Improved Distributed Turbo Code for Relay Channels

In this paper, two improved distributed turbo coded (DTC) schemes, namely, superposition DTC scheme and punctured DTC scheme, are proposed for a two-hop relay system using decode-and-forward protocol. The performance of a communication system using relay mainly depends on the successful decoding of source information at the relay. The proposed techniques increase the decoding success rate at the relay thanks to the unique encoding procedures used at the source to relay link. Here, the input information symbols are first encoded using two rate 1/2 parallel concatenated recursive systematic convolutional (RSC) encoders, and the two parity streams of the two RSC encoders are converted into one stream by superposition and puncturing in the proposed superposition DTC scheme and punctured DTC scheme, respectively. Simulation results show that the error performance of the proposed superposition DTC scheme and the punctured DTC scheme are superior to the conventional DTC scheme by around 1.2 and 0.8 dB respectively.