AoD-based Positioning for Wi-Fi OFDM Receivers

Wi-Fi client self-positioning based on estimated azimuth and elevation angles of departure ( AoD), is presented. The devised method takes advantage of the Wi-Fi OFDM symbol structure, and enables an unlimited number of ( single-antenna) Wi-Fi client stations operating simultaneously, to obtain a simple and direct estimate of the transmitted signal AoD. Unlike other AoD positioning methods, the method outlined eliminates the client's need to estimate any signal phase differences. The transmitter applies different beamforming to the modulating signal of each OFDM tone, thereby effectively steering its array beam to a different direction for each tone. Furthermore, the burden of calibrating and compensating for the transmitter's array spatial response is undertaken by the transmitter itself. The following paper formulates the problem and outlines the beamforming criteria, for which numerical performance analysis results are presented.