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Title The max-log list algorithm (MLLA) - A list-sequence decoding algorithm that provides soft-symbol output
Author/s Carl Fredrik Leanderson, CEW Sundberg
Department/s Faculty of Engineering, LTH at Lund University
Full-text Full text is not available in this archive
Alternative location (URL) http://dx.doi.org/10.1109/TCOM... Restricted Access (Alternative Location)
Publication/Series IEEE TRANSACTIONS ON COMMUNICATIONS
Publishing year 2005
Volume 53
Issue 3
Pages 433 - 444
Document type Journal article
Status published
Quality controlled yes
Language English
Publisher IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Abstract English We present a soft decoding algorithm for convolutional codes that simultaneously yields soft-sequence output, i.e., list sequence (LS) decoding, and soft-symbol output. The max-log list algorithm (MLLA) introduced in this paper provides near- optimum soft-symbol output equal to that of the max-log maximum a posteriori (MAP) probability algorithm. Simultaneously, the algorithm produces an ordered list containing LS-MAP estimates. The MLLA exists in an optimum and a suboptimum version that are different in that the optimum version produces optimum LS-MAP decoding for arbitrary list lengths, while the suboptimum low-complexity version only provides the MAP, the second-order MAP, and the third-order MAP sequence estimates. For lists with more than three elements, MAP decoding is not guaranteed, but the LS decoding is close to the optimal. It is demonstrated that the suboptimum/optimum MLLA can be used to obtain the combination of soft-symbol and soft-sequence outputs at lower complexity than a previously published algorithm. Furthermore, the suboptimum MLLA is well suited for operation in an iterative list (turbo) decoder, since it is obtained by only minor modifications of the well-known Max-Log-MAP algorithm frequently used for decoding of the component codes of turbo codes. Another potential area of application for the suboptimum/optimum MLLA is joint source-channel LS decoding. Estimates of complexity and memory use, as well as performance evaluations of the suboptimum/optimum MLLA, are provided in this paper.
Subject Technology and Engineering
Keywords combined source-channel decoding, list decoding, convolutional codes, soft symbol, turbo decoding
ISBN/ISSN/Other ISSN: 0090-6778

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