Single-anchor localization in inductively coupled sensor networks using passive relays and load switching

Wireless physical layers based on inductive coupling are receiving attention in the context of RFID and, more recently, sensor networks. In this work we present the first method for localization in inductively coupled networks which only requires a single anchor. The utilization of passive relays with known positions resolves the associated problem of localization ambiguity. We demonstrate that a single impedance measurement can be sufficient to locate a node in two dimensions. Localization performance can further be increased by deterministic load switching. Numerical results indicate that a median localization error in the millimeter range is possible under realistic conditions.