A Soft-Output Viterbi Equalizer Employing Expanded Memory Length in a Trellis

Takayuki NAGAYASU  Hiroshi KUBO  Keishi MURAKAMI  Tadashi FUJINO  

IEICE TRANSACTIONS on Communications   Vol.E80-B   No.2   pp.381-385
Publication Date: 1997/02/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Radio Communication
soft-output Viterbi equalizer,  MAP algorithm,  Viterbi algorithm,  soft-decision,  intersymbol interference,  

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This paper presents a novel approach to a soft-output equalizer, which makes a symbol-by-symbol soft-decision based on a posteriori probabilities (APP's) criterion in the presence of intersymbol interference. The authors propose a soft-output Viterbi equalizer (SOVE) employing expanded memory length in a trellis of the Viterbi algorithm with small arithmetic complexity. The proposed equalizer gives suboptimum soft-decision closer to that of a equalizer with the maximum a posteriori probabilities (MAP) algorithm than the conventional SOVE.