Multiple Accessing Network Coding In Wireless Cooperative Relay Networks

Network coding is a new kind of signal processing mechanism. It allows the relay node to combine multiple messages to be a single integrated one for forwarding. And then the destination can recover the original messages with several independent combined versions.The relay node imported to the wireless network is to improve the coverage at the edge of the cell.The broadcasting nature of wireless network is quite suitable for the application of network coding and the mixing ability of network coding can effectively improve the spectral efficiency of the wireless relay network.In this paper, we study multiple accessing network coding of the wireless cooperative relay network. For the single antenna based wireless uplink multiple accessing network consisting of a single source,multiple relays and a single base station, we design a multi-timeslots complex field network coding (MTNC) scheme. In MTNC, the relay nodes perform random network coding on the messages successfully decoded, and the base station recovers the original messages by joint processing of the direct and relay path.We analyze the performance from the viewpoint of ergodic capacity, outage probability and symbol error rate, and obtain the closed form of ergodic capacity, the approximated closed form of outage probability and symbol error rate with high SNR assumption.Also we compare the performance of MTNC scheme and the traditional best relay scheme.For the multiple antennas based uplink multiple accessing wireless network composed of multiple users, single relay and single base station, we present a galois field network coding transmission strategy. In the strategy, the relay performs network coding on the messages received previously, selects an antenna randomly in the condition of no channel state information, and then the base station can obtain the source messages with receiving diversity. We compare the performance of three kinds of strategies,the proposed network coding one, the traditional relaying one and the orthogonal space-time coding based one from the perspective of ergodic capacity and outage probability. And we get the performance gain of network coding and also the relationship between the antenna number and the system spectral efficiency.