Research Of Reliable Routing Protocols For Underwater Acoustic Sensor Networks

Underwater acoustic networks (UANs) are newly arisen network technique. They are generally formed by acoustically connected ocean bottom sensor nodes, autonomous underwater vehicles (AUVs), and surface stations that serve as gate-ways and provide radio communication links to on-shore stations, which are kinds of underwater wireless communication network. They are deployed to perform collaborative monitoring tasks over a given area. Underwater communication applications mostly involve long-term monitoring of selected ocean areas, which will find applications in disaster prevention, object localization and tracking, oceanographic data collection and tactical surveillance applications. More and more researchers from academic world and military world are engaged in the development of UWA due to the great promise and potential in many application areas.Due to the complicated of underwater channel, the links between any nodes are subjected to noise interference, large Doppler shifts and spreads. These characteristics seriously affect the data transmission rate, reliable data communication, available radio range, the throughput of network and energy expended in UWA. Therefore, a routing protocol design must ensure that a network can achieve self-configurability, self-adaptation and resilient to failure with low energy consumption. At first, this paper introduces the basic concept, characteristics, communicate channel character, system structure, and also the application foreground and development problem in underwater acoustic network are introduced. Then the typical routing protocol of wireless sensor network is analyzed. Afterwards, we give the research of the related question of routing protocol in wireless sensor network. In the basis of improving the reliability of packet delivery, reducing the energy consumption of network, with the purpose of enhancing the efficiency of underwater acoustic sensor network, an energy efficient and reliable routing protocol which is suitable of underwater environment is proposed. And through theory analysis and simulation, the excellent performance and feasibility of the protocol is proved.A multi-hop routing protocol is proposed for underwater acoustic sensor networks, which reduces overhead of communication and energy, achieves the purpose of reliable transmission. This algorithm describe initialization of route tree, routing table management, route selection, route update and optimize route depth separately, and make packets arrived at uw-sink successfully by providing solve method of link disconnect, sensor dead and lost check. By introducing random relay for each node to begin initialization process, this algorithm enables fast propagation of routes and also saves on the amount of control packets generated in the setup phase. In route management, three metrics are used to admit a route into route table; this is the depth of route tree, residual energy level of next-hop and the quality of link between two nodes. A routing replace algorithm is proposed for storing the best routes in the route table. Packets are guaranteed to travel on the best route from a node to the uw-sink. This provides reliable packet delivery and little packet lost. The route selection strategy guarantee the node will forward packet to travel with the best link, and no circle occurs. The size of buffer of node is considered to avoid deadlock. Routing update makes every node to update routing table information immediately, by introducing CTS/RTS handshaking theory in MAC layer, it can avoid the conflict of packet and save energy. In order to reduce the energy consumption of network and prolong the life cycle, we optimize the depth of routing tree by minimum the energy consumption of inner node.At last, we analyze and evaluate the performance of proposed protocol and conventional protocol. We process the simulation from packet successful transmission rate, packet latency and average energy extended per packet, in the aspect of number of sensors according to the characteristics of underwater network. The simulation results show that the proposed routing algorithm can efficiently and reliably transmit the packet to uw-sink. It can reduce the count of re-transmission, packet latency, minimize the energy consumption of network and prolong network lifetime.