VITERBI DECODING WITH PATH METRIC UPDATE IMPLEMENTED IN THE ORDER OF BIT-SLICES

摘要

The invention concerns a bit-slice implementation of the ACS operation for a Viterbi decoder suitable for software implementations on digital computers. At first bit-slice is formed as a single word containing the LSBs of the path metrics for all states, a second bit slice is formed with the next most significant bits, and so on until the MSB bit-slice. The adding of the ACS operation is performed in units of bit-slices, starting with the additions involving the LSBs of the path metrics. Moreover, the comparison part of the ACS operation is performed using substractions in units of bit-slices. Thus, the invention enables the path metrics for all states to be updated simultaneously and offers speed improvements over the known prior art techniques. In order to further increase the processing speed, only one bank of path metrics is used.