Abstract
In this paper, a unified viewpoint is proposed to interpret the relation between various trellis-based soft-output decoding algorithms. From the unified viewpoint, we can easily obtain new algorithms of low complexity and good performance, and a unified decoding structure is devised for the newly proposed algorithms and those reported previously. Under the unified structure, all of the algorithms are mapped into a single decoding process and different algorithms can be easily switched between one another. Owing to the modularity and flexibility, this unified structure is especially suitable for the turbo decoder with programmable DSP implementation to optimize the trade-off between the performance and complexity.