DocumentCode :
1161409
Title :
Performance analysis and design criteria for finite-alphabet source-channel codes
Author :
Hedayat, Ahmadreza ; Nosratinia, Aria
Author_Institution :
Multimedia Commun. Lab., Univ. of Texas, Richardson, TX, USA
Volume :
52
Issue :
11
fYear :
2004
Firstpage :
1872
Lastpage :
1879
Abstract :
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.
Keywords :
channel coding; computational complexity; convolutional codes; entropy codes; iterative decoding; source coding; variable length codes; finite-alphabet source-channel code; iterative source-channel decoding; redundant entropy codes; serial concatenated convolutional codes; signal-to-noise ratio; variable-length codes; Concatenated codes; Convergence; Convolutional codes; Degradation; Entropy; Interconnected systems; Iterative decoding; Performance analysis; Signal analysis; Signal design; 65; Concatenated coding; VLCs; iterative decoding; joint source-channel coding; variable-length codes;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/TCOMM.2004.836562
Filename :
1356198
Link To Document :
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