Secrecy Downlink Multi-User MISO Networks

This paper proposes two strategies of secrecy downlink multi-user multiple-input single-output (MISO) transmission, namely, beamforming strategy and nulling strategy, for wireless communication networks with single multi-antenna base station and multiple single-antenna mobile stations. All mobile stations can eavesdropper each other. The transmission rate of the link from the base station to a mobile station is limited at the secrecy rate, which is the transmission rate that the base station can communicate with the target mobile station without eavesdropping by any other mobile station in the network. We compare the performance of two proposed strategies in terms of the obtained instantaneous secrecy rate by Monte-Carlo simulations. It is found that neither of them is better than the other for all Monte-Carlo realizations. The beamforming strategy is better than the nulling strategy in some situations, which depends on two factors: the number of transmit antennas at the base station and the number of mobile stations in the network.