A Novel Relay Scheme For The Asymmetry Multiple Access Relay Channel

Cooperative communication and relay technology can expand the coverage of network. And the blind spots can be eliminated by cooperation between multiple nodes. The transmission between the blind spot and the other ones can improve the communication link quality effectively. It has been proved that wireless relay technology can get diversity gain or multiplex gain both in theory and experiments. Thereby the throughput and transmission reliability of the wireless link can be improved. Therefore, in recent years, cooperative communication and relay technology have got more and more attention and research, and it has become one of the key technologies of the 3GPPG LTE-Advanced wireless communication standards.Multiple access model is the base of the existing and future wired and wireless communication network. The multiple access relay channel joins the cooperative transmission of relay node in the multi-access channel, in order to effectively improve system performance, which has been extensively studied. Common to all the existing relay transmission strategy is the assumption that the channel gains from different sources to the relay link are same. However, in reality, the link qualities may vary because of fading and different distance. All the Existing relay transmission strategy have not considered the influence of the asymmetric multiple access relay channel on the system performance.In this paper, relay scheme for the asymmetry multiple access relay channel has been studied. Include the following aspects:1. In this paper, we study the transmission mechanism for the asymmetry multiple access relay channel (AMARC), where the channel qualities from the sources to the relay are different. We propose a novel relay scheme, where network coding and cooperation between users are introduced, and Turbo like decoders are employed at both the relay and destination nodes. We compare the bit error rate (BER) performance of the proposed scheme with the schemes in the literature via simulation. The simulation results show that, from the perspective of the average system BER, our proposed scheme significantly outperforms conventional relay schemes. 2. The problem of critical link in the relay system is studied. The influence of the S-R link and R-D link’s channel state on the system performance is analyzed specifically, which focus on the basic relay model. The distributed Turbo code is used for transmission. The convergence performance of the iterative decoding in different circumstances is analyzed. We use the EXIT chart to investigate which is the critical link that contributes more towards the performance. Thereby it is confirmed that in the relay system the S-R transmission reliability has a critical influence on the overall performance. It provides a basis for the selection of the relay and partner in the cooperative communication.