Saving viterbi decoder states for general rate 1/2, constraint length K, quick look‐in codes
Masato Tajima, Kenzo Kobayashi, Hideo Suzuki · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 1990
Abstract This paper discusses how to reduce the number of states in the main decoder placed in an SST Viterbi decoder for general rate 1/2, constraint length K, and quick look‐in codes. Presented are three different cell configurations for which state elimination is possible if an MAP estimation method is applied for branch metric computation. It is shown that for each of these cell configurations, a considerable portion of decoder states can be eliminated without any accompanying performance degradation. It is clarified also that, by transforming encoder states to syndrome former states (i.e., dual states), these cell configurations can be mapped to those discussed in Schalkwijk's paper.