Implementation of an improved reconfigurable SOVA/log-MAP turbo decoder in 3GPP

SOVA (soft-output Viterbi algorithm) and log-MAP turbo decoding algorithms share common operations, making feasible a reconfigurable SOVA/log-MAP turbo decoder for reduced power consumption. We show that the improved reconfigurable SOVA/log-MAP turbo decoder is suitable for implementation in 3GPP systems. Simulations of turbo coding and decoding have been done using the parameters of 3GPP with AWGN and uncorrelated Rayleigh fading channels, and an outer block interleaver-deinterleaver. We concentrate on the dedicated transport channel (DCH) and use a pipeline turbo decoder architecture with 8 decoding iterations. We examine two typical bit rates, and for each we consider four different service classes (as possible service examples) using suitable turbo interleaver lengths. Considering the BER and latency constraints for SOVA and log-MAP, it is shown that there is an optimum decoding algorithm for each possible implementation scenario.