Patent Document ID: 5432821
Application ID: 07985004
Patent Flag: 1

Claim One:
1. A system for estimating data sequences in digital transmissions, with a transmission channel and a received observed digital signal y.sub.k comprising: a survivor memory circuit for storing a digital representation of each of a plurality of N possible data paths as a sequence of N initial survivor sequences s.sub.1,. .. , s.sub.N, where N is an integer; for each initial survivor sequence, an individual channel estimator; for each initial survivor sequence, an individual transition metrics computation circuit for computing a transition metric from the initial survivor sequence at a time k to each of a plurality of data states at a time k+1; an accumulated metrics computation circuit for cumulatively computing and storing accumulated metrics for each initial survivor sequence plus each associated transition metric up to time k+1; a survivor selection circuit for selecting candidate survivor sequences from among the initial survivor sequences stored in the accumulated metrics computation circuit; a best survivor circuit for selecting and transmitting as an estimated encoding sequence a.sub.k-D corresponding to a most likely estimate of an actually transmitted data sequence; in which: each channel estimator has an inputs the corresponding initial survivor sequence and the observed digital signal y.sub.k and has as an output signal a channel estimate signal corresponding to an estimate of the transmission channel as a predetermined function only of the corresponding initial survivor sequence and the observed digital signal; each metrics computation circuit has as inputs the corresponding initial survivor sequence, the corresponding channel estimate signal, and the observed digital signal y.sub.k and has as outputs transition metrics computation signals corresponding to the input initial survivor sequence; the accumulated metrics computation circuit has as inputs the metrics computation signals from all of the metrics computation circuits and has as outputs accumulated metrics signals; the survivor selection circuit has as inputs the accumulated metrics signals and has as outputs the N candidate survivor signals; the best survivor selection circuit has as inputs the N candidate survivor signals and has as an output the estimated encoding sequence a.sub.k-D ; whereby metrics computation is performed independently for each initial survivor sequence using the separate channel estimators for each survivor.