Dual-Tone Radio Interferometric Positioning Systems Using Undersampling Techniques

High accuracy and low cost are challenging requirements for localization in wireless sensor networks (WSNs). The radio interferometric positioning system (RIPS) proposed in aims to meet both requirements at the same time. However, it is vulnerable to channel fading, and suffers from the noise aggravation due to the square operation. In this paper, we propose a dual-tone radio interferometric positioning system (DRIPS) using undersampling techniques, named uDRIPS. Our proposed methodology is immune to flat fading effects, and avoids the amplification of measurement noise by directly undersampling the received signal. Furthermore, the time-of-arrival (TOA) information is extracted from the phases of the received dual-tone signals in the uDRIPS. As a result, it is able to localize an asynchronous target with the help of synchronous anchors (nodes with known positions). Moreover, we investigate the integer ambiguity problem due to phase wrapping, and develop a localization algorithm to estimate the unknowns alternatively. Simulation results corroborate the efficiency of our proposed algorithm.