An Energy Efficient Distributed Localization Scheme for Underwater Acoustic Sensor Network

Underwater acoustic sensor network (UASN) is proven to be enabling technology for a variety of applications such as naval surveillance, oil platform monitoring, earthquake and tsunami forewarning and scientific and commercial exploitation of the ocean. UASN is formed by wireless sensor nodes distributed over a certain area within the underwater environment and communicating via acoustic signal. Unlike terrestrial wireless sensor network, GPS cannot be used in underwater environment as it requires line of sight communication with the satellites. On the other hand, radio frequency (RF) signal suffers from many anomalies in underwater environment. In spite of the data centric nature of the UASN, sometimes data without its location of occurrence is meaningless. Localization is one of the fundamental topics being researched by many institutes. Several limitation of acoustic channel like low bandwidth, high bit error rate etc. as well as node mobility poses challenge to UASN. This thesis proposes an event based energy efficient localization scheme for UASN using three-dimensional recursive estimation process. The concept of localization confidence threshold has been used to restrict error to a certain level with the cost of the localization success ratio. The simulated results show that number of localized nodes increases with decreasing confidence value. Basically, all the results presented in this thesis demonstrate the impact of the localization confidence threshold to the different types of simulation output.