Research On Node Localization In Wireless Sensor Networks Based On UAV

With the current rapid development of the Io T industry,the role of WSN has become increasingly prominent.The location information is information with very practical significance in WSN,so the research on NP is necessary.In the research of NP,the positioning combined with MAN has the characteristics of low cost and flexible use.But when the MAN cannot move on the plane where the unknown node is located,it is a good choice to use the drone as the MAN.In this thesis,the UAV is used as the MAN for NP and UAV trajectory planning.In the WCL,FAN need to be deployed in large numbers for NP,resulting in relatively high costs.UAVs are used as MAN,and a ratio based on signal strength is proposed.A WCL algorithm combined with an exponential function as a weight coefficient.The algorithm uses UAVs to fly along a statically planned track and broadcasts signals on the track points;The unknown node calculates the weight according to the RSS,and estimates its own coordinates in combination with the planar projection method.Compared with other improved algorithms,the improved algorithm effectively reduces the positioning error.And combined with the UAV,it solves the problems of high positioning cost,inflexible use,and space constraints.The problem of large errors when the nodes are located solely by MLE is addressed.A hybrid and improved positioning algorithm based on UAVs is proposed: first use Taylor series to linearize the equation of the MLE positioning algorithm to find the set of rough estimated coordinates of unknown nodes;then use the ratio of signal strength combined with the exponential function and sum as the weight to improve the weight of the weighted centroid location algorithm,the USN coordinates are finally estimated and positioned.The improved algorithm effectively reduces the positioning error.UAV's static trajectory path planning has poor flexibility.Broadcasting information packets under the condition of random non-uniform distribution of unknown nodes will cause a lot of waste of drone broadcast information packets.Therefore,a drone based on weight selection is proposed.Dynamic trajectory planning.First prepare the flying flight direction of the drone according to the principle of circumscribed regular polygon,and then divide the drone broadcast area according to the drone signal broadcast area mechanism,and then select the drone according to the improved proportional weight.Flight direction,and finally use the fault-tolerant back mechanism to solve the problem of the drone falling into the located area.In the same simulation environment,the proposed UAV dynamic trajectory planning algorithm can effectively improve the positioning coverage and reduce the positioning error compared with other trajectory planning algorithms.