Patent Document ID: 5537444
Application ID: 08004360
Patent Status: 1

Claim One:
1. A method of processing a sequence of signals, said method comprising the steps of: receiving said signals over a communications channel corrupted by noise, determining a set of L best candidate sequences of signals, wherein each candidate sequence l, 1.ltoreq.l.ltoreq.L, in said set of best candidate sequences represents a sequence of length N, wherein candidate sequence l, 1.ltoreq.l.ltoreq.L, in said set of L best candidate sequences corresponds to a path through a trellis structure having N stages and a plurality of states at each stage, wherein the (l+1) th best candidate sequence is derived from knowledge of the first l best candidate sequences, wherein the l=1 best path through said trellis is known, wherein each path entering each state at each stage has a cumulative metric associated with it, wherein each path entering each state at each stage has a metric increment associated with a transition to another state at a next stage, wherein the state at each stage for each path is known, wherein l' is the number of the path with which the (l+1).sup.th best path re-merges, wherein the stage where the (l+1).sup.th best path re-merges with path l' is a re-merging point, and wherein initially the re-merging point is set equal to the N.sup.th stage of said trellis and wherein l=l'=1, and further comprising the steps of: a. calculating and storing along the l.sup.th best path a plurality of absolute differences, said absolute differences representing at each stage the magnitude of the difference of the cumulative metrics of the paths merging at said stage; b. excluding all re-merging points; c. finding the minimum absolute difference along the l.sup.th best path and storing the position of said minimum absolute difference; d. computing and storing the cumulative metric at the last state of the next best candidate to path l which goes through said re-merging point; e. repeating steps (b) through (d) if candidate l exists on the list of proposed candidates for the (l+1).sup.th best path; f. repeating steps (b) through (d) for path l' if l.gtoreq.2; g. selecting as the (l+1).sup.th best candidate the one of l candidate paths with the best cumulative metric at the final state; storing as l' the path with which the (l+1).sup.th best path re-merges and storing the re-merging point; h. incrementing l by one; i. repeating steps (a)-(h) until l=L.