Patent ID: 7382831

Claim:
A method in a Viterbi decoder for decoding received encoded bit pairs, the method comprising: first storing in a survivor metric register file, for each received bit pair at a corresponding time instance, a survivor metric that specifies a corresponding probability of the received bit pair and a previous surviving bit sequence having been generated by a convolutional encoder according to a corresponding possible encoder state, the first storing step including selectively subtracting from each survivor metric, prior to storage thereof, by a prescribed subtraction operator based on a prescribed event, and storing the subtracted survivor metric as the stored survivor metric; second storing in a state history table memory, for each of the received bit pairs at the corresponding time instance, a prior encoder state entry configured for identifying a surviving predecessor state relative to a corresponding encoder state; and outputting at least one decoded bit pair based on execution of a backtracing operation that includes accessing a prescribed number of the prior encoder state entries for the respective prescribed number of time instances, the accessing including identifying one of the encoder states, stored at a corresponding first time instance, as an initial backtracing state based on having the corresponding survivor metric specifying a highest probability relative to the other survivor metrics at the corresponding first time instance.