Primary user DoA and RSS estimation in cognitive Radio networks using sectorized antennas

Received-signal-strength (RSS) and direction-of arrival (DoA) are the sufficient measurements to solve the primary user localization problem in cognitive radio networks. In this paper we consider using energy measurements from sectorized antenna to estimate RSS and DoA of a primary user. Abstracting from practical antenna types, we define a sectorized antenna as an antenna that can be set to different operating modes, each of which resulting in a selectivity of those signals that arrive from within a certain, continuous range of angles, i.e. a sector. We first characterize the achievable performance of RSS and DoA estimations using energy measurements from sectorized antennas by means of the Cramer-Rao Bound (CRB), which provides a lower bound on the estimation accuracy of any unbiased estimator. We then propose a practical RSS and DoA estimator, namely the simplified least squares (SLS) algorithm. The SLS algorithm minimizes a cost function obtained from two largest energy measurements among all sectors, and its accuracy closely approaches the CRB. Simulation results studying the impact of important system parameters, such as SNR, number of sectors and number of samples, on the achievable accuracy specified by the CRB and the SLS algorithm are presented.