): outcome findings from a pilot test of the CyBER/testing internet intervention.

    Science.gov (United States)

    Rhodes, Scott D; Vissman, Aaron T; Stowers, Jason; Miller, Cindy; McCoy, Thomas P; Hergenrather, Kenneth C; Wilkin, Aimee M; Reece, Michael; Bachmann, Laura H; Ore, Addison; Ross, Michael W; Hendrix, Ellen; Eng, Eugenia

    2011-06-01

    The Internet has emerged as an important tool for the delivery of health promotion and disease prevention interventions. Our community-based participatory research (CBPR) partnership developed and piloted CyBER/testing, a culturally congruent intervention designed to promote HIV testing among men who have sex with men (MSM) within existing Internet chat rooms. Using a quasi-experimental, single-group study design, cross-sectional data were collected from chat room participants, known as "chatters," at pretest (n = 346) and posttest (n = 315). Extant profile data also were collected to describe the demographics of the online population. The intervention significantly increased self-reported HIV testing among chatters overall, increasing rates from 44.5% at pretest to nearly 60% at posttest (p testing at posttest. Findings suggest that chat room-based HIV testing intervention may increase testing among MSM who may be difficult to reach in traditional physical spaces.

  10. Über die Verknüpfung von Hörspiel und Pädagogik

    Directory of Open Access Journals (Sweden)

    Leah Lobensommer

    2013-09-01

    Full Text Available Dieser Artikel legt die Ergebnisse einer Bachelorarbeit zum Thema „Hörspiel als Lernmethode unter besonderer Berücksichtigung sonderpädagogischer Aspekte“ dar. Die Beziehung von Hörspiel und Pädagogik wird durchleuchtet und zeitgemäße Ansätze zur Verwirklichung eines Hörspielprojektes mit Jugendlichen werden dargestellt. Mit Hilfe der Aussagen der qualitativen Forschung wird ein Fazit und ein Ausblick in die Zukunft gewagt.The following article focuses on the results of a Bachelor’s thesis on the subject of "Radio drama as a learning method in supportive educational settings". The link between pedagogics and radio drama and contemporary efforts to create radio dramas in class will be shown. The statements obtained by empiric research have the goal to transport insights of radio drama professionals in order to enlighten the subject. Finally, on the basis of the gained knowledge a conclusion will be made.

  11. Mediennutzung und Informationsbeschaffung über Studium- bzw. Berufswahl - Ingenieurberufe in den Medien

    Directory of Open Access Journals (Sweden)

    Amina Ovcina Cajacob

    2014-06-01

    Full Text Available Diese Publikation basiert auf der Befragung von 4 125 Jugendlichen (SchülerInnen der Altersgruppe 12 bis 21 Jahre. Dafür wurden im Zeitraum vom 22. Oktober bis 12. November 2013 Jugendliche befragt, um Antworten auf folgenden Fragen zu bekommen: Welches Bild haben die Schüler vom Ingenieurberuf? Wie ist ihr allgemeines Mediennutzungsverhalten und wie beeinflussen Medien das Bild des Ingenieurs? Welche Berufe interessieren Jugendliche und wie informieren sie sich über Studien- bzw. Berufswahl? Welche Einflüsse spielen bei den Jugendlichen bezüglich der eigenen Berufs- und Studienwahl eine Rolle? Die Ergebnisse dieser umfassenden Analyse sind Grundlage für die Konzeption einer crossmedialen Sensibilisierungskampage, die zum Ziel hat, Vorurteile über den Ingenieurberuf abzubauen, Wissen und ein zeitgemässes Berufsbild zu vermitteln sowie Neugier auf ein Ingenieurstudium zu wecken. This publication is based on a survey of 4125 young people (pupils and students aged 12 to 21 years. In the period from October 22 to November 12, 2013 young people were interviewed to obtain answers to the following questions: . What an idea do young people have about an engineer and his profession? . What is their general media usage behavior? . How do media influence the image of the engineer? . Which professions are the most attractive for young people and how do they inform themselves about study or career choices? . Which influences are important for the study and career choice of young people? The results of this comprehensive analysis are the basis for the conception of a cross-media awareness campaign, which aims to reduce prejudices about the engineering profession, to impart knowledge as well as a contemporary professional image of engineer and to arouse interest for an engineering degree.

  12. Natura2000 : Information und Kommunikation über die Ausweisung und die Pflege von Natura2000 Schutsgebieten : Zusammenfassung Hauptbericht 1: die Ausweisung in 27 EU Mitgliedsstaten

    NARCIS (Netherlands)

    Apeldoorn, van R.C.; Kruk, R.W.; Bouwma, I.M.; Ferranti, F.; Blust, De G.; Sier, A.R.J.

    2010-01-01

    Die Europäischen Kommission (EK) möchte die Mitgliedsstaaten unterstützen und den Austausch von Wissen, Information und Praxiserfahrung fördern: sowohl über den Prozess der Ausweisung von Vogelschutz- und FFH- Gebieten, als über mögliche Schutzmassnahmen und Instrumente für diese Gebiete in den

  13. Vorläufige Mitteilung über die Beschaffenheit der Ovarialtasche von Chrysochloris, Galeopithecus und Tupaja

    NARCIS (Netherlands)

    Lange, de Daniel

    1922-01-01

    Im Jahre 1917 ist in den Anatomischen Heften die bekannte und schöne Arbeit Sobotta’s erschienen über das Vorkommen und die Bedeutung der Ovarialtasche bei den Säugetieren ¹). Das Hauptergebniss dieser Arbeit ist, dass bei alien Säugetieren (vielleicht mit Ausnahne der Primaten und des Menschen) die

  14. Die kupferzeitliche Siedlung Pietrele an der Unteren Donau. Bericht über die Ausgrabungen und geomorphologischen Untersuchungen im Sommer 2010

    DEFF Research Database (Denmark)

    Nørgaard, Heide Wrobel

    2012-01-01

    Seit der Kampagne 2008 und dem letzten Zwischenbericht über den nichtmetallenen Schmuck wurden zahlreiche weitere Stücke dieser Kleinfundkategorie auf dem Tell und in der Außensiedlung gefunden. Auch das Formenspektrum hat sich erheblich erweitert. Der in der bisherigen Forschung als elitär anges...

  15. Rating af banker og banksystemer

    DEFF Research Database (Denmark)

    Grosen, Anders

    2010-01-01

    Banksystemer over hele verdenen er med nød og næppe blevet reddet af diverse statslige hjælpepakker. Derfor er der i disse år øget fokus på banker og banksystemers rating. Denne interesse bliver ikke mindre af, at de statslige garantier til bankerne i mange lande udløber i de kommende år. Rating ...

  16. soyjaudah vol 5

    African Journals Online (AJOL)

    cistvr

    In time varying channels the noise and interference vary randomly. Forward error ... essarily yields a higher throughput and a lower bit error rate. ..... ance of the additive white Gaussian noise was adjusted for a range of average bit errors.

  17. Q FUNCTION AWARE OPTICAL PACKET SWITCH WITH LOW PACKET LOSS RATE

    Directory of Open Access Journals (Sweden)

    OMPAL SINGH

    2017-03-01

    Full Text Available Optical packet switching (OPS is a very promising technology for the next generation data transfer due to the very large bandwidth of the optical fiber. The success of the OPS relies heavily on design of the node architecture which supports comparatively larger buffering capacity without detiorating signal quality too much and it should provide very low packet loss probability with reasonably low average delay. In this paper, a design analysis of low complexity OPS node architecture is discussed along-with its advantages. The presented architecture support both fixed and variable length packets. The packets are stored in a single piece of fiber using the WDM technology. Physical layer analysis presented in this paper is to obtain the Q function (Bit Error Rate. Finally, the Monte Carlo simulation is done to obtain the packet loss. The average delay performance of the switch and effect of Q values on packet loss rates are discussed.

  18. Damage by insect pests to the Djingarey Ber Mosque in Timbuktu: detection and control

    Directory of Open Access Journals (Sweden)

    Lara Maistrello

    2011-08-01

    Full Text Available The Djingarey Ber Mosque in Timbuktu (Mali is one of the most significant earthen construction in West Africa. Originally constructed in 1327, it was included in 1988 on the World Heritage UNESCO List for its unique architecture and historical importance. During its restoration, recently undertaken by the Aga Khan Trust for Culture, the wooden parts of the roof and architraves showed clear signs of threatening insect presence. In order to identify the pests responsible of the damage, evaluate its extent and suggest a proper control strategy, a detailed survey was performed inside the Mosque complex and in its immediate surroundings. The entomological inspection, performed in the dry-cold season, allowed to detect signs of insect damage in most of the wooden elements, even in the recently replaced beams, but also in walls, pillars and the precious decorated panels. Damages in the wood elements could be attributed to Amitermes evuncifer Silvestri (Termitidae, Bostrychoplites zycheli Marseuli (Bostrichidae and Lyctus africanus Lesne (Lyctidae, which were collected alive on site. Injures in the walls and decorated panels appeared to be performed by hymenopterans such as “plasterer bees” (Colletidae and Sphecidae. From the evaluation of the type and extent of damage in relation to the architecture and materials used in its construction and decoration, the most serious pest and the worse threat for the mosque is represented by termites. Control and preventive measures, in the view of a sustainable, long-lasting integrated management are suggested.

  19. Echt und modern? Diskurse über Männlichkeit

    Directory of Open Access Journals (Sweden)

    Florian Kahofer

    2014-09-01

    Full Text Available Der vorliegende Artikel befasst sich mit Repräsentationen von Männlichkeit im österreichischen Lifestyle-Magazin für Männer Wiener. Durch eine korpusbasierte Diskursanalyse wird ein umfassendes Korpus aller Ausgaben des Wieners von Anfang 2002 bis Ende 2012 untersucht. Auf theoretischer Ebene wird dabei eine Verbindung von Kritischer Männlichkeitsforschung (KMF und Feministisch Kritischer Diskursanalyse (FCDA unternommen. Es werden aktuelle Veröffentlichungen zu Kritischer Diskursanalyse und Männlichkeit vorgestellt und diskutiert. Durch den Einsatz einer Konkordanzsoftware werden Konkordanzen des Nomens MANN analysiert. Diese werden allerdings insofern eingeschränkt betrachtet, als nur Nominationen in der Form der häufigsten Adjektiv-Konstruktionen untersucht werden. Die Ergebnisse zeigen, dass neben den Diskursen über Krise und Neue Männlichkeit Themen wie Alter, Körper oder Beziehung auftauchen. Männlichkeit wird als ambivalent und vielfältig dargestellt. Deutungskämpfe um Männlichkeit lassen sich ausmachen.

  20. Error-free 5.1 Tbit/s data generation on a single-wavelength channel using a 1.28 Tbaud symbol rate

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Galili, Michael; Oxenløwe, Leif Katsuo

    2009-01-01

    We demonstrate a record bit rate of 5.1 Tbit/s on a single wavelength using a 1.28 Tbaud OTDM symbol rate, DQPSK data-modulation, and polarisation-multiplexing. Error-free performance (BER......We demonstrate a record bit rate of 5.1 Tbit/s on a single wavelength using a 1.28 Tbaud OTDM symbol rate, DQPSK data-modulation, and polarisation-multiplexing. Error-free performance (BER...

  1. DESIGN AND IMPLEMENTATION OF IMPROVED SUPERIMPOSED CYCLIC OPTICAL ORTHOGONAL CODES (SCOOC BASED OPTICAL ENCODER/DECODER STRUCTURE FOR 1GBPS OPTICAL CDMA SYSTEM

    Directory of Open Access Journals (Sweden)

    GURJIT KAUR

    2010-12-01

    Full Text Available In this paper, an improved form of two dimensional optical orthogonal codes is introduced for optical CDMA system by using just six lasers. This new technique not only reduces the length of the code but also improves the bit error rate (BER performance of the system. The uniqueness of this coding architecture is that the two adjacent codes are not only different by their time slots but have different wavelength combination as well. The encoder and decoder structure has been designed with the help of filters and optical delay lines. An OCDMA system at 1 Gbps bit rate is designed for above codes and performance is evaluated and compared for various parameters i.e. number of simultaneous users, bit error rate, quality factor. The OCDMA system can accommodate 25 users for permissible BER of 10-9, with -15db received power at 1 Gbps bit rate respectively. If received power is kept low i.e. -22db, the OCDMA system can support 16 users with extremely low BER of 1.58e-41 for 1G bps bit rate.

  2. ALS Ice Bucket Challenge: Warum die Kampagne über einen „Tsunami Effekt“ beim Spendenverhalten Eisberge versetzen kann

    OpenAIRE

    Decieux, Jean Philippe Pierre

    2015-01-01

    Im Sommer 2014 beherrschte eine Kampagne die sozialen Medien, welche auf originelle Art und Weise auf die Nervenkrankheit Amyotrophe Lateralsklerose (ALS) aufmerksam machen und dadurch Spendengelder für die Erforschung dieser Krankheit generieren wollte. Im Rahmen der sogenannten ALS-Ice-Bucket-Challenge-Kampagne gossen sich die Hauptdarsteller/innen von kleinen Internetclips eiskaltes Wasser über den Kopf und nominierten im Anschluss weitere Personen für die Challenge. Die Herausforderung bz...

  3. Effects of plasma on polyethylene fiber surface for prosthodontic application

    Directory of Open Access Journals (Sweden)

    Silvana Marques Miranda SPYRIDES

    2015-12-01

    Full Text Available ABSTRACT Plasma technology has the potential to improve the adherence of fibers to polymeric matrices, and there are prospects for its application in dentistry to reinforce the dental particulate composite. Objectives This study aimed to investigate the effect of oxygen or argon plasma treatment on polyethylene fibers. Material and Methods Connect, Construct, InFibra, and InFibra treated with oxygen or argon plasma were topographically evaluated by scanning electron microscopy (SEM, and chemically by X-ray photoelectron spectroscopy (XPS. For bending analysis, one indirect composite (Signum was reinforced with polyethylene fiber (Connect, Construct, or InFibra. The InFibra fiber was subjected to three different treatments: (1 single application of silane, (2 oxygen or argon plasma for 1 or 3 min, (3 oxygen or argon plasma and subsequent application of silane. The samples (25x2x2 mm, 6 unreinforced and 60 reinforced with fibers, were subjected to three-point loading tests to obtain their flexural strength and deflection. The results were statistically analyzed with ANOVA and the Bonferroni correction for multiple comparison tests. Results SEM analysis showed that oxygen and argon plasma treatments promote roughness on the polyethylene fiber surface. X-ray photoelectron spectroscopy (XPS analysis shows that both plasmas were effective in incorporating oxygenated functional groups. Argon or oxygen plasma treatment affected the flexural strength and deflection of a fiber reinforced composite. The application of silane does not promote an increase in the flexural strength of the reinforced composites. Conclusions Oxygen and argon plasma treatments were effective in incorporating oxygenated functional groups and surface roughness. The highest strength values were obtained in the group reinforced with polyethylene fibers treated with oxygen plasma for 3 min.

  4. Over-Sampling Codebook-Based Hybrid Minimum Sum-Mean-Square-Error Precoding for Millimeter-Wave 3D-MIMO

    KAUST Repository

    Mao, Jiening; Gao, Zhen; Wu, Yongpeng; Alouini, Mohamed-Slim

    2018-01-01

    Hybrid precoding design is challenging for millimeter-wave (mmWave) massive MIMO. Most prior hybrid precoding schemes are designed to maximize the sum spectral efficiency (SSE), while seldom investigate the bit-error-rate (BER). Therefore, this letter designs an over-sampling codebook (OSC)-based hybrid minimum sum-mean-square-error (min-SMSE) precoding to optimize the BER. Specifically, given the effective baseband channel consisting of the real channel and analog precoding, we first design the digital precoder/combiner based on min-SMSE criterion to optimize the BER. To further reduce the SMSE between the transmit and receive signals, we propose an OSC-based joint analog precoder/combiner (JAPC) design. Simulation results show that the proposed scheme can achieve the better performance than its conventional counterparts.

  5. Underwater wireless optical MIMO system with spatial modulation and adaptive power allocation

    Science.gov (United States)

    Huang, Aiping; Tao, Linwei; Niu, Yilong

    2018-04-01

    In this paper, we investigate the performance of underwater wireless optical multiple-input multiple-output communication system combining spatial modulation (SM-UOMIMO) with flag dual amplitude pulse position modulation (FDAPPM). Channel impulse response for coastal and harbor ocean water links are obtained by Monte Carlo (MC) simulation. Moreover, we obtain the closed-form and upper bound average bit error rate (BER) expressions for receiver diversity including optical combining, equal gain combining and selected combining. And a novel adaptive power allocation algorithm (PAA) is proposed to minimize the average BER of SM-UOMIMO system. Our numeric results indicate an excellent match between the analytical results and numerical simulations, which confirms the accuracy of our derived expressions. Furthermore, the results show that adaptive PAA outperforms conventional fixed factor PAA and equal PAA obviously. Multiple-input single-output system with adaptive PAA obtains even better BER performance than MIMO one, at the same time reducing receiver complexity effectively.

  6. Fast converging minimum probability of error neural network receivers for DS-CDMA communications.

    Science.gov (United States)

    Matyjas, John D; Psaromiligkos, Ioannis N; Batalama, Stella N; Medley, Michael J

    2004-03-01

    We consider a multilayer perceptron neural network (NN) receiver architecture for the recovery of the information bits of a direct-sequence code-division-multiple-access (DS-CDMA) user. We develop a fast converging adaptive training algorithm that minimizes the bit-error rate (BER) at the output of the receiver. The adaptive algorithm has three key features: i) it incorporates the BER, i.e., the ultimate performance evaluation measure, directly into the learning process, ii) it utilizes constraints that are derived from the properties of the optimum single-user decision boundary for additive white Gaussian noise (AWGN) multiple-access channels, and iii) it embeds importance sampling (IS) principles directly into the receiver optimization process. Simulation studies illustrate the BER performance of the proposed scheme.

  7. RLS Channel Estimation with Adaptive Forgetting Factor for DS-CDMA Frequency-Domain Equalization

    Science.gov (United States)

    Kojima, Yohei; Tomeba, Hiromichi; Takeda, Kazuaki; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can increase the downlink bit error rate (BER) performance of DS-CDMA beyond that possible with conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. Recently, we proposed a pilot-assisted channel estimation (CE) based on the MMSE criterion. Using MMSE-CE, the channel estimation accuracy is almost insensitive to the pilot chip sequence, and a good BER performance is achieved. In this paper, we propose a channel estimation scheme using one-tap recursive least square (RLS) algorithm, where the forgetting factor is adapted to the changing channel condition by the least mean square (LMS)algorithm, for DS-CDMA with FDE. We evaluate the BER performance using RLS-CE with adaptive forgetting factor in a frequency-selective fast Rayleigh fading channel by computer simulation.

  8. Over-Sampling Codebook-Based Hybrid Minimum Sum-Mean-Square-Error Precoding for Millimeter-Wave 3D-MIMO

    KAUST Repository

    Mao, Jiening

    2018-05-23

    Abstract: Hybrid precoding design is challenging for millimeter-wave (mmWave) massive MIMO. Most prior hybrid precoding schemes are designed to maximize the sum spectral efficiency (SSE), while seldom investigate the bit-error-rate (BER). Therefore, this letter designs an over-sampling codebook (OSC)-based hybrid minimum sum-mean-square-error (min-SMSE) precoding to optimize the BER. Specifically, given the effective baseband channel consisting of the real channel and analog precoding, we first design the digital precoder/combiner based on min-SMSE criterion to optimize the BER. To further reduce the SMSE between the transmit and receive signals, we propose an OSC-based joint analog precoder/combiner (JAPC) design. Simulation results show that the proposed scheme can achieve the better performance than its conventional counterparts.

  9. Performance analysis of coherent free space optical communications with sequential pyramid wavefront sensor

    Science.gov (United States)

    Liu, Wei; Yao, Kainan; Chen, Lu; Huang, Danian; Cao, Jingtai; Gu, Haijun

    2018-03-01

    Based-on the previous study on the theory of the sequential pyramid wavefront sensor (SPWFS), in this paper, the SPWFS is first applied to the coherent free space optical communications (FSOC) with more flexible spatial resolution and higher sensitivity than the Shack-Hartmann wavefront sensor, and with higher uniformity of intensity distribution and much simpler than the pyramid wavefront sensor. Then, the mixing efficiency (ME) and the bit error rate (BER) of the coherent FSOC are analyzed during the aberrations correction through numerical simulation with binary phase shift keying (BPSK) modulation. Finally, an experimental AO system based-on SPWFS is setup, and the experimental data is used to analyze the ME and BER of homodyne detection with BPSK modulation. The results show that the AO system based-on SPWFS can increase ME and decrease BER effectively. The conclusions of this paper provide a new method of wavefront sensing for designing the AO system for a coherent FSOC system.

  10. Construction and performance research on variable-length codes for multirate OCDMA multimedia networks

    Science.gov (United States)

    Li, Chuan-qi; Yang, Meng-jie; Luo, De-jun; Lu, Ye; Kong, Yi-pu; Zhang, Dong-chuang

    2014-09-01

    A new kind of variable-length codes with good correlation properties for the multirate asynchronous optical code division multiple access (OCDMA) multimedia networks is proposed, called non-repetition interval (NRI) codes. The NRI codes can be constructed by structuring the interval-sets with no repetition, and the code length depends on the number of users and the code weight. According to the structural characteristics of NRI codes, the formula of bit error rate (BER) is derived. Compared with other variable-length codes, the NRI codes have lower BER. A multirate OCDMA multimedia simulation system is designed and built, the longer codes are assigned to the users who need slow speed, while the shorter codes are assigned to the users who need high speed. It can be obtained by analyzing the eye diagram that the user with slower speed has lower BER, and the conclusion is the same as the actual demand in multimedia data transport.

  11. Successive Interference Cancellation for DS-Optical PPM-CDMA Systems

    Science.gov (United States)

    Alsowaidi, N.; Eltaif, Tawfig; Mokhtar, M. R.

    2016-06-01

    In this paper we introduce a successive interference cancellation (SIC) scheme for direct sequence optical code division multiple access (DS-OCDMA) systems using pulse position modulation (PPM). Considering double-padded modified prime code (DPMPC) as a signature sequence code, results show that the system has better performance in terms of both capacity and bit error rate (BER) as compared to the one without cancellation scheme, where the system with SIC scheme can support up to 88 users while the system without SIC scheme can support only 38 users at similar BER=10-9. Although the receiver sensitivity is affected by the overlapping between users, which limits the system performance, the theoretical analysis of this issue indicates the influence of the size of M-ary PPM on OCDMA system. Hence, the BER value is still sufficient for good system performance.

  12. Kollektivismus, Individualismus und Persönlichkeit als Prädiktoren von Einstellungen gegenüber psychologischer Beratung - Ein Kulturvergleich zwischen deutschen und chinesischen Studierenden

    OpenAIRE

    Schmahl, Anne

    2007-01-01

    Die vorliegende Diplomarbeit beschäftigt sich mit einem Kulturvergleich zwischen deutschen (n=103) und chinesischen Studierenden (n=98) bezüglich ihrer Einstellungen gegenüber psychologischer Beratung. Als Prädiktoren der Einstellungen wurden hierbei zum einen die kulturelle Dimension Individualismus-Kollektivismus nach Hofstede (2005) und zum anderen das Fünf-Faktoren-Modell der Persönlichkeit (FFM) herangezogen. Der Einfluss der Persönlichkeit auf die Einstellungen gegenüber psychologischer...

  13. Monitoring of the spatial and temporal dynamics of BER/SSBR pathway proteins, including MYH, UNG2, MPG, NTH1 and NEIL1-3, during DNA replication.

    Science.gov (United States)

    Bj Rås, Karine Ø; Sousa, Mirta M L; Sharma, Animesh; Fonseca, Davi M; S Gaard, Caroline K; Bj Rås, Magnar; Otterlei, Marit

    2017-08-21

    Base lesions in DNA can stall the replication machinery or induce mutations if bypassed. Consequently, lesions must be repaired before replication or in a post-replicative process to maintain genomic stability. Base excision repair (BER) is the main pathway for repair of base lesions and is known to be associated with DNA replication, but how BER is organized during replication is unclear. Here we coupled the iPOND (isolation of proteins on nascent DNA) technique with targeted mass-spectrometry analysis, which enabled us to detect all proteins required for BER on nascent DNA and to monitor their spatiotemporal orchestration at replication forks. We demonstrate that XRCC1 and other BER/single-strand break repair (SSBR) proteins are enriched in replisomes in unstressed cells, supporting a cellular capacity of post-replicative BER/SSBR. Importantly, we identify for the first time the DNA glycosylases MYH, UNG2, MPG, NTH1, NEIL1, 2 and 3 on nascent DNA. Our findings suggest that a broad spectrum of DNA base lesions are recognized and repaired by BER in a post-replicative process. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  14. Analysis of physical layer performance of data center with optical wavelength switches based on advanced modulation formats

    Science.gov (United States)

    Ahmad, Iftikhar; Chughtai, Mohsan Niaz

    2018-05-01

    In this paper the IRIS (Integrated Router Interconnected spectrally), an optical domain architecture for datacenter network is analyzed. The IRIS integrated with advanced modulation formats (M-QAM) and coherent optical receiver is analyzed. The channel impairments are compensated using the DSP algorithms following the coherent receiver. The proposed scheme allows N2 multiplexed wavelengths for N×N size. The performance of the N×N-IRIS switch with and without wavelength conversion is analyzed for different Baud rates over M-QAM modulation formats. The performance of the system is analyzed in terms of bit error rate (BER) vs OSNR curves.

  15. Two-Stage Maximum Likelihood Estimation (TSMLE for MT-CDMA Signals in the Indoor Environment

    Directory of Open Access Journals (Sweden)

    Sesay Abu B

    2004-01-01

    Full Text Available This paper proposes a two-stage maximum likelihood estimation (TSMLE technique suited for multitone code division multiple access (MT-CDMA system. Here, an analytical framework is presented in the indoor environment for determining the average bit error rate (BER of the system, over Rayleigh and Ricean fading channels. The analytical model is derived for quadrature phase shift keying (QPSK modulation technique by taking into account the number of tones, signal bandwidth (BW, bit rate, and transmission power. Numerical results are presented to validate the analysis, and to justify the approximations made therein. Moreover, these results are shown to agree completely with those obtained by simulation.

  16. High performance multi-channel high-speed I/O circuits

    CERN Document Server

    Oh, Taehyoun

    2013-01-01

    This book describes design techniques that can be used to mitigate crosstalk in high-speed I/O circuits. The focus of the book is in developing compact and low power integrated circuits for crosstalk cancellation, inter-symbol interference (ISI) mitigation and improved bit error rates (BER) at higher speeds. This book is one of the first to discuss in detail the problem of crosstalk and ISI mitigation encountered as data rates have continued beyond 10Gb/s. Readers will learn to avoid the data performance cliff, with circuits and design techniques described for novel, low power crosstalk cancel

  17. A Novel Method for Performance Analysis of OFDM Polarization Diversity System in Ricean Fading Environment

    DEFF Research Database (Denmark)

    Ilic-Delibasic, M.; Pejanovic-Djurisic, M.; Prasad, R.

    2012-01-01

    OFDM (Orthogonal Frequency Division Multiplexing) is proven to be a very effective modulation and multiple access technique that enables high data rate transmission. Due to its good performance it is already implemented in several standardized technologies, and it is very promising technique...... conditions. In order to calculate BER (Bit Error Rate) for the considered OFDM polarization diversity system with a certain level of the received signals correlation, we propose a novel analytical method. The obtained results are compared with the ones attained by simulation....

  18. Quantitative analysis and demonstration of modified triple-branch signal detection scheme for SAC-OCDMA systems

    Science.gov (United States)

    Chen, Fujun; Feng, Gang; Zhang, Siwei

    2016-10-01

    The triple-branch signal detection (TBSD) scheme can eliminate multiple-user interference (MUI) without fixed in-phase cross-correlation (IPCC) stipulation in the spectral-amplitude-coding optical code division multiple access (SACOCDMA) systems. In this paper, we modify the traditional TBSD scheme and theoretically analyze the principle of the MUI elimination. Then, the bit-error-rate (BER) performance of the modified TBSD scheme is investigated under multiple transmission rates. The results show that the modified TBSD employing the codes with unfixed IPCC can achieve simultaneous optical code recognition and MUI elimination in the SAC-OCDMA.

  19. Modeling of aviation telecommunications

    Directory of Open Access Journals (Sweden)

    В. Харченко

    2012-04-01

    Full Text Available The aim of this article consists in construction of communication channel "aircraft - satellite - ground station" model using MATLAB Simulink software. The new model allowed to receive graphic dependences of Bit Error Rate (BER on type of signal modulation, rate of information transfer, signal power, diameter of antennas and nonlinearity of the high power amplifier. These dependences have been compared for the first time with the similar dependences received by means of a program complex "Albatross-budget" for the geostationary satellite. Comparison has shown not only qualitative, but, in some cases, and quite good numerical coincidence of results.

