Patent ID: 6625225
Filing Date: 2003-09-23
Classification: H04L

Abstract:
A trellis decoder for performing decoding of a trellis encoded modulated signal, comprising:signal conversion means for converting a received signal point into a converted signal point situated in any one of all quadrants on a complex plane specified by a real and an imaginary number axis and for outputting said converted signal point and a quadrant signal representative of a quadrant where said received signal point is situated; branch metric arithmetic means for deciding, by making use of said quadrant signal, the maximum likelihood between said converted signal point and a subset signal point and for outputting a branch metric and a subset decision signal; ACS (Add Compare Selection) means for performing arithmetic operations to compute, from said branch metric, a path metric according to a trellis diagram and for outputting a path selection signal for selection of a path having a high likelihood; first storage means for storing said quadrant signal; second storage means for storing said subset decision signal; third storage means for storing said path selection signal; and output means for outputting an encoded bit decoding signal and a non-encoded bit decoding signal by making use of results of performing traceback of said quadrant signal stored in said first storage means, said subset decision signal stored in said second storage means, and said path selection signal stored in said third storage means.