A Fractional Programming Method for Target Localization in Asynchronous Networks

In this paper, we address the target device localization problem in the asynchronous networks. For the purpose of saving power resources, the target device is not synchronized with the anchor nodes, but is only required to listen to the signals transmitted from the anchors, which, however, introduces two extra nuisance parameters: the target’s clock skew and clock offset. By transforming the time-of-arrival measurements into time-difference-of-arrival measurements, the clock offset of the target’s clock is eradicated. However, there still exists the unknown clock skew, which may degrade the localization performance. Since the range of the clock skew is usually known as a priori, we assume that it follows a uniform distribution within this range. By doing so, we take it as a part of measurement noise and estimate the target node position only. To estimate the target node position, we formulate a fractional programming problem and further show that it can be solved by solving one single mixed semidefinite and second-order cone program (SD/SOCP). Simulation results illustrate the superior performance of the proposed method over the existing methods.