  20. Performance Comparison between CDTD and STTD for DS-CDMA/MMSE-FDE with Frequency-Domain ICI Cancellation

    Science.gov (United States)

    Takeda, Kazuaki; Kojima, Yohei; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide a better bit error rate (BER) performance than rake combining. However, the residual inter-chip interference (ICI) is produced after MMSE-FDE and this degrades the BER performance. Recently, we showed that frequency-domain ICI cancellation can bring the BER performance close to the theoretical lower bound. To further improve the BER performance, transmit antenna diversity technique is effective. Cyclic delay transmit diversity (CDTD) can increase the number of equivalent paths and hence achieve a large frequency diversity gain. Space-time transmit diversity (STTD) can obtain antenna diversity gain due to the space-time coding and achieve a better BER performance than CDTD. Objective of this paper is to show that the BER performance degradation of CDTD is mainly due to the residual ICI and that the introduction of ICI cancellation gives almost the same BER performance as STTD. This study provides a very important result that CDTD has a great advantage of providing a higher throughput than STTD. This is confirmed by computer simulation. The computer simulation results show that CDTD can achieve higher throughput than STTD when ICI cancellation is introduced.

  1. A negentropy minimization approach to adaptive equalization for digital communication systems.

    Science.gov (United States)

    Choi, Sooyong; Lee, Te-Won

    2004-07-01

    In this paper, we introduce and investigate a new adaptive equalization method based on minimizing approximate negentropy of the estimation error for a finite-length equalizer. We consider an approximate negentropy using nonpolynomial expansions of the estimation error as a new performance criterion to improve performance of a linear equalizer based on minimizing minimum mean squared error (MMSE). Negentropy includes higher order statistical information and its minimization provides improved converge, performance and accuracy compared to traditional methods such as MMSE in terms of bit error rate (BER). The proposed negentropy minimization (NEGMIN) equalizer has two kinds of solutions, the MMSE solution and the other one, depending on the ratio of the normalization parameters. The NEGMIN equalizer has best BER performance when the ratio of the normalization parameters is properly adjusted to maximize the output power(variance) of the NEGMIN equalizer. Simulation experiments show that BER performance of the NEGMIN equalizer with the other solution than the MMSE one has similar characteristics to the adaptive minimum bit error rate (AMBER) equalizer. The main advantage of the proposed equalizer is that it needs significantly fewer training symbols than the AMBER equalizer. Furthermore, the proposed equalizer is more robust to nonlinear distortions than the MMSE equalizer.

  2. Características tecnológicas do processo de trabalho em berçários

    OpenAIRE

    Rocha, Semiramis Melani de Melo; Scochi, Carmen Gracinda Silvan; Souza, Heloisa Garda Borgi Lino de

    1999-01-01

    Este estudo analisa, através de uma descrição dos instrumentos de trabalho utilizados no berçário, na assistência ao recém-nascido, as relações que se estabelecem entre os profissionais de saúde e os bebês, mediadas por conhecimentos científicos. Busca, ainda, demonstrar as possibilidades de compreender os nexos entre tecnologia, relações humanas e um cuidado individualizado cujo significado seja a restauração de vitalidade. Trata-se de um estudo exploratório de caráter qualitativo. Os dados ...

  3. Das Thema “Altern” in Arno Geigers Roman «Alles über Sally»

    Directory of Open Access Journals (Sweden)

    Meike Dackweiler

    2013-11-01

    Full Text Available Alles über Sally (All about Sally is the fifth novel of the successful Austrian author Arno Geiger. While it was both praised and criticized for being a contemporary adaption of the adultery novel, little importance was attached to the theme of ageing, which pervades the whole novel. Moreover, adulterous female characters over fifty are rare in contemporary German literature. Given these premises, this essay examines the composition of the ageing characters in the novel and provides a discussion of the social construction of images of ageing.

  4. Increased Efficiency of Face Recognition System using Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Rajani Muraleedharan

    2006-02-01

    Full Text Available This research was inspired by the need of a flexible and cost effective biometric security system. The flexibility of the wireless sensor network makes it a natural choice for data transmission. Swarm intelligence (SI is used to optimize routing in distributed time varying network. In this paper, SI maintains the required bit error rate (BER for varied channel conditions while consuming minimal energy. A specific biometric, the face recognition system, is discussed as an example. Simulation shows that the wireless sensor network is efficient in energy consumption while keeping the transmission accuracy, and the wireless face recognition system is competitive to the traditional wired face recognition system in classification accuracy.

  5. PAPR Reduction in OFDM-based Visible Light Communication Systems Using a Combination of Novel Peak-value Feedback Algorithm and Genetic Algorithm

    Science.gov (United States)

    Deng, Honggui; Liu, Yan; Ren, Shuang; He, Hailang; Tang, Chengying

    2017-10-01

    We propose an enhanced partial transmit sequence technique based on novel peak-value feedback algorithm and genetic algorithm (GAPFA-PTS) to reduce peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals in visible light communication (VLC) systems(VLC-OFDM). To demonstrate the advantages of our proposed algorithm, we analyze the flow of proposed technique and compare the performances with other techniques through MATLAB simulation. The results show that GAPFA-PTS technique achieves a significant improvement in PAPR reduction while maintaining low bit error rate (BER) and low complexity in VLC-OFDM systems.

  6. A novel optical transmission link with DHT-based constant envelope optical OFDM signal

    Science.gov (United States)

    Ma, Jianxin; Liang, Hao

    2013-07-01

    In this paper, we have proposed a novel optical OFDM transmission link that takes advantages of discrete Hartley Transform (DHT) and constant envelope (CE) modulation, obtaining DHT-based constant envelope optical OFDM. The numerical results show that this design achieves better performance when compared with conventional O-OFDM in terms of bit error rate (BER) and peak-to-average power ratio (PAPR). The impact of phase modulation index (PMI) on both PAPR and noise tolerance is investigated. Since the scheme has simplified design, it is believed to be a cost-effective in the practical implement.

  7. Simplified Fiber-Wireless Distribution of HD Video in Passive and Active W-band Close Proximity Terminals

    DEFF Research Database (Denmark)

    Lebedev, Alexander; Rodes Lopez, Roberto; Yu, Xianbin

    2012-01-01

    We experimentally demonstrate uncompressed high-definition (HD) video distribution at 84 GHz Radio over Fiber link achieving up to 3 meters of wireless transmission. We experimentally emulate Metro-Access architecture by deploying single/multimode fibers. Passive and active approaches for remote...... antenna unit (RAU) are experimentally investigated. The bit error rate (BER) performance of the optical and wireless channels is reported. A successful transmission of uncompressed HD video in the W-band wireless channel is demonstrated with prospects to pave the way for application-focused fiber-wireless...

  8. Crosstalk eliminating and low-density parity-check codes for photochromic dual-wavelength storage

    Science.gov (United States)

    Wang, Meicong; Xiong, Jianping; Jian, Jiqi; Jia, Huibo

    2005-01-01

    Multi-wavelength storage is an approach to increase the memory density with the problem of crosstalk to be deal with. We apply Low Density Parity Check (LDPC) codes as error-correcting codes in photochromic dual-wavelength optical storage based on the investigation of LDPC codes in optical data storage. A proper method is applied to reduce the crosstalk and simulation results show that this operation is useful to improve Bit Error Rate (BER) performance. At the same time we can conclude that LDPC codes outperform RS codes in crosstalk channel.

  9. Multi-channel WDM RZ-to-NRZ format conversion at 50 Gbit/s based on single silicon microring resonator

    DEFF Research Database (Denmark)

    Ding, Yunhong; Peucheret, Christophe; Pu, Minhao

    2010-01-01

    We comprehensively analyze multiple WDM channels RZ-to- NRZ format conversion using a single microring resonator. The scheme relies on simultaneous suppression of the first order harmonic components in the spectra of all the RZ channels. An optimized silicon microring resonator with free spectral...... range of 100 GHz and Q value of 7900 is designed and fabricated for this purpose. Multi-channel RZ-to-NRZ format conversion is demonstrated experimentally at 50 Gbit/s for WDM channels with 200 GHz channel spacing using the fabricated device. Bit error rate (BER)measurements show very good conversion...

  10. Bidirectional and simultaneous FTTX/Ethernet services using RSOA based remodulation and polarization multiplexing technique

    Science.gov (United States)

    Das, Anindya S.; Patra, Ardhendu S.

    2015-08-01

    A bidirectional and simultaneous transmission of Ethernet, FTTX services through single optical carrier wavelength employing polarization multiplexing technique in the transmitter end and the user end. 10 Gbps and 2.5 Gbps datarates are transmitted over 50 km single mode fiber employing POLMUX technique at OLT and ONU to provide Ethernet and FTTX services concurrently to the user. Reflective semiconductor optical amplifier is used to reuse and remodulate the downlink signal to uplink transmission. The upstream and the downstream transmission performances are observed by the bit error rate values and the eye diagrams obtained by the BER analyzer.

  11. Genetic Local Search for Optimum Multiuser Detection Problem in DS-CDMA Systems

    Science.gov (United States)

    Wang, Shaowei; Ji, Xiaoyong

    Optimum multiuser detection (OMD) in direct-sequence code-division multiple access (DS-CDMA) systems is an NP-complete problem. In this paper, we present a genetic local search algorithm, which consists of an evolution strategy framework and a local improvement procedure. The evolution strategy searches the space of feasible, locally optimal solutions only. A fast iterated local search algorithm, which employs the proprietary characteristics of the OMD problem, produces local optima with great efficiency. Computer simulations show the bit error rate (BER) performance of the GLS outperforms other multiuser detectors in all cases discussed. The computation time is polynomial complexity in the number of users.

  12. Selective Adaptive Parallel Interference Cancellation for Multicarrier DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Ahmed El-Sayed El-Mahdy

    2013-07-01

    Full Text Available In this paper, Selective Adaptive Parallel Interference Cancellation (SA-PIC technique is presented for Multicarrier Direct Sequence Code Division Multiple Access (MC DS-CDMA scheme. The motivation of using SA-PIC is that it gives high performance and at the same time, reduces the computational complexity required to perform interference cancellation. An upper bound expression of the bit error rate (BER for the SA-PIC under Rayleigh fading channel condition is derived. Moreover, the implementation complexities for SA-PIC and Adaptive Parallel Interference Cancellation (APIC are discussed and compared. The performance of SA-PIC is investigated analytically and validated via computer simulations.

  13. A Unified Approach to the Analysis of Multicarrier DS-CDMA over Nakagami-$M$ Fading Channels

    OpenAIRE

    Yang, L-L.; Hanzo, L.

    2001-01-01

    A class of unified multicarrier DS-CDMA (MC DS-CDMA) schemes is defined and its performance is considered over multipath Nakagami-$M$ fading channels. The spacing between two adjacent subcarriers of the unified MC DS-CDMA scheme is a variable, allowing us to gain insight into the effects of the spacing on the bit error rate (BER) performance of MC DS-CDMA systems. This unified MC DS-CDMA scheme includes the subclasses of multitone DS-CDMA and orthogonal MC DS-CDMA as special cases. The optimu...

  14. A STUDY ON DETERMINING THE REFERENCE SPREADING SEQUENCES FOR A DS/CDMACOMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    Cebrail ÇİFTLİKLİ

    2002-02-01

    Full Text Available In a direct sequence/code division multiple access (DS/CDMA system, the role of the spreading sequences (codes is crucial since the multiple access interference (MAI is the main performance limitation. In this study, we propose an accurate criterion which enables the determination of the reference spreading codes which yield lower bit error rates (BER's in a given code set for a DS/CDMA system using despreading sequences weighted by stepping chip waveforms. The numerical results show that the spreading codes determined by the proposed criterion are the most suitable codes for using as references.

  15. Performance of Generalized Multicarrier DS-CDMA over Nakagami-$m$ Fading Channels

    OpenAIRE

    Yang, L-L.; Hanzo, L.

    2002-01-01

    A class of generalized multicarrier direct sequence code-division multiple-access (MC DS-CDMA) schemes is defined and its performance is considered over multipath Nakagamifading channels. The spacing between two adjacent subcarriers of the generalized MC DS-CDMA is a variable, allowing us to gain insight into the effects of the spacing on the bit error rate (BER) performance of MC DS-CDMA systems. This generalized MC DS-CDMA scheme includes the subclasses of multitone DS-CDMA and orthogonal M...

  16. Differential Service in a Bidirectional Radio-over-Fiber System over a Spectral-Amplitude-Coding OCDMA Network

    Directory of Open Access Journals (Sweden)

    Chao-Chin Yang

    2016-10-01

    Full Text Available A new scheme of radio-over-fiber (RoF network based on spectral-amplitude-coding (SAC optical code division multiple access (OCDMA is herein proposed. Differential service is provided by a power control scheme that classifies users into several classes and assigns each of them with a specific power level. Additionally, the wavelength reuse technique is adapted to support bidirectional transmission and reduce base station (BS cost. Both simulation and numerical results show that significantly differential quality-of-service (QoS in bit-error rate (BER is achieved in both downlink and uplink transmissions.

  17. Performance analysis of LDPC codes on OOK terahertz wireless channels

    International Nuclear Information System (INIS)

    Liu Chun; Wang Chang; Cao Jun-Cheng

    2016-01-01

    Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz (THz) wireless communications. An error control coding scheme based on low density parity check (LDPC) codes with soft decision decoding algorithm is proposed to improve the bit-error-rate (BER) performance of an on-off keying (OOK) modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications. (paper)

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

    Science.gov (United States)

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

    2014-03-10

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

  19. A modified non-binary LDPC scheme based on watermark symbols in high speed optical transmission systems

    Science.gov (United States)

    Wang, Liming; Qiao, Yaojun; Yu, Qian; Zhang, Wenbo

    2016-04-01

    We introduce a watermark non-binary low-density parity check code (NB-LDPC) scheme, which can estimate the time-varying noise variance by using prior information of watermark symbols, to improve the performance of NB-LDPC codes. And compared with the prior-art counterpart, the watermark scheme can bring about 0.25 dB improvement in net coding gain (NCG) at bit error rate (BER) of 1e-6 and 36.8-81% reduction of the iteration numbers. Obviously, the proposed scheme shows great potential in terms of error correction performance and decoding efficiency.

  20. Performance of an Error Control System with Turbo Codes in Powerline Communications

    Directory of Open Access Journals (Sweden)

    Balbuena-Campuzano Carlos Alberto

    2014-07-01

    Full Text Available This paper reports the performance of turbo codes as an error control technique in PLC (Powerline Communications data transmissions. For this system, computer simulations are used for modeling data networks based on the model classified in technical literature as indoor, and uses OFDM (Orthogonal Frequency Division Multiplexing as a modulation technique. Taking into account the channel, modulation and turbo codes, we propose a methodology to minimize the bit error rate (BER, as a function of the average received signal noise ratio (SNR.

  1. A planar waveguide optical discrete Fourier transformer design for 160 Gb/s all-optical OFDM systems

    Science.gov (United States)

    Li, Wei; Liang, Xiaojun; Ma, Weidong; Zhou, Tianhong; Huang, Benxiong; Liu, Deming

    2010-01-01

    A cost-effective all-optical discrete Fourier transformer (ODFT) is designed based on a silicon planar lightwave circuit (PLC), which can be applied to all-optical orthogonal frequency division multiplexing (OFDM) transmission systems and can be achieved by current techniques. It consists of 2 × 2 directional couplers, phase shifters and optical delay lines. Metal-film heaters are used as phase shifters, according to the thermooptic effect of SiO 2. Based on the ODFT, a 160 Gb/s OFDM system is set up. Simulation results show excellent bit error rate (BER) and optical signal-to-noise ratio (OSNR) performances after 400 km transmission.

  2. Design of variable-weight quadratic congruence code for optical CDMA

    Science.gov (United States)

    Feng, Gang; Cheng, Wen-Qing; Chen, Fu-Jun

    2015-09-01

    A variable-weight code family referred to as variable-weight quadratic congruence code (VWQCC) is constructed by algebraic transformation for incoherent synchronous optical code division multiple access (OCDMA) systems. Compared with quadratic congruence code (QCC), VWQCC doubles the code cardinality and provides the multiple code-sets with variable code-weight. Moreover, the bit-error rate (BER) performance of VWQCC is superior to those of conventional variable-weight codes by removing or padding pulses under the same chip power assumption. The experiment results show that VWQCC can be well applied to the OCDMA with quality of service (QoS) requirements.

  3. Reconfigurable architecture based on fiber bragg gratings for indoor networks (Arquitectura reconfigurable basada en redes de difracción de Bragg para redes convergentes indoor ópticas

    Directory of Open Access Journals (Sweden)

    Gustavo Adolfo Puerto-Leguizamón

    2016-01-01

    Full Text Available This paper presents an approach for dynamic reconfiguration of wavelength channels for future indoor network architectures. The approach exploits the tunability and the rejection profile of Fiber Bragg Gratings (FBG to implement service distribution strategies that includes Unicast, Broadcast and Multicast scenarios for fixed and mobile users. Experimental demonstrations based on two implementations show results with 1% average degradation for Error Vector Magnitude (EVM values and up to 2,2 dB for 1x10-12 Bit Error Rate (BER. In particular, the proposed architectures fit for large in-building networks

  4. Monte-Carlo Simulation for PDC-Based Optical CDMA System

    Directory of Open Access Journals (Sweden)

    FAHIM AZIZ UMRANI

    2010-10-01

    Full Text Available This paper presents the Monte-Carlo simulation of Optical CDMA (Code Division Multiple Access systems, and analyse its performance in terms of the BER (Bit Error Rate. The spreading sequence chosen for CDMA is Perfect Difference Codes. Furthermore, this paper derives the expressions of noise variances from first principles to calibrate the noise for both bipolar (electrical domain and unipolar (optical domain signalling required for Monte-Carlo simulation. The simulated results conform to the theory and show that the receiver gain mismatch and splitter loss at the transceiver degrades the system performance.

  5. An OTDM-To-WDM Converter Using Optical Fourier Transformation

    Directory of Open Access Journals (Sweden)

    Khin Su Myat Min

    2015-08-01

    Full Text Available We demonstrate serial-to-parallel conversion of 40 Gbps optical time division multiplexed OTDM signal to 4x10 Gbps wavelength division-multiplexed WDM individual channels by using Optical Fourier Transformation OFT method. OFT is also called time lens technique and it is implemented by the combination of dispersive fiber and phase modulation. In this research electro-optic phase modulator EOM is used as time lens. As our investigations simulation results and bit error rate BER measurements are expressed.

  6. LVDS tester: a systematic test of cable signal transmission at the ALICE experiment

    CERN Document Server

    Barnby, L; Bombara, M; Evans, D; Jones, G T; Jones, P G; Jovanović, P; Jusko, A; Kour, R; Králik, I; Krivda, M; Lazzeroni, C; Lietava, R; Matthews, Z L; Navin, S; Palaha, A; Petrov, P; Platt, R; Šándor, L; Scott, P; Urbán, J; Villalobos Baillie, O; Tapia Takaki, J D

    2010-01-01

    In the ALICE experiment, the Low-Voltage Differential Signalling (LVDS) format is used for the transmission of trigger inputs from the detectors to the Central Trigger Processor (CTP), the L0 trigger outputs from Local Trigger Units (LTU) boards back to the detectors and the BUSY inputs from the sub-detectors to the CTP. ALICE has designed a set-up, called the LVDS transmission tester, that aims to measure various transmission quality parameters and the bit-error rate (BER) for long period runs in an automatic way. In this paper, this method is described and the conclusions from these tests for the ALICE LVDS cables are discussed

  7. LVDS tester: a systematic test of cable signal transmission at the ALICE experiment

    International Nuclear Information System (INIS)

    Barnby, L; Bhasin, A; Evans, D; Jones, G T; Jones, P G; Jovanovic, P; Jusko, A; Kour, R; Krivda, M; Lazzeroni, C; Lietava, R; Matthews, Z L; Navin, S; Palaha, A; Petrov, P; Platt, R; Scott, P; Bombara, M; Kralik, I; Sandor, L

    2010-01-01

    In the ALICE experiment, the Low-Voltage Differential Signalling (LVDS) format is used for the transmission of trigger inputs from the detectors to the Central Trigger Processor (CTP), the L0 trigger outputs from Local Trigger Units (LTU) boards back to the detectors and the BUSY inputs from the sub-detectors to the CTP. ALICE has designed a set-up, called the LVDS transmission tester, that aims to measure various transmission quality parameters and the bit-error rate (BER) for long period runs in an automatic way. In this paper, this method is described and the conclusions from these tests for the ALICE LVDS cables are discussed.

  8. Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti STBC in Different Modulation Schemes

    OpenAIRE

    Shams, Rifat Ara; Kabir, M. Hasnat; Ullah, Sheikh Enayet

    2012-01-01

    In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on the performance of wavelet based MC-CDMA wireless communication system with the implementation of Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel inc...

  9. Reconfigurable WDM-PON empowered by a low-cost 8-channel directly modulated laser module

    Science.gov (United States)

    Zhang, Yi-ming; Liu, Yu; Zhang, Zhi-ke; Zhao, Ze-ping; Tian, Ye; Zhu, Ning-hua

    2017-11-01

    A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network (WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser (DML) module. Compared with the case using discrete devices in conventional scheme, the proposed DML module provides a cost-effective solution with reduced complexity. The clear eye diagram and the bit error rate ( BER) of less than 2×10-7 with a sensitivity of -7 dBm are obtained. Due to the special packaging design, the crosstalk between channels under condition of simultaneous operation can be negligible.

  10. Digital scrambling for shuttle communication links: Do drawbacks outweigh advantages?

    Science.gov (United States)

    Dessouky, K.

    1985-01-01

    Digital data scrambling has been considered for communication systems using NRZ (non-return to zero) symbol formats. The purpose is to increase the number of transitions in the data to improve the performance of the symbol synchronizer. This is accomplished without expanding the bandwidth but at the expense of increasing the data bit error rate (BER). Models for the scramblers/descramblers of practical interest are presented together with the appropriate link model. The effects of scrambling on the performance of coded and uncoded links are studied. The results are illustrated by application to the Tracking and Data Relay Satellite System links. Conclusions regarding the usefulness of scrambling are also given.

  11. Effect of digital scrambling on satellite communication links

    Science.gov (United States)

    Dessouky, K.

    1985-01-01

    Digital data scrambling has been considered for communication systems using NRZ symbol formats. The purpose is to increase the number of transitions in the data to improve the performance of the symbol synchronizer. This is accomplished without expanding the bandwidth but at the expense of increasing the data bit error rate (BER). Models for the scramblers/descramblers of practical interest are presented together with the appropriate link model. The effects of scrambling on the performance of coded and uncoded links are studied. The results are illustrated by application to the Tracking and Data Relay Satellite System (TDRSS) links. Conclusions regarding the usefulness of scrambling are also given.

  12. Experimental evaluation of prefiltering for 56 Gbaud DP-QPSK signal transmission in 75 GHz WDM grid

    DEFF Research Database (Denmark)

    Borkowski, Robert; de Carvalho, Luis Henrique H.; Silva, Edson Porto da

    2014-01-01

    We investigate optical prefiltering for 56Gbaud (224Gbit/s) electrical time-division multiplexed (ETDM) dual polarization (DP) quaternary phase shift keying (QPSK) transmission. Different transmitter-side optical filter shapes are tested and their bandwidths are varied. Comparison of studied filter...... shapes shows an advantage of a pre-emphasis filter. Subsequently, we perform a fiber transmission of the 56Gbaud DP QPSK signal filtered with the 65GHz pre-emphasis filter to fit the 75GHz transmission grid. Bit error rate (BER) of the signal remains below forward error correction (FEC) limit after 300km...

  13. Cepstral domain modification of audio signals for data embedding: preliminary results

    Science.gov (United States)

    Gopalan, Kaliappan

    2004-06-01

    A method of embedding data in an audio signal using cepstral domain modification is described. Based on successful embedding in the spectral points of perceptually masked regions in each frame of speech, first the technique was extended to embedding in the log spectral domain. This extension resulted at approximately 62 bits /s of embedding with less than 2 percent of bit error rate (BER) for a clean cover speech (from the TIMIT database), and about 2.5 percent for a noisy speech (from an air traffic controller database), when all frames - including silence and transition between voiced and unvoiced segments - were used. Bit error rate increased significantly when the log spectrum in the vicinity of a formant was modified. In the next procedure, embedding by altering the mean cepstral values of two ranges of indices was studied. Tests on both a noisy utterance and a clean utterance indicated barely noticeable perceptual change in speech quality when lower range of cepstral indices - corresponding to vocal tract region - was modified in accordance with data. With an embedding capacity of approximately 62 bits/s - using one bit per each frame regardless of frame energy or type of speech - initial results showed a BER of less than 1.5 percent for a payload capacity of 208 embedded bits using the clean cover speech. BER of less than 1.3 percent resulted for the noisy host with a capacity was 316 bits. When the cepstrum was modified in the region of excitation, BER increased to over 10 percent. With quantization causing no significant problem, the technique warrants further studies with different cepstral ranges and sizes. Pitch-synchronous cepstrum modification, for example, may be more robust to attacks. In addition, cepstrum modification in regions of speech that are perceptually masked - analogous to embedding in frequency masked regions - may yield imperceptible stego audio with low BER.

  14. Berlin Brandenburg International (BER: planning and implementation of a concrete supply chain for the airport construction site

    Directory of Open Access Journals (Sweden)

    Guido Riedel

    2012-12-01

    Full Text Available Background: With the decision to extend the airport Berlin-Schönefeld to the new airport Berlin Brandenburg International (BER in 2006, a construction of superlatives has emerged. One of the biggest challenges was the supply of around 2.5 million cubic meters of high quality concrete that had to be produced for the construction of the airport. Due to the scale of this enterprise as well as its environment, the logistic solution of raw material supply has to be found.       Method: The planning of the concrete supply chain for the airport construction site BER had to be carried out with two major goals: the stability of the supply chain to assure that the demands of the construction site are met and delays are prevented, as well as assurance of the high quality standards of the concrete production and to avoid an alkali silica reaction and the resulting unavoidable disaggregation of the concrete. External effects, such as the carbon dioxide emission and the effect of the supply chain on adjoining residents were key factors that had to be integrated in a holistic supply chain concept.  The principle underlying method is an analysis of limiting conditions for two approaches: a centralized supply chain with on-site concrete factory and upstream transport of raw materials versus a decentralized supply chain with off-site factories and downstream transport of ready-mixed concrete. Results: The analysis of constraints and the effects on key requirements of the concrete supply chain for the BER airport construction site lead to the installation of the most modern concrete plant in Europe. The benefits of a centralized supply chain are significant. On one hand, the high quality standards can be met with the on-site mixture of the concrete and centralized quality assurance, on the other hand, the majority of the supply traffic for the construction site was moved from the road to train-bound logistics, meeting the emission requirements of the

  15. Adaptive Modulation with Best User Selection over Non-Identical Nakagami Fading Channels

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  16. Multiuser Diversity with Adaptive Modulation in Non-Identically Distributed Nakagami Fading Environments

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded/coded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  17. Design of free-space optical transmission system in computer tomography equipment

    Science.gov (United States)

    Liu, Min; Fu, Weiwei; Zhang, Tao

    2018-04-01

    Traditional computer tomography (CT) based on capacitive coupling cannot satisfy the high data rate transmission requirement. We design and experimentally demonstrate a free-space optical transmission system for CT equipment at a data rate of 10 Gb / s. Two interchangeable sections of 12 pieces of fiber with equal length is fabricated and tested by our designed laser phase distance measurement system. By locating the 12 collimators in the edge of the circle wheel evenly, the optical propagation characteristics for the 12 wired and wireless paths are similar, which can satisfy the requirement of high-speed CT transmission system. After bit error rate (BER) measurement in several conditions, the BER performances are below the value of 10 - 11, which has the potential in the future application scenario of CT equipment.

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

    KAUST Repository

    Yilmaz, Ferkan; Alouini, Mohamed-Slim

    2012-01-01

    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

  19. 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.

  20. Simultaneous chemical modification and structural transformation of Stöber silica spheres for integration of nanocatalysts

    KAUST Repository

    Yao, Kexin

    2012-01-10

    A synthetic approach has been devised to convert conventional Stöber silica (SiO 2) spheres into a new type of porous structural platform for supporting multicomponent catalysts. With this approach, we have first prepared zinc-doped SiO 2 (Zn-SiO 2) hollow spheres, on which zinc oxide (ZnO) phase and ruthenium (Ru) nanoparticles have been deposited and assembled sequentially in solution phase. A series of complex Ru/ZnO/Zn-SiO 2 nanocatalysts has been thus been integrated onto the zinc-doped SiO 2 supports after additional thermal treatment and reduction. To test their workability under harsh reactive environments, we have further evaluated the above prepared catalysts using arene hydrogenation as model reactions. These integrated nanocatalysts have shown superior activity, high robustness, and easy recovery in the studied heterogeneous catalysis. © 2011 American Chemical Society.

