3858 Category: Mobile & Wireless Computing Underwater Wireless Networking Techniques Manuel Perez Malumbres Miguel Hernandez University, Spain Pedro Pablo Garrido Miguel Hernandez University, Spain Carlos Tavares Calafate Technical University of Valencia, Spain Jose Oliver Gil Technical University of Valencia, Spain INTRODUCTION Underwater sound has probably been used by marine speci- mens for millions of years as a communication capability among the members of a same species. It is said that in 1490, Leonardo Da Vinci wrote the following sentence: “If you cause your ship to stop and place the head of a long tube in the water and place the outer extremity to your ear, you will hear ships at a great distance from you” (Urick, 1983); being perhaps the first recorded experiments about hearing underwater sounds. In 1826 on Lake Geneva, Switzerland, the physicist Jean-Daniel Colladon, and his mathematician friend Charles-Francois Sturm, made the first recorded attempt to determine the speed of sound in water. In their experiment, the underwater bell was struck simultaneously with ignition of gunpowder on the first boat. The sound of the bell and flash from the gunpowder were observed 10-miles away on the second boat. The time between the gunpowder flash and the sound reaching the second boat was used to calculate the speed of sound in water. Colladon and Sturm were able to determine the speed of sound in water fairly accurately with this method. (Colladon, 1893). This experiment on sound propagation through water laid the foundation for underwater acoustic technology, which paved the way for the development of this technology up to our days. In 1906, Lewis Nixon invented the very first sonar-type listening device, increasing the demand of this technology during World War I to detect submarines. In 1915, the physicist Paul Langévin and the engineer Constantine Chilowski, invented the first sonar-type device for detecting submarines, called an “echo location to detect submarines,” using the piezoelectric properties of the quartz. He was too late to offer any help to the war effort; however, Langévin’s work heavily influenced future sonar designs. After using underwater sound technology for measuring the proximity to the shore and other ships, researchers soon realized that, if the sound device was pointed down at the seafloor, the depth could be accurately determined. So, new applications of sonar devices were discovered, like active depth measuring (bathymetry), seafloor shape registering, search for geological resources (i.e., oil, gas, etc.), detect- ing and tracking fish banks, submarine archaeology, and so forth. Although the underwater acoustic applications were mainly focused in ranging applications, exploration of sea- floor and fishery by means of sonar devices, the interest in underwater multipoint communications was stressed in the 1990’s, where synoptic, spatially sampled oceanographic surveillance has provided an impetus to the transfer of networked communication technology to the underwater environment. One of the former deployments was the au- tonomous oceanographic surveillance network (AOSN), supported by the US Office of Naval Research (ONR) (Curtin, Bellingham, Catipovic, & Webb, 1993). It calls for a system of moorings, surface buoys, underwater sensor nodes, and autonomous underwater vehicles (AUVs) to coordinate their sampling via an acoustic telemetry network. BACKGROUND Wireless networking technologies have experienced a con- siderable development in the last 15 years, not only in the standardization areas, but also in the market deployment of a bunch of devices, services, and applications. Among this plethora of wireless products, wireless sensor networks are exhibiting an incredible boom, being one of the technologi- cal areas with greater scientific and industrial development pace (Akyildiz, Sankarasubramaniam, & Cayirci, 2002). The interest and opportunity in working on wireless sen- sor network technologies is endorsed by (a) technological indicators like the ones published by MIT (Massachusetts Institute of Technology) in 2003 (van der Werff, 2003), Copyright © 2009, IGI Global, distributing in print or electronic forms without written permission of IGI Global is prohibited.