Security Enhancement for Multiple Multi-Antenna Relaying Networks

In this paper, we investigate the secrecy performance of the multi-antenna relaying networks over Rayleigh fading channels, by taking the reliability of the first link spanning the transmitter to the relays into consideration. To improve the secrecy performance, two secure transmission strategies are designed at relays, namely, 1) Maximal ratio combining/Transmitter antenna selection (MRC/TAS) and 2) MRC/Maximal ratio transmission (MRC/MRT), assisted by a friendly jammer. Specifically, in order to present the advantages of the two proposed schemes, we derive the exact closed-form expressions of the outage probability (OP) and intercept probability (IP) to evaluate the security-reliability tradeoff (SRT) of the considered system, respectively. From our theoretical analysis as well as simulation results, we find that a) our proposed schemes outperform the conventional scheme with no cooperative jammer (CJ), and b) the MRT scheme is superior to the TAS one conditioned on the same set of system parameters.