Spectrum sensing based on estimation of direction of arrival

Spectrum sensing is one of the most important components for the establishment of cognitive radio (CR) system. The traditional spectrum sensing technology is to detect that a band of frequencies is occupied or not by the primary user of that band at the appointment time and location. However, with multi-antenna technologies, e.g. beamforming, multiple users can be multiplexed into the same channel at the same time in same geographical areas. In this paper, an angle dimension is introduced into the detection algorithm as a new spectrum opportunity. The Ratio of maximum to minimum eigenvalue (MME) detector is applied to detect the presence of primary signal, and then the MUSIC algorithm is involved into the direction-of-arrival (DOA) estimation of the primary signal. It is obviously demonstrated by the simulation results that the proposed method has the more spectrum sensing opportunities without interference to the primary user.