Underwater Target Location Estimator Network Using Array-TDOA Algorithm

Underwater target localization encounters different challenges compared to free-space networks. Variable sound speed in an underwater medium and low propagation speed of acoustic waves are fundamental challenges of underwater communications. This paper aims to present a location estimator network for an underwater target using sensor arrays and propose the Array-TDOA location estimation algorithm. For this purpose, the challenges of the variable sound speed in underwater medium and the sensors’ asynchrony with the target are examined. By considering these challenges, a network structure using sensor arrays is presented which has the capability of location estimation of an asynchronous underwater target. In the presented network, beamforming in an inhomogeneous underwater medium and the Array-TDOA algorithm is applied to estimate the target location. Moreover, the Cramer-Rao lower bound (CRLB) is computed. Then, the location estimation error of the proposed method based on the RMSE criterion is computed and compared with that of the TDOA methods for homogeneous and also TOA method for inhomogeneous environments through computer simulations in MATLAB. Simulation results indicate that the proposed approach, which considers the inhomogeneity challenge in beamforming and location estimation is more accurate, approximately nine times the accuracy of TDOA based method for homogeneous environments. Moreover, the results reveal that the increase in the number of sensors arrays from 4 to 25 leads to the same estimation error by consuming 33% less SNR.