Direction of Arrival Based Positioning in Three Dimensional Coordinates

In this paper we study the potential of Direction of Arrival (DoA) estimation for positioning in future cellular networks. The accurate DoA estimation is enabled by large array antennas considered in present and next standards. The position in three dimensional space is derived based on the known position of two Base Stations and their DoA estimates. Due to uncertainty these DoA estimates result to skew lines and the estimated position is obtained from the shortest distance between these skew lines. A closed form expression taking into account array orientations is provided in this work. Numerical results confirm that with DoA based localization in cellular networks areas exist where large estimation errors are caused by Dilution of Precision (DoP). A main finding of this work is that by average of multiple narrowband measurements, large estimation errors caused by DoP can be significantly reduced. This requires no additional signaling or change in the network.