LAUSR

For a wireless cooperative system in which feedback delay exists, the channel state information of the link at the time of relay selection may be outdated with respect to the time of data transmission. The use of outdated channel state information for the selection of relay node will inevitably affect the reliability of selection. Considering the existence of feedback delay, unlike other methods of estimating the true received signal-to-noise ratio during the data transmission to optimize relay selection, the security outage performance of the cooperative communication system is taken as the starting point in this paper, the minimum security outage probability is proposed as the selection basis to optimize the opportunistic relay selection strategy, and the theoretical derivation under the condition of high input signal-to-noise ratio is provided. The simulation results show that the relay selection strategy proposed in this paper can achieve higher security performance under outdated scenarios.