Study On Clustering Protocols For The Underwater Acoustic Sensor Networks

With the rapid development of underwater acoustic communication technology, more and more research attention has been attracted to the area of Underwater Acoustic Sensor Networks (UWASN). UWASN which combines the terrestrial wireless sensor network technology with underwater acoustic communication technology has a wide range of applications, such as underwater information collection, environmental monitoring and assisted navigation. However, the technologies or protocols that are suitable for the terrestrial wireless sensor networks cannot be applied to UWASN directly because of the huge differences between the underwater acoustic environment and the terrestrial environment. The harsh conditions of the underwater environment, such as high propagation delay, narrow bandwidth, multiple propagation, bring many challenges to the UWASN technology and the corresponding network protocols design.The energy of sensor nodes in UWASN is very precious for these nodes are powered by batteries. As an energy efficient clustering protocol, the LEACH protocol can not only reduce the network energy consumption but also balance the energy consumption between nodes, then the network lifetime can be prolonged significantly. This dissertation presents two improved methods to solve the problems and shortcomings of the LEACH when it is applied to underwater environment. These two proposed clustering protocols are S-LEACH and C-LEACH, respectively, which are more suitable for the underwater environment.In this dissertation, firstly, relevant knowledge of UWASN is introduced, including shallow water channel, network topology, network layering with corresponding key technology. Secondly, an introduction of the network simulator NS2which is the simulation tool in this dissertation is presented, and the underwater environment platform in NS2.28is built. Thirdly, the energy-efficient protocol, LEACH, is introduced simply and a survey of underwater LEACH protocols is made. In addition, the problems and shortcomings of these underwater LEACH protocols are analyzed, then two improved protocols are proposed in order to save the network energy consumption and prolong the network lifetime. Fourthly, the LEACH module is added into the simulation tool NS2.28, then C++and Otcl programs for the S-LEACH and C-LEACH modules are written in NS2.28. Finally, the simulation script files are programmed based on the experimental requirements. Simulation results show that the proposed protocols can save the network energy and prolong the network lifetime significantly when compared to the LEACH protocol.