Turbo network coding for efficient and reliable relay

A turbo network coding based relay model and its decoding method are proposed for the quasi-static fading multi-access up-link channel. In the model a relay assists two mobile nodes simultaneously by forwarding a network coded version of the two interleaved messages. Access Point (AP) performs joint channel and network decoding with signals received from two mobile nodes and the relay. Compared with existing schemes, the proposed turbo network coding scheme has two main contributions: (i) Only parity check bits of two messages are forwarded by relay and they are further XORed together to improve relay efficiency. (ii) The iterative decoding is used in joint network and channel decoding to salvage packets from erroneous signals in the absence of a priori knowledge. Simulation results indicate that the proposed scheme provides up to 1.8 dB gain to the existing scheme in the case of mutual cooperation among mobile nodes.