International Journal of Applied Engineering Research ISSN 0973-4562 Volume 14, Number 8 (2019) pp. 2002-2008 © Research India Publications. http://www.ripublication.com 2002 Target Localization Scheme for Underwater Acoustic Sensor Network Mitali Patel 1 , Prof. Pritesh Saxena 2 , Prof. Chintan Panchal 3 1,2 Electronics & Communication Department, SCET, Surat, India. Abstract As electromagnetic waves do not propagate well underwater, acoustics plays a key role in underwater communication. Due to significant differences in the characteristics of electromagnetic and acoustic channels, networking protocols for underwater systems differ from those developed for wired and wireless radio networks. In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two dimensional and three dimensional underwater sensor networks are discussed, and the characteristics of the underwater channel are detailed. Underwater sensor network removes large and expensive equipment used in ocean monitoring. In UWSN, localization of sensor node is a major problem. Localization is mostly used for presentation of the collected data, tracking the location of underwater nodes, underwater target’s location detection and a group of node’s motion coordination. Localization generally requires object with known location or distance and angle measurement between these known nodes and the object to the unknown nodes. The position of sensor node is predicted by using the reference of the position of neighbor nodes which are having static or mobile behavior. Accurate prediction of location and the localization technique is appropriate for UWSNs [5]. Keywords: Underwater Sensor Network, Localization of UWSN, Acoustic Communication, Fault Tolerance. I. INTRODUCTION Underwater Acoustic Sensor Networks (UWASN) is emerging technology that enables timely and effective exploring and monitoring of world under the surface of the water. It enables a wide range of applications like environmental monitoring, ocean sampling networks, disaster prevention and distributed tactile surveillance. The most important advantage of underwater sensor network is the underwater sensor nodes are small and less expensive which are capable of communicating with one another using acoustic signal. Underwater acoustic communication is a technique of sending and receiving messages below water. There are several ways of employing such communication but the most common by using hydrophones. Underwater communication is difficult due to factors such as multipath propagation, time variations of the channel, small available bandwidth and signal attenuation, over a long ranges. Compared to terrestrial communication, underwater - communication has low data rates because it uses acoustic waves instead of electromagnetic waves. In UWSN, localization of sensor node is a major problem. Localization is mostly used for presentation of the collected data, tracking the location of underwater nodes, underwater target’s location detection and a group of node’s motion coordination. Localization generally requires object with known location or distance and angle measurement between these known nodes and the object to the unknown nodes. Accurate prediction of location and the localization technique is appropriate for UWSN. In an Adaptive localization scheme with minimum communication and GPS support is required [5].Radio signal cannot propagate in underwater environment and hence use of GPS is not possible. In underwater environment, a sensor node knows location of Anchor nodes. If an anchor node failure occurs, a sensor node predicts its position by learning the mobility behaviour of its neighbors using multiple linear regression (MLR).Therefore the data dissemination process can continue even after an unexpected case of anchor node failure. The design of wireless sensor network depends on the following parameters:  Environment  System Constraints of limited energy resources, communication range, bandwidth, processing and storage of each node.  Cost simulators and models  Hardware platform  Application domains The underwater sensors are equipped Autonomous Underwater Vehicles (AUVs) which are find various applications such as exploring the natural under sea resources and the scientific data is gathered for monitoring. A. Difference between Terrestrial and Underwater Sensor Networks: The terrestrial sensor networks are designed to operate on the land. It needs air as communication channel for communication. A typical terrestrial sensor network composed of transmitter and receiver part. It uses electromagnetic radio waves for carrying the information of data and voice. Wireless sensor network uses wide number of sensor nodes and hence uses high amount of energy. Traditional routing protocols of WSN [10] cannot be applied directly to UWSN. The following points indicates the major difference between Traditional WSN and UWSN,  Deployment: The underwater sensor network is easily expand whereas the terrestrial sensor networks are heavily deployed.