Underwater sound speed profile parameters estimation in asynchronous network

Abstract

The technology of underwater wireless acoustic sensor networks (UWSNs) plays an important role in many commercial and military applications in underwater. In UWSNs, there exist many challenges posed by the specific characteristics of underwater acoustic channel, such as sound propagation speed is a function of depth with unknown parameters. Besides, time synchronization of anchor nodes is a crucial part of the applicable network. Time synchronization of anchor nodes as well as estimation of sound speed parameters considering an isogradient profile is explored here. While the previous efforts do not take into account these factors, this article assumes only one synchronized anchor node in the network and enables joint synchronization of the other anchor nodes and the estimation of the propagation delays between the anchor nodes using a weighted linear least square solution. Then, it uses the estimated propagation delays to estimate the unknown parameters of the sound speed profile using a conventional Gauss‐Newton algorithm with approximately three iterations to converge. Validation of the proposed method is done by the numerical simulations and to demonstrate the effectiveness of the proposed method we compare the results with Cramer‐Rao bound average.