Implementation of an efficient two-step SOVA turbo decoder for wireless communication systems

The authors present a soft-input soft-output (SISO) turbo decoder based on the two-step soft-output Viterbi algorithm (SOVA). The turbo decoder has been implemented with the trace-back algorithm (TBA). It achieves power and area reduction by employing an additional transition metric unit (TMU) for the generation of reliability values, instead of using a FIFO block for retrieving the previously stored reliability values in the survivor memory unit (SMU). Simulation results are provided for bit error rate (BER) performance using constraint lengths of K=3, 4, and 5. Implementation results for K=5 are also provided showing 46% area and 15% power savings compared to a conventional SOVA decoder