High-speed VLSI architectures for soft-output Viterbi decoding

During the last few years decoding algorithms that make not only the use of soft quantized inputs but also deliver soft decision outputs have attracted considerable attention because additional coding gains are obtainable in concatenated systems. A prominent member of this class of algorithms is the soft-output viterbi algorithm. In this paper two architectures for high speed VLSI implementations of the soft-output viterbi-algorithm are proposed and area estimates are given for both architectures. The well known trade-off between computational complexity and storage requirements is played to obtain new VLSI architectures with increased implementation efficiency. Area savings in excess of 40% in comparison to straightforward solutions are reported. >