Dual-hop cognitive MIMO wiretap networks with outdated channel state information

Abstract

The transmit antenna selection/maximal-ratio combining (TAS/MRC) scheme is proposed to improve the secrecy performance of dual-hop randomize-and-forward (RaF) cognitive multiple-input multiple-output (MIMO) wiretap networks when the channel state information (CSI) is outdated. In this network, the secondary transmitter adopts TAS scheme to choose the strongest antenna to transmit signals, while MRC scheme is used by secondary receiver and eavesdropper to strengthen their received signals. Firstly, we investigate the secrecy outage probability (SOP) of dual-hop RaF cognitive MIMO wiretap networks. To gain more observation on the influence of the proposed TAS/MRC scheme and outdated CSI, we further present tractable asymptotic SOP at high SNR regimes. From the analysis, we derive that outdated CSI will affect SOP by decreaseing the secrecy coding gain of TAS/MRC scheme. In addition, the RaF relaying strategy can achieve better secrecy performance than that of DF relaying strategy for dual-hop cognitive MIMO wiretap networks.