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Performance analysis and design criteria for finite-alphabet source-channel codes

IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第11期52卷 1872-1879页

作者： Hedayat, A Nosratinia, A Univ Texas Multimedia Commun Lab Richardson TX 75083 USA

Efficient compression of finite-alphabet sources requires variable-length codes. (VLCs). However, in the presence of noisy channels, error propagation in the decoding of VLCs severely degrades performance. To address this problem, redundant entropy codes and iterative source-channel decoding have been suggested, but to date, neither performance bounds nor design criteria for the composite system have been available. We calculate performance bounds for the source-channel system by generalizing techniques originally developed for serial concatenated convolutional codes. Using this analysis, we demonstrate the role of a recursive structure for the inner code and the distance properties of the outer code. We use density evolution to study the convergence of our decoders. Finally, we pose the question: Under a fixed rate and complexity constraint, when should we use source-channel decoding (as opposed to separable decoding)? We offer answers in several specific cases. For our analysis and design rules, we use union bounds that are technically valid only above the cutoff rate, but interestingly, the codes designed with union-bound criteria perform well even in low signal-to-noise ratio regions, as shown by our simulations as well as previous works on concatenated codes.

关键词： concatenated coding iterative decoding joint source-channel coding variable-length codes (VLCs)

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concatenated decoding with a reduced-search BCJR algorithm

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1998年第2期16卷 186-195页

作者： Franz, V Anderson, JB Siemens AG D-8000 Munich Germany Rensselaer Polytech Inst Dept Elect Comp & Syst Engn Troy NY 12180 USA

We apply two reduced-computation variants of the BCJR algorithm to the decoding of serial and parallel cancatenated convolutional codes, One computes its recursions at only M states per trellis stage;one computes only at states with values above a threshold, The threshold scheme is much more efficient, and it greatly reduces the computation of the BCJR algorithm, By computing only when the channel demands it, the threshold scheme reduces the turbo decoder computation to one-four nodes per trellis stage after the second iteration.

关键词： complexity reduction concatenated coding decoders error correction

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Unsourced Random Access With Coded Compressed Sensing: Integrating AMP and Belief Propagation

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IEEE TRANSACTIONS ON INFORMATION THEORY 2022年第4期68卷 2384-2409页

作者： Amalladinne, Vamsi K. Pradhan, Asit Kumar Rush, Cynthia Chamberland, Jean-Francois Narayanan, Krishna R. Qualcomm Technol Inc Qualcomm Res San Diego CA 92121 USA Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA Columbia Univ Dept Stat New York NY 10027 USA Texas A&M Univ Dept Elect & Comp Engn College Stn TX 77843 USA

Sparse regression codes with approximate message passing (AMP) decoding have gained much attention in recent times. The concepts underlying this coding scheme extend to unsourced random access with coded compressed sensing (CCS), as first demonstrated by Fengler, Jung, and Caire. Specifically, their approach employs a concatenated coding framework with an inner AMP decoder followed by an outer tree decoder. In their original implementation, these two components work independently of each other, with the tree decoder acting on the static output of the AMP decoder. This article introduces a novel framework where the inner AMP decoder and the outer decoder operate in tandem, dynamically passing information back and forth to take full advantage of the underlying CCS structure. This scheme necessitates the redesign of the outer code as to enable belief propagation in a computationally tractable manner. The enhanced architecture exhibits significant performance benefits over a range of system parameters. The error performance of the proposed scheme can be accurately predicted through a set of equations known as state evolution of AMP. These findings are supported both analytically and through numerical methods.

关键词： Decoding Encoding Parity check codes Compressed sensing Convergence Payloads Forward error correction Unsourced random access sparse regression codes approximate message passing belief propagation coded compressed sensing concatenated coding

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Iterative estimation and decoding for FH-SS with slow Rayleigh fading

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IEEE TRANSACTIONS ON COMMUNICATIONS 2000年第12期48卷 2014-2023页

作者： Kang, JH Stark, WE Univ Michigan Dept Elect Engn & Comp Sci Ann Arbor MI 48109 USA