  1. Utopia ou distopia? A ansiedade e o vazio em Schimmernder Dunst über CobyCounty de Leif Randt

    Directory of Open Access Journals (Sweden)

    Valéria Sabrina Pereira

    2014-06-01

    Full Text Available Em Schimmernder Dunst über CobyCounty (2011, Leif Randt apresenta um condado que seria a mais perfeita representação de uma utopia consumista: localizado à beira-mar, CobyCounty é um lugar de festas abundantes, consumo e bem-estar. O livro, contudo, é narrado por um jovem atormentado pela possibilidade de uma catástrofe que se aproxima, desde que seu melhor amigo abandonou a cidade, ouvindo os conselhos da mãe que se afiliou a uma religião esotérica. Se a perfeição do funcionamento dessa sociedade se aproxima muito de uma utopia, o temor de uma catástrofe anunciada aproxima a obra de uma distopia. Deve-se notar, no entanto, que, ao contrário de utopias e distopias, a obra não apresenta uma força centralizadora de poder - mesmo que a menção ao consumismo e às propagandas seja frequente. Neste artigo, Schimmernder Dunst über CobyCounty será apresentado à luz dos estudos da utopia e distopia, enfatizando seus laços com o tempo atual, marcado pela dicotomia entre a sociedade de conforto produzida pelo alto desenvolvimento tecnológico e a necessidade de se evitar os excessos produzidos por essa mesma sociedade em nome de uma possível catástrofe ecológica, anunciada por cientistas e ativistas, mas da qual não se percebe o impacto diretamente.

  2. Cooperative MIMO communication at wireless sensor network: an error correcting code approach.

    Science.gov (United States)

    Islam, Mohammad Rakibul; Han, Young Shin

    2011-01-01

    Cooperative communication in wireless sensor network (WSN) explores the energy efficient wireless communication schemes between multiple sensors and data gathering node (DGN) by exploiting multiple input multiple output (MIMO) and multiple input single output (MISO) configurations. In this paper, an energy efficient cooperative MIMO (C-MIMO) technique is proposed where low density parity check (LDPC) code is used as an error correcting code. The rate of LDPC code is varied by varying the length of message and parity bits. Simulation results show that the cooperative communication scheme outperforms SISO scheme in the presence of LDPC code. LDPC codes with different code rates are compared using bit error rate (BER) analysis. BER is also analyzed under different Nakagami fading scenario. Energy efficiencies are compared for different targeted probability of bit error p(b). It is observed that C-MIMO performs more efficiently when the targeted p(b) is smaller. Also the lower encoding rate for LDPC code offers better error characteristics.

  3. Design and Implementation of a Chaotic Scheme in Additive White Gaussian Noise Channel

    Directory of Open Access Journals (Sweden)

    Nizar Al Bassam

    2016-01-01

    Full Text Available A new chaotic scheme named Flipped Chaotic On-Off Keying (FCOOK is proposed for binary transmission. In FCOOK, the low correlation value between the stationary signal and its mirrored version is utilized. Transmitted signal for binary 1 is a chaotic segment added to its time flipped (mirrored version within one bit duration, while in binary 0, no transmission takes place within the same bit duration. The proposed scheme is compared with the standard chaotic systems: Differential Chaos Shift Keying (DCSK and Correlation Delay Shift Keying (CDSK. The Bit Error Rate (BER of FCOOK is studied analytically based on Gaussian approximation method. Results show that the BER performance of FCOOK outperforms DCSK and CDSK in AWGN channel environment and with various Eb/No levels. Additionally, FCOOK offers a double bit rate compared with the standard DCSK.

  4. Worst-case residual clipping noise power model for bit loading in LACO-OFDM

    KAUST Repository

    Zhang, Zhenyu

    2018-03-19

    Layered ACO-OFDM enjoys better spectral efficiency than ACO-OFDM, but its performance is challenged by residual clipping noise (RCN). In this paper, the power of RCN of LACO-OFDM is analyzed and modeled. As RCN is data-dependent, the worst-case situation is considered. A worst-case indicator is defined for relating the power of RCN and the power of noise at the receiver, wherein a linear relation is shown to be a practical approximation. An LACO-OFDM bit-loading experiment is performed to examine the proposed RCN power model for data rates of 6 to 7 Gbps. The experiment\\'s results show that accounting for RCN has two advantages. First, it leads to better bit loading and achieves up to 59% lower overall bit-error rate (BER) than when the RCN is ignored. Second, it balances the BER across layers, which is a desired property from a channel coding perspective.

  5. An overview of Space Communication Artificial Intelligence for Link Evaluation Terminal (SCAILET) Project

    Science.gov (United States)

    Shahidi, Anoosh K.; Schlegelmilch, Richard F.; Petrik, Edward J.; Walters, Jerry L.

    1991-11-01

    A software application to assist end-users of the link evaluation terminal (LET) for satellite communications is being developed. This software application incorporates artificial intelligence (AI) techniques and will be deployed as an interface to LET. The high burst rate (HBR) LET provides 30 GHz transmitting/20 GHz receiving (220/110 Mbps) capability for wideband communications technology experiments with the Advanced Communications Technology Satellite (ACTS). The HBR LET can monitor and evaluate the integrity of the HBR communications uplink and downlink to the ACTS satellite. The uplink HBR transmission is performed by bursting the bit-pattern as a modulated signal to the satellite. The HBR LET can determine the bit error rate (BER) under various atmospheric conditions by comparing the transmitted bit pattern with the received bit pattern. An algorithm for power augmentation will be applied to enhance the system's BER performance at reduced signal strength caused by adverse conditions.

  6. The effect of total noise on two-dimension OCDMA codes

    Science.gov (United States)

    Dulaimi, Layth A. Khalil Al; Badlishah Ahmed, R.; Yaakob, Naimah; Aljunid, Syed A.; Matem, Rima

    2017-11-01

    In this research, we evaluate the performance of total noise effect on two dimension (2-D) optical code-division multiple access (OCDMA) performance systems using 2-D Modified Double Weight MDW under various link parameters. The impact of the multi-access interference (MAI) and other noise effect on the system performance. The 2-D MDW is compared mathematically with other codes which use similar techniques. We analyzed and optimized the data rate and effective receive power. The performance and optimization of MDW code in OCDMA system are reported, the bit error rate (BER) can be significantly improved when the 2-D MDW code desired parameters are selected especially the cross correlation properties. It reduces the MAI in the system compensate BER and phase-induced intensity noise (PIIN) in incoherent OCDMA The analysis permits a thorough understanding of PIIN, shot and thermal noises impact on 2-D MDW OCDMA system performance. PIIN is the main noise factor in the OCDMA network.

  7. Worst-case residual clipping noise power model for bit loading in LACO-OFDM

    KAUST Repository

    Zhang, Zhenyu; Chaaban, Anas; Shen, Chao; Elgala, Hany; Ng, Tien Khee; Ooi, Boon S.; Alouini, Mohamed-Slim

    2018-01-01

    Layered ACO-OFDM enjoys better spectral efficiency than ACO-OFDM, but its performance is challenged by residual clipping noise (RCN). In this paper, the power of RCN of LACO-OFDM is analyzed and modeled. As RCN is data-dependent, the worst-case situation is considered. A worst-case indicator is defined for relating the power of RCN and the power of noise at the receiver, wherein a linear relation is shown to be a practical approximation. An LACO-OFDM bit-loading experiment is performed to examine the proposed RCN power model for data rates of 6 to 7 Gbps. The experiment's results show that accounting for RCN has two advantages. First, it leads to better bit loading and achieves up to 59% lower overall bit-error rate (BER) than when the RCN is ignored. Second, it balances the BER across layers, which is a desired property from a channel coding perspective.

  8. A new two-code keying scheme for SAC-OCDMA systems enabling bipolar encoding

    Science.gov (United States)

    Al-Khafaji, Hamza M. R.; Ngah, Razali; Aljunid, S. A.; Rahman, T. A.

    2015-03-01

    In this paper, we propose a new two-code keying scheme for enabling bipolar encoding in a high-rate spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) system. The mathematical formulations are derived for the signal-to-noise ratio and bit-error rate (BER) of SAC-OCDMA system based on the suggested scheme using multi-diagonal (MD) code. Performance analyses are assessed considering the effects of phase-induced intensity noise, as well as shot and thermal noises in photodetectors. The numerical results demonstrated that the proposed scheme exhibits an enhanced BER performance compared to the existing unipolar encoding with direct detection technique. Furthermore, the performance improvement afforded by this scheme is verified using simulation experiments.

  9. Performance and capacity analysis of Poisson photon-counting based Iter-PIC OCDMA systems.

    Science.gov (United States)

    Li, Lingbin; Zhou, Xiaolin; Zhang, Rong; Zhang, Dingchen; Hanzo, Lajos

    2013-11-04

    In this paper, an iterative parallel interference cancellation (Iter-PIC) technique is developed for optical code-division multiple-access (OCDMA) systems relying on shot-noise limited Poisson photon-counting reception. The novel semi-analytical tool of extrinsic information transfer (EXIT) charts is used for analysing both the bit error rate (BER) performance as well as the channel capacity of these systems and the results are verified by Monte Carlo simulations. The proposed Iter-PIC OCDMA system is capable of achieving two orders of magnitude BER improvements and a 0.1 nats of capacity improvement over the conventional chip-level OCDMA systems at a coding rate of 1/10.

  10. A CBPR Partnership Increases HIV Testing among Men Who Have Sex with Men (MSM): Outcome Findings from a Pilot Test of the "CyBER/Testing" Internet Intervention

    Science.gov (United States)

    Rhodes, Scott D.; Vissman, Aaron T.; Stowers, Jason; Miller, Cindy; McCoy, Thomas P.; Hergenrather, Kenneth C.; Wilkin, Aimee M.; Reece, Michael; Bachmann, Laura H.; Ore, Addison; Ross, Michael W.; Hendrix, Ellen; Eng, Eugenia

    2011-01-01

    The Internet has emerged as an important tool for the delivery of health promotion and disease prevention interventions. Our community-based participatory research (CBPR) partnership developed and piloted "CyBER/testing", a culturally congruent intervention designed to promote HIV testing among men who have sex with men (MSM) within existing…

  11. Expanded bed adsorption as a fast technique for the large-scale purification of the complete isoform pool of Ber e 1, the major allergen from Brazil nuts.

    NARCIS (Netherlands)

    Boxtel, van E.L.; Koningsveld, van G.A.; Koppelman, S.J.; Broek, van den L.A.M.; Voragen, A.G.J.; Gruppen, H.

    2006-01-01

    A new, fast, large-scale purification method for Ber e 1, the major allergen from Brazil nuts, using expanded bed adsorption (EBA) chromatography, is presented. Using EBA, crude extracts can be applied to a fluidized column, which allows the unhindered passage of particulate impurities, thereby

  12. Blockchain - Von Supply Chain Finance über Smart Payment bis Smart Contracting: BLOG-Beitrag auf https://www.de-hub.de

    OpenAIRE

    Henke, Michael

    2018-01-01

    Alle reden über die Blockchain. Das Thema wird engagiert bis overhyped diskutiert. Gleichzeitig jedoch werden der mächtige Einfluss und die künftigen Auswirkungen von Blockchains auf Supply Chain Management und Handel immer noch unterschätzt.

  13. Intermedialität als Grundsatzdiskussion. Zum Sammelband Sprechen über Bilder. Sprechen in Bildern: Studien zum Wechselverhältnis von Bild und Sprache

    Directory of Open Access Journals (Sweden)

    Angela Oster

    2016-01-01

    Full Text Available Der Sammelband Sprechen über Bilder. Sprechen in Bildern bietet mehr als nur einen weiteren Beitrag zur Intermedialität. Er erforscht anlässlich des interartialen Austauschs zwischen Bild unf Text die Modi der Wissenschaft und versucht, diesbezüglich neue Impulse zu geben. Methodisch wird dabei die Rezeptionsästhetik favorisiert.

  14. Keim, Karl-Dieter, Das Fenster zum Raum : Traktat über die Erforschung sozialräumlicher Transformation / [rezensiert von] Helmut Klüter

    OpenAIRE

    Klüter, Helmut

    2009-01-01

    Rezensiertes Werk: Keim, Karl-Dieter: Das Fenster zum Raum : Traktat über die Erforschung sozialräumlicher Transformation / Karl-Dieter Keim. - Opladen : Leske + Budrich, 2003. - 171 S. : graph. Darst. - (Lehrtexte : Sozialwissenschaften) ISBN 3-8100-4050-9

  15. Regulation of Burkholderia cenocepacia biofilm formation by RpoN and the c-di-GMP effector BerB

    DEFF Research Database (Denmark)

    Fazli, Mustafa; Rybtke, Morten Levin; Steiner, Elisabeth

    2017-01-01

    Knowledge about the molecular mechanisms that are involved in the regulation of biofilm formation is essential for the development of biofilm-control measures. It is well established that the nucleotide second messenger cyclic diguanosine monophosphate (c-di-GMP) is a positive regulator of biofilm...... formation in many bacteria, but more knowledge about c-di-GMP effectors is needed. We provide evidence that c-di-GMP, the alternative sigma factor RpoN (σ54), and the enhancer-binding protein BerB play a role in biofilm formation of Burkholderia cenocepacia by regulating the production of a biofilm......-stabilizing exopolysaccharide. Our findings suggest that BerB binds c-di-GMP, and activates RpoN-dependent transcription of the berA gene coding for a c-di-GMP-responsive transcriptional regulator. An increased level of the BerA protein in turn induces the production of biofilm-stabilizing exopolysaccharide in response to high...

  16. High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

    Science.gov (United States)

    Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

    2016-01-01

    We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

  17. Revision of the stiletto fly genera Acupalpa Kröber and Pipinnipons Winterton (Diptera, Therevidae, Agapophytinae using cybertaxonomic methods, with a key to Australasian genera

    Directory of Open Access Journals (Sweden)

    Shaun Winterton

    2011-05-01

    Full Text Available Australian stiletto flies of the sister-genera Acupalpa Kröber, 1912 and Pipinnipons Winterton, 2001 (Diptera: Therevidae: Agapophytinae are revised. Twelve new species of Acupalpa are described, while Acupalpa imitans (White, 1915, comb. n. is transferred from Pipinnipons and Acupalpa albimanis (Kröber, 1914, comb. n. is transferred from Ectinorhynchus Macquart as a senior synonym of Acupalpa pollinosa Mann. The total number of species of Acupalpa is therefore increased to 19: A. albimanis (Kröber, comb. n., A. albitarsa Mann, A. boharti sp. n., A. divisa (Walker, A. dolichorhyncha sp. n., A. glossa sp. n., A. imitans (White, comb. n., A. irwini Winterton, A. melanophaeos sp. n., A. miaboolya sp. n., A. minuta sp. n., A. minutoides sp. n., A. notomelas sp. n., A. novayamarna sp. n., A. rostrata Kröber, A. semirufa Mann, A. westralica sp. n., A. yalgoo sp. n. and A. yanchep sp. n. Three new species of Pipinnipons are described, increasing the total number of species to five: P. chauncyvallis sp. n., P. fascipennis (Kröber, P. kampmeierae sp. n., P. kroeberi Winterton, and P. sphecoda sp. n. Pipinnipons and Acupalpa are rediagnosed in light of the new species presented herein and revised keys to species are included. A dichotomous key to genera of Australasian Therevidae is included. As an empirical example of cybertaxonomy, taxonomic descriptions were composed using a character matrix developed in Lucid Builder (in Structured Descriptive Data (SDD format to generate natural language descriptions supplemented by online specimen and image databases. Web resources are provided throughout the document including: a links to high resolution colour images of all species on Morphbank, b registration of authors, publications, taxon names and other nomenclatural acts in Zoobank, with assignment of Life Science Identifiers (LSIDs for each, c links to Genbank accession records for DNA sequences, and d assignment of LSIDs to specimen records with links

  18. Effect of calcium chloride spraying on BER in two varieties of watermelon (Citrullus lanatus (Thunb Matsum and Nakai

    Directory of Open Access Journals (Sweden)

    mohammad salahifarahi

    2017-10-01

    Full Text Available Introduction: Watermelon, originated from warm regions of Africa, is one of the most important vegetable crops used as human food, forage and for producing alcohol. The area under its cultivation in our province was 1031 ha as irrigated and 3829 ha as rainfed. The average fruit yields under above-mentioned conditions were 23784 and 14888kg ha-1, respectively. Watermelon fruits suffer from a nutritional disorder that is attributed to shortage of calcium in developing fruits. The adsorption and uptake process of calcium by plants is comprised of three main stages; the first stage is passing through root cortex into xylem, the second one is its transport within xylem, and the last one is its distribution into leaves and fruits. Plants obtain calcium preferably from soil solution. Calcium moves upward in apoplastic pathways (with transpiration flow, and reaches different organs of the plants through xylem. Blossom-end rot (BER is a nutritional disorder of watermelon, tomato and pepper that is caused by a shortage of calcium in enlarging fruits. Blossom-end rot of watermelon commonly occurs in our province when fruits are growing rapidly. BER is frequently seen in watermelon genotypes with long fruits, Charleston gray type in particular. Calcium requirement increases at rapidly developing stage of fruit. BER might happen as a result of increased demand of blossom-end rot of fruit (rapidly growing section of the fruits for calcium. It can occur even when there is abundant calcium in the soil, because demand exceeds supply. Since fruits do not transpire as much as leaves, less calcium is deposited when calcium containing water is transpired, resulting in a localized calcium deficiency in the fruit. Materials and methods: In order to investigate the effects of foliar application of calcium on BER of watermelon, an experiment was carried out at the agricultural research station of Gonbad, Gonbad-e Qabus, Iran, in 2008. The soil of the experiment site was

  19. Maximal Ratio Combining Using Channel Estimation in Chaos Based Pilot-Added DS-CDMA System with Antenna Diversity

    Directory of Open Access Journals (Sweden)

    Meher Krishna Patel

    2017-01-01

    Full Text Available This paper presents an adaptive multiuser transceiver scheme for DS-CDMA systems in which pilot symbols are added to users’ data to estimate complex channel fading coefficients. The performance of receiver antenna diversity with maximal ratio combining (MRC technique is analyzed for imperfect channel estimation in flat fading environments. The complex fading coefficients are estimated using least mean square (LMS algorithm and these coefficients are utilized by the maximal ratio combiner for generating the decision variable. Probability of error in closed form is derived. Further, the effect of pilot signal power on bit error rate (BER and BER performance of multiplexed pilot and data signal transmission scenario are investigated. We have compared the performance of added and multiplexed pilot-data systems and concluded the advantages of both systems. The proposed CDMA technique uses the chaotic sequence as spreading sequence. Assuming proper synchronization, the computer simulation results demonstrate the better bit error rate performance in the presence of channel estimator in the chaotic based CDMA system and the receiver antenna diversity technique further improves the performance of the proposed system. Also, no channel estimator is required if there is no phase distortion to the transmitted signal.

  20. The effect of jitter on the performance of space coherent optical communication system with Costas loop

    Science.gov (United States)

    Li, Xin; Hong, Yifeng; Wang, Jinfang; Liu, Yang; Sun, Xun; Li, Mi

    2018-01-01

    Numerous communication techniques and optical devices successfully applied in space optical communication system indicates a good portability of it. With this good portability, typical coherent demodulation technique of Costas loop can be easily adopted in space optical communication system. As one of the components of pointing error, the effect of jitter plays an important role in the communication quality of such system. Here, we obtain the probability density functions (PDF) of different jitter degrees and explain their essential effect on the bit error rate (BER) space optical communication system. Also, under the effect of jitter, we research the bit error rate of space coherent optical communication system using Costas loop with different system parameters of transmission power, divergence angle, receiving diameter, avalanche photodiode (APD) gain, and phase deviation caused by Costas loop. Through a numerical simulation of this kind of communication system, we demonstrate the relationship between the BER and these system parameters, and some corresponding methods of system optimization are presented to enhance the communication quality.

  1. Experiment und Wissensvermittlung. Alexander von Humboldts Darstellungsmethoden in seinen Versuchen über die gereizte Muskel- und Nervenfaser

    Directory of Open Access Journals (Sweden)

    Alexander Stöger

    2016-11-01

    Full Text Available Zusammenfassung Alexander von Humboldt hat sich in jungen Jahren mit galvanischen Experimenten beschäftigt und die Resultate in einem umfassenden, zweibändigen Werk publiziert. Dabei zeigte er nicht nur, dass er als Experimentator und Teil der wissenschaftlichen Gemeinschaft fähig war, sich mit einem so neuen und komplexen Phänomen zu beschäftigen. Es lässt sich auch erkennen, dass er bereits in dieser frühen Schrift versuchte, das umfangreiche Wissen dem Leser zugänglich zu machen. Der Artikel betrachtet Humboldts Galvanismusschrift Versuche über die gereizte Muskel- und Nervenfaser (1797–1798 und untersucht einige Elemente wie Anhänge und Schreibstil, die Humboldt nutzte, um die umfangreichen Informationen zu ordnen und dem Leser so neben den Big Data seiner Erkenntnisse auch passende Suchfunktionen zur Verfügung zu stellen, die eine gezielte Nutzung überhaupt ermöglichen.  Abstract In the early stages of his scientific career, Alexander von Humboldt took an interest in experiments in galvanism. He publicised the results in a two-volume work under the title Versuche über die gereizte Muskel- und Nervenfaser (Experiments on the Stimulated Muscle and Nerve Fibre in 1797 and 1798. In this treatise, he presented himself as competent experimenter and member of the scientific community, but also demonstrated that he was capable of researching new and complex phenomena. These volumes also provide insight into his early attempts to facilitate the readers’ access to the extensive information he had compiled. This article analyses some aspects of Humboldt’s efforts to arrange his vast numbers of observations and theories, for example by means of appendices and narrative style, which he used not only to present the resulting big data collected during his research, but also to make it possible for the reader to organise and utilise this data.   Resumen A temprana edad Alexander von Humboldt se dedicó a galvanismo. En 1797 y 1798

  2. Image secure transmission for optical orthogonal frequency-division multiplexing visible light communication systems using chaotic discrete cosine transform

    Science.gov (United States)

    Wang, Zhongpeng; Zhang, Shaozhong; Chen, Fangni; Wu, Ming-Wei; Qiu, Weiwei

    2017-11-01

    A physical encryption scheme for orthogonal frequency-division multiplexing (OFDM) visible light communication (VLC) systems using chaotic discrete cosine transform (DCT) is proposed. In the scheme, the row of the DCT matrix is permutated by a scrambling sequence generated by a three-dimensional (3-D) Arnold chaos map. Furthermore, two scrambling sequences, which are also generated from a 3-D Arnold map, are employed to encrypt the real and imaginary parts of the transmitted OFDM signal before the chaotic DCT operation. The proposed scheme enhances the physical layer security and improves the bit error rate (BER) performance for OFDM-based VLC. The simulation results prove the efficiency of the proposed encryption method. The experimental results show that the proposed security scheme not only protects image data from eavesdroppers but also keeps the good BER and peak-to-average power ratio performances for image-based OFDM-VLC systems.

  3. Influence of Camera Setting on Vehicle-to-Vehicle VLC Employing Undersampled Phase Shift On-Off Keying

    Directory of Open Access Journals (Sweden)

    S. Vitek

    2017-12-01

    Full Text Available This paper focuses on the performance analysis of a camera based vehicle-to-vehicle visible light communication system employing undersampled phase shift on-off keying modulation under interference scenario. Two Nissan Qashqai front lights with daylight running light emitting diodes based lamps are used for communications. The bit error rate (BER performance of the proposed system is experimentally measured for a transmission span up to 24m focusing mostly on the side interference due to reflections. Based on experimental data we demonstrate reduction of the system performance due to the side reflection and illumination of the detector by other light sources which has to taken into account during further data processing. We provide with further statistics for particular shuter speed and transmitter power setting and discus BER improvement especially to meet FEC via the method of adaptive region of interest.

  4. Design, comparative study and analysis of CDMA for different modulation techni

    Directory of Open Access Journals (Sweden)

    Arun Kumar

    2015-11-01

    Full Text Available In this work, we have design a MIMO–CDMA using 4 ∗ 8 antennas with the combination of MMSE (Minimum Mean square Error Equalizer for BPSK (Binary Phase shift Keying, QPSK (Quadrature Phase Shift Keying, 16-QAM, 64-QAM and 256-QAM (Quadrature Amplitude Modulation modulation schemes. The analysis is built on the basis of transmit–received signal, constellation and MMSE plot simulated on a MatLab/Simulink. On the basis of BER (Bit-Error-Rate, it is also concluded that this work is mostly suitable for high order modulation schemes as the BER of 16-qam, 64-QAM and 256-QAM is zero. The proposed study has increased the quality of the wireless link and Inter-Symbol-Interference (ISI is likewise cut by applying a combination of MMSE and MIMO (Multiple In and Multiple Out with OSTBC (Orthogonal space Time Block Code encoder and combiner.

  5. Stochastic resonance in a bistable system subject to multi-time-delayed feedback and aperiodic signal

    International Nuclear Information System (INIS)

    Li Jianlong; Zeng Lingzao

    2010-01-01

    We discuss in detail the effects of the multi-time-delayed feedback driven by an aperiodic signal on the output of a stochastic resonance (SR) system. The effective potential function and dynamical probability density function (PDF) are derived. To measure the performance of the SR system in the presence of a binary random signal, the bit error rate (BER) defined by the dynamical PDF is employed, as is commonly used in digital communications. We find that the delay time, strength of the feedback, and number of time-delayed terms can change the effective potential function and the effective amplitude of the signal, and then affect the BER of the SR system. The numerical simulations strongly support the theoretical results. The goal of this investigation is to explore the effects of the multi-time-delayed feedback on SR and give a guidance to nonlinear systems in the application of information processing.

  6. Optimal threshold of error decision related to non-uniform phase distribution QAM signals generated from MZM based on OCS

    Science.gov (United States)

    Han, Xifeng; Zhou, Wen

    2018-03-01

    Optical vector radio-frequency (RF) signal generation based on optical carrier suppression (OCS) in one Mach-Zehnder modulator (MZM) can realize frequency-doubling. In order to match the phase or amplitude of the recovered quadrature amplitude modulation (QAM) signal, phase or amplitude pre-coding is necessary in the transmitter side. The detected QAM signals usually have one non-uniform phase distribution after square-law detection at the photodiode because of the imperfect characteristics of the optical and electrical devices. We propose to use optimal threshold of error decision for non-uniform phase contribution to reduce the bit error rate (BER). By employing this scheme, the BER of 16 Gbaud (32 Gbit/s) quadrature-phase-shift-keying (QPSK) millimeter wave signal at 36 GHz is improved from 1 × 10-3 to 1 × 10-4 at - 4 . 6 dBm input power into the photodiode.

  7. Amplify-and-Forward Cooperative Diversity for Green UWB-Based WBSNs

    Directory of Open Access Journals (Sweden)

    Heba Shaban

    2013-01-01

    Full Text Available This paper proposes a novel green cooperative diversity technique based on suboptimal template-based ultra-wideband (UWB wireless body sensor networks (WBSNs using amplify-and-forward (AF relays. In addition, it analyzes the bit-error-rate (BER performance of the proposed nodes. The analysis is based on the moment-generating function (MGF of the total signal-to-noise ratio (SNR at the destination. It also provides an approximate value for the total SNR. The analysis studies the performance of equally correlated binary pulse position modulation (EC-BPPM assuming the sinusoidal and square suboptimal template pulses. Numerical results are provided for the performance evaluation of optimal and suboptimal template-based nodes with and without relay cooperation. Results show that one relay node provides ~23 dB performance enhancement at BER, which mitigates the effect of the nondesirable non-line-of-sight (NLOS links in WBSNs.

  8. Performance of DS-UWB in MB-OFDM and multi-user interference over Nakagami-m fading channels

    KAUST Repository

    Mehbodniya, Abolfazl

    2011-01-18

    The mutual interference between the two ultra wideband (UWB) technologies, which use the same frequency spectrum, will be a matter of concern in the near future. In this context, we present a performance analysis of direct-sequence (DS) UWB communication in the presence of multiband orthogonal frequency division multiplexing (MB-OFDM) UWB interfering transmissions. The channel fading is modeled according to Nakagami-m distribution, and multi-user interference is taken into account. The DS-UWB system performance is evaluated in terms of bit error rate (BER). Specifically, using the characteristic function approach, an analytical expression for the average BER is derived conditioned on the channel impulse response. Numerical and simulation results are provided and compared for different coexistence scenarios. © 2011 John Wiley & Sons, Ltd.

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

    International Nuclear Information System (INIS)

    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.

  10. Design and Performance Analysis of an Adaptive Receiver for Multicarrier DS-CDMA

    Directory of Open Access Journals (Sweden)

    Wang Huahui

    2007-01-01

    Full Text Available An adaptive parallel interference cancelation (APIC scheme is proposed for the multicarrier direct sequence code division multiple access (MC-DS-CDMA system. Frequency diversity inherent in the MC system is exploited through maximal ratio combining, and an adaptive least mean square algorithm is used to estimate the multiple access interference. Theoretical analysis on the bit-error rate (BER of the APIC receiver is presented. Under a unified signal model, the conventional PIC (CPIC is shown to be a special case of the APIC. Hence the BER derivation for the APIC is also applicable to the CPIC. The performance and the accuracy of the theoretical results are examined via simulations under different design parameters, which show that the APIC outperforms the CPIC receiver provided that the adaptive parameters are properly selected.

