Patent ID: 6226773
Filing Date: 2001-05-01
Classification: H03M

Abstract:
A method for minimizing memory requirements for computations for decoding using Maximum Likelihood Probability MAP-based decoding, comprising the steps of:computing corresponding alpha .alpha. values and beta .beta. values simultaneously and storing said alpha .alpha. values and beta .beta. values computed for .alpha. at time k=1,2, . . . , N/2 and .beta. at time k=N, . . . , (N/2)+1; andcomputing soft output data for alpha at time k=(N/2)+i and beta at time (N/2)-i+1, i being a positive integer, for N.gtoreq..alpha.>N/2and 1.ltoreq..beta..ltoreq.N/2, wherein .alpha. and .beta. are parameter values computed by forward and backward recursion, respectively, based on transition probabilities of a selected channel and on input binary data at discrete time k and a parity bit corresponding to one of: a first recursive systematic convolutional encoder and a second recursive systematic convolutional encoder.