IEEE COMMUNICATIONS LETTERS, VOL. 17, NO. 4, APRIL 2013
Abstract—In this letter, we study quickest spectrum sensing for cognitive radios with multiple receive antennas in Gaussian and Rayleigh channels. We derive the probability density function for the fading case and analytically compute the upper bound and asymptotic worst-case detection delay for both of the cases. The extension into multiple antennas allows us to gain insights into the reduction in detection delay that multiple antennas can provide. Although sensing in a Rayleigh channel is more challenging, good sensing performance is still demonstrated. Index Terms—Cognitive radio, quickest spectrum sensing, CUSUM, multiple antennas, Gaussian channel, Rayleigh channel.