Node Deployment And Connectivity Restoration Methods Of Wireless Sensor Networks

A typical wireless sensor network(WSN)is a wireless self-organizing network consisting of a large number of sensor nodes in the monitoring area.WSNs are widely used in military defense,industrial control,environmental monitoring,healthy care,intelligent home and so on.The node deployment of WSNs is one of the basic problems of the network.The effect of node deployment directly determines the network's working condition,life cycle and service quality.Sensor nodes are limited in their own resources,and in harsh environment are vulnerable to damage.This may lead to network communication blocked or even split into multiple isolated partitions.Therefore,it is critical to restore the connectivity timely and effectively in such networks.In this paper,the node deployment and connectivity restoration methods of WSNs are researched as follows:1.Considering the distribution of sensor nodes in WSNs can affect the cost and lifetime of the network,this paper proposes a Node Density Control Strategy(NDCS)based on energy consumption equilibrium.For the circular network model and the rectangular layered model,NDCS deduces the precise expression of node density when the network energy consumption is in the equilibrium,and the network life cycle is significantly extended.The characteristics of NDCS are that it analyzes the distribution of node density in the two cases of cluster and non-cluster,and demonstrates the influence of monitoring area on data quantity,and uses more precise transmission distances.2.Aiming at the problem of energy hole in WSNs' multi-to-one transmission mode,this paper proposes a Super Links based on Data Drainage method(SLDD)using super sensor node to establish super link.The main idea of SLDD is to use ant colony algorithm(Ant Colony Optimization,ACO)to realize the basic coverage and connectivity of the whole network,and then choose the appropriate location to deploy super nodes to establish super links and realize data drainage.The starting point of the super link is the location where the load is relatively large and the distance from the base station is relatively far,which is not too close to the base station and the flux has mutation.The ending point of the super link selectsthe location where the load is smaller and closer to the base station.Through the data drainage of super links,SLDD finally realizes the redistribution of load between different regions,thus relieving the energy hole.3.Dealing with the situation of network partitioning,this paper proposes the Movement-Assisted Connectivity Restoration Algorithm connectivity(MACRA).MACRA includes two parts: firstly,the fuzzy connectivity restoration is to find the approximate starting point and the approximate ending point of the node moving between the isolated partitions,and then the precise connectivity restoration is to find the precise starting point and the precise ending point position of the node.The Fuzzy connectivity restoration uses the technology of mesh partitioning to solve the approximate distance of each isolated partition to reduce the computational complexity,and to reduce the connection distance and the transmission delay by judging the connected direction.The precise connectivity restoration selects the two sensor nodes with smaller connected distances and more neighbor nodes as the round-trip starting point and ending point of the mobile node in the approximate position of the fuzzy connected selection.After that,this paper makes a simulation and analysis of network cost,network life,the transmission delay,the moving distance and the energy consumption.The results show that:both NDCS and SLDD can significantly reduce the network cost and prolong the network lifetime,SLDD and MACRA are optimized in time delay,MACRA reduces the moving distance in connectivity restoration,NDCS and SLDD show the better energy consumption equilibrium.