A TOA-Based Localization Algorithm With Simultaneous NLOS Mitigation and Synchronization Error Elimination

Time of arrival (TOA) is one of the most commonly used localization techniques in wireless networks. However, it requires strict time synchronization between source and base stations or anchor nodes, and nonline-of-sight (NLOS) propagation significantly degrades the localization accuracy. In this article, the condition of perfect time synchronization is relaxed, and synchronization error is introduced into TOA-based NLOS localization model, which can be suitable for a asynchronous wireless network. A simultaneous NLOS mitigation and synchronization error elimination localization algorithm consisting of two steps is proposed. In the first step, by defining two new variables, we transform nonlinear range measurements into linear forms and construct a quadratic programming model. In the second step, by analyzing the error vector and the nonlinear relation among variables, a linear model is derived. Simulation results show that the proposed algorithm outperforms the existing algorithms in different NLOS conditions. Average location error of our proposed algorithm is below 100 m when the maximum NLOS error is 100 m and synchronization error is 1 μs. Moreover, compared with the existing algorithms, the localization accuracy of our proposed algorithm is improved by more than 50% on average. Further, the computational complexities of different algorithms are analyzed and compared.