Research On Cooperative Communication Strategy With Network Coding

Cooperative communication makes the relay node forward data of source node to obtain diversity gain and can improve the reliability of the wireless communication system effectively. On the other hand, network coding makes the data packets from different sources or the different data packets from single node coded together. It can improve the robustness and throughput of the system. How to integrate the thought of network coding into the cooperative communication technology is the focus of the research.We propose a cooperative communication strategy with network coding in GF(2n)in the multi-users cooperative communication network. It makes the user node code the data of itself and the data received at the first phase together, and then forward it out at the second phase. The receiver node constructs the decoding set of equations and solves it to obtain the users data. Because the network coding is processed in GF(2n), there is more extensive range to select coding coefficients compared to the conventional network-coding cooperation. We propose the construction rule of the network coding matrix and searching algorithm of it. The coding matrix which meets this rule can guarantee that all users data can be got so long as the number of correctly received data packets is not fewer than the number of users. The solvability of the set of equations formed at receiver node is improved effectively. So this strategy can make the system obtain higher diversity gain.In the wireless communication networks without direct path between source node and destination node, we do some research to the cooperative communication strategy with the thought of network coding. Firstly, we introduce the cooperative communication strategy with network coding in physical layer into this scenery. This strategy utilizes the trait of broadcast of the wireless channel to code the data naturally. The theory analysis and simulation result demonstrate that it can improve the transmission efficiency and obtain the diversity gain at the same time. Secondly, we propose a new full-rate cooperative communication strategy. This strategy utilizes multiple relay nodes to take turns to amplify and forward data package for the transmitter at different time slot. Thus the source node could continue sending without cessation. On the other hand, considering the thought of network coding to combine the data, prevailing linear constellation precoding process is adopted at the source node. By this method, the ability of the system to resist fading is improved and theimbalance of the error performance of the data sent at odd and even time slots is avoided. The theory analysis and simulation result demonstrate that this strategy could achieve full-rate cooperative transmission with full diversity gain obtained.