Underlay Cognitive Radio With Instantaneous Interference Constraint: A Secrecy Performance

We examine the secrecy performance of the receive antenna selection scheme in interference-limited underlay cognitive radio network (CRN) where the antenna that results in the highest signal-to-interference ratio at the secondary receiver is chosen to improve the secrecy performance of the secondary transmission. Exact and asymptotic expressions for the secrecy outage probability and intercept probability are derived for an interference-limited scenario over a general fading scenario with the assumption that the channel state information (CSI) on the secondary transmitter (ST)- primary receiver (PR) channel is perfect. However, CSI on the ST-PR channel may be outdated due to the time-varying properties or feedback latency from the PU. If the ST allocates transmission power using this outdated CSI, PR's interference constraint will not be satisfied. Therefore, we investigate the impact of outdated CSI on the secrecy performance of an interference-limited CRN when interference from the primary transmitter to SU exits under peak interference power constraint.