Patent ID: 6259749
Filing Date: 2001-07-10
Classification: H03M

Abstract:
A Viterbi decoder for receiving a sequence of convolutional codewords, comprising:means for deriving a sequence of branch metrics from a received codeword sequence;means for dividing the branch metric sequence into a plurality of branch metric sequences,a plurality of add/compare/select (ACS) circuits for adding said branch metric sequences to a plurality of previous path metrics and determining therefrom a plurality of sequences of path metrics of maximum likelihood paths and plurality of indicators identifying the maximum likelihood paths;means for pipelining state metrics of said path metrics of said maximum likelihood paths and supplying the pipelined state metrics to said circuits as said ACS previous path metrics; andmeans for receiving indicators form said circuits and recovering therefrom an original bit sequence,wherein said pipelining means comprises:a first bank of first and second memories and a second bank of first and second memories; andcontrol means for controlling the memories of said banks during write operation such that state metrics of respective path metric sequences from said ACS circuits are stored into the first and second memories of the first bank and state metrics of said respective sequences are subsequently stored into the first and second memories of the second bank,said control means controlling the memories of said banks during read operation such that a first sequence of even-numbered state metrics and a second sequence of odd-numbered state metrics are read from the first memory of the first bank and supplied to said ACS circuits, and a first sequence of odd-numbered state metrics and a second sequence of even-numbered state metrics are read from the second memory of the first bank and supplied to said ACS circuits,said first sequence of even-numbered state metrics and said first sequence of odd-numbered state metrics forming state metrics of consecutive numbers of a first group, and said second sequence of even-numbered state metrics and said second sequence of odd-numbered state metrics forming state metrics of consecutive numbers of a second group following the consecutive numbers of said first group.