Patent ID: 6289060
Filing Date: 2001-09-11
Classification: H04L

Abstract:
A generalized Viterbi search method for maximum likelihood sequence estimation (MLSE) to demodulate a sequence of symbols received, the method comprising the steps of:receiving the sequence of symbols;computing a metric corresponding to the sequence of symbols, the metric selected from one of:(a) a recursive metric having a structurem(a.sub.k)=m(a.sub.k-1)+m( a.sub.k-N, . . . , a.sub.k-1, a.sub.k),wherein m(a.sub.k-1) and m(a.sub.k) are the cumulative metrics for symbols up to a.sub.k-1 and a.sub.k, respectively, and m(a.sub.k-N, . . . , a.sub.k-1, a.sub.k) is the incremental metric, a function of (N+1) symbols {a.sub.k-N, . . . , a.sub.k-1, a.sub.k }, and(b) a non-recursive metric m(a.sub.k) that is an arbitrary function of a set of L submetrics {z.sub.1 (a.sub.k), z.sub.2 (a.sub.k), . . . , z.sub.L (a.sub.k)}m(a.sub.k)=m[z.sub.1 (a.sub.k), z.sub.2 (a.sub.k), . . . , z.sub.L (a.sub.k)],wherein the set of L submetrics have a generalized recursive structurez.sub.l (a.sub.k)=z.sub.l (a.sub.k-1)+z.sub.l (a.sub.k), l=1, 2, . . . , L;andoptimizing the one of the recursive metric and the non-recursive metric by iteratively extending surviving paths on a trellis diagram to demodulate the sequence of symbols, wherein states of the trellis diagram at t=kT are specified by {a.sub.k-N'+1, . . . , a.sub.k }, and wherein N'.gtoreq.1 is a predetermined integer selected to determine performance and efficiency of computation, and wherein 1.ltoreq.N'.ltoreq.N when metric selected is the recursive metric.