Directional Spectrum Sensing for Cognitive Radio Using ESPAR Arrays with a Single RF Chain

In this paper, we propose to use the electronically steerable parasitic array radiator (ESPAR) antenna, which relies on a single radio frequency (RF) front end coupled with a number of parasitic elements to steer beams in prescribed directions in the angular domain on a time division basis, to identify the directional spectrum sensing opportunities for cognitive radios. In particular, we propose a two stage spectrum sensing: First ESPAR signal measurements from different directional beam-patterns are fed as input to the generalized likelihood ratio test (GLRT) algorithm to detect the existence of primary user signals. If signal existence is detected by the GLRT, then the directional measurements are used to obtain the direction of arrival (DoA) using a multiple signal classification (MUSIC) algorithm. We show that the DoA estimation performance using the ESPAR is comparable to that of the traditional uniform linear array when the signal-to-noise ratio (SNR) is larger than -15dB.