Spherical Wave Positioning Based on Curvature of Arrival by an Antenna Array

Array processing is a key technology for emerging mobile networks, especially in short to moderate range and line-of-sight scenarios. In these scenarios, the incoming wavefront can be modeled by a spherical wave. The wavefront curvature, i.e., curvature of arrival (CoA), contains position information of the transmitter and is observable by an antenna array potentially asynchronous and non-coherent to the transmitter. We derive a simplified expression of the spherical wave positioning (SWP) Cramér-Rao bound for arbitrary centro-symmetric arrays, which provides a geometrical inference about the achievable performance. Additionally, a low complexity CoA positioning algorithm is proposed. In contrast to conventional methods, the proposed algorithm requires neither multiple anchors nor coordination between devices. It also outperforms the Fresnel approximation based SWP algorithms by overcoming the model mismatch. Therefore, the proposed CoA positioning algorithm is promising for precise positioning in future mobile networks.