New iterative turbo code list decoder

Abstract

Turbo decoder performance improvement is considered in the work. While on the first iteration of the conventional turbo decoder a priori reliabilities are supposed to be zero in the new scheme it is proposed to estimate and set these values. Algorithm for generation of a list of a priori LLRs is described, where each list sequence is used as an input to independent turbo decoder. As a result list of decoded sequences is obtained from independent turbo decoding processes. Thus new turbo code list decoding algorithm is proposed and parallel turbo decoding technique is introduced. FER simulation results for 3GPP LTE turbo code show 0.4 dB gain for short information sequences and 0.15 dB gain for longer ones. As a criterion of choosing of correct sequence in the list CRC is used.