A Survey on TOA Based Wireless Localization and NLOS Mitigation Techniques

TLDR

Time‑of‑arrival (TOA) wireless localization has been extensively studied, yielding diverse algorithms with varying accuracy, complexity, and robustness to non‑line‑of‑sight (NLOS) bias, yet a comprehensive unified survey of these methods is lacking. This survey reviews TOA‑based localization algorithms and their NLOS mitigation techniques, highlighting technical challenges and suggesting future research directions. The authors summarize fundamental lower bounds and near‑optimal estimators for LOS scenarios, present lower bounds for NLOS systems, classify mitigation techniques, and compare their performance through simulations. The survey concludes with a comparative table summarizing the key characteristics of the investigated localization and NLOS mitigation techniques.

Abstract

Localization of a wireless device using the time-of-arrivals (TOAs) from different base stations has been studied extensively in the literature. Numerous localization algorithms with different accuracies, computational complexities, a-priori knowledge requirements, and different levels of robustness against non-line-of-sight (NLOS) bias effects also have been reported. However, to our best knowledge, a detailed unified survey of different localization and NLOS mitigation algorithms is not available in the literature. This paper aims to give a comprehensive review of these different TOA-based localization algorithms and their technical challenges, and to point out possible future research directions. Firstly, fundamental lower bounds and some practical estimators that achieve close to these bounds are summarized for line-of-sight (LOS) scenarios. Then, after giving the fundamental lower bounds for NLOS systems, different NLOS mitigation techniques are classified and summarized. Simulation results are also provided in order to compare the performance of various techniques. Finally, a table that summarizes the key characteristics of the investigated techniques is provided to conclude the paper.