Patent ID: 6304617
Filing Date: 2001-10-16
Classification: H03M,H04L

Abstract:
A viterbi decoder comprising:a branch metric calculation unit that calculates a likelihood of a branch obtained through a received convolutional code;a path selection unit that adds metrics of branches extending from a time point t=n to a time point t=n+1 (said time point t=n+1 indicates a point in time one clock cycle after said time point t=n) obtained at said branch metric calculation unit to path metrics of a plurality of states that a convolutional code may assume at said time point t=n (said time point t=n indicates an arbitrary point in time) and compares path metrics for each state at said time point t=n+1 to select an optimal path for each state at said time point t=n+1; anda path memory unit that stores in memory path data corresponding to said optimal path for each state at individual points in time, wherein said path memory unit is provided with a memory unit that stores path data corresponding to optimal paths at individual points in time and a selection circuit group that is capable of selecting one state at said time point t=m-1 (said time point t=m-1 indicates a point in time one clock cycle before a point in time t=m) that corresponds to a specific state at said time point t=m (said time point t=m indicates an arbitrary point in time) in conformance to said path data stored in said memory unit.