An Improved TDoA Localization Algorithm Based on AUV for Underwater Acoustic Sensor Networks

Now localization is one of the major issues in underwater environment work. In terrestrial application, time different of arrival (TDoA) localization algorithm has been widely used. However, most localization systems rely on radio or optical signals while they cannot propagate well in water. Therefore, with complicated environment in underwater acoustic sensor networks (UASNs), traditional TDoA localization algorithm suffers various unstable factors, such as they can only work in a finite region or need clock synchronization. In this paper, we propose an improved TDoA localization algorithm (ITLA) based on AUV for UASNs. The mobile AUV first finds its own accurate three-dimensional coordinates in the surface with the help of GPS or other terrestrial location systems. Then we deployed AUV at predefined depth in underwater as reference nodes. AUV periodically sends packets with coordinates information to unlocalized nodes in different positions. After receiving data and a series of calculation, we quantify the conditions for unique localization and propose another condition to evaluate the reliability of results. This algorithm can achieve relatively higher accuracy with relatively smaller calculation and overcome some traditional localization drawbacks. We demonstrate the trade-offs between location coverage, the cost in placing reference nodes, and energy consumption.