Research On Multiple Relay Selection Strategy In Cooperative Communication Networks

In recent years,wireless communication equipment has developed rapidly,people are pursuing higher efficiency and high-quality communication experience.The cooperative multi-antenna matrix is constructed by the cooperative communication technology of the relay,so that the communication node obtains a higher diversity gain,thereby resisting the fading characteristics and instability of the wireless channel,expand communication coverage,improve link quality and improve spectral efficiency.In the multi-relay cooperation scenario,selecting the optimal relay node cooperative transmission can greatly improve the overall performance of the system and ensure the communication quality.This paper mainly studies the multi-relay system of cooperative communication and the optimal relay selection strategy.The innovative contents of this paper are as follows.(1)For the full-duplex relay system,the performance of decoding and forwarding(DF)relay system in Rayleigh channel environment is studied.Considering the average packet error rate that occur in the process of data transmission and the self-interference effect that occur between the full-duplex relay receiver and transmitter,and summarizing the self-interference cancellation technology,the end-to-end system stability expression is derived.The expression can be used to select relay and judge whether the system is good or bad.The simulation results of MATLAB show that the system stability of the full-duplex relay system is better than that of the half-duplex relay system when the self-interference is small,and the number of relays can improve the stability of the system.(2)n order to achieve spatial diversity gain at the cost of spectral efficiency in cooperative relay systems,the performance of decoding-forwarding relay systems in Rayleigh channel and Nakagami-m channel mixed channels is studied.Combining with the average packet error rate of data in the process of information transmission,the expression of dual-relay end-to-end spectrum efficiency and the expression of system stability with the modulation level ofsource node and relay node as design variables are derived.The optimal relay selection is carried out through the expression to maximize end-to-end spectrum efficiency.At the same time,the effects of different channel parameters and threshold on link spectrum efficiency and system stability are analyzed.The simulation results show that,compared with the traditional adaptive DF transmission strategy,the proposed strategy is better in improving the spectral efficiency.(3)In order to obtain more space resources,the communication nodes in the network play games with each other,but often the energy-intensive nodes will occupy a large number of resources to achieve information priority transmission,and the energy-weak nodes will appear information stagnation phenomenon.How to ensure fairness and choose the best Relay-assisted transmission in cooperative networks? In order to solve the above problems,a hybrid relay strategy based on network fairness(NFHDAF)is proposed.Firstly,the network fairness is guaranteed by setting "reward" values.Secondly,AF and DF relay sets are screened by channel gain and transmission threshold.Finally,the optimal HDR/FDR is selected and the outage probability expression is calculated.The simulation results show that the NFHDAF strategy has lower interruption probability than the single HDR/FDR transmission scheme and the common optimal relay selection algorithm.