Jin Wang, Beng Meng, Dr. Lie-liang Yang et al. · ePrints Soton (University of Southampton) · 2007
<p>In this thesis, we apply EXtrinsic Information Transfer (EXIT) charts for analysing iterative decoding and detection schemes. We first consider a two-stage iterative source/channel decoding scheme, which is then extended to a three-stage serially concatenated turbo equalisation scheme. As a result, useful design guidelines are obtained for optimising the system’s performance.</p> <p>More explicitly, in Chapter 2 various source codes such as Huffman codes, Reversible Variable-Length Codes (RVLCs) and Variable-Length Error-Correcting (VLEC) codes are introduced and a novel algorithm is proposed for the construction of efficient RVLCs and VLEC codes. In Chapter 3, various iterative source decoding, channel decoding and channel equalisation schemes are investigated and their convergence behaviour is analysed by using EXIT charts. The effects of different source codes and channel precoders are also considered. In Chapter 4, a three-stage serially concatenated turbo equalisation scheme consisting of an inner channel equaliser, an intermediate channel code and an outer channel code separated by interleavers is proposed. With the aid of the novel concept of EXIT modules, conventional 3D EXIT chart analysis may be simplified to 2D EXIT chart analysis. Interestingly, it is observed that for the three-stage scheme relatively weak convolutional codes having short memories result in lower convergence thresholds than strong codes having long memories. Additionally, it is found that by invoking the outer and the intermediate decoder more frequently the total number of decoder activations is reduced, resulting in a relatively lower decoding complexity. Furthermore, the three-stage turbo equalisation schemes employing non-unity rate intermediate codes or IRregular Convolutional Codes (IRCCs) as the outer constituent codes are investigated. The performance of the resultant schemes is found to become gradually closer to the channel’s capacity at the expense of the increase of decoding complexity.</p>
Cited by 1
Nataša Živić, Christoph Ruland · Advances in intelligent systems and computing · 2018
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A. Knickenberg, B.L. Yeap, J. Hamorsky et al. · Electronics Letters · 1999
A non-iterative joint equaliser and decoder scheme is proposed which outperforms the iterative turbo equaliser by ~3.4 dB at a BER of 10-3 over a five-path Gaussian channel.
Cited by 6
Andres Kwasinski, Vinay Chande · 2022
This chapter focuses on joint source–channel coding techniques that use at the decoders different forms of side information, other than the source information being communicated. It describes statistical information of the source that can improve the error correction capability of the channel decoder. One of the first works to study a priori and a posteriori source information to improve channel decoding was, where the term source-controlled channel decoding was introduced. The Turbo principle was introduced as an iterative decoding technique for concatenated channel codes. The turbo decoder is formed by one-channel decoder for each channel encoder, connected in the same parallel or serial configuration used for encoding. While the derivation of the Joint Source-Channel Decoding algorithm seen so far is based on the calculation of probability values, the implementation of the algorithm is based on the use of log-likelihood values for these probabilities.
Cited by 1
C.R. Nassar · Elsevier eBooks · 2001
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Ruijing Hu, Michel Kieffer, Pierre Duhamel · IEEE Signal Processing Letters · 2012
Channel decoding makes use of redundancy in the coded bits. However, any redundancy in the information bitstream can also improve the decoding process. This paper shows that a careful examination of communication standards (including the headers added by the network layers) exhibits some fields which can be considered as redundant, either based on already received packets, or on the standard. The efficient use of this knowledge in the channel decoding process is denoted as protocol-assisted channel decoding. Assuming perfect synchronization and available channel state information, the proposed method applied on 802.11a PHY and MAC layers provides a substantial link budget improvement without modifying the standard, while the introduction of an additional interleaver provides additional bit error rate improvements.
Cited by 10
VINTU JOSE ALAPPAT · National University of Singapore · 2016
Master's
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Anders Gjendemsjø, Geir E. Øien, Henrik Holm · 2013
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P.D. Alexander, Alex Grant · 2002
We investigate iterative decoding and channel estimation for multiple-access channels. Results are obtained concerning the fixed points of such iterations.
Cited by 23
A. Knickenberg, B.L. Yeap, J. Hamorsky et al. · 2003
A non-iterative turbo equaliser scheme is proposed, which outperforms the iterative turbo equaliser by about 0.7 dB at a BER of 10/sup -3/ over a symbol-spaced two-path channel and by about 3.4 dB at a BER of 10/sup -3/ over a five-path Gaussian channel.
