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Markov model for block errors on fading channels

Markov model for block errors on fading channels

Proceedings of the 1996 7th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC'96. Part 3 (of 3)

作者： Zorzi, Michele Rao, Ramesh R. Milstein, Laurence B. Univ of California La Jolla United States

In this paper, we investigate the behavior of block errors which arise in data transmission on fading channels. Our approach is more detailed than previous studies, in that it takes into account the specific coding/modulation scheme and it tracks the fading process symbol by symbol. It is shown that a Markov approximation for the block error process (possibly degenerating into an iid process for sufficiently fast fading) is a very good model for a broad range of parameters. Also, it is observed that the relationship between the marginal error rate and the transition probability is largely insensitive to parameters such as block length, degree of forward error correction and modulation format, and only depends on an appropriately normalized version of the Doppler frequency. This observation leads to a unified approach for the channel modeling which simplifies the performance analysis of upper-layer protocols.

关键词： coding errors

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Exploratory study of common coding faults in C programs

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Journal of Software Maintenance 1996年第4期8卷 241-256页

作者： Duncan, Ishbel Robson, Dave Univ of Durham Durham United Kingdom

Large scale code testing can be mad viable by determining and searching for the most probable faults in the system under examination. The results of an exploratory survey carried out to determine the common error factors for code written in C indicates that the program task and the programmer experience are important considerations. Using this information, testing can be directed efficiently towards the removal of prevalent coding faults. The results of the survey can also be useful in determining features of C which are likely to become the subject of corrective maintenance.

关键词： coding errors

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Decimation of encoding errors in an optimum SNS folding ADC

Decimation of encoding errors in an optimum SNS folding ADC

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1995 IEEE International Symposium on Circuits and Systems (ISCAS-1995)

作者： PACE, PE SCHAFER, JL USN POSTGRAD SCHDEPT ELECT & COMP ENGNMONTEREYCA 93943

ISBN: (纸本)0780325702

The symmetrical number system (SNS) can be used as an efficient preprocessing technique to reduce the number of comparators in a folding ADC. This paper examines the issue of encoding errors that result when the separate channels m_i are brought back together to derive the input analog voltage. As an example, a unipolar 7-bit SNS ADC using pairwise relatively prime (PRP) moduli m_i= 4, m₂=5 and m₃=7 is evaluated numerically. Steady state transfer functions are shown which detail encoding errors that occur when the folded input samples lie at one of the code transition points. To discard the encoding errors that occur, a decimation band is constructed at each transition point. The effectiveness of the decimation band in eliminating the encoding errors is also quantified.

关键词： coding errors

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ON DIFFERENTIALLY ENCODED STAR 16QAM WITH DIFFERENTIAL DETECTION AND DIVERSITY

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1995年第3期44卷 586-593页

作者： SVENSSON, NAB Department of Information Theory Chalmers University of Technology Gothenburg Sweden

Star 16QAM is a modulation method that transmits 4 bits per symbol and has the advantage that it may be differentially encoded and detected, It is very robust to fast multiplicative Rayleigh fading and is suitable for mobile telephone systems and personal communication networks. The main contribution of this paper is the derivation and bit error probability simulation of the maximum likelihood differential detector using phase differences and amplitude ratios from L diversity branches for bit decisions, As a comparison, much simpler previously known post detection combining techniques are generalized for star 16QAM and optimized. The bit error probability is simulated for both diversity detectors on a multiplicative Rayleigh fading channel with additive white Gaussian noise, It is found that the bit error probability of the ML detector may also be obtained by the simple combining detector, This is also true for the error floor due to maximum Doppler frequency. The diversity gain is almost 8 dB, measured in signal to noise ratio per diversity branch, at a bit error probability of 1 percent, The diversity detector can sustain an almost 3 times larger Doppler frequency again at a bit error probability of 1 percent. We also show that star 16QAM offers, at most, 3 subchannels with different bit error probabilities.