In this paper, the performance of turbo codes is investigated in a frequency-hopped spread spectrum (FH-SS) system with full-band thermal noise and Rayleigh fading. For cases where the data rate exceeds the hopping rate (i.e., there exists multiple bits per hop) and fading side information (SI) does not exist, our approach is to iteratively estimate the fading levels. Simulation is performed for coherent and noncoherent reception, variable number of bits per hop, and cases where fading Si is available or unavailable to the decoder. It is shown that iterative channel estimation performed in conjunction with iterative decoding can improve the overall decoding performance. Finally, the performance of an FH-SS system using standard fading assumptions is compared to the performance of a measured fading channel. Due to flaws in assumptions, the measured fading channel yields several decibels of performance loss relative to the ideal fading channel.

关键词： concatenated coding fading channels frequency-hop communication spread-spectrum communication turbo codes

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Iterative diversity detection for correlated continuous-time Rayleigh fading channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2003年第2期51卷 240-246页

作者： Hansson, AÅ Aulin, TM Chalmers Univ Technol Dept Comp Engn SE-41296 Gothenburg Sweden

An antenna array is proposed as a means of achieving a. space-diversity effect that partly overcomes the severity of continuous-time Rayleigh fading channels. The investigated channel is assumed to be frequency-nonselective with correlated diversity links, where the correlation is related to the array geometry and the spatial and Doppler dispersions. Further, the error performance is improved. by bit interleaving and channel coding, where the encoders/channel is viewed as a serially concatenated system: a convolutional code constitutes the outer code, whereas a differential encoder and the fading channel (having truncated memory) form a joint inner code. In order to obtain a practical detector structure it is desirable to perform iterative decoding by applying some a posteriori probability (APP) algorithms. For this purpose, we propose a novel generalization of the well-known Bahl-Cocke-Jelinek-Raviv algorithm that calculates the APPs over channels having memory. Numerical results indicate that iterative decoding becomes more powerful when the exploited channel memory depth is extended. Also, the error performance is significantly improved by introducing multiple antennas. The interleaver gain is, however, seen to be quite moderate, in contrast to additive white Gaussian noise channels.

关键词： antenna arrays concatenated coding fading channels iterative methods minimum-shift keying

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Fast tree-Trellis list Viterbi decoding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2006年第3期54卷 453-461页

作者： Röder, M Hamzaoui, R Univ Konstanz Dept Comp & Informat Sci D-78457 Constance Germany

A list Viterbi algorithm (LVA) finds the n most likely paths in a trellis diagram of a convolutional code. One of the most efficient LVAs is the tree-trellis algorithm of Soong and Huang. We propose a new implementation of this algorithm. Instead of storing the candidate paths in a single list sorted according to the metrics of the paths, we show that it is computationally more efficient to use several unsorted lists, where all paths of the same list have the same metric. For an arbitrary integer bit metric, both the time and space complexity of our implementation are linear in n. Experimental results for a binary symmetric channel and an additive white Gaussian noise channel show that our implementation is much faster than all previous LVAs.

关键词： algorithms concatenated coding convolutional codes Viterbi decoding

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Turbo-codes: the ultimate error control codes?

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 2001年第4期13卷 155-165页

作者： Burr, A Univ York Dept Elect York YO10 5DD N Yorkshire England

Turbo-codes have attracted a great deal of interest since their discovery in 1993. This paper reviews the reasons for this, in particular their attainment of the ultimate limits of the capacity of a communication channel. The paper describes the two fundamental concepts on which they are based: concatenated coding and iterative decoding. This latter is the real 'turbo-principle', which is the real secret of their remarkable performance. The paper also reviews the direction of research in this area since 1993, and shows that, far from bringing coding research to an end, turbo-codes have led to a renaissance. In particular, other applications of the 'turbo-principle' have emerged, and these are discussed, along with the practical applications of turbo-codes that have appeared, from mobile radio to deep-space exploration.

