Paper Title
Survey on Multiple User Spectrum Sensing in the Low SNR Regime (Spherical Detector Approach)

This paper presents multi-antenna cooperative spectrum sensing in cognitive radio networks, when there are multiple primary users and/or multipath channels. A noise-uncertainty free detector that is optimal in the low signal to noise ratio regime is analysed. We derive the moments of the test statistics involved, which lead to simple and accurate analytical formulae for the key performance metrics. The approximate false alarm and detection probabilities as well as receiver operating characteristic are given in closed form. From the considered simulation settings, performance gain over several known detection algorithms is observed in scenarios with relatively low signal to noise ratio. We map the problem of multi-sensor spectrum sensing in a multipath multi-primary scenario to a purely multi-primary one. Then we propose the optimal low SNR detector for multi-primary user sensing. Performance analysis of the proposed detection algorithm is addressed. A spherical test based detection algorithm has been proposed for multi-primary spectrum sensing. Although this detector is the best known multiple primary user detector, it is not the optimal one in the low Signal-to-Noise Ratio (SNR) regime. Index Terms— Signal to Noise Ratio, Cognitive Radio, Multipath-Antenna.