In this paper, a novel switched hardware approach to angle of arrival (AoA) estimation in radio systems that signal using quadrature amplitude modulations (QAM) is presented. The proposed algorithm, namely constellation statistical pattern identification and overlap (CSP-IDO), is based on the comparison of the probability density functions of successive signal snapshots from antennas (asynchronous approach). Contrariwise, other AoA techniques such as differential methods, beamforming and MUSIC techniques are designed to acquire in parallel signals from the antennas (synchronous approach). CSP-IDO allows a significantly reduced hardware usage with respect to synchronous methods, without deteriorating precision. The proposed algorithm used with a time switched antenna approach leads to better performance in terms of overall hardware complexity, power consumption and possibly costs. Furthermore, CSP-IDO is robust to transmitter hardware impairments with respect to synchronous methods.
