Patent ID: 7865814

Claim:
A path metric difference computation unit for computing differences between paths through a multiple-step trellis, wherein a first of said plurality of paths is a winning path for each single-step-trellis period of a multiple-step-trellis cycle, a second of said plurality of paths is a winning path for a first single-step-trellis period and is a losing path for a second single-step-trellis period of the multiple-step-trellis cycle and a third of said plurality of paths is a losing path for the first single-step-trellis period and is a winning path for the second single-step-trellis period of the multiple-step-trellis cycle, comprising: one or more path metric difference generators for generating a path metric difference Î” 0 for the second single-step-trellis period of the multiple-step-trellis cycle based on a difference between the first path and the second path, and a path metric difference Î” âˆ’1 for the first single-step-trellis period of the multiple-step-trellis cycle based on a difference between the first path and the third path, wherein one or more of intermediate path metric values and intermediate path metric difference values are reused to generate one or more of said path metric differences Î” 0 and Î” âˆ’1 .