Radio interferometric geolocation

TLDR

The paper introduces a novel radio interference–based sensor localization method for wireless sensor networks. The method uses two nodes transmitting at slightly different frequencies to generate a low‑frequency envelope whose phase offset measured at two receivers encodes the distances among four nodes, and by collecting multiple such measurements in networks of at least eight nodes the relative 3‑D positions can be reconstructed. Prototype tests on MICA2 nodes achieved an average localization error of only 3 cm over ranges up to 160 m, demonstrating high precision, long range, and the advantage of requiring no additional sensors beyond the communication radio.

Abstract

We present a novel radio interference based sensor localization method for wireless sensor networks. The technique relies on a pair of nodes emitting radio waves simultaneously at slightly different frequencies. The carrier frequency of the composite signal is between the two frequencies, but has a very low frequency envelope. Neighboring nodes can measure the energy of the envelope signal as the signal strength. The relative phase offset of this signal measured at two receivers is a function of the distances between the four nodes involved and the carrier frequency. By making multiple measurements in an at least 8-node network, it is possible to reconstruct the relative location of the nodes in 3D. Our prototype implementation on the MICA2 platform yields an average localization error as small as 3 cm and a range of up to 160 meters. In addition to this high precision and long range, the other main advantage of the Radio Interferometric Positioning System (RIPS) is the fact that it does not require any sensors other than the radio used for wireless communication.