Estimating DoA From Radio-Frequency RSSI Measurements Using an Actuated Reflector

We describe a proof-of-concept device and method to estimate the direction-of-arrival (DoA) of a radio signal by a receiver that is suitable for wireless sensor network (WSN) applications. The device estimates the DoA by identifying the peak of received signal strength indicator (RSSI) measurements using an actuated parabolic reflector. Automatic localization is an important requirement for deployment of wireless sensor networks. Localization from distance measurement alone is a challenging problem, but becomes easier if relative angular position measurements between pairs of radio nodes are available. Methods of DoA estimation such as phased arrays are unsuitable for wireless sensor networks due to size, cost and complexity limitations. The device and the algorithm we describe is compact and simple enough to be suitable for WSNs. Experimental results show that the error in the measured DoA has a mean smaller than 4° and standard deviation of smaller than 8°, in both indoor and outdoor environments in line of sight situations. Presence of moving objects in the vicinity of the transceivers seem to have an adverse effect of the measurement accuracy.