Research On Mobile Node Localization Algorithm For Wireless Sensor Networks

The node localization technology is one of the most important research aspects in wireless sensor networks(WSN),and it has been applied widely in target tracking,event monitoring,positioning and routing,et al.In many applications of wireless sensor networks,the anchor nodes and unknown nodes randomly distributed in the wireless sensor network are mobile in many cases,and many algorithms do not fully consider the mobility of the nodes,so that the performance of the algorithm is not satisfactory when the nodes move.At present,the mobile nodes localization algorithm is based on partial static nodes and some mobile nodes,or nodes move in accordance with a predetermined trajectory,these movements are not all random movements.On the other hand,localization algorithm based on received signal strength indicator(RSSI)estimates the distance between nodes according to the principle of signal attenuation.The most important problem of localization algorithm based on RSSI is the path loss problem,signal attenuation factors change with the change of the environment,in general,most of the algorithms will use the typical signal attenuation factor,which leads to serious errors ranging results between nodes.And in the complex geographical environment,the signal transmission irregularity(DOI)is an important problem encountered in the actual transmission.To solve the above problems,In this paper,we obtained the data through a large number of field measurements,and the data is analyzed and processed,we use MATLAB to fit the signal attenuation factor in different environments and the path loss value when the reference distance is 1m,in order to make the model more realistic and complex,the DOI is introduced into the model combining the transmission radius of the signal and the complexity of the environment,the model based on the received signal strength and distance is established,on this basis,this paper applies RSSI localization algorithm to wireless sensor networks where anchor nodes and unknown nodes move randomly.In order to solve the problem that the unknown nodes cannot be located when the number of anchor nodes are less than three,according to the number of anchor nodes that can communicate with unknown nodes,the localization process is divided into three cases: when the number of anchor nodes that can communicate with unknown nodes is three or more,the unknown node is directly located by trilateral measurement method;When the number of anchor nodes that can communicate with unknown nodes is only two,the unknown node uses the localization information of the unknown node history time to assist the unknown node of the current time,the historical location coordinates of unknown nodes are used as the location of virtual anchor node and the moving speed is used as the virtual communication radius;When thenumber of anchor nodes that can communicate with unknown nodes is only one,the moving direction of the unknown node is predicted by grey prediction,and then the node localization process is realized by combining the location information and the speed value of the unknown node.The simulation results show that,compared with the traditional RSSI localization algorithm and RSSI localization algorithm based on Kalman filter,the localization success rate of the proposed algorithm is improved by about 30%.