  11. 2-Step Maximum Likelihood Channel Estimation for Multicode DS-CDMA with Frequency-Domain Equalization

    Science.gov (United States)

    Kojima, Yohei; Takeda, Kazuaki; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide better downlink bit error rate (BER) performance of direct sequence code division multiple access (DS-CDMA) than the conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. In this paper, we propose a new 2-step maximum likelihood channel estimation (MLCE) for DS-CDMA with FDE in a very slow frequency-selective fading environment. The 1st step uses the conventional pilot-assisted MMSE-CE and the 2nd step carries out the MLCE using decision feedback from the 1st step. The BER performance improvement achieved by 2-step MLCE over pilot assisted MMSE-CE is confirmed by computer simulation.

  12. Pilot-Assisted Channel Estimation for Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

    Science.gov (United States)

    Shima, Tomoyuki; Tomeba, Hiromichi; Adachi, Fumiyuki

    Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of time-domain spreading and orthogonal frequency division multiplexing (OFDM). In orthogonal MC DS-CDMA, the frequency diversity gain can be obtained by applying frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion to a block of OFDM symbols and can improve the bit error rate (BER) performance in a severe frequency-selective fading channel. FDE requires an accurate estimate of the channel gain. The channel gain can be estimated by removing the pilot modulation in the frequency domain. In this paper, we propose a pilot-assisted channel estimation suitable for orthogonal MC DS-CDMA with FDE and evaluate, by computer simulation, the BER performance in a frequency-selective Rayleigh fading channel.

  13. On the Performance of Multihop Heterodyne FSO Systems With Pointing Errors

    KAUST Repository

    Zedini, Emna

    2015-03-30

    This paper reports the end-to-end performance analysis of a multihop free-space optical system with amplify-and-forward (AF) channel-state-information (CSI)-assisted or fixed-gain relays using heterodyne detection over Gamma–Gamma turbulence fading with pointing error impairments. In particular, we derive new closed-form results for the average bit error rate (BER) of a variety of binary modulation schemes and the ergodic capacity in terms of the Meijer\\'s G function. We then offer new accurate asymptotic results for the average BER and the ergodic capacity at high SNR values in terms of simple elementary functions. For the capacity, novel asymptotic results at low and high average SNR regimes are also obtained via an alternative moments-based approach. All analytical results are verified via computer-based Monte-Carlo simulations.

  14. Experimental demonstration of polar coded IM/DD optical OFDM for short reach system

    Science.gov (United States)

    Fang, Jiafei; Xiao, Shilin; Liu, Ling; Bi, Meihua; Zhang, Lu; Zhang, Yunhao; Hu, Weisheng

    2017-11-01

    In this paper, we propose a novel polar coded intensity modulation direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system for short reach system. A method of evaluating the channel signal noise ratio (SNR) is proposed for soft-demodulation. The experimental results demonstrate that, compared to the conventional case, ∼9.5 dB net coding gain (NCG) at the bit error rate (BER) of 1E-3 can be achieved after 40-km standard single mode fiber (SSMF) transmission. Based on the experimental result, (512,256) polar code with low complexity and satisfactory BER performance meets the requirement of low latency in short reach system, which is a promising candidate for latency-stringent short reach optical system.

  15. Generalized optical code construction for enhanced and Modified Double Weight like codes without mapping for SAC-OCDMA systems

    Science.gov (United States)

    Kumawat, Soma; Ravi Kumar, M.

    2016-07-01

    Double Weight (DW) code family is one of the coding schemes proposed for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) systems. Modified Double Weight (MDW) code for even weights and Enhanced Double Weight (EDW) code for odd weights are two algorithms extending the use of DW code for SAC-OCDMA systems. The above mentioned codes use mapping technique to provide codes for higher number of users. A new generalized algorithm to construct EDW and MDW like codes without mapping for any weight greater than 2 is proposed. A single code construction algorithm gives same length increment, Bit Error Rate (BER) calculation and other properties for all weights greater than 2. Algorithm first constructs a generalized basic matrix which is repeated in a different way to produce the codes for all users (different from mapping). The generalized code is analysed for BER using balanced detection and direct detection techniques.

  16. Impact of mode partition noise in free-running gain-switched Fabry-Perot laser for 2-dimensional OCDMA.

    Science.gov (United States)

    Wang, Xu; Chan, Kam

    2004-07-26

    Free-running gain-switched Fabry-Perot laser diode is an appropriate incoherent broadband optical source for incoherent 2-dimensional optical code division multiple access. However, the mode partition noise (MPN) in the laser seriously degrades performance. We derived a bit error rate (BER) expression in the presence of MPN using the power spectra of the laser. The theory agreed with the experimental results. There was a power penalty and BER floor due to the MPN in the laser. Therefore, this scheme should be operated with a sufficiently large number of modes. At least 9 modes should be used for error-free transmission at 1 Gbit/s for the laser we investigated in this work.

  17. Ultra-compact coherent receiver with serial interface for pluggable transceiver.

    Science.gov (United States)

    Itoh, Toshihiro; Nakajima, Fumito; Ohno, Tetsuichiro; Yamanaka, Shogo; Soma, Shunichi; Saida, Takashi; Nosaka, Hideyuki; Murata, Koichi

    2014-09-22

    An ultra-compact integrated coherent receiver with a volume of 1.3 cc using a quad-channel transimpedance amplifier (TIA)-IC chip with a serial peripheral interface (SPI) is demonstrated for the first time. The TIA with the SPI and photodiode (PD) bias circuits, a miniature dual polarization optical hybrid, an octal-PD and small optical coupling system enabled the realization of the compact receiver. Measured transmission performance with 32 Gbaud dual-polarization quadrature phase shift keying signal is equivalent to that of the conventional multi-source agreement-based integrated coherent receiver with dual channel TIA-ICs. By comparing the bit-error rate (BER) performance with that under continuous SPI access, we also confirmed that there is no BER degradation caused by SPI interface access. Such an ultra-compact receiver is promising for realizing a new generation of pluggable transceivers.

  18. Field-programmable gate array implementation of an all-digital IEEE 802.15.4-compliant transceiver

    Science.gov (United States)

    Cornetta, Gianluca; Touhafi, Abdellah; Santos, David J.; Vázquez, José M.

    2010-12-01

    An architecture for a low-cost, low-complexity digital transceiver is presented in this article. The proposed architecture targets the IEEE 802.15.4 standard for short-range wireless personal area networks and has been implemented as a synthesisable VHDL register transfer level description. The system has been evaluated and tested using a Xilinx 90 nm Virtex-4 field-programmable gate array as the target technology. Bit error rate (BER) and error vector magnitude (EVM) have been used as the figures of merit for modem performance. Simulations show that the recommended minimum BER is achieved at E b/N 0 = 8.7 dB, whereas the EVM is 19.5%. The implemented device occupies 10% of the target FPGA and has a normalised maximum power consumption of 44 mW in transmit mode and 53 mW in receiver mode.

  19. Design and Performance Analysis of MISO-ORM-DCSK System over Rayleigh Fading Channels

    Directory of Open Access Journals (Sweden)

    Gang Zhang

    2016-01-01

    Full Text Available A novel chaotic communication system, named Orthogonality-based Reference Modulated-Differential Chaos Shift Keying (ORM-DCSK, is proposed to enhance the performance of RM-DCSK. By designing an orthogonal chaotic generator (OCG, the intrasignal interference components in RM-DCSK are eliminated. Also, the signal frame format is expanded so the average bit energy is reduced. As a result, the proposed system has less interference in decision variables. Furthermore, to investigate the bit error rate (BER performance over Rayleigh fading channels, the MISO-ORM-DCSK is studied. The BER expressions of the new system are derived and analyzed over AWGN channel and multipath Rayleigh fading channel. All simulation results not only show that the proposed system can obtain significant improvement but also verify the analysis in theory.

  20. Performance analysis for a chaos-based code-division multiple access system in wide-band channel

    Directory of Open Access Journals (Sweden)

    Ciprian Doru Giurcăneanu

    2015-08-01

    Full Text Available Code-division multiple access technology is widely used in telecommunications and its performance has been extensively investigated in the past. Theoretical results for the case of wide-band transmission channel were not available until recently. The novel formulae which have been published in 2014 can have an important impact on the future of wireless multiuser communications, but limitations come from the Gaussian approximations used in their derivation. In this Letter, the authors obtain more accurate expressions of the bit error rate (BER for the case when the model of the wide-band channel is two-ray, with Rayleigh fading. In the authors’ approach, the spreading sequences are assumed to be generated by logistic map given by Chebyshev polynomial function of order two. Their theoretical and experimental results show clearly that the previous results on BER, which rely on the crude Gaussian approximation, are over-pessimistic.

  1. Performance enhancement of optical code-division multiple-access systems using transposed modified Walsh code

    Science.gov (United States)

    Sikder, Somali; Ghosh, Shila

    2018-02-01

    This paper presents the construction of unipolar transposed modified Walsh code (TMWC) and analysis of its performance in optical code-division multiple-access (OCDMA) systems. Specifically, the signal-to-noise ratio, bit error rate (BER), cardinality, and spectral efficiency were investigated. The theoretical analysis demonstrated that the wavelength-hopping time-spreading system using TMWC was robust against multiple-access interference and more spectrally efficient than systems using other existing OCDMA codes. In particular, the spectral efficiency was calculated to be 1.0370 when TMWC of weight 3 was employed. The BER and eye pattern for the designed TMWC were also successfully obtained using OptiSystem simulation software. The results indicate that the proposed code design is promising for enhancing network capacity.

  2. Performance analysis of spectral-phase-encoded optical code-division multiple-access system regarding the incorrectly decoded signal as a nonstationary random process

    Science.gov (United States)

    Yan, Meng; Yao, Minyu; Zhang, Hongming

    2005-11-01

    The performance of a spectral-phase-encoded (SPE) optical code-division multiple-access (OCDMA) system is analyzed. Regarding the incorrectly decoded signal (IDS) as a nonstationary random process, we derive a novel probability distribution for it. The probability distribution of the IDS is considered a chi-squared distribution with degrees of freedom r=1, which is more reasonable and accurate than in previous work. The bit error rate (BER) of an SPE OCDMA system under multiple-access interference is evaluated. Numerical results show that the system can sustain very low BER even when there are multiple simultaneous users, and as the code length becomes longer or the initial pulse becomes shorter, the system performs better.

  3. PERFORMANCE OF THE ZERO FORCING PRECODING MIMO BROADCAST SYSTEMS WITH CHANNEL ESTIMATION ERRORS

    Institute of Scientific and Technical Information of China (English)

    Wang Jing; Liu Zhanli; Wang Yan; You Xiaohu

    2007-01-01

    In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum capacity and BER performance are consistent with those of the perfect Channel State Information (CSI)with only a performance degradation.

  4. THz Wireless Transmission Systems Based on Photonic Generation of Highly Pure Beat-Notes

    DEFF Research Database (Denmark)

    Jia, Shi; Yu, Xianbin; Hu, Hao

    2016-01-01

    In this paper, a terahertz (THz) wireless communication system at 400 GHz with various modulation formats [on–off keying (OOK), quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM), and 32-quadrature amplitude modulation (32-QAM)] is experimentally demonstrated based...... noise of photonically generated THz beat-notes when phase correlation of two optical comb tones is damaged due to their path-length difference. In addition, we demonstrate THz wireless transmission of various modulation formats, including OOK, QPSK, 16-QAM, and 32-QAM at beyond 10 Gb/s in such a system......, and the measured bit error rate (BER) performance for all the signals after 0.5 m free-space delivery is below the hard decision forward error correction threshold of 3.8 × 10–3. Furthermore, the influence of THz carrier purity on the system performance is experimentally analyzed with respect to the BER of the THz...

  5. Analysis on applicable error-correcting code strength of storage class memory and NAND flash in hybrid storage

    Science.gov (United States)

    Matsui, Chihiro; Kinoshita, Reika; Takeuchi, Ken

    2018-04-01

    A hybrid of storage class memory (SCM) and NAND flash is a promising technology for high performance storage. Error correction is inevitable on SCM and NAND flash because their bit error rate (BER) increases with write/erase (W/E) cycles, data retention, and program/read disturb. In addition, scaling and multi-level cell technologies increase BER. However, error-correcting code (ECC) degrades storage performance because of extra memory reading and encoding/decoding time. Therefore, applicable ECC strength of SCM and NAND flash is evaluated independently by fixing ECC strength of one memory in the hybrid storage. As a result, weak BCH ECC with small correctable bit is recommended for the hybrid storage with large SCM capacity because SCM is accessed frequently. In contrast, strong and long-latency LDPC ECC can be applied to NAND flash in the hybrid storage with large SCM capacity because large-capacity SCM improves the storage performance.

  6. Tutorium Quantenfeldtheorie was Sie schon immer über QFT wissen wollten, aber bisher nicht zu fragen wagten

    CERN Document Server

    Edelhäuser, Lisa

    2016-01-01

    Dieses Buch richtet sich an alle, die sich schon immer gefragt haben, wie die kanonische Quantisierung, die LSZ-Reduktionsformel, Pfadintegrale, Feynman-Graphen und die Renormierung miteinander zusammenhängen. Als locker geschriebene Begleitlektüre zu Vorlesungen über Quantenfeldtheorie oder zum Selbststudium geeignet, gibt sich das Buch gesprächig und liefert Rechentricks und Erklärungen, die für Einsteiger sehr hilfreich sind. Im ersten Teil werden anhand von Skalarfeldern grundlegende Konzepte von der klassischen Feldtheorie bis zur Renormierung eingeführt. Der zweite Teil verallgemeinert diese für Felder mit Spin und legt mit der Einführung des Eichprinzips die Grundlagen für den dritten Teil. Hier werden „Anwendungen auf die reale Welt“ behandelt: Die Quantenelektrodynamik und ihre Renormierung, sowie das Standardmodell der Teilchenphysik und der Higgs-Mechanismus. Durch ausführlich vorgerechnete und in den Text eingebundene Aufgaben eignet sich das Tutorium sowohl zum schnellen Nachschla...

  7. Effects of heat treatment on mechanical properties and microstructure of tungsten fi ber reinforced grey cast iron matrix composites

    Directory of Open Access Journals (Sweden)

    Peng jianHong

    2009-11-01

    Full Text Available In this study, grey cast iron matrix composites reinforced by different volume fractions of tungsten fibers (Vr = 0.95 %, 1.90 %, 2.85 %, 3.80 % were investigated in as-cast and under the heat treatment temperatures of 1,000℃ and 1,100℃. The microstructure and mechanical properties of the composites were analyzed and tested by means of SEM, micro-hardness tester and three-point bend testing. The results show that with increasing of the volume fraction of tungsten fibers, the composites reinforced by the tungsten fiber have higher fl exural strength and modulus than that of cast iron without reinforcement, and the fl exural strength increases with the increasing of heat treatment temperatures. Due to diffusion reaction between matrix and reinforcing phases, the process of heat treatment, the number of graphite fl akes in the matrix seemingly becomes lower; and some hard carbide particles are formed around the residual tungsten fi bers. Not only does the hardness of both matrix and reinforcement change tremendously, but also the region of reinforcement is also extended from the original 0.11 mm to 0.19 mm in radius.

  8. Optimal Power Allocation of a Wireless Sensor Node under Different Rate Constraints

    KAUST Repository

    Solares, Jose

    2011-07-01

    Wireless sensor networks consist of the placement of sensors over a broad area in order to acquire data. Depending on the application, different design criteria should be considered in the construction of the sensors but among all of them, the battery life-cycle is of crucial interest. Power minimization is a problem that has been addressed from different approaches which include an analysis from an architectural perspective and with bit error rate and/or discrete instantaneous transmission rate constraints, among others. In this work, the optimal transmit power of a sensor node while satisfying different rate constraints is derived. First, an optimization problem with an instantaneous transmission rate constraint is addressed. Next, the optimal power is analyzed, but now with an average transmission rate constraint. The optimal solution for a class of fading channels, in terms of system parameters, is presented and a suboptimal solution is also proposed for an easier, yet efficient, implementation. Insightful asymptotical analysis for both schemes, considering a Rayleigh fading channel, are shown. Furthermore, the optimal power allocation for a sensor node in a cognitive radio environment is analyzed where an optimum solution for a class of fading channels is again derived. In all cases, numerical results are provided for either Rayleigh or Nakagami-m fading channels. The results obtained are extended to scenarios where we have either one transmitter-multiple receivers or multiple transmitters-one receiver.

  9. Exploiting spatial degrees of freedom for high data rate ultrasound communication with implantable devices

    Science.gov (United States)

    Wang, Max L.; Arbabian, Amin

    2017-09-01

    We propose and demonstrate an ultrasonic communication link using spatial degrees of freedom to increase data rates for deeply implantable medical devices. Low attenuation and millimeter wavelengths make ultrasound an ideal communication medium for miniaturized low-power implants. While a small spectral bandwidth has drastically limited achievable data rates in conventional ultrasonic implants, a large spatial bandwidth can be exploited by using multiple transducers in a multiple-input/multiple-output system to provide spatial multiplexing gain without additional power, larger bandwidth, or complicated packaging. We experimentally verify the communication link in mineral oil with a transmitter and a receiver 5 cm apart, each housing two custom-designed mm-sized piezoelectric transducers operating at the same frequency. Two streams of data modulated with quadrature phase-shift keying at 125 kbps are simultaneously transmitted and received on both channels, effectively doubling the data rate to 250 kbps with a measured bit error rate below 10-4. We also evaluate the performance and robustness of the channel separation network by testing the communication link after introducing position offsets. These results demonstrate the potential of spatial multiplexing to enable more complex implant applications requiring higher data rates.

  10. Machoideal och/eller meningslös underhållning? : Om fem mäns berättelser kring krigsfilmen Saving Private Ryan med fokus på maskulinitet och publiken som meningsskapare.

    OpenAIRE

    Olsson, Eva

    2005-01-01

    Uppsatsen undersöker fem mäns berättelser kring krigsfilmen Saving Private Ryan, med fokus på maskulinitet. Föreställningarna och bilderna kring maskulinitet som kan urskiljas i intervjupersonernas berättelser, knyts till R.W. Connells teoretiska ramverk kring hegemonisk maskulinitet och de hierarkiska relationerna mellan olika maskuliniteter. Vidare resoneras det kring hur berättelserna exemplifierar en syn på mediepublik som aktiva meningsskapare, då intervjupersonerna tar fasta på olika as...

  11. Effect of saline irrigation water on gas exchange and proline metabolism in ber (Ziziphus).

    Science.gov (United States)

    Bagdi, D L; Bagri, G K

    2016-09-01

    An experiment was conducted in pots of 25 kg capacity to study the effect of saline irrigation (EC 0,5,10,15 and 20 dSm-1) prepared by mixing NaCl, NaSO4, CaCl and MgCl2 in 3:1 ratio of chloride and sulphate on gas exchange traits, membrane stability, chlorophyll stability index and osmolytic defense mechanism in Ziziphus rotundifolia and Ziziphus nummularia species of Indian jujube (Z.mauritiana). Result showed that net photosynthetic rate (PN), transpiration (e) and stomatal conductance were comparatively lower in Ziziphus nummularia, which further declined with increasing level of saline irrigation water. Chlorophyll stability and membrane stability also declined significantly in salt stress, with higher magnitude in Ziziphus nummularia. The activity of proline anabolic enzymes; Δ1-Pyrrolline-5-carboxylate reductase, Δ1-Pyrrolline-5-carboxylate synthetase and Ornithine-δ-aminotransferase were recorded higher in Ziziphus rotundifolia with decrease in proline dehydrogenase. The sodium content was observed higher in roots of Ziziphus rotundifolia and leaves of Ziziphus nummularia. Therefore, it is suggested that salt tolerance mechanism was more efficiently operative in Ziziphus rotundifolia owing to better management of physiological attributes, osmolytic defense mechanism and restricted translocation of sodium from root to leaves along with larger accumulation of potassium in its leaves.

  12. Intervention principles and levels in the event of a nuclear accident. Final report on the Nordic Nuclear Safety Research Project BER-3

    International Nuclear Information System (INIS)

    Walmod-Larsen, O.

    1994-04-01

    The aim of the Nordic BER-3 project has been to harmonize the Nordic intervention levels after a nuclear accident. The paper deals with the findings and recommendations to be presented to the Nordic authorities as background material for common decisions on the most likely protective actions. In the report sheltering, evaluation and relocation are treated in detail. Iodine prophylaxis and foodstuff restrictions are briefly commented on. The basis for this work is the internationally accepted basic principles for interventions

  13. Preparation of chitin–silica composites by in vitro silicification of two-dimensional Ianthella basta demosponge chitinous scaffolds under modified Stöber conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wysokowski, Marcin [Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, M. Skłodowskiej-Curie 2, PL-60965 Poznan (Poland); Behm, Thomas [Institute of Experimental Physics, TU Bergakademie Freiberg, Liepziger 23, 09599 Freiberg (Germany); Born, René [Institute of Materials Science, Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden (Germany); Bazhenov, Vasilii V. [Institute of Experimental Physics, TU Bergakademie Freiberg, Liepziger 23, 09599 Freiberg (Germany); Meißner, Heike; Richter, Gert [Faculty of Medicine Carl Gustav Carus, Dresden University of Technology, Fetscherstraße 74, 01307 Dresden (Germany); Szwarc-Rzepka, Karolina [Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, M. Skłodowskiej-Curie 2, PL-60965 Poznan (Poland); Makarova, Anna; Vyalikh, Denis [Institute of Solid State Physics, Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden (Germany); Schupp, Peter [Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Emsstr. 20, 26382 Wilhelmshaven (Germany); Jesionowski, Teofil, E-mail: teofil.jesionowski@put.poznan.pl [Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, M. Skłodowskiej-Curie 2, PL-60965 Poznan (Poland); Ehrlich, Hermann, E-mail: hermann.ehrlich@physik.tu-freiberg.de [Institute of Experimental Physics, TU Bergakademie Freiberg, Liepziger 23, 09599 Freiberg (Germany)

    2013-10-15

    Chitin is a biopolymer found in cell walls of various fungi and skeletal structures of numerous invertebrates. The occurrence of chitin within calcium- and silica-containing biominerals has inspired development of chitin-based hybrids and composites in vitro with specific physico-chemical and material properties. We show here for the first time that the two-dimensional α-chitin scaffolds isolated from the skeletons of marine demosponge Ianthella basta can be effectively silicified by the two-step method with the use of Stöber silica micro- and nanodispersions under Extreme Biomimetic conditions. The chitin–silica composites obtained at 120 °C were characterized by the presence of spherical SiO{sub 2} particles homogeneously distributed over the chitin fibers, which probably follows from the compatibility of Si–OH groups to the hydroxyl groups of chitin. The biocomposites obtained were characterized by various analytical techniques such as energy dispersive spectrometry, scanning electron microscopy, thermogravimetric/differential thermal analyses as well as X-ray photoelectron spectroscopy, Fourier transform infrared and Raman spectroscopy to determine possible interactions between silica and chitin molecule. The results presented proved that the character and course of the in vitro chitin silicification in Stöber dispersions depended considerably on the degree of hydrolysis of the SiO{sub 2} precursor. - Highlights: • 2D α-chitin scaffolds isolated from marine demosponge can be effectively silicified using Stöber silica. • The chitin–silica composites were obtained under Extreme Biomimetic conditions. • Character and course of the in vitro chitin silicification in Stöber dispersions is discussed.

  14. Ein Lehrbuch über Psychiatrie und Psychotherapie – Geschlechtsunterschiede unter der Lupe? A Textbook for Psychiatry and Psychotherapy—Gender Differences under the Microscope?

    Directory of Open Access Journals (Sweden)

    Isabella Heuser

    2007-07-01

    Full Text Available Anke Rohde und Andreas Marneros haben sich ein hohes Ziel gesetzt: ein übersichtliches Lehrbuch für Psychiatrie und Psychotherapie, das erstmals eine systematische Zusammenstellung des Wissens über geschlechtsspezifische Aspekte von Symptomatologie, Epidemiologie, Diagnostik, Pharmakotherapie und Psychotherapie psychischer Störungen enthält. Bemerkenswert ist dabei zweierlei: Erstens werden bei der Betrachtung geschlechtsspezifischer Unterschiede im Sinne der Genderforschung Frauen und Männer berücksichtigt, zweitens wird ein vollständiger Überblick sowohl über die häufigen und bekannten psychischen Störungen als auch die äußerst seltenen psychiatrischen Erkrankungen der gesamten Altersspanne gegeben. Wenngleich die Qualität der einzelnen Beiträge deutlich zwischen sehr differenzierter und leider auch für ein Handbuch eindeutig zu oberflächlicher Betrachtung variiert, liegt in dem Band ein weitgehend informatives Nachschlagewerk vor, das einen ersten Überblick über die geschlechtsspezifische Psychiatrie gibt.Anke Rohde and Andres Marneros have given themselves a lofty goal: To put together a systematic collection for the first time that contains the entire body of knowledge on the gender-specific aspects of symptomatology, epidemiology, diagnostics, pharmacotherapy, and psychotherapy of psychological disturbances. There are two notable aspects: First, in accordance with contemporary gender analysis, the examination of the gender-specific differences takes both women and men into account; second, the book provides a complete overview of the common and well-known psychological disturbances as well as the extremely rare psychiatric illnesses along the entire age spectrum. Although the quality of the individual articles clearly ranges from the very sophisticated to a superficial treatment inappropriate for a textbook, the volume itself is, for the most part, an informative work of reference that offers an initial overview of

  15. Experimental investigation on the high chip rate of 2D incoherent optical CDMA system

    Science.gov (United States)

    Su, Guorui; Wang, Rong; Pu, Tao; Fang, Tao; Zheng, Jilin; Zhu, Huatao; Wu, Weijiang

    2015-08-01

    An innovative approach to realise high chip rate in OCDMA transmission system is proposed and experimentally investigation, the high chip rate is achieved through a 2-D wavelength-hopping time-spreading en/decoder based on the supercontinuum light source. The source used in the experiment is generated by high nonlinear optical fiber (HNLF), Erbium-doped fiber amplifier (EDFA) which output power is 26 dBm, and distributed feed-back laser diode which works in the gain switch state. The span and the flatness of the light source are 20 nm and 3 dB, respectively, after equalization of wavelength selective switch (WSS). The wavelength-hopping time-spreading coder can be changed 20 nm in the wavelength and 400 ps in the time, is consist of WSS and delay lines. Therefore, the experimental results show that the chip rate can achieve 500 Gchip/s, in the case of 2.5 Gbit/s, while keeping a bit error rate below forward error correction limit after 40 km transmission.

  16. Possible ways and aspects of conversions for the German low power research reactors BER II, FRM, and FMRB

    International Nuclear Information System (INIS)

    Roegler, H.-J.

    1983-01-01

    Based on the overall agreement about methods and principal results on core conversions from HEU to MEU within the work done for the IAEA Guidebook, investigations were started of the three specific cases, that means the conversions of the German Research Reactors within the German AF-Program. The first step of this work was done for the three low power MTR-reactors: the Ber II in Berlin operating at KW, FMRB in Brunswick operating at 1 MW, and FRM near Munich operating at 4 W. The simplest core from the point of view of conversion calculations was the BER II reactor. The core is made up out of 33 fuel elements and 5 control elements, it is built up on a 8 x 8 grid plate. On three sides the core is surrounded by reflector elements partially made of graphite and partially of beryllium. The main purpose of the core is to provide high neutron fluxes for the 12 beam tubes on all reflector sides. A little bit more complicated - from the conversion point of view - was the status of the Munich FRM. This is on one hand due to the two different cores they operate: a so-called normal core and a smaller beryllium core and on the other other hand due to the different uranium-loadings of fuel elements partially 230 g 235-U per element and partially 180 g 235-U per element with control elements of both plate loadings as well. The third reactor investigated was the Brunswick FMRB, which has specific design features that cause specific problems. The core is split into two parts, the so-called north core and the south core interacting via a heavy water reflector in between. Calculations with LEU-fuel - in these three cases no MEU-fuel was used - were done looking at different criteria for the conversion. The first group we call cycle length criteria and they are split into two versions, the same cycle length for LEU-fuel as for the existing HEU-fuel measured in MWd with the same excess reactivity at EOL as it exists at present; the same criterion as the previous except the cycle

  17. BER-3.2 report: Methodology for justification and optimization of protective measures including a case study

    International Nuclear Information System (INIS)

    Hedemann Jensen, P.; Sinkko, K.; Walmod-Larsen, O.; Gjoerup, H.L.; Salo, A.

    1992-07-01

    This report is a part of the Nordic BER-3 project's work to propose and harmonize Nordic intervention levels for countermeasures in case of nuclear accidents. This report focuses on the methodology for justification and optimization of protective measures in case of a reactor accident situation with a large release of fission products to the environment. The down-wind situation is very complicated. The dose to the exposed society is almost unpredictable. The task of the radiation protection experts: To give advice to the decision makers on averted doses by the different actions at hand in the situation - is complicated. That of the decision makers is certainly more: On half of the society they represent, they must decide if they wish to follow the advices from their radiation protection experts or if they wish to add further arguments - economical or political (or personal) - into their considerations before their decisions are taken. Two analysis methods available for handling such situations: cost-benefit analysis and multi-attribute utility analysis are described in principle and are utilized in a case study: The impacts of a Chernobyl-like accident on the Swedish island of Gotland in the Baltic Sea are analyzed with regard to the acute consequences. The use of the intervention principles found in international guidance (IAEA 91, ICRP 91), which can be summarized as the principles of justification, optimization and avoidance of unacceptable doses, are described. How to handle more intangible factors of a psychological or political character is indicated. (au) (6 tabs., 3 ills., 17 refs.)

