Transceiver-Aided Localization by Hybrid Time Delay and Angle Measurements in Direct-LOS Absent Environments
Danyan Lin, Gang Wang, K. C. Ho · IEEE Transactions on Wireless Communications · 2025
When we try to locate an object in a crowded urban area or an obstacle-rich environment, direct line-of-sight (LOS) propagation is usually absent and the Global Navigation Satellite System (GNSS) is often denied. In such a difficult scenario, we employ a moving transceiver that exhibits LOS propagations to connect the object and each sensor to determine its location. On the other hand, the transceiver positions and velocities are not known due to unreliable GNSS signals, which creates an extra level of challenge to the problem. By collecting the time delay and angle-of-arrival (AOA) sensor measurements with the object, two methods are proposed to address this localization problem. The first solution is efficient in computation; it linearizes the measurement model and obtains the transceiver parameters and object position by two linear weighted least squares (LWLS) estimators. The second method is resilient against large measurement noise; it solves the problem using semidefinite programming optimization by applying semidefinite relaxation. Both solutions are suboptimal due to the linearization or relaxation errors and they are refined by a separate LWLS estimator to improve the accuracy. Additionally, the theoretical analyses include the derivation of the Cramér-Rao lower bound, the contribution of AOA to the localization performance, the effect of the number of transceivers on the positioning accuracy, and the optimality of the proposed methods after refinement. The algorithms developed and the analyses performed are supported by simulations.