Patent ID: 6088404
Filing Date: 2000-07-11
Classification: H03M,H04L

Abstract:
A method for decoding a trellis encoded stream d.sub.k by the use of either an 8 state maximum likelihood response decoding mode, in short, an 8 state mode, through a Gaussian channel or a 16 state partial response decoding mode, in short, a 16 state mode, through a partial response channel, wherein the trellis encoded stream d.sub.k is obtained by an M symbol intra-segment interleaving technique using M number of trellis encoders and an index k for identifying a trellis encoded stream generated from a kth trellis encoder among total M trellis encoders is equal to or greater than 1 and equal to or smaller than M, M being a positive integer representing the number of the trellis encoders, the method comprising the steps of:(a) in response to a mode selection signal FENA, passing off the trellis encoded stream for the 8 state mode and removing the influence of a segment synchronization signal from the trellis encoded stream for the 16 state mode;(b) calculating branch metrics with different values in parallel for either the 8 or the 16 state mode determined based on the FENA;(c) selecting a predetermined number of branch metrics required for each state among the branch metrics of either the 8 or the 16 state mode determined based on the FENA, thereby finding a predetermined number of candidate path metrics and determining a survivor metric and a determination vector thereof, wherein the survivor metric represents a candidate path metric with a maximum likelihood among all the candidate path metrics;(d) providing the survivor metric for said each state determined in step (c) as a previous path metric for a previous state;(e) tracing back for a decoding depth of the 8 or the 16 state mode in response to the FENA based on the determination vector of said each state determined in step (c), thereby finding a decoded symbol; and(f) intra-segment deinterleaving the decoded symbol and converting the intra-segment deinterleaved decoded symbol in the unit of a predetermined size of packet.