Hybrid ARQ Scheme Based on TCM and Concatenated Codes

In this paper, a new type-II hybrid ARQ (HARQ) scheme based on TCM and concatenated codes is proposed and evaluated. The new scheme is divided into two major steps which are BCH processing and turbo processing. Firstly, information bits are transmitted using TCM and then the incremental parity bits based on BCH codes are transmitted upon the reception of NAK. Secondly, the incremental redundancy (IR) based on rate compatible punctured turbo (RCPT) codes is transmitted using BPSK if the decoding of BCH codes is failed. Averaged diversity combining (ADC) technology is used through all the (re)transmissions of the same packet. Performance is evaluated via computer simulation and the results are compared with the popular RCPT scheme. Simulation show that our scheme has higher throughput in medium to high SNR regions and the gains are considerable. Moreover, the average computational complexity of our scheme is lower than the pure RCPT scheme.