Patent ID: 7168028

Claim:
A method for maximum a posteriori (MAP) decoding of a received vector of corrupted transmitted symbols encoded using a code set consisting of a plurality of binary codewords, wherein each of said binary codewords has n positions, wherein each position has a binary value of one or zero, said method comprising the steps of: for each position, l, 0≦Λ≦n−1 of said received vector, computing a difference, ρ l , of the respective probability that the transmitted symbol had a binary value of one at position l and the probability that the transmitted symbol had a binary value of zero at position l; and determining, for each codeword of a dual code of said code set, a product of ρ l values corresponding to non-zero positions of codewords of the dual code of said code set using a real vector fast Walsh-Hadamard transform and a 2 [ 2 ]-vector fast Walsh-Hadamard transform.