Temporal Link Signature Measurements for Location Distinction

We investigate location distinction, the ability of a receiver to determine when a transmitter has changed location, which has application for energy conservation in wireless sensor networks, for physical security of radio-tagged objects, and for wireless network security in detection of replication attacks. In this paper, we investigate using a measured temporal link signature to uniquely identify the link between a transmitter (TX) and a receiver (RX). When the TX changes location, or if an attacker at a different location assumes the identity of the TX, the proposed location distinction algorithm reliably detects the change in the physical channel. This detection can be performed at a single RX or collaboratively by multiple receivers. We use 9,000 link signatures recorded at different locations and over time to demonstrate that our method significantly increases the detection rate and reduces the false alarm rate, in comparison to existing methods. We present a procedure to estimate the mutual information in link and link signature using the Edgeworth approximation. For the measured data set, we show that approximately 66 bits of link information is contained in each measured link signature.