Analysis of secrecy performance in fading multiple access wiretap channel with SIC receiver

Recently, a new paradigm of multiple access (MAC) along with one eavesdropper to achieve secrecy transmissions has been getting in focus. However, all existing work on such multiple access wiretap channel (MAC-WT) mainly concentrates on the secrecy performance of the system as a whole from an information theoretic perspective. In this work, we investigate the secrecy performance of a single transmitter in the quasi-static Rayleigh fading MAC-WT on basis of two decoding methods, zero-forcing (ZF) and minimum mean-square error (MMSE), jointly with successive interference cancellation (SIC). We evaluate the secrecy performance in three metrics: positive secrecy capacity probability, secrecy outage probability and effective secrecy throughput. The analytical and simulation results show that, 1) the SIC order has great impacts on the secrecy performance for both methods; 2) MMSE-SIC outperforms ZF-SIC, while the performance gap can be overcome via adjusting SIC order, or increasing SNR, or enhancing the spatial diversity gain; 3) in high SNR regime, the secrecy performance is only determined by the relative distance to eavesdropper over legitimate receiver rather than the SNR.