Ergodic Secrecy Performance Analysis of Multiuser Diversity and Energy Constrained Untrusted Relay System

A two-hop link secure communication network model, which is based on energy-constrained untrusted relay and multiuser diversity network, is proposed in this paper. In order to improve the secrecy performance of the sensor network, a hybrid time-power splitting-based relaying (TPSR) protocol is applied on untrusted relay, and an optimal destination node is selected from the multiuser diversity system as the terminal, according to the opportunistic scheduling strategy (OSS). Based on the random selection (RS) strategy, a low complexity Gaussian Q-function is used to analyze the secrecy performance and an approximate closed-form expression of the ergodic secrecy rate (ESR) is derived under the condition that the relay obtains the required power for activity. In addition, the performance of the proposed OSS technology is compared with that of the RS scheme, which proves that OSS technology is more suitable for distributed multiuser selection network.