Research On Relay Selection Algorithm In Multi-Source Cooperative Networks

Cooperative communication is a technology that in multi-user networks, according to certain rules, neighbor users with single antenna share each other's antenna building a virtual multi-antenna transceiver environment(virtual MIMO), sending and receiving information.Cooperative communication technology can obtain the same performance gain with the actual multi-antenna and multi-hop transmission networks without increasing the number of antennas. The outage performance of cooperative communication system is mainly affected by the cooperation of nodes, so the choice of relay is very important. This paper mainly studies the relay node selection in cooperative communication.First of all, this paper introduces research background, development status, application scenarios and potential problem of cooperative communication; presents several common network models and diversity combining technique; introduces several typical relaying protocols, and analyzes and simulates the outage performance and symbol error rate performance.Then, this paper summarizes the relay selection algorithm based on different objective optimization of single source cooperative communication system, giving out their advantages and disadvantages; and introduces several main multi-source relay selection algorithm.Finally, in order to make use of the resources more rationally in the system, a statistical channel information based centralized joint relay selection and power allocation algorithm is proposed while guaranteeing the outage probability at the same time for energy-constrained amplify-and-forward cooperative networks with multiple sources. According to the channel statistical information, firstly the destination node builds candidate relay nodes set; next,calculates the minimum transmit power of each source node in direct transmit and cooperative transmit and creates matrix power; at last, determines the collaborative relationship of each source node and relay node based on power allocation demand factor obtaining from the power matrix. In the determined cooperative relationship, in order to makefull use of high performance relay node, a relay node can provide forwarding service in different time slots for two source nodes. The total transmission power is saved and network lifetime of the cooperative network is prolonged significantly using the proposed scheme compared with direct transmission and DPAa RS algorithm.