On the robustness of a cooperative turbo coded system to channel estimation errors

Cooperation is an effective technique to increase the diversity in wireless relay networks and hence improve the Bit Error Rate (BER). In this paper, a scheme combining turbo coding and cooperative relay techniques, comprising one source, one destination and a single relay is proposed and studied. The aim of this study is to investigate the bit error rate (BER) performance in cooperative turbo coded systems equipped with an omni-directional antenna element at the transmission and the reception in the presence of channel estimation errors. Herein, the Amplify-and-Forward (AF) cooperation protocol is adopted at the relay level. Furthermore, a single hop scenario is considered, and the imperfect channel state information (CSI) is assumed to be present at the source-destination link. Two turbo codes, are generated at the source using the same polynomial, with overall rates of 1/2 and 1/3, respectively, the 1/2-rated one being generated from the latter using puncturing. Before iterative decoding, the destination performs a maximum ratio combing (MRC) of the signals emanating from the source and the relay transmitters. According to the authors ´knowledge, the investigation of the effect of channel estimation errors on the performance of such systems has not yet been reported.