Sensorless Sensing in Wireless Networks: Implementation and Measurements

Multipath fading and shadowing are usually regarded as negative phenomena hindering proper radio communication. Adopting a completely different stance, this paper illustrates that such phenomena enable information harvesting from received signal strength leading to a number of original applications requiring no conventional sensing hardware. The radio itself, provided that it can measure the strength of the incoming signal, is the only sensor the authors use; with this sensorless sensing approach, any wireless network becomes a sensor network. The authors show that motion of the nodes in the network or motion of bodies external to the network leaves a characteristic footprint on signal strength patterns, which may be exploited for motion detection.