Power and area efficient turbo decoder implementation for mobile wireless systems

Abstract

The authors present a low power and area efficient turbo soft-input soft-output (SISO) decoder based on two-step soft-output Viterbi algorithm (SOVA) targeting wireless mobile communication systems. Our turbo SISO decoder is based on trace back algorithm (TBA) and saves area and power by replacing the FIFO memory with an additional transition metric unit (TMU). The paper presents the implementation of SOVA decoder for constraint lengths K=3, 4, and 5, describing the design methodology and evaluation environment. Simulation results are provided showing up to 20% power saving and 46% area saving compared to a conventional SOVA decoder implementation.

HDL Implementation of Turbo Decoder Using Soft Output Viterbi Algorithm

“…The turbo codes have capability near to shannon's limit [1].They have already been adopted as a standard in 3GPP, UMTS, IEEE802.16 and are considered by other wireless applications [2] [3]. The turbo codes can be applied to various wireless communication systems such as satellite, deep space, and so on with many relevant performance results for those applications.…”

“…Turbo decoder consists mainly of one softin/soft-out (SISO) [2] decoder and memories that store both temporary decoding results and received codewords. The Two-step Soft output Viterbi algorithm (SOVA) [3] decoder gives a low complexity solution to the turbo decoder. However, the turbo decoder using SOVA has less BER performance than the MAP turbo decoder for the same SNR.…”

“…The MAP algorithm provides the best performance in BER but its complexity is higher than the two-step SOVA. Turbo SISO decoder based on trace back algorithm (TBA) designed that saves area and power by replacing the FIFO memory with an additional transition metric unit (TMU) [3]. Branch Metric Normalization improves speed of operation, the architecture presents a turbo soft in soft out (SISO) decoder based on Max-log-map algorithm using sliding window techniques [4].…”

“…Whereas, SOVA based turbo decoder can be implemented with high throughput and less complexity. Two step SOVA, which separates decoding process into two processes called survivor and update processes [3], allows us to implement the turbo decoder with less complexity when compared with the original SOVA.…”

Re-configurable Optimized Area Turbo Decoder for Wireless Applications

“…This modification results in performance improvement. Power and area efficient turbo decoder for mobile application has been presented [9]. It is based on two step SOVA and used traceback algorithm.…”