A Mobile-Anchor-Based Underwater Node Localization Mechanism With Improved Particle Swarm Optimization Algorithm

To mitigate the impact of the stratification effect, clock asynchrony, and measurement noise on underwater node localization while overcoming the restriction of the limited energy of unlocalized nodes, we propose a mobile-anchor-based underwater node localization mechanism. Specifically, we first utilize the information periodically broadcast by vertically mobile anchor nodes to calculate the clock skew and the time difference of arrival (TDoA). Then, we use the analytical expression of propagation delay based on an isogradient sound speed profile to compute the estimated TDoA, leading to the formulation of an optimization problem for node localization. Finally, we design an adaptive particle swarm optimization algorithm based on fitness value (APSO-F) to obtain the position of unlocalized nodes efficiently. Simulation results demonstrate that, compared with other localization solutions, the proposed mechanism effectively alleviates the influence of various unfavorable factors, ensuring high-precision node localization by one-way communication with anchor nodes, and APSO-F exhibits a superior convergence rate compared to the ordinary adaptive particle swarm optimization algorithm.