Localization and mobility of underwater acoustic sensor nodes

The Underwater Acoustic Sensor Network (UASN) is a network which consists of underwater wireless sensor nodes distributed randomly over the certain area of observation and communicate with each other using acoustic signals. UASN can be used in a wide variety of underwater applications, ranging from marine biology surveillance to earthquake and tsunami alert applications. Despite the fact that sensor networks are meant to collect data, in some applications, collection of data without a location of the occurrence becomes incoherent. Hence, localization for UASN has become an enthralling research topic in the recent years. However, there are several disadvantages of acoustic channel like propagation delay, limited energy sources, high bit error rate, and limited harvesting techniques underwater make the localization of UASN very challenging. Therefore, in this paper we have proposed a distributed localization scheme which employs two-way time of arrival estimation method to calculate distance and avoid the requirement of time synchronization