TOA and TDOA-Based Passive Localization Using AIS Signals for Maritime Surveillance

This paper investigates passive localization techniques that utilize physical-layer measurements, specifically Time of Arrival (TOA) and Time Difference of Arrival (TDOA), extracted from Automatic Identification System (AIS) signals intercepted by the Italian AIS Base Station network. The study evaluates three localization algorithms, viz. two classical Least Squares (LS) estimation methods based on TOA and TDOA measurements, and a Constrained Least Squares (CLS) algorithm employing TDOA measurements that integrates bespoke constraints to improve estimation accuracy. Experimental validation using measured AIS data demonstrates that the CLS-TDOA algorithm outperforms the classical LS approaches, providing enhanced positioning accuracy and robustness.