Patent ID: 7031406
Filing Date: 2006-04-18
Classification: H04L

Abstract:
1. A method of decoding q-ary encoded information symbols where q is a plural integer, comprising the steps of: providing, without any backwards computation, for each possible state of a decoding trellis at an information symbol time, q probability vectors for reaching the state via path of δ information symbols of the trellis, and a total probability of reaching the state, an updating the probability vectors and total probability for the each possible state at a next information symbol time by the steps of: (a) determining a probability for each of q possible transition paths from a state at said information symbol time to the state at said next information symbol time; (b) determining the total probability of reaching the state at said next information symbol time from the probabilities of the q possible transition paths to said state at said next information symbol time; and (c) for each q possible encoded information symbol values at the each possible state at said next information symbol time, merging respective the probability vectors for the each possible state at said one information symbol time in accordance with the respective probabilities of the transition paths from the each possible state at said one information symbol time to the state at said next information symbol time; and (d) determining a probability for an information symbol that is δ information symbols before said next information symbol time from respective elements of the probability vectors for all of possible states at said one information symbol time; wherein steps (a), (b), (c) and (d) are performed for each and every transition path and steps (b), (c) and (d) are performed for each and every information symbol.