Multiple antenna spectrum sensing for cognitive radios in unknown noise

Recently several time-domain approaches relying on the generalized likelihood ratio test (GLRT) paradigm have been proposed for multiple antenna spectrum sensing in cognitive radios. These approaches are suitable for flat-fading channels in white noise with equal noise variances across antennas; knowledge of the noise variance is not required, unlike the energy detector. In this paper we investigate a method based on analysis of the multivariate power spectral density (PSD) of the received multiantenna signal. Our proposed approach is also based on GLRT and flat-fading channels, but it allows the noise variances to be different at different antennas without requiring knowledge of their values. A performance analysis of the proposed detector is carried out. Simulation examples are provided in support of the proposed approach.