Optimal Detection of Faded Pilot Signal in MIMO Channels with Applications in Cognitive Radio Systems

Multiple transmit and receive antenna arrays can be used to form MIMO systems to improve spectrum sensing cycle of recently proposed cognitive radio (CRs) systems by utilizing diversity and/or multiplexing techniques. This paper designs an optimal spectrum detection for multiple antenna CR with a multiple antenna primary user as a backhand licensed network while the primary network protocol uses preamble or pilot signal. The MIMO channel between the primary and secondary users is modeled by Rayleigh distribution with arbitrary coherence time which is proper for slow to fast fading environments. In this situation, optimal detector is presented and closed-form expressions for probability of detection and false alarm are derived. Analytical and simulation results demonstrate that the performance of the proposed scheme outperforms other existing suboptimal detectors.