关键词： Doppler effect Gaussian channels Rayleigh channels coding errors diversity reception encoding error statistics fading land mobile radio maximum likelihood detection personal communication networks quadrature amplitude modulation radiotelephony radiowave Raleigh fading channels Personal communication networks 16-QAM wireless phone Doppler effect Quadrature amplitude modulation diversity reception fading color bit error probability coding land mobile radio maximum likelihood detection radio waves coding errors Gaussian channels

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On the influence of erasure correction on the probability of undetected error of Reed-Solomon codes

On the influence of erasure correction on the probability of...

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Proceedings of the 18th Convention of Electrical and Electronics Engineers in Israel

作者： Arieli, Moshe Motorola Communications Israel Tel-Aviv Israel

This paper analyzes several aspects of erasure correction in the decoding of Reed-Solomon (RS) codes over the q-ary Erasure Channel. It is shown, that by limiting the maximum number of erasures the decoder is allowed to correct, a significant improvement in the probability of undetected error is obtained, at relatively high channel erasure and low channel transition probabilities. Of particular interest is the errata pattern with the maximum number of erasures the RS code can correct and at least one error, which always causes an undetected error in an incomplete decoder. This 'limited erasures' approach is compared with the 'readable erasures' method [1], [2]. This approach is also analyzed for concatenated codes using an RS code as the outer code.

关键词： coding errors

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Multistage coding for data storage systems

Multistage coding for data storage systems

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Proceedings of the 1995 IEEE Singapore International Conference on Networks/International Conference on Information Engineering

作者： El-Soudani, Magdi S. Qatar Univ Doha Qatar

Typical coding schemes for magnetic or optical recording usually consist of two coding stages, error correcting coding (ECC) followed by line or modulation coding. Two methods are presented to design a line code with error correcting capability. Both methods modify the linear error-correcting codes so that they satisfy the runlength constraints of runlength-limited (RLL) sequences. Through these methods we construct combined ECC/RLL codes with different runlengths. The first method utilizes linear combination of ECC codewords with a modification vector. The second method uses two-dimensional code to design the required ECC/RLL code. Both methods are basically dependent on binary operations and minor changes to the ECC coding/decoding circuitry are required. Asymptotic upper bound on the maximum runlength for both methods is found and the performance of the proposed ECC/RLL codes with conventional multistage cascaded schemes of ECC and RLL is also studied.

关键词： coding errors

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CPFSK dual-mode error correction decoding technique over the burst-error channel

CPFSK dual-mode error correction decoding technique over the...

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Proceedings of the 1995 IEEE Singapore International Conference on Networks/International Conference on Information Engineering

作者： Chung, Jong-Moon Park, Sung-Kyung Kang, Chang Eon Cheong, Ho-Young Yonsei Univ Seoul Korea Republic of

This paper presents an error correcting adaptive decoding dual-mode algorithm as it is adapted to the Continuous Phase Frequency Shift Keying (CPFSK) modulation. The dual-mode error correcting algorithm consists of two modes which utilizes the maximum likelihood decoding technique and the burst-error detection scheme. The first mode is the random error correcting mode, which is the Viterbi decoder, and the second mode is the burst-error correcting mode that retrieves the information bits from the (L+m) delayed signal values of the received signals. The dual-mode adaptive decoder nominally operates as a Viterbi decoder and switches to time diversity error recovery, the burst-error correcting mode, whenever the decoder detects an incorrigible error pattern. The experimental results from the computer simulation demonstrate the performance of the algorithm and verify the theoretical results.

