The Research And Improvement Of DV-Hop Algorithm Based On Mobile Beacon Node

In many applications,node location plays an vital role in the whole application,such as fire alarm,when the sensor send fire alarm via wireless sensor network,fire station must known their position at the same time,according to provide location information and fire alarm fire station can take necessary measures as soon as possible,the information provided by the sensor network is useful information.Wireless Sensor network node location information is the basis of studying of the other wireless sensor network applications,such as sensor network routing protocol research and so on.Node localization is one of the important support technology of wireless sensor network(WSN).Perception without location information is meaningless,after the incident is detected,an important problem is the location of the event,such as forest fire monitoring,target tracking application problems,so the research of node location algorithm in wireless sensor network is of great significance.Research of localization algorithm based on the mobile beacon node is a hot spot in recent years.Due to node location algorithm mostly depends on the density of beacon node,the connectivity of the network and so on,but.Price of beacon node is very expensive,a large number of beacon nodes in the network will greatly increase the cost of network.So introducing a mobile beacon node in the network to broadcast its location to constitute virtual beacon,which can reduce cost,improve the efficiency of positioning,improve the connectivity of the network.DV-Hop algorithm is a kind of no ranging localization algorithm,through the network connectivity to estimate the distance between the unknown node and the beacon nodes,then through the trilateral measurement method or maximum likelihood estimation algorithm to calculate the position of the unknown node.In order to reduce positioning error of traditional DV-Hop algorithm,decrease the dependence of the positioning accuracy on the network connectivity and control the cost of location,an improved method was obtained.Specific content is as follows:(1)In this paper,the DV-Hop algorithm has been concrete analyzed,the principle of algorithm has been introduced,error sources of the algorithm have been analyzed.According to the research of domestic and foreign scholars,this paper have divided the improved DV-Hop algorithm into four types.(2)In this article,a mobile beacon node with GPS receiver unit traverse the entire monitoring area,move along the HILBERT path and periodic broadcast its location information,forming a number of virtual static beacon nodes.With the help of the virtual static beacon nodes in the calculation of the unknown node,we can reduce the cost of network layout,improving the network connectivity.(3)In the process of unknown node localization,participate of the beacon node is not the more the better,on the contrary,inappropriate beacon nodes can introduce larger positioning error.In this paper,utilizing the basic unit of HILBERT path is square area,setting the velocity and step length of the mobile beacon node to make mobile beacon nodes form a virtual beacon nodes in each square area's vertex,which are the optimal beacon nodes of the unknown node in the basic square area.(4)Different beacon nodes have different influence on the position calculation of the unknown node,beacon nodes closer to the unknown node have greater influence on the calculation of its position,and farther of the distance between the unknown node and beacon nodes,smaller of the influence the beacon nodes.Use the RSSI values to react the distance between unknown node and optimal beacon and give it different weights,finally using maximum likelihood estimation algorithm,trilateration algorithm or centroiding algorithm to calculate the unknown node's coordinates.(5)The simulation of the improved algorithms and traditional DV-Hop algorithm by Matlab simulation software is conducted in the respect of location effect,positioning error,standard deviation and network communication overhead.The simulation results show that the improved algorithm effectively improves the precision and stability,reduce the cost of positioning at the same time.