关键词： Mobile radio systems space communication links turbo codes concatenated codes error correction codes mobile radio channel coding deep-space exploration Codes turbo-codes iterative decoding concatenated coding communication channel channel capacity Space communication systems capacity error control codes

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Low-Complexity Rate- and Channel-Configurable concatenated Codes

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2021年第7期39卷 1976-1983页

作者： Barakatain, Masoud Kschischang, Frank R. Univ Toronto Edward S Rogers Sr Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

A low-complexity rate- and channel-configurable forward error-correction (FEC) scheme is proposed, consisting of an inner low-density parity-check code concatenated with an outer zipper code. A tool is developed to optimize a multi-level code architecture so that it can operate at multiple transmission rates, channel qualities, and modulation orders. The optimization criterion is selected to maintain a low estimated data-flow in its decoding operation. A hardware-friendly quasi-cyclic structure is considered for the inner code and the performance and complexity is reported for various designed FEC configurations. Compared to existing FEC schemes, the proposed designs deliver a similar performance with up to 63% reduction in decoding complexity or provide up to 0.6 dB coding gain at a similar decoding complexity.

关键词： Channel-adaptivity concatenated coding low-complexity codes multilevel coding quasi-cyclic low-density parity-check codes rate-adaptivity zipper codes

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Effects of Multipath on OFDM Systems for Indoor Broadband Power-Line Communication Networks

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IEEE TRANSACTIONS ON POWER DELIVERY 2009年第3期24卷 1190-1197页

作者： Anatory, Justinian Theethayi, Nelson Thottappillil, Rajeev Univ Dodoma Coll Informat & Virtual Educ Sch Virtual Educ Dodoma Tanzania Uppsala Univ Div Elect S-75121 Uppsala Sweden Royal Inst Technol Stockholm Sweden

Power-line networks are an excellent infrastructure for broadband data transmission. However, various multipaths within a broadband power-line communication (BPLC) system exist due to stochastic changes in the network load impedances, branches, etc. This further affects network performance. This paper attempts to investigate the performance of indoor channels of a BPLC system that uses orthogonal frequency-division multiplexing (OFDM) techniques. It is observed that when a branch is added in the link between the sending and receiving end of an indoor channel, an average of 4-dB power loss is found. Additionally, when the terminal impedances of the branch change from the line characteristic impedance to impedance of lower values, the power loss (signal-to-noise ratio) is about 0.67 dB/Omega. On the contrary, for every increase in the terminal impedances by 100 Omega, above the line characteristic impedance, the power loss is 0.1. dB/Omega. When the line terminal impedances are close to short or open circuits, OFDM techniques show degraded performance. This situation is also observed when the number of branches increases. In this paper, it is shown that to overcome such performance degradation, the concatenated Reed-Solomon codes/interleaved Viterbi methods can be used. The observations presented in the paper could be useful for an efficient design of a BPLC system that uses OFDM techniques.

关键词： Branched network broadband power-line communication (BPLC) communication channel model concatenated coding convolutional codes impulsive noise interleaving orthogonal frequency-division multiplexing (OFDM) Reed-Solomon codes

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Space-time codes and concatenated channel codes for wireless communications

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PROCEEDINGS OF THE IEEE 2002年第2期90卷 187-219页

作者： Liew, TH Hanzo, L Univ Southampton Dept Elect & Comp Sci Southampton SO17 1BJ Hants England

Following a brief historical perspective on channel coding, an introduction to space-time block codes is given. The various space-time codes considered are then concatenated with a range of channel codecs, such as convolutional and block-based turbo codes as well as conventional and turbo trellis codes. The associated estimated complexity issues and memory requirements are also considered. These discussions are followed by a performance study of various space-time and channel-coded transceivers. Our aim is first to identify, a space-time code/channel code combination constituting a good engineering tradeoff in terms of its effective throughput, bit-error-rate performance, and estimated complexity. Specifically, the issue of bit-to-symbol mapping is addressed in the context of convolutional codes (CCs) and convolutional coding as well as Bose-Chaudhuri-Hocquenghem coding-based turbo codes in conjunction with an attractive unity-rate space-time code and multilevel modulation is detailed. It is concluded that over the nondispersive or narrow-band fading channels, the best performance versus complexity tradeoff is constituted by Alamouti's twin-antenna block space-time code concatenated with turbo convolutional codes. Further comparisons with space-time trellis codes result in similar conclusions.

关键词： channel coding concatenated coding FEC history of channel coding space-time coding STBC STTC

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