Secrecy Performance Analysis of MIMO Decode-and-forward Relay Systems in Nakagami Channels

The physical layer security performances of low-complexity opportunistic transmission strategy based on multiple antenna are investigated for cooperative adaptive decode-and-forward relaying system in Nakagami-m fading channels. To fully utilize the antenna diversity gain to improve the system security performance, the transmitting nodes apply the transmit antenna selection strategy, and the receiving nodes apply the maximal ratio combining strategy. The closed-form expressions of secrecy outage probability are derived, the asymptotic analysis of secrecy performance is further provided, and the secrecy diversity order are also obtained. Simulation results verify the correctness of theoretical analysis and identify the effects of several system parameters on the secrecy performance of the opportunistic transmission strategy. It is shown that the system secrecy performance can be greatly improved by increasing the number of antennas at the legitimate nodes and increasing the Nakagami fading channel parameters of legitimate channels.