Patent ID: 7222288

Claim:
A method of obtaining reliability values and hard decisions for a set of transmitted symbols using a Viterbi equalizer at a wireless receiver, a Viterbi trellis having a memory of L stages, the method comprising the steps of: a. advancing the Viterbi trellis by all stages corresponding to the set of transmitted symbols, for each stage performing the steps of: i. selecting a surviving path from two paths leading to each Viterbi state at the stage, wherein the path not being selected as the surviving path is considered as the non-surviving path; and ii. obtaining a difference parameter corresponding to each Viterbi state at the stage; b. obtaining hard decisions corresponding to all symbols of the set of transmitted symbols using a maximum likelihood path selected from the surviving paths at the stage corresponding to the last symbol of the set of transmitted symbols; and c. obtaining reliability values for hard decisions obtained at all stages, for each stage performing the step of: if the stage does not correspond to the last L symbols of the set of transmitted symbols then performing the step of: i. establishing that the difference parameter corresponding to the state on the maximum likelihood path at L stages ahead of the stage is the reliability value for the hard decision obtained at the stage; else performing the step of: i. analyzing the surviving paths at the stage corresponding to the last symbol of the set of transmitted symbols to obtain reliability value for the hard decision obtained at the stage.