A New Viterbi Algorithm with Adaptive Path Reduction Method

Takaya YAMAZATO  Iwao SASASE  Shinsaku MORI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E76-A   No.9   pp.1422-1429
Publication Date: 1993/09/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Information Theory and Its Applications)
Viterbi algorithm,  reduced computation method,  adaptive decoding system,  

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A new Viterbi algorithm with adaptive path reduction method is presented. The proposed system consists of the pre-decoder and reduced path Virerbi decoder. The predecoder separates the mixed channel noise from the received sequence. The number of errors in the pre-decoded error sequence is counted and the path reduction is implemented by the number of errors in pre-decoded error sequence. The path reduction is implemented as a function of channel condition because the errors in the pre-decoded error sequence can be considered as the channel error sequence. Due to the reduction of the path, the number of ACS (add compare select) operations can be reduced, which occupies the dominant part in Viterbi decoding. The ACS reduction ratio for the proposed system achieves up to 30% for the case of (2, 1, 2) Ungerboeck code without degradation of the error performance.