DmF Cooperation Based on Joint Network-Channel Coding in Wireless Communication

In this paper, we study the strategy of Demodulation-and-Forward(DmF) based on joint network and channel coding and extend it to multi-user access relay channel . In DmF model, there are two users accessing the relay. Users encode original signals using LDPC codes. In the relay, we conduct demodulation instead of decoding and implement network coding that is the Demodulation-and-Forward(DmF) method which based on joint network-channel coding. Throughout the whole DmF system, we implement encoding with LDPC codes only once in users. And at the base station, we only use one matrix H to decode all of these signals from the users and the relay jointly. Finally, we extend the DmF model to cases of three users and four and take some improvement in the relay and base station which is called extended DmF model. In the extended model, we encode the codeword using LDPC codes again after network coding in the relay, namely, we encode signals twice using LDPC codes throughout the whole system. In the base station, we redesign the parity check matrix H which can also decode all of signals from the users and relay jointly. The result shows us that the DmF model has lower hardware complexity and more practicability than DF. And we can apply it to multi-user access relay channel effectively.