Research Of Relay Node Selection For Wireless Cooperative Communication Network

With the rapid development of the Internet and multimedia technology, future wireless communication networks will bear more high-speed, real-time services. Therefore, increase spectrum efficiency and data rate has become a problem demanding urgent solution. Cooperative relay technology is derived from the idea of the virtual MIMO. It has advantages of no need to change the existing network architecture and small changes of upper layer communication protocol to put cooperative communication mode into practice. Simultaneously, It can significantly increase system capacity and overcome the situation of wireless communication terminals being smaller, lower power consumption and cheaper. Thus, it becomes the technology to solve the bottleneck of future wireless communications development. Cooperative relay selection is the key technology for cooperative relay technology. The existing results show that only relay nodes are selected rationally according to the system requirements that communication performance can obtain the maximum enhancement. Therefore, the research of relay selection in cooperation communication network is of great practical significance. This paper is supported by the research of utility-based cooperative communication for ad hoc network, one of National Natural Science Foundation of China with Grant (60802009) and virtual multi-antenna transmission key technologies for area network, one of National High-tech R&D Program of China with Grant (2008AA01Z204), focusing on the research of new cooperative relay selection algorithm and the related cooperative communication performances with single relay node and multiple relay nodes.In this paper, the research scenario is the wireless cooperative communication network. Firstly, according to the previous relay selection algorithms are of much concern at a specific performance index, this paper proposes a joint relay selection algorithm, which gives a comprehensive consideration of outage probability, bit error rate and fairness of relay selection, using linear weighted method. This algorithm does an overall consideration of the cooperative relay nodes selection and makes an good tradeoff between these performance indexes of cooperative communication. Then, based on the question of the relationship between the cooperative communication performance and the number cooperative relay nodes, this paper analyzes the performance difference between single relay cooperation situation and multi-relay cooperation situation, with outage capacity as the evaluation standard, and presents a SNR threshold, which is an inflection point of these two performances. This threshold can tell us which cooperative mode should be used in the established condition. Furthermore, in the established communication scenarios, in order to ensure communication performance not decrease, the maximum of relay nodes involved in cooperative communication is deduced. This analysis can avoid more unnecessary relay nodes cooperating communications, consequently, ensure the network energy to be utilized efficiently.The joint relay selection algorithm and the analysis between cooperative communication performance and the number of cooperative nodes proposed in this paper survey cooperative node selection from a new perspective. And the selected nodes through our research results give more performance improvements than the nodes selected by the previous algorithms. At the same time, these research results reduce the blindness of nodes taking part in communications and have practical meaning for future cooperative communication technology application.