  18. Lethal and mutagenic properties of MMS-generated DNA lesions in Escherichia coli cells deficient in BER and AlkB-directed DNA repair.

    Science.gov (United States)

    Sikora, Anna; Mielecki, Damian; Chojnacka, Aleksandra; Nieminuszczy, Jadwiga; Wrzesinski, Michal; Grzesiuk, Elzbieta

    2010-03-01

    Methylmethane sulphonate (MMS), an S(N)2-type alkylating agent, generates DNA methylated bases exhibiting cytotoxic and mutagenic properties. Such damaged bases can be removed by a system of base excision repair (BER) and by oxidative DNA demethylation catalysed by AlkB protein. Here, we have shown that the lack of the BER system and functional AlkB dioxygenase results in (i) increased sensitivity to MMS, (ii) elevated level of spontaneous and MMS-induced mutations (measured by argE3 --> Arg(+) reversion) and (iii) induction of the SOS response shown by visualization of filamentous growth of bacteria. In the xth nth nfo strain additionally mutated in alkB gene, all these effects were extreme and led to 'error catastrophe', resulting from the presence of unrepaired apurinic/apyrimidinic (AP) sites and 1-methyladenine (1meA)/3-methylcytosine (3meC) lesions caused by deficiency in, respectively, BER and AlkB dioxygenase. The decreased level of MMS-induced Arg(+) revertants in the strains deficient in polymerase V (PolV) (bearing the deletion of the umuDC operon), and the increased frequency of these revertants in bacteria overproducing PolV (harbouring the pRW134 plasmid) indicate the involvement of PolV in the error-prone repair of 1meA/3meC and AP sites. Comparison of the sensitivity to MMS and the induction of Arg(+) revertants in the double nfo alkB and xth alkB, and the quadruple xth nth nfo alkB mutants showed that the more AP sites there are in DNA, the stronger the effect of the lack of AlkB protein. Since the sum of MMS-induced Arg(+) revertants in xth, nfo and nth xth nfo and alkB mutants is smaller than the frequency of these revertants in the BER(-) alkB(-) strain, we consider two possibilities: (i) the presence of AP sites in DNA results in relaxation of its structure that facilitates methylation and (ii) additional AP sites are formed in the BER(-) alkB(-) mutants.

  19. Stalin Coctail: Schostakowitsch Kammersinfonie Nr. 2 (aus Streichquartett Nr. 3 op. 73). Pärt, Arvo: Collage über das Thema B-A-C-H / Susanne Benda

    Index Scriptorium Estoniae

    Benda, Susanne

    1995-01-01

    Uuest heliplaadist "Stalin Coctail: Schostakowitsch Kammersinfonie Nr. 2 (aus Streichquartett Nr. 3 op. 73). Pärt, Arvo: Collage über das Thema B-A-C-H. Cantus in memoriam B. Britten. Denisov Variationen über Haydns Kanon Tod ist ein langer Schlaf. Schtschedrin Stalin Coctail. Moskauer Virtuosen, Vladimir Spivakov. RCA/BMG-Ariola CD 09026 68061 2 (WD: 67'33")

  20. Mytedræber

    DEFF Research Database (Denmark)

    Albris, Kristoffer

    2016-01-01

    ANALYSE Når katastrofen rammer, er det ikke panik og egoisme, der råder, men derimod næstekærlige værdier.......ANALYSE Når katastrofen rammer, er det ikke panik og egoisme, der råder, men derimod næstekærlige værdier....

  1. Digital modulation and achievable information rates of thru-body haptic communications

    Science.gov (United States)

    Hanisch, Natalie; Pierobon, Massimiliano

    2017-05-01

    The ever increasing biocompatibility and pervasive nature of wearable and implantable devices demand novel sustainable solutions to realize their connectivity, which can impact broad application scenarios such as in the defense, biomedicine, and entertainment fields. Where wireless electromagnetic communications are facing challenges such as device miniaturization, energy scarcity, limited range, and possibility of interception, solutions not only inspired but also based on natural communication means might result into valid alternatives. In this paper, a communication paradigm where digital information is propagated through the nervous system is proposed and analyzed on the basis of achievable information rates. In particular, this paradigm is based on an analytical framework where the response of a system based on haptic (tactile) information transmission and ElectroEncephaloGraphy (EEG)-based reception is modeled and characterized. Computational neuroscience models of the somatosensory signal representation in the brain, coupled with models of the generation and propagation of somatosensory stimulation from skin mechanoreceptors, are employed in this paper to provide a proof-of-concept evaluation of achievable performance in encoding information bits into tactile stimulation, and decoding them from the recorded brain activity. Based on these models, the system is simulated and the resulting data are utilized to train a Support Vector Machine (SVM) classifier, which is finally used to provide a proof-of-concept validation of the system performance in terms of information rates against bit error probability at the reception.

  2. Contexto dos berçários e um programa de intervenção no desenvolvimento de bebés

    Directory of Open Access Journals (Sweden)

    Carla Skilhan Almeida

    2013-12-01

    Full Text Available O objetivo deste estudo foi investigar o contexto de berçários que atendesse a famílias de baixa renda e verificar o impacto de uma intervenção cognitivo-motora no desenvolvimento de bebés quanto à motricidade ampla, motricidade fina, linguagem e interação. Participaram do estudo 40 bebés, entre seis e oito meses, provenientes de dez berçários para famílias de baixa renda. As escolas foram agrupadas quanto à qualidade dos cuidados oferecidos; os bebés foram estratificados por gênero e aleatoriamente distribuídos em grupos interventivo (n= 20 e controle (n= 20. Foi utilizada uma ficha de observação para verificar a rotina dos berçários. A motricidade ampla e fina, a linguagem e a interação dos bebés foram avaliadas no pré e no pós intervenção. O programa de intervenção propiciou experiências de perseguição visual, manipulação de brinquedos e controle postural. Observaram-se restrições no espaço físico e nas oportunidades para brincar e interagir. Educadores centravam sua atenção no cuidado com higiene e alimentação dos bebés. Bebés provenientes de escolas com contextos mais apropriadas ao desenvolvimento apresentaram desempenhos superiores; e, a intervenção repercutiu positivamente no desenvolvimento global dos participantes. Em conclusão, ações educativas e estratégias interventivas devem ser implementadas nas creches, priorizando o processo de desenvol­vimento infantil.

  3. 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.

  4. Multi-link faults localization and restoration based on fuzzy fault set for dynamic optical networks.

    Science.gov (United States)

    Zhao, Yongli; Li, Xin; Li, Huadong; Wang, Xinbo; Zhang, Jie; Huang, Shanguo

    2013-01-28

    Based on a distributed method of bit-error-rate (BER) monitoring, a novel multi-link faults restoration algorithm is proposed for dynamic optical networks. The concept of fuzzy fault set (FFS) is first introduced for multi-link faults localization, which includes all possible optical equipment or fiber links with a membership describing the possibility of faults. Such a set is characterized by a membership function which assigns each object a grade of membership ranging from zero to one. OSPF protocol extension is designed for the BER information flooding in the network. The BER information can be correlated to link faults through FFS. Based on the BER information and FFS, multi-link faults localization mechanism and restoration algorithm are implemented and experimentally demonstrated on a GMPLS enabled optical network testbed with 40 wavelengths in each fiber link. Experimental results show that the novel localization mechanism has better performance compared with the extended limited perimeter vector matching (LVM) protocol and the restoration algorithm can improve the restoration success rate under multi-link faults scenario.

  5. Arbeid som berører : en studie av miljøarbeideres møter med ungdom på ungdomshjem

    OpenAIRE

    Viervang, Irene

    2008-01-01

    Master i sosialt arbeid Det er miljøarbeideres fortellinger om relasjonen og møtet med ungdommer på institusjon som mitt blikk er rettet mot i denne studien. Det settes derfor søkelys på interaksjonen mellom miljøarbeideren og ungdommer, og spesielt hvordan denne berører miljøarbeideren. Dette er en kvalitativ undersøkelse hvor jeg intervjuer syv miljøarbeidere som arbeider på fire forskjellige ungdomshjem. Alle informantene hadde sosialfaglig utdanning og praksiserfaring fr...

  6. Combined peak-to-average power ratio reduction and physical layer security enhancement in optical orthogonal frequency division multiplexing visible-light communication systems

    Science.gov (United States)

    Wang, Zhongpeng; Chen, Shoufa

    2016-07-01

    A physical encryption scheme for discrete Hartley transform (DHT) precoded orthogonal frequency division multiplexing (OFDM) visible-light communication (VLC) systems using frequency domain chaos scrambling is proposed. In the scheme, the chaos scrambling, which is generated by a modified logistic mapping, is utilized to enhance the physical layer of security, and the DHT precoding is employed to reduce of OFDM signal for OFDM-based VLC. The influence of chaos scrambling on peak-to-average power ratio (PAPR) and bit error rate (BER) of systems is studied. The experimental simulation results prove the efficiency of the proposed encryption method for DHT-precoded, OFDM-based VLC systems. Furthermore, the influence of the proposed encryption to the PAPR and BER of systems is evaluated. The experimental results show that the proposed security scheme can protect the DHT-precoded, OFDM-based VLC from eavesdroppers, while keeping the good BER performance of DHT-precoded systems. The BER performance of the encrypted and DHT-precoded system is almost the same as that of the conventional DHT-precoded system without encryption.

  7. Optimization of an Angle-Aided Mirror Diversity Receiver for Indoor MIMO-VLC Systems

    KAUST Repository

    Park, Kihong

    2017-02-07

    In this paper, we investigate the channel correlation problem which affects the performance of indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems. More specifically, in order to reduce the high correlation of channel matrix in MIMO-VLC intensity channel, we propose a non-imaging receiver called angle-aided mirror diversity receiver (AMDR) which utilizes not only a mirror placement but also a variation of orientation angle for the photodetector (PD) plane. Deploying a mirror helps reducing the correlation by blocking the reception of the light in one specific direction and by receiving additional light reflected in the mirror in another direction, while orienting the angle of PD plane into specific direction enables the directional reception of light. Applying a zero-forcing decorrelator at the receiver, we analyze the bit error rate (BER) performance for a 2×2 multiplexing MIMO-VLC system using a 2-dimensional geometric model. In particular, we formulate a min-max BER problem and find the optimal height of mirror and elevation angle of PD plane. Some selected numerical results validate our proposed optimal solution to our min-max BER problem and show that the BER performance of our proposed AMDR outperforms that of the previous non-imaging receivers.

  8. Cooperative Transmission in Mobile Wireless Sensor Networks with Multiple Carrier Frequency Offsets: A Double-Differential Approach

    Directory of Open Access Journals (Sweden)

    Kun Zhao

    2014-01-01

    Full Text Available As a result of the rapidly increasing mobility of sensor nodes, mobile wireless sensor networks (MWSNs would be subject to multiple carrier frequency offsets (MCFOs, which result in time-varying channels and drastically degrade the network performance. To enhance the performance of such MWSNs, we propose a relay selection (RS based double-differential (DD cooperative transmission scheme, termed RSDDCT, in which the best relay sensor node is selected to forward the source sensor node’s signals to the destination sensor node with the detect-and-forward (DetF protocol. Assuming a Rayleigh fading environment, first, exact closed-form expressions for the outage probability and average bit error rate (BER of the RSDDCT scheme are derived. Then, simple and informative asymptotic outage probability and average BER expressions at the large signal-to-noise ratio (SNR regime are presented, which reveal that the RSDDCT scheme can achieve full diversity. Furthermore, the optimum power allocation strategy in terms of minimizing the average BER is investigated, and simple analytical solutions are obtained. Simulation results demonstrate that the proposed RSDDCT scheme can achieve excellent performance over fading channels in the presence of unknown random MCFOs. It is also shown that the proposed optimum power allocation strategy offers substantial average BER performance improvement over the equal power allocation strategy.

  9. Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

    Science.gov (United States)

    Tanaka, Ken; Tomeba, Hiromichi; Adachi, Fumiyuki

    Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of orthogonal frequency division multiplexing (OFDM) and time-domain spreading, while multi-carrier code division multiple access (MC-CDMA) is a combination of OFDM and frequency-domain spreading. In MC-CDMA, a good bit error rate (BER) performance can be achieved by using frequency-domain equalization (FDE), since the frequency diversity gain is obtained. On the other hand, the conventional orthogonal MC DS-CDMA fails to achieve any frequency diversity gain. In this paper, we propose a new orthogonal MC DS-CDMA that can obtain the frequency diversity gain by applying FDE. The conditional BER analysis is presented. The theoretical average BER performance in a frequency-selective Rayleigh fading channel is evaluated by the Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the orthogonal MC DS-CDMA signal transmission.

  10. The Research on Improved Companding Transformation for Reducing PAPR in Underwater Acoustic OFDM Communication System

    Directory of Open Access Journals (Sweden)

    Jinqiu Wu

    2016-01-01

    Full Text Available To solve the problem of the high peak-to-average power ratio (PAPR in Orthogonal Frequency Division Multiplexing (OFDM for the underwater acoustic communication system, the paper offers a method of reducing PAPR which combines the amplitude limiting and the improved nonlinear transformation. Traditional amplitude limiting technique can reduce PAPR in OFDM system effectively, at the cost of reducing the bit error rate (BER. However the companding transformation has far less computation complexity than SLM or PTS technologies and can improve the BER performance compared to the amplitude limiting technique simultaneously. The paper combines these two kinds of techniques, takes full use of advantages of the two method, and puts forward a low-complexity scheme choosing parameters that are more appropriate to the underwater acoustic field, with the result of improved BER performance even in lower SNR. Both simulation and experiment results show that the new method which combines clipping and companding transformation can effectively reduce the PAPR in the underwater acoustic OFDM communication system and improve the BER performance simultaneously.

  11. Array design considerations for exploitation of stable weakly dispersive modal pulses in the deep ocean

    Science.gov (United States)

    Udovydchenkov, Ilya A.

    2017-07-01

    Modal pulses are broadband contributions to an acoustic wave field with fixed mode number. Stable weakly dispersive modal pulses (SWDMPs) are special modal pulses that are characterized by weak dispersion and weak scattering-induced broadening and are thus suitable for communications applications. This paper investigates, using numerical simulations, receiver array requirements for recovering information carried by SWDMPs under various signal-to-noise ratio conditions without performing channel equalization. Two groups of weakly dispersive modal pulses are common in typical mid-latitude deep ocean environments: the lowest order modes (typically modes 1-3 at 75 Hz), and intermediate order modes whose waveguide invariant is near-zero (often around mode 20 at 75 Hz). Information loss is quantified by the bit error rate (BER) of a recovered binary phase-coded signal. With fixed receiver depths, low BERs (less than 1%) are achieved at ranges up to 400 km with three hydrophones for mode 1 with 90% probability and with 34 hydrophones for mode 20 with 80% probability. With optimal receiver depths, depending on propagation range, only a few, sometimes only two, hydrophones are often sufficient for low BERs, even with intermediate mode numbers. Full modal resolution is unnecessary to achieve low BERs. Thus, a flexible receiver array of autonomous vehicles can outperform a cabled array.

  12. Optimization of an Angle-Aided Mirror Diversity Receiver for Indoor MIMO-VLC Systems

    KAUST Repository

    Park, Kihong; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, we investigate the channel correlation problem which affects the performance of indoor multiple-input multiple-output (MIMO) visible light communication (VLC) systems. More specifically, in order to reduce the high correlation of channel matrix in MIMO-VLC intensity channel, we propose a non-imaging receiver called angle-aided mirror diversity receiver (AMDR) which utilizes not only a mirror placement but also a variation of orientation angle for the photodetector (PD) plane. Deploying a mirror helps reducing the correlation by blocking the reception of the light in one specific direction and by receiving additional light reflected in the mirror in another direction, while orienting the angle of PD plane into specific direction enables the directional reception of light. Applying a zero-forcing decorrelator at the receiver, we analyze the bit error rate (BER) performance for a 2×2 multiplexing MIMO-VLC system using a 2-dimensional geometric model. In particular, we formulate a min-max BER problem and find the optimal height of mirror and elevation angle of PD plane. Some selected numerical results validate our proposed optimal solution to our min-max BER problem and show that the BER performance of our proposed AMDR outperforms that of the previous non-imaging receivers.

  13. Transmission of 2.5 Gbit/s Spectrum-sliced WDM System for 50 km Single-mode Fiber

    Science.gov (United States)

    Ahmed, Nasim; Aljunid, Sayed Alwee; Ahmad, R. Badlisha; Fadil, Hilal Adnan; Rashid, Mohd Abdur

    2011-06-01

    The transmission of a spectrum-sliced WDM channel at 2.5 Gbit/s for 50 km of single mode fiber using an system channel spacing only 0.4 nm is reported. We have investigated the system performance using NRZ modulation format. The proposed system is compared with conventional system. The system performance is characterized as the bit-error-rate (BER) received against the system bit rates. Simulation results show that the NRZ modulation format performs well for 2.5 Gbit/s system bit rates. Using this narrow channel spectrum-sliced technique, the total number of multiplexed channels can be increased greatly in WDM system. Therefore, 0.4 nm channel spacing spectrum-sliced WDM system is highly recommended for the long distance optical access networks, like the Metro Area Network (MAN), Fiber-to-the-Building (FTTB) and Fiber-to-the-Home (FTTH).

  14. Utilização da artêmia nacional como dieta para pós-larvas do Litopenaeus vannamei (Boone, 1931 na fase berçário = Brazilian artemia as feed for Litopenaeus vannamei post-larvae through the nursery phase

    Directory of Open Access Journals (Sweden)

    Adriano Prysthon da Silva

    2006-07-01

    Full Text Available Experimentos foram realizados em uma fazenda comercial de criação decamarões marinhos, objetivando avaliar a taxa de crescimento e sobrevivência das pós-larvas do Litopenaeus vannamei, quando cultivadas em tanques-berçário e submetidas a diferentes dietas. As pós-larvas utilizadas encontravam-se com 19 dias (PL19 e foram estocadas a 16 PL/L, em tanques-berçário de 60 m3. As pós-larvas foram submetidas ao Método de Alimentação Convencional (MAC e o Método de Alimentação com Artêmia (MAA. Verificou-se que ao se correlacionar o peso em função do comprimento e do tempo de cultivo,o MAA apresentou uma relação estatisticamente superior (pExperiments were carried out in a commercial marine shrimp farm toevaluate growth and survival rate of the Litopenaeus vannamei post-larvae during nursery phase using different diets. The nursery tanks (60 m3 will be provided with post-larvae of 19 days (PL19 with a density of 16 PL/liter. The post-larvae were submitted to a Commercial Feeding Method (MAC and an Artemia Feeding Method (MAA. Considering the correlations between weight and length, and between weight and culture duration, a better efficiency (p<0.05 of the MAA was verified. The survival rate of the post-larvae fed with MAA was 86.25%, while MAC yielded survivorship of 62.12%. Thus, artemia nauplii were proved to be more efficient, providing higher growth and survival rates of Litopenaeus vannamei post-larvae.

  15. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong

    2013-04-01

    In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

  16. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong; Ko, Youngchai; Alouini, Mohamed-Slim

    2013-01-01

    In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

  17. Social Bots und Fake News - Was EU- und UNESCO-Referenzrahmen zum Lernen im digitalen Zeitalter darüber (nicht sagen

    Directory of Open Access Journals (Sweden)

    Dietmar Janetzko

    2017-07-01

    Full Text Available In den letzten Jahren haben internationale Organisationen wie die EU und die UNESCO eine Reihe von Vorschlägen und Strategiepapieren zur Bildung und Ausbildung im Zusammenhang mit digitalen Medien entwickelt. Mit den dabei entstandenen Rahmenkonzepten der EU (Digital Competence, DigComp sowie der UNESCO (Media and Information Literacy, MIL werden im Kern zwei zusammenhängende Ziele verfolgt: (i digitale Bildung bzw. digitale Kompetenzen, Fähigkeiten und zugehörige Einstellungen umfassend zu kartographieren sowie (ii über die dabei konzipierten edukativ-politischen Rahmenkonzepte Projektförderungen, Bildungs- bzw. Ausbildungsinitiativen sowie Gesetzesvorlagen anzustossen. Tatsächlich sind DigComp und MIL bereits dabei, auf internationaler Ebene einen prägenden Einfluss zu nahezu allen Fragen der Bildung und Ausbildung im Bereich digitaler Medien auszuüben. Beide Initiativen haben innerhalb der genannten Organisationen Leuchtturmcharakter, werden bislang aber von der allgemeinen Öffentlichkeit und der medienpädagogischen Fachöffentlichkeit kaum wahrgenommen. Dessen ungeachtet verbindet sich mit DigComp und MIL jeweils ein impliziter Anspruch auf einen – im Bedarfsfall zu aktualisierenden – Gesamtentwurf zur Analyse und Gestaltung medienpädagogischer Bildung und Ausbildung. Dies gilt für Gesetzesvorlagen, Regulierungen, Forschungsaktivitäten. Sind diese Rahmenkonzepte anschlussfähig an medienpädagogische Debatten über disruptive Versuche, in via soziale Medien geführte öffentliche Debatten einzugreifen, die sich über social bots, fake news oder andere Formen der Einflussnahme manifestieren? Erschliessen sie dazu Reflexionsräume und Handlungsoptionen? Geleitet von diesen Fragen betrachtet der vorliegende Aufsatz, die Rahmenkonzepte der EU und UNESCO, DigComp and MIL. Dabei zeigt sich, dass beide Rahmenkonzepte von Schieflagen gekennzeichnet sind. DigComp und MIL überbetonen die instrumentelle, auf Verwertung am

  18. Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

    Directory of Open Access Journals (Sweden)

    Lawrence R. Chen

    2005-06-01

    Full Text Available We present performance limits of the optical code-division multiple-access (OCDMA networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless case, and extend this analysis to the case when additive white Gaussian noise (AWGN is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and M-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences with good bit error rate system performance.

  19. Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

    Science.gov (United States)

    Garba, Aminata A.; Yim, Raymond M. H.; Bajcsy, Jan; Chen, Lawrence R.

    2005-12-01

    We present performance limits of the optical code-division multiple-access (OCDMA) networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD) is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless) case, and extend this analysis to the case when additive white Gaussian noise (AWGN) is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and[InlineEquation not available: see fulltext.]-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences) with good bit error rate system performance.

  20. A Golay complementary TS-based symbol synchronization scheme in variable rate LDPC-coded MB-OFDM UWBoF system

    Science.gov (United States)

    He, Jing; Wen, Xuejie; Chen, Ming; Chen, Lin

    2015-09-01

    In this paper, a Golay complementary training sequence (TS)-based symbol synchronization scheme is proposed and experimentally demonstrated in multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband over fiber (UWBoF) system with a variable rate low-density parity-check (LDPC) code. Meanwhile, the coding gain and spectral efficiency in the variable rate LDPC-coded MB-OFDM UWBoF system are investigated. By utilizing the non-periodic auto-correlation property of the Golay complementary pair, the start point of LDPC-coded MB-OFDM UWB signal can be estimated accurately. After 100 km standard single-mode fiber (SSMF) transmission, at the bit error rate of 1×10-3, the experimental results show that the short block length 64QAM-LDPC coding provides a coding gain of 4.5 dB, 3.8 dB and 2.9 dB for a code rate of 62.5%, 75% and 87.5%, respectively.

  1. The wavelength frame multiplication chopper system for the ESS test beamline at the BER II reactor—A concept study of a fundamental ESS instrument principle

    International Nuclear Information System (INIS)

    Strobl, M.; Bulat, M.; Habicht, K.

    2013-01-01

    Contributing to the design update phase of the European Spallation Source ESS–scheduled to start operation in 2019–a test beamline is under construction at the BER II research reactor at Helmholtz Zentrum Berlin (HZB). This beamline offers experimental test capabilities of instrument concepts viable for the ESS. The experiments envisaged at this dedicated beamline comprise testing of components as well as of novel experimental approaches and methods taking advantage of the long pulse characteristic of the ESS source. Therefore the test beamline will be equipped with a sophisticated chopper system that provides the specific time structure of the ESS and enables variable wavelength resolutions via wavelength frame multiplication (WFM), a fundamental instrument concept beneficial for a number of instruments at ESS. We describe the unique chopper system developed for these purposes, which allows constant wavelength resolution for a wide wavelength band. Furthermore we discuss the implications for the conceptual design for related instrumentation at the ESS

  2. Rezension von: Barbara Holland-Cunz: Gefährdete Freiheit. Über Hannah Arendt und Simone de Beauvoir. Opladen u.a.: Verlag Barbara Budrich 2012.

    Directory of Open Access Journals (Sweden)

    Mirjam Dierkes

    2012-11-01

    Full Text Available Von Barbara Holland-Cunz, die sich mit Simone de Beauvoir und Hannah Arendt bereits einzeln beschäftigt hat, liegt nun ein Band vor, in dem sie sich diesen herausragenden Denkerinnen des 20. Jahrhunderts gemeinsam widmet. In einer beinahe synoptisch anmutenden Herangehensweise fokussiert sie dabei auf den Begriff der Freiheit, der bei beiden von eminenter Bedeutung für das jeweilige Theoriegebäude ist. Holland-Cunz zufolge verstehen beide, bei einigen Unterschieden, Freiheit so, dass sie sich vor allem durch eine in sich eingeschriebene Gefährdung auszeichnet: Diese resultiert aus einem heroisch-emphatischen Gestus, der in paradoxer Weise gepaart wird mit einem abgeklärten Realismus. Über weite Strecken liest sich der Weg zu dieser Deutung, v. a. auch wegen einer teilweise sympathisch unkonventionellen und originellen Herangehensweise, sehr anregend und überzeugend.

  3. "Das Konkrete ist das Abstrakte, an das man sich schließlich gewöhnt hat." (Laurent Schwartz) Über den Ablauf des mathematischen Verstehens

    Science.gov (United States)

    Lowsky, Martin

    Die im Titel genannte Aussage findet sich in den Lebenserinnerungen von Laurent Schwartz (1915-2002), einem der fruchtbarsten Mathematiker, Mitglied der Gruppe Bourbaki. Im Original lautet die Aussage: "un objet concret est un objet abstrait auquel on a fini par s'habituer." Schwartz erläutert sie am Beispiel des Integrals über {e^{-1/2{x^2}}} , das den Wert Wurzel aus 2π hat und in dem sich also die Zahlen e und π verknüpfen. Was Schwartz aber vor allem ausdrücken will, ist dies: Das mathematische Verständnisd geht langsam vor sich und es bedarf der Anstrengung. "Es ist eine Frage der Zeit und der Energie", sagt Schwartz, und gerade dies mache es so schwer, die höhere Mathematik unter das Volk zu bringen. Das Lernen und Lehren von Mathematik laufe eben mühevoll und langsam ab.

  4. The NAA system at the reactor BER II clinical analysis of fluorine, calcium, phosphorus and aluminium in bone biopsies, comparison with photon activation analysis and ion sensitive electrode

    International Nuclear Information System (INIS)

    Gawlik, D.; Gatschke, W.; Behne, D.; Braetter, P.

    1981-01-01

    Over the past few years an irradiation and measuring system has been developed for the reactor BER II at the Hahn-Meitner-Institute. It was to be suited in particular to the neutron activation analysis of biological material via short lived radionuclides. The general characteristics of this equipment and some experimental details as the recycling facility and the device used for measuring the irradiation time, the waiting time and the neutron fluency are described. This equipment was used to determine physiological concentrations of the elements sodium, chlorine, aluminium, phosphorus, fluorine, calcium, copper and selenium in biological material. The results have been compared with those obtained by photon activation analysis or ion sensitive electrode. As an example of the application of the apparatus the authors report on the clinical analysis of Ca, F, P and Al in the control of the treatment of patients suffering from osteoporosis. (author)

  5. Performance evaluations of hybrid modulation with different optical labels over PDQ in high bit-rate OLS network systems.

    Science.gov (United States)

    Xu, M; Li, Y; Kang, T Z; Zhang, T S; Ji, J H; Yang, S W

    2016-11-14

    Two orthogonal modulation optical label switching(OLS) schemes, which are based on payload of polarization multiplexing-differential quadrature phase shift keying(POLMUX-DQPSK or PDQ) modulated with identifications of duobinary (DB) label and pulse position modulation(PPM) label, are researched in high bit-rate OLS network. The BER performance of hybrid modulation with payload and label signals are discussed and evaluated in theory and simulation. The theoretical BER expressions of PDQ, PDQ-DB and PDQ-PPM are given with analysis method of hybrid modulation encoding in different the bit-rate ratios of payload and label. Theoretical derivation results are shown that the payload of hybrid modulation has a certain gain of receiver sensitivity than payload without label. The sizes of payload BER gain obtained from hybrid modulation are related to the different types of label. The simulation results are consistent with that of theoretical conclusions. The extinction ratio (ER) conflicting between hybrid encoding of intensity and phase types can be compromised and optimized in OLS system of hybrid modulation. The BER analysis method of hybrid modulation encoding in OLS system can be applied to other n-ary hybrid modulation or combination modulation systems.

