Research On Relay Selection In Wireless Relay Network

The rapid development of wireless networks, as well as the growing business of communication, is putting forward higher requirements on network capacity and communication quality. The technology of relay cooperation is an important way to improve the quality of communication against multi-path fading. The relay nodes assist the communication between source and destination, which provides some spatial diversity without the need of multi-antenna configuration, and improves the communication quality.However, higher power consumption and complexity comes with relay cooperation, which is unacceptable in wireless network communication, especially in mobile communication. Relay selection is a simple solution to this problem. One or several qualified relay nodes are selected among a set of nodes by certain rules, to cooperate in the communication, while other nodes stay in idle state. Obviously, this scheme is more power-efficient.The content of this thesis is research on relay selection schemes, which contains two parts. First, the author discovers and proves by simulation, that the Channel-State Information (CSI) of direct link can be used to adjust and improve the existed relay selection scheme, in network-coding-based MARC network. We also propose some improved schemes, and simulation results show that the improved schemes outperform the present ones.Second, the author studies relay selection in MIMO relay network. By using SVD method, the author improves the multi-antenna relay selection scheme based on MMSE. The author extends the single antenna configuration scheme to multiple antenna configuration, and also the simulation results show that the extended scheme is better than the present one.