Date Added: Feb 2012
In this paper, the authors analyze the problem of localizing and tracking a mobile node in an underwater environment with an iso-gradient Sound Speed Profile (SSP). They will show that range-based localization algorithms are not so accurate in such an environment, and they should be replaced by time-based ones. Therefore, they relate the mobile node location to the travel time of a propagating sound wave from (to) an anchor node to (from) the mobile node. After obtaining sufficient time measurements, positioning can be achieved through multilateration. To accomplish this, they utilize the Extended Kalman Filter (EKF) for multilateration and tracking the mobile node's location in a recursive manner.