Relay selection method giving consideration to channel conditions and traffic states in cooperative communication system

A relay selection method giving consideration to channel conditions and traffic states in multi-user cooperative communication is characterized by introducing a traffic arrival model which can embody traffic burstiness and self-similar characteristic to each user of the network, then comprehensively considering the different QoS requirements of each user traffic, and selecting the direct transmission mode when the channel conditions meet the threshold of signal to noise ratio corresponding to the minimal transmission rate requirement according to the current real-time channel condition and the traffic state; and based on the principles of proportional fairness and user satisfaction, selecting a cooperative partner as the relay user to participate in cooperative transmission when the channel conditions are less than the threshold of signal to noise ratio corresponding to the minimal transmission rate requirement and the cache region at the relay end is not full according to the multi-optimization objective of relay selection, so as to reduce the outage probability of the source user and the influence on the traffic transmission of the relay user, improve the traffic transmission performance of the source user, minimize the influence on the traffic transmission performance of the cooperative user, ensure the different QoS requirements of the user traffics and improve the communication reliability of the cooperative relay system.