  6. Polychlorinated biphenyl quinone induces oxidative DNA damage and repair responses: The activations of NHEJ, BER and NER via ATM-p53 signaling axis

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Shi, Qiong; Song, Xiufang; Fu, Juanli; Hu, Lihua; Xu, Demei; Su, Chuanyang; Xia, Xiaomin; Song, Erqun; Song, Yang, E-mail: songyangwenrong@hotmail.com

    2015-07-01

    Our previous studies demonstrated that polychlorinated biphenyl (PCB) quinone induced oxidative DNA damage in HepG2 cells. To promote genomic integrity, DNA damage response (DDR) coordinates cell-cycle transitions, DNA repair and apoptosis. PCB quinone-induced cell cycle arrest and apoptosis have been documented, however, whether PCB quinone insult induce DNA repair signaling is still unknown. In this study, we identified the activation of DDR and corresponding signaling events in HepG2 cells upon the exposure to a synthetic PCB quinone, PCB29-pQ. Our data illustrated that PCB29-pQ induces the phosphorylation of p53, which was mediated by ataxia telangiectasia mutated (ATM) protein kinase. The observed phosphorylated histone H2AX (γ-H2AX) foci and the elevation of 8-hydroxy-2′-deoxyguanosine (8-OHdG) indicated that DDR was stimulated by PCB29-pQ treatment. Additionally, we found PCB29-pQ activates non-homologous end joining (NHEJ), base excision repair (BER) and nucleotide excision repair (NER) signalings. However, these repair pathways are not error-free processes and aberrant repair of DNA damage may cause the potential risk of carcinogenesis and mutagenesis. - Highlights: • Polychlorinated biphenyl quinone induces oxidative DNA damage in HepG2 cells. • The elevation of γ-H2AX and 8-OHdG indicates the activation of DNA damage response. • ATM-p53 signaling acts as the DNA damage sensor and effector. • Polychlorinated biphenyl quinone activates NHEJ, BER and NER signalings.

  7. Performance evaluation of FSO system using wavelength and time diversity over malaga turbulence channel with pointing errors

    Science.gov (United States)

    Balaji, K. A.; Prabu, K.

    2018-03-01

    There is an immense demand for high bandwidth and high data rate systems, which is fulfilled by wireless optical communication or free space optics (FSO). Hence FSO gained a pivotal role in research which has a added advantage of both cost-effective and licence free huge bandwidth. Unfortunately the optical signal in free space suffers from irradiance and phase fluctuations due to atmospheric turbulence and pointing errors which deteriorates the signal and degrades the performance of communication system over longer distance which is undesirable. In this paper, we have considered polarization shift keying (POLSK) system applied with wavelength and time diversity technique over Malaga(M)distribution to mitigate turbulence induced fading. We derived closed form mathematical expressions for estimating the systems outage probability and average bit error rate (BER). Ultimately from the results we can infer that wavelength and time diversity schemes enhances these systems performance.

  8. Cooperative decoding in femtocell networks: Performance-complexity tradeoff

    KAUST Repository

    Benkhelifa, Fatma

    2012-06-01

    Femtocells, which are low cost low power, stand alone cellular access points, are a potential solution to provide good indoor coverage with high data rate. However, the femtocell deployment may also increase the co-channel interference (CCI) by reducing the distance reuse of the spectrum. In this paper, we introduce methods to cancel out the interference among the femtocells while considering that macrocells operate orthogonally to the femtocells. The femtocells may also cooperate through joint detection of the received signal and improve the overall error performance at the expense of an increased computational complexity. In this paper, the performance-complexity tradeoff of cooperative detection is investigated for uplink transmissions. Numerical results show that the cooperative detection gain may reach 10 dB at a Bit-Error Rate (BER) of 10 -2 when compared to the case without cooperation. © 2012 IEEE.

  9. New results on performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-12-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may be unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the selected relay. We first derive the signal-to-noise (SNR) statistics for each hop, which are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation and end-to-end outage probability for a transmission rate R over Rayleigh fading channels. Furthermore, we evaluate the asymptotical performance and deduce the diversity order. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network architecture. © 2013 Elsevier B.V.

  10. Ultra Wideband Signal Detection with a Schottky Diode Based Envelope Detector

    DEFF Research Database (Denmark)

    Rommel, Simon; Cimoli, Bruno; Valdecasa, Guillermo Silva

    error correction threshold are achieved for wireless distances of 20 cm and 50 cm at respective data rates of 2.5 Gbit/s and 1.25 Gbit/s. uwb transmission is one of the most attractive alternatives for low-power high-speed wireless communication systems over short distances, its popularity stemming from....... The receiver is able to detect an ultra-wideband signal compliant with the Federal Communications Commission (fcc) regulations for uwb transmission and consisting of a 2.5 Gbit/s non-return-to-zero (nrz) data signal on a 6.9 GHz carrier after 20 cm wireless transmission. Bit error rates (ber) below the forward...... its interoperability with existing wireless services and its license free operation. The latter is conditioned on meeting a number of standards and regulations for maximum radiated powers, designed to ensure the former by defining uwb signals as signals with large bandwidths in the frequency range...

  11. Simulation and Evaluation of Ethernet Passive Optical Network

    Directory of Open Access Journals (Sweden)

    Salah A. Jaro Alabady

    2013-05-01

    Full Text Available      This paper studies simulation and evaluation of Ethernet Passive Optical Network (EPON system, IEEE802.3ah based OPTISM 3.6 simulation program. The simulation program is used in this paper to build a typical ethernet passive optical network, and to evaluate the network performance when using the (1580, 1625 nm wavelength instead of (1310, 1490 nm that used in Optical Line Terminal (OLT and Optical Network Units (ONU's in system architecture of Ethernet passive optical network at different bit rate and different fiber optic length. The results showed enhancement in network performance by increase the number of nodes (subscribers connected to the network, increase the transmission distance, reduces the received power and reduces the Bit Error Rate (BER.   

  12. The Parallel Algorithm Based on Genetic Algorithm for Improving the Performance of Cognitive Radio

    Directory of Open Access Journals (Sweden)

    Liu Miao

    2018-01-01

    Full Text Available The intercarrier interference (ICI problem of cognitive radio (CR is severe. In this paper, the machine learning algorithm is used to obtain the optimal interference subcarriers of an unlicensed user (un-LU. Masking the optimal interference subcarriers can suppress the ICI of CR. Moreover, the parallel ICI suppression algorithm is designed to improve the calculation speed and meet the practical requirement of CR. Simulation results show that the data transmission rate threshold of un-LU can be set, the data transmission quality of un-LU can be ensured, the ICI of a licensed user (LU is suppressed, and the bit error rate (BER performance of LU is improved by implementing the parallel suppression algorithm. The ICI problem of CR is solved well by the new machine learning algorithm. The computing performance of the algorithm is improved by designing a new parallel structure and the communication performance of CR is enhanced.

  13. Detect-and-forward in two-hop relay channels: a metrics-based analysis

    KAUST Repository

    Benjillali, Mustapha

    2010-06-01

    In this paper, we analyze the coded performance of a cooperative system with multiple parallel relays using "Detect-and-Forward" (DetF) strategy where each relay demodulates the overheard signal and forwards the detected binary words. The proposed method is based on the probabilistic characterization of the reliability metrics given under the form of L-values. First, we derive analytical expressions of the probability density functions (PDFs) of the L-values in the elementary two-hop DetF relay channel with different source-relay channel state information assumptions. Then, we apply the obtained expressions to calculate the theoretically achievable rates and compare them with the practical throughput of a simulated turbo-coded transmission. Next, we derive tight approximations for the end-to-end coded bit error rate (BER) of a general cooperative scheme with multiple parallel relays. Simulation results demonstrate the accuracy of our derivations for different cooperation configurations and conditions. © 2010 IEEE.

  14. Cooperative decoding in femtocell networks: Performance-complexity tradeoff

    KAUST Repository

    Benkhelifa, Fatma; Rezki, Zouheir; Alouini, Mohamed-Slim

    2012-01-01

    Femtocells, which are low cost low power, stand alone cellular access points, are a potential solution to provide good indoor coverage with high data rate. However, the femtocell deployment may also increase the co-channel interference (CCI) by reducing the distance reuse of the spectrum. In this paper, we introduce methods to cancel out the interference among the femtocells while considering that macrocells operate orthogonally to the femtocells. The femtocells may also cooperate through joint detection of the received signal and improve the overall error performance at the expense of an increased computational complexity. In this paper, the performance-complexity tradeoff of cooperative detection is investigated for uplink transmissions. Numerical results show that the cooperative detection gain may reach 10 dB at a Bit-Error Rate (BER) of 10 -2 when compared to the case without cooperation. © 2012 IEEE.

  15. Influence of Inter Carrier Interference on Link Adaptation Algorithms in OFDM Systems

    DEFF Research Database (Denmark)

    Das, Suvra S.; Rahman, Muhammad Imadur; Wang, Yuanye

    2007-01-01

    The performance of Link Adaptation (LA) under the influence of inter carrier interference (ICI), which is cause by carrier frequency offset (CFO) and Doppler frequency spread due to mobility, in orthogonal frequency division multiplexing (OFDM) based wireless systems is analyzed in this work. LA...... maximizes throughput while maintaining a target bit error rate (BER)or Block Error Rate (BLER) at the receiver using the signal to noise ratio (SNR) fed back from the receiver to the transmitter. Since ICI power is proportional to the signal strength, the implications of such an impairment on LA OFDM...... can over the problem. It is also noted that ICI severely reduces the spectral efficiency of OFDM systems even when LA is used....

  16. An approach enabling adaptive FEC for OFDM in fiber-VLLC system

    Science.gov (United States)

    Wei, Yiran; He, Jing; Deng, Rui; Shi, Jin; Chen, Shenghai; Chen, Lin

    2017-12-01

    In this paper, we propose an orthogonal circulant matrix transform (OCT)-based adaptive frame-level-forward error correction (FEC) scheme for fiber-visible laser light communication (VLLC) system and experimentally demonstrate by Reed-Solomon (RS) Code. In this method, no extra bits are spent for adaptive message, except training sequence (TS), which is simultaneously used for synchronization and channel estimation. Therefore, RS-coding can be adaptively performed frames by frames via the last received codeword-error-rate (CER) feedback estimated by the TSs of the previous few OFDM frames. In addition, the experimental results exhibit that over 20 km standard single-mode fiber (SSMF) and 8 m visible light transmission, the costs of RS codewords are at most 14.12% lower than those of conventional adaptive subcarrier-RS-code based 16-QAM OFDM at bit error rate (BER) of 10-5.

  17. A Comparative Study of Multiplexing Schemes for Next Generation Optical Access Networks

    Science.gov (United States)

    Imtiaz, Waqas A.; Khan, Yousaf; Shah, Pir Mehar Ali; Zeeshan, M.

    2014-09-01

    Passive optical network (PON) is a high bandwidth, economical solution which can provide the necessary bandwidth to end-users. Wavelength division multiplexed passive optical networks (WDM PONs) and time division multiplexed passive optical networks (TDM PONs) are considered as an evolutionary step for next-generation optical access (NGOA) networks. However they fail to provide highest transmission capacity, efficient bandwidth access, and robust dispersion tolerance. Thus future PONs are considered on simpler, efficient and potentially scalable, optical code division multiplexed (OCDM) PONs. This paper compares the performance of existing PONs with OCDM PON to determine a suitable scheme for NGOA networks. Two system parameter are used in this paper: fiber length, and bit rate. Performance analysis using Optisystem shows that; for a sufficient system performance parameters i.e. bit error rate (BER) ≤ 10-9, and maximum quality factor (Q) ≥ 6, OCDMA PON efficiently performs upto 50 km with 10 Gbit/s per ONU.

  18. MIMO-OFDM System's Performance Using LDPC Codes for a Mobile Robot

    Science.gov (United States)

    Daoud, Omar; Alani, Omar

    This work deals with the performance of a Sniffer Mobile Robot (SNFRbot)-based spatial multiplexed wireless Orthogonal Frequency Division Multiplexing (OFDM) transmission technology. The use of Multi-Input Multi-Output (MIMO)-OFDM technology increases the wireless transmission rate without increasing transmission power or bandwidth. A generic multilayer architecture of the SNFRbot is proposed with low power and low cost. Some experimental results are presented and show the efficiency of sniffing deadly gazes, sensing high temperatures and sending live videos of the monitored situation. Moreover, simulation results show the achieved performance by tackling the Peak-to-Average Power Ratio (PAPR) problem of the used technology using Low Density Parity Check (LDPC) codes; and the effect of combating the PAPR on the bit error rate (BER) and the signal to noise ratio (SNR) over a Doppler spread channel.

  19. 4.8 Gbit/s 16-QAM-OFDM transmission based on compact 450-nm laser for underwater wireless optical communication

    KAUST Repository

    Oubei, Hassan M.; Duran, Jose R.; Janjua, Bilal; Wang, Huai-Yung; Tsai, Cheng-Ting; Chi, Yu-Cheih; Ng, Tien Khee; Kuo, Hao-Chung; He, Jr-Hau; Alouini, Mohamed-Slim; Lin, Gong-Ru; Ooi, Boon S.

    2015-01-01

    We experimentally demonstrate an underwater wireless optical communications (UWOC) employing 450-nm TO-9 packaged and fiberpigtailed laser diode (LD) directly encoded with an orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) data. A record data rate of up to 4.8 Gbit/s over 5.4-m transmission distance is achieved. By encoding the full 1.2-GHz bandwidth of the 450-nm LD with a 16-QAM-OFDM data, an error vector magnitude (EVM) of 16.5%, a signal-to-noise ratio (SNR) of 15.63 dB and a bit error rate (BER) of 2.6 × 10-3, well pass the forward error correction (FEC) criterion, were obtained. © 2015 Optical Society of America.

  20. 4.8 Gbit/s 16-QAM-OFDM transmission based on compact 450-nm laser for underwater wireless optical communication

    KAUST Repository

    Oubei, Hassan M.

    2015-08-26

    We experimentally demonstrate an underwater wireless optical communications (UWOC) employing 450-nm TO-9 packaged and fiberpigtailed laser diode (LD) directly encoded with an orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) data. A record data rate of up to 4.8 Gbit/s over 5.4-m transmission distance is achieved. By encoding the full 1.2-GHz bandwidth of the 450-nm LD with a 16-QAM-OFDM data, an error vector magnitude (EVM) of 16.5%, a signal-to-noise ratio (SNR) of 15.63 dB and a bit error rate (BER) of 2.6 × 10-3, well pass the forward error correction (FEC) criterion, were obtained. © 2015 Optical Society of America.

  1. High-efficient full-duplex WDM-RoF system with sub-central station

    Science.gov (United States)

    Liu, Anliang; Yin, Hongxi; Wu, Bin

    2018-05-01

    With an additional sub-central station (S-CS), a high-efficient full-duplex radio-over-fiber (RoF) system compatible with the wavelength-division-multiplexing technology is proposed and experimentally demonstrated in this paper. To improve the dispersion tolerance of the RoF system, the baseband data format for the downlink and an all-optical down-conversion approach for the uplink are employed. In addition, this RoF system can not only make full use of the fiber link resources but also realize the upstream transmission without any local light sources at remote base stations (BSs). A 10-GHz RoF experimental system with a 1.25-Gb/s rate bidirectional transmission is established based on the S-CS structure. The feasibility and reliability of this RoF system are verified through eye diagrams and bit error rate (BER) curves experimentally obtained.

  2. Two-mode multiplexing at 2 × 10.7 Gbps over a 7-cell hollow-core photonic bandgap fiber

    DEFF Research Database (Denmark)

    Xu, Jing; Peucheret, Christophe; Lyngsø, Jens Kristian

    2012-01-01

    mode division multiplexing (MDM). In this work, we demonstrate MDM over a HC-PBGF for the first time. Two 10.7 Gbps channels are simultaneously transmitted over two modes of a 30-m long 7-cell HC-PBGF. Bit error ratio (BER) performances below the FEC threshold limit (3.3 × 10−3) are shown for both data...

  3. Dohmen, Dieter, Erbes, Annegret, Fuchs, Kathrin & Günzel, Juliane (2008). Was wissen wir über Nachhilfe? Sachstand und Auswertung der Forschungsliteratur zu Angebot, Nachfrage und Wirkungen. Bielefeld: Bertelsmann, 150 S. [Rezension

    OpenAIRE

    Mayr, Thomas

    2014-01-01

    Rezension von Dohmen, Dieter, Erbes, Annegret, Fuchs, Kathrin & Günzel, Juliane (2008). Was wissen wir über Nachhilfe? Sachstand und Auswertung der Forschungsliteratur zu Angebot, Nachfrage und Wirkungen. Bielefeld: Bertelsmann, 150 S. 29,90 EUR, ISBN 978-3763936656

  4. Die Wahrnehmung der Figur „Adolf Hitler“ in Daniel Levys „Mein Führer- die wirklich wahrste Wahrheit über Adolf Hitler“ durch internationales Filmpublikum.

    OpenAIRE

    Herzner, Dominik

    2017-01-01

    Filme beeinflussen die Wahrnehmungen von Figuren. Daniel Levys Film "Mein Führer" (die erste deutschsprachige Komödie über Adolf Hitler) führte zu einer positiven Wahrnehmung der Hauptfigur. In einer empirischen Untersuchung wurde gezeigt, dass sich dieser Effekt bei internationalem Filmpublikum, die einen anderen Zugang zur Thematik Nationalsozialismus haben, verstärkt.

  5. Cardinality enhancement utilizing Sequential Algorithm (SeQ code in OCDMA system

    Directory of Open Access Journals (Sweden)

    Fazlina C. A. S.

    2017-01-01

    Full Text Available Optical Code Division Multiple Access (OCDMA has been important with increasing demand for high capacity and speed for communication in optical networks because of OCDMA technique high efficiency that can be achieved, hence fibre bandwidth is fully used. In this paper we will focus on Sequential Algorithm (SeQ code with AND detection technique using Optisystem design tool. The result revealed SeQ code capable to eliminate Multiple Access Interference (MAI and improve Bit Error Rate (BER, Phase Induced Intensity Noise (PIIN and orthogonally between users in the system. From the results, SeQ shows good performance of BER and capable to accommodate 190 numbers of simultaneous users contrast with existing code. Thus, SeQ code have enhanced the system about 36% and 111% of FCC and DCS code. In addition, SeQ have good BER performance 10-25 at 155 Mbps in comparison with 622 Mbps, 1 Gbps and 2 Gbps bit rate. From the plot graph, 155 Mbps bit rate is suitable enough speed for FTTH and LAN networks. Resolution can be made based on the superior performance of SeQ code. Thus, these codes will give an opportunity in OCDMA system for better quality of service in an optical access network for future generation's usage

  6. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Haibing Yang

    2007-05-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a K-factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  7. Nonlinear demodulation and channel coding in EBPSK scheme.

    Science.gov (United States)

    Chen, Xianqing; Wu, Lenan

    2012-01-01

    The extended binary phase shift keying (EBPSK) is an efficient modulation technique, and a special impacting filter (SIF) is used in its demodulator to improve the bit error rate (BER) performance. However, the conventional threshold decision cannot achieve the optimum performance, and the SIF brings more difficulty in obtaining the posterior probability for LDPC decoding. In this paper, we concentrate not only on reducing the BER of demodulation, but also on providing accurate posterior probability estimates (PPEs). A new approach for the nonlinear demodulation based on the support vector machine (SVM) classifier is introduced. The SVM method which selects only a few sampling points from the filter output was used for getting PPEs. The simulation results show that the accurate posterior probability can be obtained with this method and the BER performance can be improved significantly by applying LDPC codes. Moreover, we analyzed the effect of getting the posterior probability with different methods and different sampling rates. We show that there are more advantages of the SVM method under bad condition and it is less sensitive to the sampling rate than other methods. Thus, SVM is an effective method for EBPSK demodulation and getting posterior probability for LDPC decoding.

  8. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Yang Haibing

    2007-01-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a -factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  9. Cardinality enhancement utilizing Sequential Algorithm (SeQ) code in OCDMA system

    Science.gov (United States)

    Fazlina, C. A. S.; Rashidi, C. B. M.; Rahman, A. K.; Aljunid, S. A.

    2017-11-01

    Optical Code Division Multiple Access (OCDMA) has been important with increasing demand for high capacity and speed for communication in optical networks because of OCDMA technique high efficiency that can be achieved, hence fibre bandwidth is fully used. In this paper we will focus on Sequential Algorithm (SeQ) code with AND detection technique using Optisystem design tool. The result revealed SeQ code capable to eliminate Multiple Access Interference (MAI) and improve Bit Error Rate (BER), Phase Induced Intensity Noise (PIIN) and orthogonally between users in the system. From the results, SeQ shows good performance of BER and capable to accommodate 190 numbers of simultaneous users contrast with existing code. Thus, SeQ code have enhanced the system about 36% and 111% of FCC and DCS code. In addition, SeQ have good BER performance 10-25 at 155 Mbps in comparison with 622 Mbps, 1 Gbps and 2 Gbps bit rate. From the plot graph, 155 Mbps bit rate is suitable enough speed for FTTH and LAN networks. Resolution can be made based on the superior performance of SeQ code. Thus, these codes will give an opportunity in OCDMA system for better quality of service in an optical access network for future generation's usage

  10. Exact analysis of Packet Reversed Packet Combining Scheme and Modified Packet Combining Scheme; and a combined scheme

    International Nuclear Information System (INIS)

    Bhunia, C.T.

    2007-07-01

    Packet combining scheme is a well defined simple error correction scheme for the detection and correction of errors at the receiver. Although it permits a higher throughput when compared to other basic ARQ protocols, packet combining (PC) scheme fails to correct errors when errors occur in the same bit locations of copies. In a previous work, a scheme known as Packet Reversed Packet Combining (PRPC) Scheme that will correct errors which occur at the same bit location of erroneous copies, was studied however PRPC does not handle a situation where a packet has more than 1 error bit. The Modified Packet Combining (MPC) Scheme that can correct double or higher bit errors was studied elsewhere. Both PRPC and MPC schemes are believed to offer higher throughput in previous studies, however neither adequate investigation nor exact analysis was done to substantiate this claim of higher throughput. In this work, an exact analysis of both PRPC and MPC is carried out and the results reported. A combined protocol (PRPC and MPC) is proposed and the analysis shows that it is capable of offering even higher throughput and better error correction capability at high bit error rate (BER) and larger packet size. (author)

  11. Soft Decision Analyzer

    Science.gov (United States)

    Lansdowne, Chatwin; Steele, Glen; Zucha, Joan; Schlesinger, Adam

    2013-01-01

    We describe the benefit of using closed-loop measurements for a radio receiver paired with a counterpart transmitter. We show that real-time analysis of the soft decision output of a receiver can provide rich and relevant insight far beyond the traditional hard-decision bit error rate (BER) test statistic. We describe a Soft Decision Analyzer (SDA) implementation for closed-loop measurements on single- or dual- (orthogonal) channel serial data communication links. The analyzer has been used to identify, quantify, and prioritize contributors to implementation loss in live-time during the development of software defined radios. This test technique gains importance as modern receivers are providing soft decision symbol synchronization as radio links are challenged to push more data and more protocol overhead through noisier channels, and software-defined radios (SDRs) use error-correction codes that approach Shannon's theoretical limit of performance.

  12. Closed-Loop Analysis of Soft Decisions for Serial Links

    Science.gov (United States)

    Lansdowne, Chatwin A.; Steele, Glen F.; Zucha, Joan P.; Schlesinger, Adam M.

    2013-01-01

    We describe the benefit of using closed-loop measurements for a radio receiver paired with a counterpart transmitter. We show that real-time analysis of the soft decision output of a receiver can provide rich and relevant insight far beyond the traditional hard-decision bit error rate (BER) test statistic. We describe a Soft Decision Analyzer (SDA) implementation for closed-loop measurements on single- or dual- (orthogonal) channel serial data communication links. The analyzer has been used to identify, quantify, and prioritize contributors to implementation loss in live-time during the development of software defined radios. This test technique gains importance as modern receivers are providing soft decision symbol synchronization as radio links are challenged to push more data and more protocol overhead through noisier channels, and software-defined radios (SDRs) use error-correction codes that approach Shannon's theoretical limit of performance.

  13. 6.4 Tb/s (32 × 200 Gb/s) WDM direct-detection transmission with twin-SSB modulation and Kramers-Kronig receiver

    Science.gov (United States)

    Zhu, Yixiao; Jiang, Mingxuan; Ruan, Xiaoke; Chen, Zeyu; Li, Chenjia; Zhang, Fan

    2018-05-01

    We experimentally demonstrate 6.4 Tb/s wavelength division multiplexed (WDM) direct-detection transmission based on Nyquist twin-SSB modulation over 25 km SSMF with bit error rates (BERs) below the 20% hard-decision forward error correction (HD-FEC) threshold of 1.5 × 10-2. The two sidebands of each channel are separately detected using Kramers-Kronig receiver without MIMO equalization. We also carry out numerical simulations to evaluate the system robustness against I/Q amplitude imbalance, I/Q phase deviation and the extinction ratio of modulator, respectively. Furthermore, we show in simulation that the requirement of steep edge optical filter can be relaxed if multi-input-multi-output (MIMO) equalization between the two sidebands is used.

  14. Study of SPM tolerances of electronically compensated DML based systems.

    Science.gov (United States)

    Papagiannakis, I; Klonidis, D; Birbas, Alexios N; Kikidis, J; Tomkos, I

    2009-05-25

    This paper experimentally investigates the effectiveness of electronic dispersion compensation (EDC) for signals limited by self phase modulation (SPM) and various dispersion levels. The sources considered are low-cost conventional directly modulated lasers (DMLs), fabricated for operation at 2.5 Gb/s but modulated at 10 Gb/s. Performance improvement is achieved by means of electronic feed-forward and decision-feedback equalization (FFE/DFE) at the receiver end. Experimental studies consider both transient and adiabatic chirp dominated DMLs sources. The improvement is evaluated in terms of required optical signal-to-noise ratio (ROSNR) for bit-error-rate (BER) values of 10(-3) versus launch power over uncompensated links of standard single mode fiber (SSMF).

  15. Blind channel estimation for MLSE receiver in high speed optical communications: theory and ASIC implementation.

    Science.gov (United States)

    Gorshtein, Albert; Levy, Omri; Katz, Gilad; Sadot, Dan

    2013-09-23

    Blind channel estimation is critical for digital signal processing (DSP) compensation of optical fiber communications links. The overall channel consists of deterministic distortions such as chromatic dispersion, as well as random and time varying distortions including polarization mode dispersion and timing jitter. It is critical to obtain robust acquisition and tracking methods for estimating these distortions effects, which, in turn, can be compensated by means of DSP such as Maximum Likelihood Sequence Estimation (MLSE). Here, a novel blind estimation algorithm is developed, accompanied by inclusive mathematical modeling, and followed by extensive set of real time experiments that verify quantitatively its performance and convergence. The developed blind channel estimation is used as the basis of an MLSE receiver. The entire scheme is fully implemented in a 65 nm CMOS Application Specific Integrated Circuit (ASIC). Experimental measurements and results are presented, including Bit Error Rate (BER) measurements, which demonstrate the successful data recovery by the MLSE ASIC under various channel conditions and distances.

  16. Wavelet-Based Watermarking and Compression for ECG Signals with Verification Evaluation

    Directory of Open Access Journals (Sweden)

    Kuo-Kun Tseng

    2014-02-01

    Full Text Available In the current open society and with the growth of human rights, people are more and more concerned about the privacy of their information and other important data. This study makes use of electrocardiography (ECG data in order to protect individual information. An ECG signal can not only be used to analyze disease, but also to provide crucial biometric information for identification and authentication. In this study, we propose a new idea of integrating electrocardiogram watermarking and compression approach, which has never been researched before. ECG watermarking can ensure the confidentiality and reliability of a user’s data while reducing the amount of data. In the evaluation, we apply the embedding capacity, bit error rate (BER, signal-to-noise ratio (SNR, compression ratio (CR, and compressed-signal to noise ratio (CNR methods to assess the proposed algorithm. After comprehensive evaluation the final results show that our algorithm is robust and feasible.

  17. Low Complexity V-BLAST MIMO-OFDM Detector by Successive Iterations Reduction

    Directory of Open Access Journals (Sweden)

    AHMED, K.

    2015-02-01

    Full Text Available V-BLAST detection method suffers large computational complexity due to its successive detection of symbols. In this paper, we propose a modified V-BLAST algorithm to decrease the computational complexity by reducing the number of detection iterations required in MIMO communication systems. We begin by showing the existence of a maximum number of iterations, beyond which, no significant improvement is obtained. We establish a criterion for the number of maximum effective iterations. We propose a modified algorithm that uses the measured SNR to dynamically set the number of iterations to achieve an acceptable bit-error rate. Then, we replace the feedback algorithm with an approximate linear function to reduce the complexity. Simulations show that significant reduction in computational complexity is achieved compared to the ordinary V-BLAST, while maintaining a good BER performance.

  18. Multi-stage decoding of multi-level modulation codes

    Science.gov (United States)

    Lin, Shu; Kasami, Tadao; Costello, Daniel J., Jr.

