Research On Range-free Localization Algorithm For Wireless Sensor Networks Based On DV-HOP

As a new real-time monitoring and information processing technology,wireless sensor network plays an important role in the future social development.In many applications of wireless sensor networks,node location technology is one of its supporting technologies applied to target monitoring,target identification and target tracking,and therefore has great research significance.In the node location algorithm,the DV-HOP algorithm based on the non-ranging mechanism has many advantages such as low cost,low energy consumption,simple algorithm implementation,etc.However,the algorithm also has the disadvantage of large positioning error.This paper analyzes the reasons why DV-HOP algorithm generates large errors in positioning and proposes an optimization scheme to improve it.The main work is as follows:(1)In order to improve the positioning accuracy of the DV-HOP algorithm,and in the process of solving the unknown node coordinates using the maximum likelihood estimation method for the algorithm,the matrix equation contained in the algorithm has an accumulated error and requires a large number of floating-point operations,leading to a higher calculation cost.For the problem,An immune particle swarm optimization algorithm based on DV-HOP algorithm.was proposed.This paper applies the PSO algorithm,which is simple and easy to implement,to the DV-HOP algorithm.By analyzing the shortcomings of the PSO algorithm,the immune mechanism is introduced to improve the PSO algorithm,which overcomes the instability in iterative optimization and is easily trapped in the local area.To solve the problem of superior solution,the improved immune particle swarm algorithm is used to replace the position of unknown nodes in the DVHOP algorithm using the maximum likelihood method,so as to optimize the positioning result of the DV-HOP algorithm.(2)In this paper,the two-dimensional DV-HOP algorithm is extended to three-dimensional space,and the three-dimensional DV-HOP algorithm is studied.Aiming at the irrationality in the calculation of hops and hops for DV-HOP algorithm in three-dimensional space,a threedimensional DV-HOP positioning algorithm based on hop count correction and average hop distance selection strategy is proposed.Firstly,the minimum hop number estimation method is improved.By refining the communication radius,multiple beacons are used when the beacons broadcast,and the neighbor node group communication is divided so as to obtain the minimum hops of non-integer numbers,and the minimum hop count is improved.The accuracy of the calculation;In addition,because a single reference beacon can not reflect the characteristics of the entire network,using the same average distance to calculate the distance will produce a larger error,this paper proposes a different average distance calculation method according to the specific location of the node to choose When the beacon node is far away from the unknown node,it uses multiple beacon weighted averages to calculate,making the average hop distance calculation more accurate;Finally,the improved immune particle swarm optimization algorithm is used to optimize the unknown node coordinates.In summary,the simulation environment was built by MATLAB software and simulation experiments were performed on the above two algorithms.Experimental results show that the two improved algorithms can effectively reduce the positioning error and improve the positioning accuracy without adding additional hardware.At the same time,the improved algorithm has better robustness and is more suitable for wireless sensors in complex network environments.Positioning.