Performance Analysis of Primary User Detection in a Multiple Antenna Cognitive Radio

We consider the problem of detecting a primary user signal over a wireless channel by a cognitive radio with multiple antennas. We present a multiple antenna processing based energy detector. In this detection method, the multiple copies of the primary user signal at the antennas of the cognitive radio receiver are combined and input to an energy detector. We consider two multiple antenna processing methods and analyze their detection performance - the achieved probability of detection for a pre-specified probability of false alarm and given signal-to-noise ratio. We derive closed-form expressions for the probabilities for detection and false alarm for each of the processing schemes. Finally, we show through numerical results the potential improvement in primary user detection with multiple antenna processing based energy detection at the cognitive radio receiver.