RF angle of arrival-based node localisation

Several localisation algorithms exist for wireless sensor networks that use angle of arrival measurements to derive node position. However, there are limited options for actually obtaining the angle of arrival using resource-constrained devices. In this paper, we describe a technique for determining node bearings based on radio interferometric angle of arrival measurements from multiple anchor nodes to any number of target nodes at unknown positions. Least squares triangulation is then used to estimate node position. The position estimation is carried out by the node itself, hence the method is distributed, scalable, and fast. Furthermore, this technique does not require modification of the mote hardware because it relies only on the radio. Experimental results demonstrate that our approach can estimate node bearing with an average accuracy of 3°, and node position with sub-metre accuracy in approximately 1 s.