Research On Routing Mechanism Of Underwater Wireless Sensor Networks

Underwater wireless sensor networks(UWSNs)have many problems,such as long delay,limited energy,dynamic topology,high bit error rate and so on.The algorithms applied terrestrial wireless sensor networks can not be directly applied to underwater wireless sensor networks.Designing a routing protocol for UWSNs is of great significance for improving the network performance.For the reasons stated above,some researches are carried out in this paper as the following aspects:(1)A shortest path routing based on the vertical angle protocol(SPRVA)for the network with multiple sink nodes is proposed.The end-to-end delay and energy consumption of UWSNs increase with the increasing of the propagation distance.In this algorithm,for the networks with multiple sink nodes,the shortest transmission path is the path nearst to the vertical direction to the water surface.The shortest path is got by calculating the angle between propagation direction and depth direction.In order to achieve the energy balance and reduce the impact of noise in the link,residual energy and link quality are introduced when calculating the priority of the neighbor node.In addition,in order to avoid choosing the nodes in the void area as the next hop and leading to delivery failure,a recovery algorithm is designed.The performance of the algorithm is superior in energy consumption and delay in networks with multiple sink nodes.(2)A location-independent vector-based routing algorithm is proposed for networks with multiple sink nodes and single sink node.In this section,according to the actual applications the routing algorithms based on the received signal strength(RRSS)and instant messaging environment(IMER)are proposed.In the routing algorithm based on the received signal strength,each underwater node establishes two vectors via the received signal strength value of the beacon signal from the sink node and the control packet from the neighbor node,and determines the best next hop according to the vectors respectively.In order to avoid the absence of the next 2 hops node,a void avoidance algorithm is designed.In the routing algorithm based on the instant messaging environment,the underwater node establishes two vectors based on the time of beacon signal from sink and the control packet from the neighbor node.The neighbor node nearest to the vector has the highest priority.There is no restriction on the direction of the next hop in the algorithm.In order to avoid data packets forwarding between the two nodes repeat,a cyclic avoidance algorithm is designed.The simulation and theoretical analysis show that the designed algorithm can shorten the delay and decrease energy consumption in the network with one sink node.(3)A cross-layer routing algorithm based on harmony search algorithm and coding technology is proposed.Harmony search algorithm and coding technology are combined to solve the problems of the high bit error rate and the unbalanced energy consumption in underwater wireless sensor networks.In the algorithm,the underwater nodes are divided into cluster head nodes and common nodes according to the initial energy value.When clustering,an optimized harmony search algorithm is used,which makes the energy of cluster head nodes and ordinary nodes more balanced.During the process of data transmitting from the source node to a sink node,the coding technology is used.Meanwhile,the forwarding node is determined according to the residual energy value and forward distance.In order to solve the problem of dynamic topology,a routing update algorithm is designed.The algorithm not only increases the reliability of the network,but also improves the performance of energy balance among nodes.