Cited by 13
Vary, Peter, Fingscheidt, Tim · RWTH Publications (RWTH Aachen) · 1998
Cited by 4
2015
(CCOE) is an algorithm which combines source-statistics, bit-reliability informations at the chan-nel output and the redundancy introduced by some channel code to compute the a-posteriori probabil-ities of the possibly transmitted source-encoder in-dices at the receiver. A recursive formula for the computation of the a-posteriori probabilities is de-rived and some special cases are given. The algo-rithm is generalized for the parallel transmission of several quantizer indices which commonly encode each source-signal vector. Simulation results are pre-sented and the performances of several algorithms for source-channel decoding are compared. I.
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Boulos Wadih Khoueiry, M. Reza Soleymani · 2014
In this paper, we present a comparative study of joint channel estimation and decoding of factor graph-based codes over flat fading channels. A new simple channel approximation scheme is proposed. Specifically, when channel state information is not available at the receiver, a simpler approach is to estimate the channel state of a group of received symbols, then use the approximated value of the channel with the received signal to compute the log likelihood ratio. Simulation results show that the proposed scheme exhibits about 0.4 dB loss compared to the optimal solution when perfect channel state information is available at the receiver.
Cited by 6
Seth Lloyd, Vittorio Giovannetti, Lorenzo Maccone · Physical Review Letters · 2011
We study the transmission of classical information in quantum channels. We present a decoding procedure that is very simple but still achieves the channel capacity. It is used to give an alternative straightforward proof that the classical capacity is given by the regularized Holevo bound. This procedure uses only projective measurements and is based on successive "yes-no" tests only.
Cited by 41Open access
Yu Guo · Scholarship at UWindsor (University of Windsor) · 2014
A new adaptive filter is proposed for the turbo decoding on Rayleigh fading channels with noisy channel estimates. The extrinsic information generated from the turbo decoder has some priority information about the transmitted data bits, which can help us better understand the channel characters. By using the soft extrinsic information after each iteration of decoding, we re-estimate the channel and the minimum mean square error (m.m.s.e.) and further update the channel reliability factor and decision variables at each iteration. Simulations show that signal to noise (SNR) gain is improved by up to about 1dB at bit error probability of 3.5&times10-4.
Cited by 0Open access
Michel Kieffer, Pierre Duhamel · HAL (Le Centre pour la Communication Scientifique Directe) · 2014
International audience
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Marc Adrat, Thorsten Clevorn, Laurent Schmalen · RWTH Publications (RWTH Aachen) · 2008
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Luis Salamanca, Juan José Murillo-Fuentes, Fernando Pérez‐Cruz · IEEE Transactions on Signal Processing · 2012
We describe the channel equalization problem, and its prior estimate of the channel state information (CSI), as a joint Bayesian estimation problem to improve each symbol posterior estimates at the input of the channel decoder. Our approach takes into consideration not only the uncertainty due to the noise in the channel, but also the uncertainty in the CSI estimate. However, this solution cannot be computed in linear time, because it depends on all the transmitted symbols. Hence, we also put forward an approximation for each symbol's posterior, using the expectation propagation algorithm, which is optimal from the Kullback-Leibler divergence viewpoint and yields an equalization with a complexity identical to the BCJR algorithm. We also use a graphical model representation of the full posterior, in which the proposed approximation can be readily understood. The proposed posterior estimates are more accurate than those computed using the ML estimate for the CSI. In order to illustrate this point, we measure the error rate at the output of a low-density parity-check decoder, which needs the exact posterior for each symbol to detect the incoming word and it is sensitive to a mismatch in those posterior estimates. For example, for QPSK modulation and a channel with three taps, we can expect gains over 0.5 dB with same computational complexity as the ML receiver.
Cited by 9Open access
Tariq Haddad, Abbas Yongaçoğlu · 2003
The design criterion of a joint source/channel soft decision decoder is developed with both binary convolutional codes and nonbinary dual-k codes. The performance of the modified decoder is evaluated and compared to the performance of the decoder proposed by Sayood et al. (1994) by Monte Carlo simulations. As expected, the soft decision system outperforms the hard decision system simulated by Sayood (1994). In the context of decoding 2 and 3-bit DPCM compressed images, we show the advantage of using the nonbinary dual-k code, which matches the alphabets of the source encoder output, over binary convolutional codes. Furthermore, simulation results verify that a coding gain is achieved by exploiting higher residual redundancy levels at the source encoder output.
Cited by 1
Garik Markarian, Bahram Honary · Lancaster EPrints (Lancaster University) · 1995
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