Improved joint network-channel coding for the multiple-access relay channel

This paper proposes a novel joint network- channel coding (JNCC) system based on improved distributed turbo coded (DTC) scheme for multiple-access relay channel, using decode-and-forward protocol. The diversity of improved DTC scheme is that the two parity streams of the two RSC encoders of UE are converted into one stream by puncturing. In addition, we adopt the punctured parity streams of Convolutional Turbo Code (CTC) at the relay and BS, which takes advantage of the feature of two inputs for the decoded information bits from two mobile stations. Here, CTC acts as a network coding as well as channel coding between relay and BS. The performance of this communication system depends on the twice decoding at the BS according to the side information and CTC punctured parity information. The simulation results show that performance of proposed scheme overperforms the reference network-coding scheme which separates channel decoding from network coding, and has 0.8dB improvement at a bit error rate (BER) of 10^-3 in AWGN channel than the reference scheme.