    1991-01-01

    Various types of multi-stage decoding for multi-level modulation codes are investigated. It is shown that if the component codes of a multi-level modulation code and types of decoding at various stages are chosen properly, high spectral efficiency and large coding gain can be achieved with reduced decoding complexity. Particularly, it is shown that the difference in performance between the suboptimum multi-stage soft-decision maximum likelihood decoding of a modulation code and the single-stage optimum soft-decision decoding of the code is very small, only a fraction of dB loss in signal to noise ratio at a bit error rate (BER) of 10(exp -6).

  19. PAPR reduction based on tone reservation scheme for DCO-OFDM indoor visible light communications.

    Science.gov (United States)

    Bai, Jurong; Li, Yong; Yi, Yang; Cheng, Wei; Du, Huimin

    2017-10-02

    High peak-to-average power ratio (PAPR) leads to out-of-band power and in-band distortion in the direct current-biased optical orthogonal frequency division multiplexing (DCO-OFDM) systems. In order to effectively reduce the PAPR with faster convergence and lower complexity, this paper proposes a tone reservation based scheme, which is the combination of the signal-to-clipping noise ratio (SCR) procedure and the least squares approximation (LSA) procedure. In the proposed scheme, the transmitter of the DCO-OFDM indoor visible light communication (VLC) system is designed to transform the PAPR reduced signal into real-valued positive OFDM signal without doubling the transmission bandwidth. Moreover, the communication distance and the light emitting diode (LED) irradiance angle are taking into consideration in the evaluation of the system bit error rate (BER). The PAPR reduction efficiency of the proposed scheme is remarkable for DCO-OFDM indoor VLC systems.

  20. The Channel Estimation and Modeling in High Altitude Platform Station Wireless Communication Dynamic Network

    Directory of Open Access Journals (Sweden)

    Xiaoyang Liu

    2017-01-01

    Full Text Available In order to analyze the channel estimation performance of near space high altitude platform station (HAPS in wireless communication system, the structure and formation of HAPS are studied in this paper. The traditional Least Squares (LS channel estimation method and Singular Value Decomposition-Linear Minimum Mean-Squared (SVD-LMMS channel estimation method are compared and investigated. A novel channel estimation method and model are proposed. The channel estimation performance of HAPS is studied deeply. The simulation and theoretical analysis results show that the performance of the proposed method is better than the traditional methods. The lower Bit Error Rate (BER and higher Signal Noise Ratio (SNR can be obtained by the proposed method compared with the LS and SVD-LMMS methods.

  1. Atmospheric free-space coherent optical communications with adaptive optics

    Science.gov (United States)

    Ting, Chueh; Zhang, Chengyu; Yang, Zikai

    2017-02-01

    Free-space coherent optical communications have a potential application to offer last mile bottleneck solution in future local area networks (LAN) because of their information carrier, information security and license-free status. Coherent optical communication systems using orthogonal frequency division multiplexing (OFDM) digital modulation are successfully demonstrated in a long-haul tens Giga bits via optical fiber, but they are not yet available in free space due to atmospheric turbulence-induced channel fading. Adaptive optics is recognized as a promising technology to mitigate the effects of atmospheric turbulence in free-space optics. In this paper, a free-space coherent optical communication system using an OFDM digital modulation scheme and adaptive optics (FSO OFDM AO) is proposed, a Gamma-Gamma distribution statistical channel fading model for the FSO OFDM AO system is examined, and FSO OFDM AO system performance is evaluated in terms of bit error rate (BER) versus various propagation distances.

  2. High performance waveguide-coupled Ge-on-Si linear mode avalanche photodiodes.

    Science.gov (United States)

    Martinez, Nicholas J D; Derose, Christopher T; Brock, Reinhard W; Starbuck, Andrew L; Pomerene, Andrew T; Lentine, Anthony L; Trotter, Douglas C; Davids, Paul S

    2016-08-22

    We present experimental results for a selective epitaxially grown Ge-on-Si separate absorption and charge multiplication (SACM) integrated waveguide coupled avalanche photodiode (APD) compatible with our silicon photonics platform. Epitaxially grown Ge-on-Si waveguide-coupled linear mode avalanche photodiodes with varying lateral multiplication regions and different charge implant dimensions are fabricated and their illuminated device characteristics and high-speed performance is measured. We report a record gain-bandwidth product of 432 GHz for our highest performing waveguide-coupled avalanche photodiode operating at 1510nm. Bit error rate measurements show operation with BER-12, in the range from -18.3 dBm to -12 dBm received optical power into a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm.

  3. Receiver IQ mismatch estimation in PDM CO-OFDM system using training symbol

    Science.gov (United States)

    Peng, Dandan; Ma, Xiurong; Yao, Xin; Zhang, Haoyuan

    2017-07-01

    Receiver in-phase/quadrature (IQ) mismatch is hard to mitigate at the receiver via using conventional method in polarization division multiplexed (PDM) coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. In this paper, a novel training symbol structure is proposed to estimate IQ mismatch and channel distortion. Combined this structure with Gram Schmidt orthogonalization procedure (GSOP) algorithm, we can get lower bit error rate (BER). Meanwhile, based on this structure one estimation method is deduced in frequency domain which can achieve the estimation of IQ mismatch and channel distortion independently and improve the system performance obviously. Numerical simulation shows that the proposed two methods have better performance than compared method at 100 Gb/s after 480 km fiber transmission. Besides, the calculation complexity is also analyzed.

  4. Experimental demonstration of a real-time PAM-4 Q-band RoF system based on CMMA equalization and interleaved RS code

    Science.gov (United States)

    Deng, Rui; Yu, Jianjun; He, Jing; Wei, Yiran

    2018-05-01

    In this paper, we experimentally demonstrated a complete real-time 4-level pulse amplitude modulation (PAM-4) Q-band radio-over-fiber (RoF) system with optical heterodyning and envelope detector (ED) down-conversion. Meanwhile, a cost-efficient real-time implementation scheme of cascaded multi-modulus algorithm (CMMA) equalization is proposed in this paper. By using the proposed scheme, the CMMA equalization is applied in the system for signal recovery. In addition, to improve the transmission performance of the system, an interleaved Reed-Solomon (RS) code is applied in the real-time system. Although there is serious power impulse noise in the system, the system can still achieve a bit error rate (BER) at below 1 × 10-7 after 25 km standard single mode fiber (SSMF) transmission and 1-m wireless transmission.

  5. Effect of dust storms on FSO communications links

    KAUST Repository

    Esmail, Maged Abdullah

    2017-05-18

    In literature, there is a lake of information about free space optic (FSO) systems\\' performance in arid and semi-arid areas that are prone to frequent dust storms. Therefore, in this paper, we investigate the performance of FSO links under dust storm conditions. We aim to determine the limits and capabilities of such systems in this harsh environment. To achieve this goal, we use some performance metrics including signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. The results show that dust is a rough impairment that causes link drop under low visibility range. Moreover, we found that the system performance can be improved by using short segments or multi-hop system. Furthermore, the results show negligible improvement in system performance under dense dust. The comparison of fog and dust impairments show that dust introduces much higher attenuation than fog. Therefore, dust can be considered as the ultimate impairment for FSO links.

  6. Exact performance analysis of decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-06-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the source may or may not be able to communicate directly with the destination. In our study, we consider a regenerative relaying scheme in which the decision to cooperate takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive an exact closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact statistics of each hop. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results.

  7. Demonstration of an 8 × 25-Gb/s optical time-division multiplexing system

    Science.gov (United States)

    Wang, Dong; Huo, Li; Li, Yunbo; Wang, Lei; Li, Han; Jiang, Xiangyu; Chen, Xin; Lou, Caiyun

    2017-11-01

    An 8 × 25-Gb/s optical time-division multiplexing (OTDM) system is demonstrated experimentally. The optical pulse source is based on optical frequency comb (OFC) generation and pulse shaping, which can generate nearly chirp-free 25-GHz 1.6-ps optical Gaussian pulse. The eightfold optical time-division demultiplexer consists of a single-driven dual-parallel Mach-Zehnder modulator (DPMZM) and a Mamyshev reshaper. Error-free demultiplexing of 8 × 25-Gb/s back-to-back (B2B) signal with a power penalty of 4.1 dB to 4.4 dB at a bit error rate (BER) of 10-9 is achieved to confirm the performance of the proposed system.

  8. Effect of dust storms on FSO communications links

    KAUST Repository

    Esmail, Maged Abdullah; Fathallah, Habib; Alouini, Mohamed-Slim

    2017-01-01

    In literature, there is a lake of information about free space optic (FSO) systems' performance in arid and semi-arid areas that are prone to frequent dust storms. Therefore, in this paper, we investigate the performance of FSO links under dust storm conditions. We aim to determine the limits and capabilities of such systems in this harsh environment. To achieve this goal, we use some performance metrics including signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. The results show that dust is a rough impairment that causes link drop under low visibility range. Moreover, we found that the system performance can be improved by using short segments or multi-hop system. Furthermore, the results show negligible improvement in system performance under dense dust. The comparison of fog and dust impairments show that dust introduces much higher attenuation than fog. Therefore, dust can be considered as the ultimate impairment for FSO links.

  9. Joint Impact of Frequency Synchronization Errors and Intermodulation Distortion on the Performance of Multicarrier DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Rugini Luca

    2005-01-01

    Full Text Available The performance of multicarrier systems is highly impaired by intercarrier interference (ICI due to frequency synchronization errors at the receiver and by intermodulation distortion (IMD introduced by a nonlinear amplifier (NLA at the transmitter. In this paper, we evaluate the bit-error rate (BER of multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA downlink systems subject to these impairments in frequency-selective Rayleigh fading channels, assuming quadrature amplitude modulation (QAM. The analytical findings allow to establish the sensitivity of MC-DS-CDMA systems to carrier frequency offset (CFO and NLA distortions, to identify the maximum CFO that is tolerable at the receiver side in different scenarios, and to find out the optimum value of the NLA output power backoff for a given CFO. Simulation results show that the approximated analysis is quite accurate in several conditions.

  10. Iterative Overlap FDE for Multicode DS-CDMA

    Science.gov (United States)

    Takeda, Kazuaki; Tomeba, Hiromichi; Adachi, Fumiyuki

    Recently, a new frequency-domain equalization (FDE) technique, called overlap FDE, that requires no GI insertion was proposed. However, the residual inter/intra-block interference (IBI) cannot completely be removed. In addition to this, for multicode direct sequence code division multiple access (DS-CDMA), the presence of residual interchip interference (ICI) after FDE distorts orthogonality among the spreading codes. In this paper, we propose an iterative overlap FDE for multicode DS-CDMA to suppress both the residual IBI and the residual ICI. In the iterative overlap FDE, joint minimum mean square error (MMSE)-FDE and ICI cancellation is repeated a sufficient number of times. The bit error rate (BER) performance with the iterative overlap FDE is evaluated by computer simulation.

  11. A New Quantum Watermarking Based on Quantum Wavelet Transforms

    International Nuclear Information System (INIS)

    Heidari, Shahrokh; Pourarian, Mohammad Rasoul; Naseri, Mosayeb; Gheibi, Reza; Baghfalaki, Masoud; Farouk, Ahmed

    2017-01-01

    Quantum watermarking is a technique to embed specific information, usually the owner’s identification, into quantum cover data such for copyright protection purposes. In this paper, a new scheme for quantum watermarking based on quantum wavelet transforms is proposed which includes scrambling, embedding and extracting procedures. The invisibility and robustness performances of the proposed watermarking method is confirmed by simulation technique. The invisibility of the scheme is examined by the peak-signal-to-noise ratio (PSNR) and the histogram calculation. Furthermore the robustness of the scheme is analyzed by the Bit Error Rate (BER) and the Correlation Two-Dimensional (Corr 2-D) calculation. The simulation results indicate that the proposed watermarking scheme indicate not only acceptable visual quality but also a good resistance against different types of attack. (paper)

  12. Quasi Cyclic Low Density Parity Check Code for High SNR Data Transfer

    Directory of Open Access Journals (Sweden)

    M. R. Islam

    2010-06-01

    Full Text Available An improved Quasi Cyclic Low Density Parity Check code (QC-LDPC is proposed to reduce the complexity of the Low Density Parity Check code (LDPC while obtaining the similar performance. The proposed QC-LDPC presents an improved construction at high SNR with circulant sub-matrices. The proposed construction yields a performance gain of about 1 dB at a 0.0003 bit error rate (BER and it is tested on 4 different decoding algorithms. Proposed QC-LDPC is compared with the existing QC-LDPC and the simulation results show that the proposed approach outperforms the existing one at high SNR. Simulations are also performed varying the number of horizontal sub matrices and the results show that the parity check matrix with smaller horizontal concatenation shows better performance.

  13. Transmission over UWB channels with OFDM system using LDPC coding

    Science.gov (United States)

    Dziwoki, Grzegorz; Kucharczyk, Marcin; Sulek, Wojciech

    2009-06-01

    Hostile wireless environment requires use of sophisticated signal processing methods. The paper concerns on Ultra Wideband (UWB) transmission over Personal Area Networks (PAN) including MB-OFDM specification of physical layer. In presented work the transmission system with OFDM modulation was connected with LDPC encoder/decoder. Additionally the frame and bit error rate (FER and BER) of the system was decreased using results from the LDPC decoder in a kind of turbo equalization algorithm for better channel estimation. Computational block using evolutionary strategy, from genetic algorithms family, was also used in presented system. It was placed after SPA (Sum-Product Algorithm) decoder and is conditionally turned on in the decoding process. The result is increased effectiveness of the whole system, especially lower FER. The system was tested with two types of LDPC codes, depending on type of parity check matrices: randomly generated and constructed deterministically, optimized for practical decoder architecture implemented in the FPGA device.

  14. Interference Mitigation Technique for Coexistence of Pulse-Based UWB and OFDM

    Directory of Open Access Journals (Sweden)

    Ohno Kohei

    2008-01-01

    Full Text Available Abstract Ultra-wideband (UWB is a useful radio technique for sharing frequency bands between radio systems. It uses very short pulses to spread spectrum. However, there is a potential for interference between systems using the same frequency bands at close range. In some regulatory systems, interference detection and avoidance (DAA techniques are required to prevent interference with existing radio systems. In this paper, the effect of interference on orthogonal frequency division multiplexing (OFDM signals from pulse-based UWB is discussed, and an interference mitigation technique is proposed. This technique focuses on the pulse repetition cycle of UWB. The pulse repetition interval is set the same or half the period of the OFDM symbol excluding the guard interval to mitigate interference. These proposals are also made for direct sequence (DS-UWB. Bit error rate (BER performance is illustrated through both simulation and theoretical approximations.

  15. Parameter allocation of parallel array bistable stochastic resonance and its application in communication systems

    International Nuclear Information System (INIS)

    Liu Jian; Zhai Qi-Qing; Wang You-Guo; Liu Jin

    2016-01-01

    In this paper, we propose a parameter allocation scheme in a parallel array bistable stochastic resonance-based communication system (P-BSR-CS) to improve the performance of weak binary pulse amplitude modulated (BPAM) signal transmissions. The optimal parameter allocation policy of the P-BSR-CS is provided to minimize the bit error rate (BER) and maximize the channel capacity (CC) under the adiabatic approximation condition. On this basis, we further derive the best parameter selection theorem in realistic communication scenarios via variable transformation. Specifically, the P-BSR structure design not only brings the robustness of parameter selection optimization, where the optimal parameter pair is not fixed but variable in quite a wide range, but also produces outstanding system performance. Theoretical analysis and simulation results indicate that in the P-BSR-CS the proposed parameter allocation scheme yields considerable performance improvement, particularly in very low signal-to-noise ratio (SNR) environments. (paper)

  16. A design of a wavelength-hopping time-spreading incoherent optical code division multiple access system

    International Nuclear Information System (INIS)

    Glesk, I.; Baby, V.

    2005-01-01

    We present the architecture and code design for a highly scalable, 2.5 Gb/s per user optical code division multiple access (OCDMA) system. The system is scalable to 100 potential and more than 10 simultaneous users, each with a bit error rate (BER) of less than 10 -9 . The system architecture uses a fast wavelength-hopping, time-spreading codes. Unlike frequency and phase sensitive coherent OCDMA systems, this architecture utilizes standard on off keyed optical pulses allocated in the time and wavelength dimensions. This incoherent OCDMA approach is compatible with existing WDM optical networks and utilizes off the shelf components. We discuss the novel optical subsystem design for encoders and decoders that enable the realization of a highly scalable incoherent OCDMA system with rapid reconfigurability. A detailed analysis of the scalability of the two dimensional code is presented and select network deployment architectures for OCDMA are discussed (Authors)

  17. An Analytical Approach for Performance Enhancement of FSO Communication System Using Array of Receivers in Adverse Weather Conditions

    Science.gov (United States)

    Nagpal, Shaina; Gupta, Amit

    2017-08-01

    Free Space Optics (FSO) link exploits the tremendous network capacity and is capable of offering wireless communications similar to communications through optical fibres. However, FSO link is extremely weather dependent and the major effect on FSO links is due to adverse weather conditions like fog and snow. In this paper, an FSO link is designed using an array of receivers. The disparity of the link for very high attenuation conditions due to fog and snow is analysed using aperture averaging technique. Further effect of aperture averaging technique is investigated by comparing the systems using aperture averaging technique with systems not using aperture averaging technique. The performance of proposed model of FSO link has been evaluated in terms of Q factor, bit error rate (BER) and eye diagram.

  18. Experimental research of UWB over fiber system employing 128-QAM and ISFA-optimized scheme

    Science.gov (United States)

    He, Jing; Xiang, Changqing; Long, Fengting; Chen, Zuo

    2018-05-01

    In this paper, an optimized intra-symbol frequency-domain averaging (ISFA) scheme is proposed and experimentally demonstrated in intensity-modulation and direct-detection (IMDD) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband over fiber (UWBoF) system. According to the channel responses of three MB-OFDM UWB sub-bands, the optimal ISFA window size for each sub-band is investigated. After 60-km standard single mode fiber (SSMF) transmission, the experimental results show that, at the bit error rate (BER) of 3.8 × 10-3, the receiver sensitivity of 128-quadrature amplitude modulation (QAM) can be improved by 1.9 dB using the proposed enhanced ISFA combined with training sequence (TS)-based channel estimation scheme, compared with the conventional TS-based channel estimation. Moreover, the spectral efficiency (SE) is up to 5.39 bit/s/Hz.

  19. Performance Analysis of OFDM 60GHz System and SC-FDE 60GHz System

    Directory of Open Access Journals (Sweden)

    Han Xueyan

    2016-01-01

    Full Text Available In this paper, the performance of 60GHz wireless communication system with SC and OFDM is studied, the models of OFDM 60GHz system and SC 60GHz frequency domain equalization (SC-FDE system are established, and the bit error rate (BER performance of OFDM 60GHz system and SC-FDE 60GHz system in 802.15.3c channels is compared. The simulation results show that SC-FDE 60GHz system has a slight advantage over OFDM system in line-of-sight (LOS channels, while OFDM 60GHz system has a slight advantage over SC-FDE system in non-line-of-sight (NLOS channels. For 60GHz system, OFDM 60GHz system has a slight advantage over SC-FDE system in overcoming multipath fading, but the performance of both is close whether in the LOS or NLOS case.

  20. New hybrid technique for impulsive noise suppression in OFDM systems

    International Nuclear Information System (INIS)

    Mirza, A.; Zeb, A.; Sheikh, S.A.

    2017-01-01

    In this paper, a new hybrid technique employing RS (Reed Solomon) coding and adaptive filter for impulsive noise suppression in OFDM (Orthogonal Frequency Division Multiplexing) systems is presented. Adaptive filter creates a more accurate estimate of the original OFDM signal after impulsive noise cancellation. The residual impulsive noise is further mitigated by RS decoder in the second stage of proposed technique. Three members of adaptive filters family i.e. NLMS (Normalized Least Mean Square) algorithm, RLS (Recursive Least Square) algorithm and Bhagyashri algorithm are tested with RS decoder in the proposed hybrid technique. Furthermore, the results in terms of steady state MSE (Mean Square Error) reduction, BER (Bit Error Rate) improvement and SNR (Signal to Noise Ratio) enhancement confirm the effectiveness of the proposed dual faceted technique when compared with the recently reported techniques in literature. (author)

  1. A hybrid lightwave transmission system based on light injection/optoelectronic feedback techniques and fiber-VLLC integration

    International Nuclear Information System (INIS)

    Tsai, Wen-Shing; Lu, Hai-Han; Li, Chung-Yi; Chen, Bo-Rui; Lin, Hung-Hsien; Lin, Dai-Hua

    2016-01-01

    A hybrid lightwave transmission system based on light injection/optoelectronic feedback techniques and fiber-visible laser light communication (VLLC) integration is proposed and experimentally demonstrated. To be the first one of its kind in employing light injection and optoelectronic feedback techniques in a fiber-VLLC integration lightwave transmission system, the light is successfully directly modulated with Community Access Television (CATV), 16-QAM, and 16-QAM-OFDM signals. Over a 40 km SMF and a 10 m free-space VLLC transport, good performances of carrier-to-noise ratio (CNR)/composite second-order (CSO)/composite triple-beat (CTB)/bit error rate (BER) are achieved for CATV/16-QAM/16-QAM-OFDM signals transmission. Such a hybrid lightwave transmission system would be very useful since it can provide broadband integrated services including CATV, Internet, and telecommunication services over both distribute fiber and in-building networks. (letter)

  2. A Fast LMMSE Channel Estimation Method for OFDM Systems

    Directory of Open Access Journals (Sweden)

    Zhou Wen

    2009-01-01

    Full Text Available A fast linear minimum mean square error (LMMSE channel estimation method has been proposed for Orthogonal Frequency Division Multiplexing (OFDM systems. In comparison with the conventional LMMSE channel estimation, the proposed channel estimation method does not require the statistic knowledge of the channel in advance and avoids the inverse operation of a large dimension matrix by using the fast Fourier transform (FFT operation. Therefore, the computational complexity can be reduced significantly. The normalized mean square errors (NMSEs of the proposed method and the conventional LMMSE estimation have been derived. Numerical results show that the NMSE of the proposed method is very close to that of the conventional LMMSE method, which is also verified by computer simulation. In addition, computer simulation shows that the performance of the proposed method is almost the same with that of the conventional LMMSE method in terms of bit error rate (BER.

  3. Mitigation of MIMO Co-Channel Interference using robust interference cancellation receiver

    DEFF Research Database (Denmark)

    Rahman, Muhammad Imadur; De Carvalho, Elisabeth; Prasad, Ramjee

    2007-01-01

    (STBC) link may become equivalent to an interfering Spatial Multiplexing (SM) link. Using this knowledge and understanding, we propose an interference cancellation receiver robust to different types of MIMO interferers at cell edge for the Downlink (DL) of cellular systems. The receiver systematically...... performs a multiple symbol processing: this is the appropriate processing when the signal of interest or the signal of interferer is correlated across symbols, which is the case for STBC transmission. We evaluated different link combinations in terms of Signal to Interference and Noise Ratio (SINR......) statistics and Bit Error Rate (BER) performance in cellular Orthogonal Frequency Division Multiple Access (OFDMA) systems. We have found that the proposed multiple-symbol linear interference cancellation receiver performs satisfactorily when any kind of single 'logical' stream MIMO scheme is present...

  4. Performance Analysis of Diversity-Controlled Multi-User Superposition Transmission for 5G Wireless Networks.

    Science.gov (United States)

    Yeom, Jeong Seon; Chu, Eunmi; Jung, Bang Chul; Jin, Hu

    2018-02-10

    In this paper, we propose a novel low-complexity multi-user superposition transmission (MUST) technique for 5G downlink networks, which allows multiple cell-edge users to be multiplexed with a single cell-center user. We call the proposed technique diversity-controlled MUST technique since the cell-center user enjoys the frequency diversity effect via signal repetition over multiple orthogonal frequency division multiplexing (OFDM) sub-carriers. We assume that a base station is equipped with a single antenna but users are equipped with multiple antennas. In addition, we assume that the quadrature phase shift keying (QPSK) modulation is used for users. We mathematically analyze the bit error rate (BER) of both cell-edge users and cell-center users, which is the first theoretical result in the literature to the best of our knowledge. The mathematical analysis is validated through extensive link-level simulations.

  5. LiFi: transforming fibre into wireless

    Science.gov (United States)

    Yin, Liang; Islim, Mohamed Sufyan; Haas, Harald

    2017-01-01

    Light-fidelity (LiFi) uses energy-efficient light-emitting diodes (LEDs) for high-speed wireless communication, and it has a great potential to be integrated with fibre communication for future gigabit networks. However, by making fibre communication wireless, multiuser interference arises. Traditional methods use orthogonal multiple access (OMA) for interference avoidance. In this paper, multiuser interference is exploited with the use of non-orthogonal multiple access (NOMA) relying on successive interference cancellation (SIC). The residual interference due to imperfect SIC in practical scenarios is characterized with a proportional model. Results show that NOMA offers 5 -10 dB gain on the equivalent signal-to-interference-plus-noise ratio (SINR) over OMA. The bit error rate (BER) performance of direct current optical orthogonal frequency division multiplexing (DCO-OFDM) is shown to be significantly improved when SIC is used.

  6. A hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks.

    Science.gov (United States)

    Choi, Yong-Kyu; Hosoya, Kenta; Lee, Chung Ghiu; Hanawa, Masanori; Park, Chang-Soo

    2011-03-28

    We propose and experimentally demonstrate a hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks. Dynamic function is implemented by mechanically tuning the Fourier encoder/decoder for optical code division multiple access (OCDMA) encoding/decoding. Wavelength division multiplexing (WDM) is utilized for node assignment and 4-chip Fourier code recovers the matched signal from the codes. For an optical source well adapted to WDM channels and its short optical pulse generation, reflective semiconductor optical amplifiers (RSOAs) are used with a fiber Bragg grating (FBG) and gain-switched. To demonstrate we experimentally investigated a two-node hybrid WDM/OCDMA ring with a 4-chip Fourier encoder/decoder fabricated by cascading four FBGs with the bit error rate (BER) of <10(-9) for the node span of 10.64 km at 1.25 Gb/s.

  7. Construction and Analysis of a Novel 2-D Optical Orthogonal Codes Based on Modified One-coincidence Sequence

    Science.gov (United States)

    Ji, Jianhua; Wang, Yanfen; Wang, Ke; Xu, Ming; Zhang, Zhipeng; Yang, Shuwen

    2013-09-01

    A new two-dimensional OOC (optical orthogonal codes) named PC/MOCS is constructed, using PC (prime code) for time spreading and MOCS (modified one-coincidence sequence) for wavelength hopping. Compared with PC/PC, the number of wavelengths for PC/MOCS is not limited to a prime number. Compared with PC/OCS, the length of MOCS need not be expanded to the same length of PC. PC/MOCS can be constructed flexibly, and also can use available wavelengths effectively. Theoretical analysis shows that PC/MOCS can reduce the bit error rate (BER) of OCDMA system, and can support more users than PC/PC and PC/OCS.

  8. Study of passive optical network monitoring based on non-OTDR

    Science.gov (United States)

    Li, Chuan-qi; Wang, Da-chi; Hu, Jin-lin

    2014-03-01

    Aiming at the defects of passive optical network (PON) monitoring based on optical time domain reflectometry (OTDR) technology, we research the non-OTDR monitoring technology. The coding scheme based on periodic encoder monitoring is discussed, and its limitation is analyzed. On this basis, the monitoring technology based on optical code division multiple access (OCDMA) is put forward. We analyze the feasibility of monitoring scheme based on PON of OCDMA, design a monitoring plan, and then use OptiSystem to simulate the design. The results of simulation and bit error rate (BER) analysis show that this monitoring technology can overcome the deficiencies of OTDR and distinguish the monitoring signals of different fiber branches clearly, which meets the demands for high beam split ratio of multi-user communication.

  9. Modified Single Photo-diode (MSPD) Detection Technique for SAC-OCDMA System

    Science.gov (United States)

    Abdulqader, Sarah G.; Fadhil, Hilal A.; Aljunid, S. A.

    2015-03-01

    In this paper, a new detection technique called modified single photo-diode (MSPD) detection for SAC-OCDMA system is proposed. The proposed system based on the single photo-diode (SPD) detection technique. The new detection technique is proposed to overcome the limitation of phase-induced intensity noise (PIIN) in SPD detection technique. However, the proposed detection is based on an optical hard limiter (OHL) followed by a SPD and a low-pass filter (LPF) in order to suppress the phase intensity noise (PIIN) at the receiver side. The results show that the MSPD detection based on OHL has a good performance even when the transmission distance is long, which is different from the case of SPD detection technique. Therefore, the MSPD detection technique is shown to be effective to improve the bit error rate (BER<10-9) and to suppress the noise in the practical optical fiber network.

