Secrecy-Throughput-Optimal Artificial Noise Design Against Randomly Located Eavesdroppers

This paper investigates the parameter design and optimization on the artificial-noise-aided multi-antenna transmission in the presence of randomly located eavesdroppers. Our objective is to maximize the secrecy throughput subject to a secrecy outage constraint. We propose an on-off strategy in which the transmitter decides when to start transmissions according to the instantaneous channel state information of the main channel. System parameters, including the wiretap code rates, the transmission threshold of the on-off strategy, and the power allocation between information signals and artificial noises, are optimized based on the statistic channel state information of both the legitimate channel and the wiretap channels. The whole optimization procedure is performed off-line. We formulate the optimization problem and provide explicit solutions on the optimal parameters. Numerical results are demonstrated to verify our theoretical analysis and show the effectiveness of our design.