关键词： coding errors

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ERROR RATE ANALYSIS OF MDPSK CPSK WITH DIVERSITY RECEPTION UNDER VERY SLOW RAYLEIGH FADING AND COCHANNEL INTERFERENCE

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1994年第2期43卷 252-263页

作者： ADACHI, F SAWAHASHI, M Research and Development Department NTT Mobile Communications Network Inc. Kanagawa Japan

The distribution of the phase noise due to additive white Gaussian noise (AWGN) and cochannel interference is analyzed for differential phase detection (DPD) and coherent phase detection (CPD) in a very slow nonfrequency selective Rayleigh fading environment. The effects of modulation timing offset between the desired signal and the CCI and of the overall channel filter response are considered. Simple closed-form expressions are derived for ideal selection diversity reception. The derived phase noise distributions are used for evaluating the bit error rate (BER) performance of 2-16DPSK/CPSK assuming square-root raised cosine Nyquist transmit/receive filters. It is found that the BER performance of CPSK is less sensitive to CCI modulation timing offset than DPSK, and that increasing the filter rolloff factor can improve the BER performance due to CCI. Finally, the accuracy of the BER approximation that uses the symbol error rate is discussed.

关键词： coding errors demodulation diversity reception error analysis fading mobile radio systems phase shift keying radiofrequency interference random noise white noise AWGN BER performance CPSK DPSK MDPSK/CPSK additive white Gaussian noise bit error rate chann

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AN EFFICIENT ADAPTIVE CIRCULAR VITERBI ALGORITHM FOR DEcoding GENERALIZED TAILBITING CONVOLUTIONAL-CODES

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 1994年第1期43卷 57-68页

作者： COX, RV SUNDBERG, CEW Information Principles Research Laboratory AT and T Bell Laboratories Inc. Murray Hill NJ USA

Viterbi decoding algorithms for convolutional codes are being considered for a number of applications in cellular mobile radio systems. There are three classes of Viterbi decoders depending on the nature of the formatting of the data: continuous decoding with a finite path memory, blockwise decoding with a terminating tail (known to the decoder), and blockwise decoding without a known tail. The latter class is also known as decoding of tailbiting convolutional codes. In this case, a coded message begins and ends in the same state which is unknown to the receiver. In this paper, we present a class of Viterbi algorithms for tailbiting convolutional codes. These algorithms are used in blockwise transmission to save the overhead of a known tail. We call the new algorithm the circular Viterbi algorithm (CVA). The basic ideas are: 1) continue conventional seamless continuous Viterbi decoding beyond the block boundary by recording and repeating the received block of (soft) symbols;(2) start the decoding process in all states;3) end the decoding process either adaptively or with a fixed length. Three robust adaptive stopping rules are constructed and evaluated. Simulation results and comparison to previously known algorithms as well as the optimum algorithm are presented. The amount of computation required for previously reported iterative algorithms tends to increase dramatically as the channel bit error rate (BER) increases. In one reported instance, computation increased by over 900% while decoded BER increased from 8 x 10(-6) to 8 x 10(-3). For the same example, the CVA increase in computation was 11.4% and the worst case decoded BER was 4 x 10(-3). We conclude that for noisy channels the CVA decodes in a much shorter time with better performance than previously published iterative algorithms.

关键词： cellular radio coding errors convolutional codes decoding maximum likelihood estimation BER Viterbi decoding algorithms adaptive circular Viterbi algorithm adaptive stopping rules block boundary blockwise decoding blockwise transmission cellular mobile r

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ADAPTIVE RATE ERROR CONTROL FOR THE LAND-MOBILE SATELLITE CHANNEL

ADAPTIVE RATE ERROR CONTROL FOR THE LAND-MOBILE SATELLITE CH...

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1994 IEEE International Conference on Communications (SUPERCOMM/ICC 94): Serving Humanity Through Communications

作者： RICE, M BRIGHAM YOUNG UNIV DEPT ELECT & COMP ENGNPROVOUT 84602

ISBN: (纸本)0780318250

An adaptive rate error control system is presented for communication over a land mobile satellite channel described by a finite state Markov chain. In channel states where the fading is moderate, the code rate is high thus providing increased throughput. In channel states where the fading is more severe, a low rate code is used to provide the necessary error protection. Retransmission requests used by hybrid-ARQ error control are incorporated into the Viterbi decoder following a modification proposed by Yamamoto and Itoh. The decision to change code rates is made by a sequential statistical test which monitors the frequency of retransmissions. The essentials are presented in an example which illustrates the significant performance improvements realized by the adaptive system.

关键词： coding errors

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