DSD (Double Soft Decision) Concatenated Forward Error Correction Scheme

Shunji HONDA  Shuji KUBOTA  Masahiro MORIKURA  Shuzo KATO  

IEICE TRANSACTIONS on Communications   Vol.E75-B   No.8   pp.747-754
Publication Date: 1992/08/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on the 4th Japan-Korea Joint Conference on Communications, Networks, Switching Systems and Satellite Communications (4th JC-CNSS))
concatenated codes,  soft decision,  Viterbi decoding,  

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The DSD (Double Soft Decision) concatenated forward error correction scheme is proposed to realize a higher-coding-gain forward error correction system with simple hardware. The novel scheme soft decision decodes inner codes as well as outer codes. In this scheme, likelihood information from an inner Viterbi decoder is used for the decoding of outer codes. Path memory circuit status 1,0 ratio is newly proposed as a measure of likelihood information and it is shown that this method is the most reliable even though it has the simplest hardware among the alternative likelihood information extracting methods. Computer simulation clarifies that the proposed DSD scheme improves Pe performance to one-third that of the conventional hard decision outer decoding.