Topology Recovery Algorithm Based Onredundancy Node Selection Model Inunderwater Sensor Networks

In recent years,with the world's attention to the marine rights and interests,it makes the underwater sensor network gradually becomes popular.Compared to the terrestrial sensor networks,underwater sensor networks have different characteristics in the communication channel and environment.Because of attenuation serious in water,radio waves are not suitable in long-distance underwater sensor networks.Sound waves have better performance in water,so underwater sensor networks adopt acoustic as main communication method.The complex and changeable environment in underwater,the vulnerability of underwater sensor network nodes,as well as energy consumption all challenge the development of underwater sensor network.Most existing repair algorithms of underwater sensor network topology either complete topology repair at the expense of network lifetime or need special nodes,it do not have perfect topology repair algorithm at present.To deal with the above problems,an algorithm based on redundant nodes selection model RNMR is proposed to complete topology repair in this thesis.A distributed manner is adopted to select critical nodes and more restrictions against invalid critical nodes are added in the critical node select phase after the completion of network deployment.When critical nodes fail,the redundant nodes are selected to complete the topology repair.In the redundant nodes selection phase,redundant nodes are selected level by level,meanwhile node energy and the distance to critical nodes are considered so that the redundant nodes can complete topology repair while forwarding data as long as possible.After the redundant nodes are selected,the redundant nodes are used to repair topology meanwhile the sleep/wake strategy is adopted to prolong the network lifetime.Extensive simulations are carried out on the Aqua-Sim simulator,compared with representative topology repair algorithm BMR in the lifetime of underwater sensor networks,the nodes' total moving distance,the time of failure node appearing for the first time and delivery ratio.As the number of nodes increases from 400 to 600,the lifetime of underwater sensor networks which use BMR to repair topology decreases30%.However,the lifetime of network which use RNMR does not decrease obviously,besides the nodes' total moving distance decreases 70%,failure node'sappears for the first time was delayed and the delivery ratio is improved.The results have shown that RNMR can significantly reduce the node's moving distance during topology recovery,prolong the network lifetime and guarantee delivery ratio,which provides a reference for the further study of the topology repair of underwater sensor networks.