  10. Analysis of mobile fronthaul bandwidth and wireless transmission performance in split-PHY processing architecture.

    Science.gov (United States)

    Miyamoto, Kenji; Kuwano, Shigeru; Terada, Jun; Otaka, Akihiro

    2016-01-25

    We analyze the mobile fronthaul (MFH) bandwidth and the wireless transmission performance in the split-PHY processing (SPP) architecture, which redefines the functional split of centralized/cloud RAN (C-RAN) while preserving high wireless coordinated multi-point (CoMP) transmission/reception performance. The SPP architecture splits the base stations (BS) functions between wireless channel coding/decoding and wireless modulation/demodulation, and employs its own CoMP joint transmission and reception schemes. Simulation results show that the SPP architecture reduces the MFH bandwidth by up to 97% from conventional C-RAN while matching the wireless bit error rate (BER) performance of conventional C-RAN in uplink joint reception with only 2-dB signal to noise ratio (SNR) penalty.

  11. 40-Gb/s PDM-QPSK signal transmission over 160-m wireless distance at W-band.

    Science.gov (United States)

    Xiao, Jiangnan; Yu, Jianjun; Li, Xinying; Xu, Yuming; Zhang, Ziran; Chen, Long

    2015-03-15

    We experimentally demonstrate a W-band optical-wireless transmission system over 160-m wireless distance with a bit rate up to 40 Gb/s. The optical-wireless transmission system adopts optical polarization-division-multiplexing (PDM), multiple-input multiple-output (MIMO) reception and antenna polarization diversity. Using this system, we experimentally demonstrate the 2×2 MIMO wireless delivery of 20- and 40-Gb/s PDM quadrature-phase-shift-keying (PDM-QPSK) signals over 640- and 160-m wireless links, respectively. The bit-error ratios (BERs) of these transmission systems are both less than the forward-error-correction (FEC) threshold of 3.8×10-3.

  12. Real-time validation of receiver state information in optical space-time block code systems.

    Science.gov (United States)

    Alamia, John; Kurzweg, Timothy

    2014-06-15

    Free space optical interconnect (FSOI) systems are a promising solution to interconnect bottlenecks in high-speed systems. To overcome some sources of diminished FSOI performance caused by close proximity of multiple optical channels, multiple-input multiple-output (MIMO) systems implementing encoding schemes such as space-time block coding (STBC) have been developed. These schemes utilize information pertaining to the optical channel to reconstruct transmitted data. The STBC system is dependent on accurate channel state information (CSI) for optimal system performance. As a result of dynamic changes in optical channels, a system in operation will need to have updated CSI. Therefore, validation of the CSI during operation is a necessary tool to ensure FSOI systems operate efficiently. In this Letter, we demonstrate a method of validating CSI, in real time, through the use of moving averages of the maximum likelihood decoder data, and its capacity to predict the bit error rate (BER) of the system.

  13. Design of pulse waveform for waveform division multiple access UWB wireless communication system.

    Science.gov (United States)

    Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu

    2014-01-01

    A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.

  14. Demonstration of hybrid orbital angular momentum multiplexing and time-division multiplexing passive optical network.

    Science.gov (United States)

    Wang, Andong; Zhu, Long; Liu, Jun; Du, Cheng; Mo, Qi; Wang, Jian

    2015-11-16

    Mode-division multiplexing passive optical network (MDM-PON) is a promising scheme for next-generation access networks to further increase fiber transmission capacity. In this paper, we demonstrate the proof-of-concept experiment of hybrid mode-division multiplexing (MDM) and time-division multiplexing (TDM) PON architecture by exploiting orbital angular momentum (OAM) modes. Bidirectional transmissions with 2.5-Gbaud 4-level pulse amplitude modulation (PAM-4) downstream and 2-Gbaud on-off keying (OOK) upstream are demonstrated in the experiment. The observed optical signal-to-noise ratio (OSNR) penalties for downstream and upstream transmissions at a bit-error rate (BER) of 2 × 10(-3) are less than 2.0 dB and 3.0 dB, respectively.

  15. Reduced complexity and latency for a massive MIMO system using a parallel detection algorithm

    Directory of Open Access Journals (Sweden)

    Shoichi Higuchi

    2017-09-01

    Full Text Available In recent years, massive MIMO systems have been widely researched to realize high-speed data transmission. Since massive MIMO systems use a large number of antennas, these systems require huge complexity to detect the signal. In this paper, we propose a novel detection method for massive MIMO using parallel detection with maximum likelihood detection with QR decomposition and M-algorithm (QRM-MLD to reduce the complexity and latency. The proposed scheme obtains an R matrix after permutation of an H matrix and QR decomposition. The R matrix is also eliminated using a Gauss–Jordan elimination method. By using a modified R matrix, the proposed method can detect the transmitted signal using parallel detection. From the simulation results, the proposed scheme can achieve a reduced complexity and latency with a little degradation of the bit error rate (BER performance compared with the conventional method.

  16. An Efficient Beam Steerable Antenna Array Concept for Airborne Applications

    Directory of Open Access Journals (Sweden)

    H. Aliakbarian

    2014-04-01

    Full Text Available Deployment of a satellite borne, steerable antenna array with higher directivity and gain in Low Earth Orbit makes sense to reduce ground station complexity and cost, while still maintaining a reasonable link budget. The implementation comprises a digitally beam steerable phased array antenna integrated with a complete system, comprising the antenna, hosting platform, ground station, and aircraft based satellite emulator to facilitate convenient aircraft based testing of the antenna array and ground-space communication link. This paper describes the design, development and initial successful interim testing of the various subsystems. A two element prototype used in this increases the signal-to-noise ratio (SNR by 3 dB which is corresponding to more than 10 times better bit error rate (BER.

  17. Fuzzy control of optical PPM CDMA with M-ary orthogonal signaling

    Science.gov (United States)

    Cui, K.; Leeson, M. S.; Hines, E. L.

    2008-06-01

    This paper introduces an incorporated spectral-amplitude coding (SAC) optical code-division multiple-access (OCDMA) scheme. One novel class of optical signature codes based on combinatorial designs is employed with M-ary pulse-position modulation (PPM) signaling to improve the system performance beyond the interference limit. A union upper bound on the bit error rate (BER) is derived and the performance characteristics are then discussed with a variety of system parameters. Furthermore, fuzzy logic (FL) control is proposed to provide tolerance of different degrees of reliability in multirate transmission and to achieve distinct service differentiation for multimedia applications. It is shown that the proposed system can effectively suppress noise effects and offer improved adaptation capabilities for multi-quality network requirements in comparison with systems without optimization.

  18. Fast frequency hopping codes applied to SAC optical CDMA network

    Science.gov (United States)

    Tseng, Shin-Pin

    2015-06-01

    This study designed a fast frequency hopping (FFH) code family suitable for application in spectral-amplitude-coding (SAC) optical code-division multiple-access (CDMA) networks. The FFH code family can effectively suppress the effects of multiuser interference and had its origin in the frequency hopping code family. Additional codes were developed as secure codewords for enhancing the security of the network. In considering the system cost and flexibility, simple optical encoders/decoders using fiber Bragg gratings (FBGs) and a set of optical securers using two arrayed-waveguide grating (AWG) demultiplexers (DeMUXs) were also constructed. Based on a Gaussian approximation, expressions for evaluating the bit error rate (BER) and spectral efficiency (SE) of SAC optical CDMA networks are presented. The results indicated that the proposed SAC optical CDMA network exhibited favorable performance.

  19. Considerations of digital phase modulation for narrowband satellite mobile communication

    Science.gov (United States)

    Grythe, Knut

    1990-01-01

    The Inmarsat-M system for mobile satellite communication is specified as a frequency division multiple access (FDMA) system, applying Offset Quadrature Phase Shift Keying (QPSK) for transmitting 8 kbit/sec in 10 kHz user channel bandwidth. We consider Digital Phase Modulation (DPM) as an alternative modulation format for INMARSAT-M. DPM is similar to Continuous Phase Modulation (CPM) except that DPM has a finite memory in the premodular filter with a continuous varying modulation index. It is shown that DPM with 64 states in the VA obtains a lower bit error rate (BER). Results for a 5 kHz system, with the same 8 kbit/sec transmitted bitstream, is also presented.

  20. On Transform Domain Communication Systems under Spectrum Sensing Mismatch: A Deterministic Analysis.

    Science.gov (United States)

    Jin, Chuanxue; Hu, Su; Huang, Yixuan; Luo, Qu; Huang, Dan; Li, Yi; Gao, Yuan; Cheng, Shaochi

    2017-07-08

    Towards the era of mobile Internet and the Internet of Things (IoT), numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, traditional wireless communication technologies are facing challenges both in terms of the increasing shortage of spectrum resources and massive multiple access. The transform-domain communication system (TDCS) is considered as an alternative multiple access system, where 5G and mobile IoT are mainly focused. However, previous studies about TDCS are under the assumption that the transceiver has the global spectrum information, without the consideration of spectrum sensing mismatch (SSM). In this paper, we present the deterministic analysis of TDCS systems under arbitrary given spectrum sensing scenarios, especially the influence of the SSM pattern to the signal to noise ratio (SNR) performance. Simulation results show that arbitrary SSM pattern can lead to inferior bit error rate (BER) performance.

  1. Dense Wavelength Division (De Multiplexers Based on Fiber Bragg Gratings

    Directory of Open Access Journals (Sweden)

    S. BENAMEUR

    2014-05-01

    Full Text Available This study is to measure the impact of demultiplexers based on Fiber Bragg Grating (FBG filter on performance of DWDM system for optical access network. An optical transmission link has been established in which we have inserted a demultiplexer based on four different FBG filters. The first step will be the characterization of FBG’s filters (i.e. uniform FBG, Gaussian apodized Grating, chirped FBG to explain their behavior in the optical link. The simulations were conducted for different fiber’s lengths, filter bandwidth and different received power to get the best system performance. This helped to assess their impact on the link performance in terms of Bit Error Rate (BER.

  2. Covert Communication in MIMO-OFDM System Using Pseudo Random Location of Fake Subcarriers

    Directory of Open Access Journals (Sweden)

    Rizky Pratama Hudhajanto

    2016-08-01

    Full Text Available Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM is the most used wireless transmission scheme in the world. However, its security is the interesting problem to discuss if we want to use this scheme to transmit a sensitive data, such as in the military and commercial communication systems. In this paper, we propose a new method to increase the security of MIMO-OFDM system using the change of location of fake subcarrier. The fake subcarriers’ location is generated per packet of data using Pseudo Random sequence generator. The simulation results show that the proposed scheme does not decrease the performance of conventional MIMO-OFDM. The attacker or eavesdropper gets worse Bit Error Rate (BER than the legal receiver compared to the conventional MIMO-OFDM system.

  3. DEADS: Depth and Energy Aware Dominating Set Based Algorithm for Cooperative Routing along with Sink Mobility in Underwater WSNs

    Directory of Open Access Journals (Sweden)

    Amara Umar

    2015-06-01

    Full Text Available Performance enhancement of Underwater Wireless Sensor Networks (UWSNs in terms of throughput maximization, energy conservation and Bit Error Rate (BER minimization is a potential research area. However, limited available bandwidth, high propagation delay, highly dynamic network topology, and high error probability leads to performance degradation in these networks. In this regard, many cooperative communication protocols have been developed that either investigate the physical layer or the Medium Access Control (MAC layer, however, the network layer is still unexplored. More specifically, cooperative routing has not yet been jointly considered with sink mobility. Therefore, this paper aims to enhance the network reliability and efficiency via dominating set based cooperative routing and sink mobility. The proposed work is validated via simulations which show relatively improved performance of our proposed work in terms the selected performance metrics.

  4. Cost-effective TCM-based WDM-PON for highly asymmetric traffic conditions.

    Science.gov (United States)

    Lee, Danbi; Kwon, Won-Bae; Chae, Chang-Joon; Park, Chang-Soo

    2015-11-16

    A time compression multiplexing (TCM)-based wavelength division multiplexing passive optical network (WDM-PON) using a reflective semiconductor optical amplifier (RSOA) is proposed, and its feasibility is experimentally demonstrated. In the proposed system, the RSOA pre-amplifies a 10 Gb/s downstream signal and modulates the RSOA output, wavelength-locked to the downstream signal, with a 1.25 Gb/s upstream signal simultaneously. The sensitivity of the downstream signal is improved by about 3 dB through the RSOA. The downstream and upstream signals have power penalties of about 0.1 dB and 1.1 dB, respectively, at bit error rates (BERs) of 10(-9) after 20 km transmission.

  5. Diversity and MIMO Performance Evaluation of Common Phase Center Multi Element Antenna Systems

    Directory of Open Access Journals (Sweden)

    V. Papamichael

    2008-06-01

    Full Text Available The diversity and Multiple Input Multiple Output (MIMO performance provided by common phase center multi element antenna (CPCMEA systems is evaluated using two practical methods which make use of the realized active element antenna patterns. These patterns include both the impact of the mutual coupling and the mismatch power loss at antenna ports. As a case study, two and four printed Inverted F Antenna (IFA systems are evaluated by means of Effective Diversity Gain (EDG and Capacity (C. EDG is measured in terms of the signal-to-noise ratio (SNR enhancement at a specific outage probability and in terms of the SNR reduction for achieving a desired average bit error rate (BER. The concept of receive antenna selection in MIMO systems is also investigated and the simulation results show a 43% improvement in the 1% outage C of a reconfigurable 2x2 MIMO system over a fixed 2x2 one.

  6. Digital Signal Processing for Optical Coherent Communication Systems

    DEFF Research Database (Denmark)

    Zhang, Xu

    spectrum narrowing tolerance 112-Gb/s DP-QPSK optical coherent systems using digital adaptive equalizer. The demonstrated results show that off-line DSP algorithms are able to reduce the bit error rate (BER) penalty induced by signal spectrum narrowing. Third, we also investigate bi...... wavelength division multiplex (U-DWDM) optical coherent systems based on 10-Gbaud QPSK. We report U-DWDM 1.2-Tb/s QPSK coherent system achieving spectral efficiency of 4.0-bit/s/Hz. In the experimental demonstration, digital decision feed back equalizer (DFE) algorithms and a finite impulse response (FIR......In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing...

  7. 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.

  8. Performance Analysis of Blind Beamforming Algorithms in Adaptive Antenna Array in Rayleigh Fading Channel Model

    International Nuclear Information System (INIS)

    Yasin, M; Akhtar, Pervez; Pathan, Amir Hassan

    2013-01-01

    In this paper, we analyze the performance of adaptive blind algorithms – i.e. Kaiser Constant Modulus Algorithm (KCMA), Hamming CMA (HAMCMA) – with CMA in a wireless cellular communication system using digital modulation technique. These blind algorithms are used in digital signal processor of adaptive antenna to make it smart and change weights of the antenna array system dynamically. The simulation results revealed that KCMA and HAMCMA provide minimum mean square error (MSE) with 1.247 dB and 1.077 dB antenna gain enhancement, 75% reduction in bit error rate (BER) respectively over that of CMA. Therefore, KCMA and HAMCMA algorithms give a cost effective solution for a communication system

  9. Novel half-coherent receivers for amplify-and-forward relaying

    KAUST Repository

    Khan, Fahd Ahmed

    2012-06-01

    Consider a system in which the signal is transmitted from the source to the destination via an amplify-and-forward relay. For such a system, we derive in this paper, novel receivers that have complete knowledge of either the source-relay link or the relay-destination link. These receivers are termed as, \\'half-coherent receivers\\' as they have channel-state-information (CSI) of only one of two links. These receivers can be very useful in a system in which only the relay can afford high complexity by having a channel estimation module and the destination is unable to support channel estimation or a system in which only the destination can afford higher complexity and includes the channel estimation module. The analytical bit-error-rate (BER) performances of the proposed receivers are derived for Rician fading. Numerical results show considerable performance gains of the new receivers, especially at low signal-to-noise ratio. © 2012 IEEE.

  10. Mobile User Connectivity in Relay-Assisted Visible Light Communications

    Directory of Open Access Journals (Sweden)

    Petr Pešek

    2018-04-01

    Full Text Available In this paper, we investigate relay-assisted visible light communications (VLC where a mobile user acts as a relay and forwards data from a transmitter to the end mobile user. We analyse the utilization of the amplify-and-forward (AF and decode-and-forward (DF relaying schemes. The focus of the paper is on analysis of the behavior of the mobile user acting as a relay while considering a realistic locations of the receivers and transmitters on a standard mobile phone, more specifically with two photodetectors on both sides of a mobile phone and a transmitting LED array located upright. We also investigate dependency of the bit error rate (BER performance on the azimuth and elevation angles of the mobile relay device within a typical office environment. We provide a new analytical description of BER for AF and DF-based relays in VLC. In addition we compare AF and DF-based systems and show that DF offers a marginal improvement in the coverage area with a BER < 10–3 and a data rate of 100 Mb/s. Numerical results also illustrate that relay-based systems offer a significant improvement in terms of the coverage compared to direct non-line of sight VLC links.

  11. The Rainfall Intensity Effects on 1–13 GHz UWB-Based 5G System for Outdoor Applications

    Directory of Open Access Journals (Sweden)

    Joko Suryana

    2017-01-01

    Full Text Available This paper reports a research contribution on tropical outdoor channel characterization in 1–13 GHz band for 5G systems. This 1–13 GHz ultra-wideband (UWB channel characterization is formulated with rain intensity as the most important variable, from 20 mm/h to 200 mm/h. Tropical rain will cause pulse broadening and distorts the transmitted symbols, so the probability of symbol errors will increase. In this research, the bit error rate (BER performance evaluation is done using both matched filtering or correlator-based receivers. At no rain conditions, BER 10−6 will be attained at signal to noise ratio (SNR 5 dB, but at rainfall intensity 200 mm/h, the BER will fall to 10−2 for matched filter and 5×10-2 for correlator-based receivers. For improving the BER performance, an adaptive nonlinear phase equalizer is proposed which adopts multiple allpass biquad infinite impulse response (IIR filters combined with low-order finite impulse response (FIR filter to mitigate the nonlinearity phase and differential attenuation of magnitude responses due to antenna and tropical outdoor UWB channel effects. Our simulation results show that the proposed equalizer has worked successfully with BER 10−6 on the rain rate that is exceeded for 0.01% of the time (R0.01 rain intensity or 99.99% availability. In addition, at rainfall rate 120 mm/h, the proposed nonlinear phase equalizer can give 9 dB signal improvement.

  12. Männer und Frauen sind nicht gleich. Über Geschlechterstereotype in juristischen Verfahren Men and Women are not Equal. On Gender Stereotypes in Legal Proceedings

    Directory of Open Access Journals (Sweden)

    Claudia Fröhlich

    2004-07-01

    Full Text Available Weibliche und männliche Angeklagte wurden in den NS-Prozessen nach 1945 nicht gleich behandelt. In den Aufsätzen des von Ulrike Weckel und Edgar Wolfrum herausgegebenen Sammelbandes ‚Bestien‘ und ‚Befehlsempfänger‘. Frauen und Männer in NS-Prozessen nach 1945 werden der unmittelbar nach der Kapitulation Deutschlands von den Alliierten initiierte Nürnberger Prozess gegen die Hauptkriegsverbrecher, die Verfahren gegen SS-Aufseherinnen sowie die Hochverratsprozesse in der Weimarer Republik und im Nationalsozialismus analysiert. Daneben ist die Berichterstattung über den Nürnberger Prozess als einem „medialen Großereignis“ ebenso Gegenstand der Untersuchung wie die Fernsehberichterstattung über das in den 1970er Jahren geführte Majdanek-Verfahren gegen SS-Aufseher und -Aufseherinnen. Die Autorinnen fragen, ob und welche Geschlechterstereotype Rechtsprechung und Berichterstattung geprägt haben, welche Funktionen den dabei formulierten Männer- und Frauenbildern im Kontext der Konstituierung der beiden deutschen Gesellschaften nach 1945 zukamen und wie sie kulturgeschichtlich zu verorten sind. Nach der mittlerweile etablierten Täterinnenforschung rückt ein geschlechtergeschichtlicher Ansatz in das Blickfeld der Forschung zu NS-Prozessen und ihrer Wahrnehmung, der frauen- und männergeschichtliche Studien gleichermaßen anregen kann.Accused men and women were not treated equally in the Nazi trials after 1945. In the articles of the volume edited by Ulrike Weckel und Edgar Wolfrum ‘Bestien’ und ‘Befehlsempfänger’. Frauen und Männer in NS-Prozessen nach 1945, the Nuremberg Trials—initiated by the Allies against the main war criminals immediately after the capitulation of Germany, trials against SS concentration camp guards, and trials of high treason during the Weimar Republic and National Socialism are analyzed. A further subject of the study is the reporting of the Nuremberg Trials as a “major media event”, as

  13. Performance analysis of EM-based blind detection for ON-OFF keying modulation over atmospheric optical channels

    Science.gov (United States)

    Dabiri, Mohammad Taghi; Sadough, Seyed Mohammad Sajad

    2018-04-01

    In the free-space optical (FSO) links, atmospheric turbulence lead to scintillation in the received signal. Due to its ease of implementation, intensity modulation with direct detection (IM/DD) based on ON-OFF keying (OOK) is a popular signaling scheme in these systems. Over turbulence channel, to detect OOK symbols in a blind way, i.e., without sending pilot symbols, an expectation-maximization (EM)-based detection method was recently proposed in the literature related to free-space optical (FSO) communication. However, the performance of EM-based detection methods severely depends on the length of the observation interval (Ls). To choose the optimum values of Ls at target bit error rates (BER)s of FSO communications which are commonly lower than 10-9, Monte-Carlo simulations would be very cumbersome and require a very long processing time. To facilitate performance evaluation, in this letter we derive the analytic expressions for BER and outage probability. Numerical results validate the accuracy of our derived analytic expressions. Our results may serve to evaluate the optimum value for Ls without resorting to time-consuming Monte-Carlo simulations.

  14. Compression and Combining Based on Channel Shortening and Rank Reduction Technique for Cooperative Wireless Sensor Networks

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2013-12-18

    This paper investigates and compares the performance of wireless sensor networks where sensors operate on the principles of cooperative communications. We consider a scenario where the source transmits signals to the destination with the help of L sensors. As the destination has the capacity of processing only U out of these L signals, the strongest U signals are selected while the remaining (L?U) signals are suppressed. A preprocessing block similar to channel-shortening is proposed in this contribution. However, this preprocessing block employs a rank-reduction technique instead of channel-shortening. By employing this preprocessing, we are able to decrease the computational complexity of the system without affecting the bit error rate (BER) performance. From our simulations, it can be shown that these schemes outperform the channel-shortening schemes in terms of computational complexity. In addition, the proposed schemes have a superior BER performance as compared to channel-shortening schemes when sensors employ fixed gain amplification. However, for sensors which employ variable gain amplification, a tradeoff exists in terms of BER performance between the channel-shortening and these schemes. These schemes outperform channel-shortening scheme for lower signal-to-noise ratio.

  15. Performance of BICM-T transceivers over Gaussian mixture noise channels

    KAUST Repository

    Malik, Muhammad Talha

    2014-04-01

    Experimental measurements have shown that the noise in many communication channels is non-Gaussian. Bit interleaved coded modulation (BICM) is very popular for spectrally efficient transmission. Recent results have shown that the performance of BICM using convolutional codes in non-fading channels can be significantly improved if the coded bits are not interleaved at all. This particular BICM design is called BICM trivial (BICM-T). In this paper, we analyze the performance of a generalized BICM-T design for communication over Gaussian mixture noise (GMN) channels. The results disclose that for an optimal bit error rate (BER) performance, the use of an interleaver in BICM for GMN channels depends upon the strength of the impulsive noise components in the Gaussian mixture. The results presented for 16-QAM show that the BICM-T can result in gains up to 1.5 dB for a target BER of 10-6 if the impulsive noise in the Gaussian mixture is below a certain threshold level. The simulation results verify the tightness of developed union bound (UB) on BER performance.

  16. An accurate evaluation of the performance of asynchronous DS-CDMA systems with zero-correlation-zone coding in Rayleigh fading

    Science.gov (United States)

    Walker, Ernest; Chen, Xinjia; Cooper, Reginald L.

    2010-04-01

    An arbitrarily accurate approach is used to determine the bit-error rate (BER) performance for generalized asynchronous DS-CDMA systems, in Gaussian noise with Raleigh fading. In this paper, and the sequel, new theoretical work has been contributed which substantially enhances existing performance analysis formulations. Major contributions include: substantial computational complexity reduction, including a priori BER accuracy bounding; an analytical approach that facilitates performance evaluation for systems with arbitrary spectral spreading distributions, with non-uniform transmission delay distributions. Using prior results, augmented by these enhancements, a generalized DS-CDMA system model is constructed and used to evaluated the BER performance, in a variety of scenarios. In this paper, the generalized system modeling was used to evaluate the performance of both Walsh- Hadamard (WH) and Walsh-Hadamard-seeded zero-correlation-zone (WH-ZCZ) coding. The selection of these codes was informed by the observation that WH codes contain N spectral spreading values (0 to N - 1), one for each code sequence; while WH-ZCZ codes contain only two spectral spreading values (N/2 - 1,N/2); where N is the sequence length in chips. Since these codes span the spectral spreading range for DS-CDMA coding, by invoking an induction argument, the generalization of the system model is sufficiently supported. The results in this paper, and the sequel, support the claim that an arbitrary accurate performance analysis for DS-CDMA systems can be evaluated over the full range of binary coding, with minimal computational complexity.

  17. OFDM AF Variable Gain Relay System for the Next Generation Mobile Cellular

    Directory of Open Access Journals (Sweden)

    E. Kocan

    2012-06-01

    Full Text Available In this paper we present analytical performance evaluation of a dual-hop OFDM amplify-andforward (AF variable gain (VG relay system implementing ordered subcarrier mapping (SCM at the relay station (R, considered to be a very interesting solution for the next generation mobile cellular networks. A scenario with no direct communication between the source of information (S and destination terminal (D, with the Rayleigh fading statistics on both hops is assumed. A closed form analytical expression for the bit error rate (BER performance of the considered system with DPSK modulation is derived, while for its ergodic capacity performance, a tight upper bound expression is obtained. The accuracy of the undertaken analytical approach is confirmed through comparison with simulation results. It is shown that significant capacity enhancement can be achieved through SCM implementation at R, for all the signal-to-noise ratio (SNR values on both hops, but especially in the region of small SNRs on hops. BER analysis reveals that in the region of small and medium average SNRs on both hops BER performance may also be improved with SCM at R station.

  18. Low complexity detectors for cooperative wireless sensor networks

    KAUST Repository

    Ahmed, Qasim Zeeshan

    2012-09-01

    This paper investigates and compares the performance of wireless sensor networks (WSN) when sensors operate on the principles of cooperative communications. We consider a scenario where the source transmits signals to the destination with the help of L sensors. As the destination has the capacity of processing only U out of these L signals, U strongest signals are selected while the remaining (L - U) signals are suppressed. A preprocessing block similar to channel-shortening (CS) is proposed in this contribution. However, this preprocessing block employs rank-reduction technique instead of CS. This detector operates on the principles of principal components (PC). From our simulations it can be observed that this detector is capable of achieving a similar bit error rate (BER) performance as the full-rank MMSE detector with significantly lower complexity. It outperforms the CS-based detector in terms of BER performance when using fixed amplification factor. However, for variable gain amplification factor a tradeoff between the diversity gain and the receiver complexity can be observed. From the simulations it can be concluded that the BER performance of the PC-based detector when using variable gain amplification factor are better than that of the CS-based detector for lower signal to noise ratio. © 2012 IEEE.

  19. Impact of Primary User Traffic on Adaptive Transmission for Cognitive Radio with Partial Relay Selection

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive relay system, the secondary user is permitted to transmit data via a relay when licensed frequency bands are detected to be free. Previous studies mainly focus on reducing or limiting the interference of the secondary transmission on the primary users. On the other hand, however, the primary user traffic will also affect the data transmission performance of the secondary users. In this paper, we investigate the impact of the primary user traffic on the bit error rate (BER) of the secondary transmission, when the secondary user adopts adaptive transmission with a relay partially selected. From the numerical results, we can see that the primary user traffic seriously degrades average BER. The worse-link partial selection can perform almost as well as the global selection when the channel conditions of the source-relay links and the relay-destination links differ a lot. In addition, although the relay selection improves the spectral efficiency of the secondary transmission, numerical results show that it only has slight impact on the overall average BER, so that the robustness of the system will not be affected by the relay selection.

  20. Catadioptric lenses in Visible Light Communications

    Science.gov (United States)

    Garcia-Marquez, J.; Valencia, J. C.; Perez, H.; Topsu, S.

    2015-04-01

    Since few years ago, visible light communications (VLC) have experience an accelerated interest from a research point of view. The beginning of this decade has seen many improvements in VLC at an electronic level. High rates of transmission at low bit error ratios (BER) have been reported. A few numbers of start-ups have initiated activities to offer a variety of applications ranging from indoor geo-localization to internet, but in spite of these advancements, some other problems arise. Long-range transmissions mean a high BER which reduce the number of applications. In this sense, new redesigned optical collectors or in some cases, optical reflectors must be considered to ensure a low BER at higher distance transmissions. Here we also expose a preliminary design of a catadioptric and monolithical lens for a LI-FI receiver with two rotationally symmetrical main piecewise surfaces za and zb. These surfaces are represented in a system of cylindrical coordinates with an anterior surface za with a central and refractive sector surrounded by a peripheral reflective sector and a back piecewise surface zb with a central refractive sector and a reflective sector, both characterized as ideal for capturing light within large acceptance angles.