Algorithm Design For The Localization Of Wireless Sensor Networks Nodes In Wheat Field Environment

Wireless sensor networks(WSNs)have received widespread attention in recent years.These devices which used in wireless sensor networks are small in size,low cost and low power consumption and also widely used in different occasions,including environmental monitoring,target tracking,biomedical monitoring.In many applications,the node localization has made a significant contribution to reduce the cost of building a wireless sensor network.How to improve the accuracy of nodes localization algorithm has become an urgent problem.After analyzing the wireless sensor networks localization algorithms at home and abroad,this paper studied the wireless sensor networks localization algorithms based on the wheat field environment.Subsequently,we focused on the three aspects of signal propagation models,distribution uniformity and node localization algorithms in wheat field environment.Here is the main contents of this paper:(1)Selected the basic localization algorithm for farmland environment.We described the basic concepts of wireless sensor networks localization,classified and collated the current wireless sensor network localization technologies according to whether the algorithm have a single degree and whether it is ranging.(2)Proposed a multi-stage single-reflection path model OP-1-R based on 01/ H,02 / H,04 / H..The CC2530 system based on Z-stack protocol stack was selected to measure the signal strength and packet loss rate of the nodes in the wheat field environment,and the signal loss value was calculated in this experiment.Based on the comparison of the measured data and the three models,we proposed a multi-stage single-reflection path model OP-1-R,which can better fit the signal loss value and improved the distance calculation precision between nodes.(3)Designed the centroid iterative-maximum likelihood estimation localization algorithm based on uniformity analysis.In this paper,we provide the localization algorithm flowchart based on wheat field environment.After selecting the uniformity analysis algorithm,we used the MATLAB to simulate the situation of nodes distribution and observed whether this algorithm can accurately judge the nodes distribution.Besides,the optimal iterative parameter value ?,η was obtained by simulating the improved centroid iterative algorithm.After the analysis of the localization error of the improved centroid iterative algorithm and the maximum likelihood estimation algorithm,the conversion factor(37)in the algorithm was valued.Finally,the experimental results showed that the errors were reduced by 26.77%,5.55%,1.72% and 0.06%,respectively,under the number of nodes 5,11,16,21 by comparing the centriod iterative-maximum likelihood estimation method based on the uniformity analysis with the traditional algorithm in the area of 90?90m.(4)Designed the algorithm of minimum anchor nodes placement in wheat field.Based on the coverage of the signal in the farmland,we designed the algorithm to find the minimum number of anchor nodes to cover the sensing domain(95%)and ensured the feasibility of the unknown nodes.