Patent ID: 7647547

Claim:
A method for decoding using branch metrics generated using a decoding trellis, the method comprising: generating, during a forward recursion of the decoding trellis, a first subset of a plurality of forward branch metrics of the decoding trellis from a primary combination of extrinsic, parity and information data associated with at least one symbol, the first subset having a property that a second subset of the plurality of forward branch metrics can be determined based on a symmetry of the plurality of forward branch metrics; storing the first subset of the plurality of forward branch metrics and discarding the second subset of the plurality of forward branch metrics; upon commencing a reverse recursion of the decoding trellis, retrieving the stored first subset and determining the second subset using the symmetry of the plurality of forward branch metrics, the first and second subsets being applied in the further decoding operation; generating, during the reverse recursion of the decoding trellis, a plurality of reverse branch metrics using the plurality of forward branch metrics; and decoding said at least one symbol using the forward and reverse branch metrics.