Silicon Laboratories Inc.
Viterbi equalizer with soft decisions

Abstract:

A Viterbi Equalizer having a limited number of stages is disclosed. In some embodiments, the Viterbi Equalizer may have only four stages. The Viterbi Equalizer produces soft decisions, which comprise a final decision and reliability information related to that final decision. The Viterbi Equalizer is able to provide reliability information even if all paths do not converge on the final decision at the last stage. The reliability information is calculated based on if and when the paths in the trellis converge on a final decision. This reliability information can be used downstream, such as by another Viterbi Algorithm block to perform forward error correction. The use of soft decision provides gains of up to several dB in performance. Additionally, the Viterbi Equalizer is low cost and readily implemented in hardware or software.