Patent ID: 6510536
Filing Date: 2003-01-21
Classification: H03M

Abstract:
A method of max-log-APP decoding of a sequence of samples representing a transmitted sequence of symbols obtained from encoding a data sequence of bits, each having a bit time i, with a binary convolutional encoding method having Ns states and an encoding trellis, said decoding method comprising the steps of:(a) receiving said sequence of samples; (b) computing a set of branch metrics, at each time i, from the received sequence of samples; (c) computing a set of Ns forward state metrics, at each time i, from the set of branch metrics; (d) computing a set of Ns backward state metrics, at each time i, from the set of branch metrics; (e) finding a maximum metric M for an MLSE sequence corresponding to the received sequence of samples; (f) computing the maximum of all combined metrics at time i for at least one of the data bit values of 0 and 1, where a combined metric for a bit value at time i is the sum of a forward state metric, a branch metric, and a backward state metric, corresponding to a branch of the encoding trellis for said bit value at time i; and (g) computing at least one output log likelihood ratio, corresponding to the data bit at time i, as the difference between one of the maximum of all combined metrics for data bit values 0 and 1at time i and the maximum metric M.