Research On Relay Selection Strategy For Multi-source Wireless Cooperative Networks

Cooperative communication network technology utilizes distributed concepts to share radio resources with each other to achieve spatial diversity,which can effectively resist fading,improve transmission reliability,and expand network coverage.A key issue in the research of cooperative communication networks is the selection of relay nodes.How to choose the appropriate cooperative relay for users is the prerequisite for the stable operation of the cooperative communication system.This thesis focuses on the relay selection strategy in cooperative communication networks,and analyzes the relay selection strategies for single-source and multi-source scenario models.This thesis starts from the single-source scenario,studies the opportunistic relay selection strategy in the non-eavesdropping environment,and compares it with the traditional relay selection strategies,which verify the relative superiority of the opportunistic relay selection.In the eavesdropping environment with eavesdropping nodes,the optimal relay selection strategy taking into account channel state information(CSI)of the primary channel and the eavesdropping channel is studied.The simulation results show that the optimal relay selection can effectively improve the security performance of the system.Based on the optimal relay selection strategy in the eavesdropping environment,this thesis studies a scheme of relay selection and power allocation to maximize the utilization of system resources.The simulation results show that this scheme can further improve the security performance of the system with respect to equal power allocation.Then,in the non-eavesdropping environment for multi-source scenarios,aiming at maximizing system capacity,this thesis studies a low complexity maximum channel capacity relay selection strategy,which makes the system performance close to the performance of the exhaustive algorithm.Considering the impact of eavesdropping nodes in the eavesdropping environment,this thesis expands the relay selection strategy in non-eavesdropping environment,and the improved strategy can effectively improve the security performance of the system.For the eavesdropping environment,this thesis also applies the power allocation scheme of single-source scenarios to multi-source scenarios.The simulation results show that multi-source scenarios can also achieve better security performance under the condition of improving system resource utilization.In order to optimize the system network life and improve energy efficiency,in the multi-source scenario,this thesis also proposes a relay selection strategy based on residual energy,which plays the role of relay residual energy in relay selection.Through comparative analysis,it is found that the proposed strategy can significantly extend the system network life and increase the total system throughput.