Research On Wireless Sensor Network Node Localization Algorithm Without Ranging

Wireless sensor network have developed rapidly with the progress of science and technology,it is a comprehensive technology. The widely application of wireless sensor network enables thevirtual network and the physical world together. With in-depth study of wireless sensor network,it will gradually penetrate into all areas of human life.Node localization technology is very important for the application of wireless sensornetwork; Forest control, target tracking need to locate the target. WSN is meaningless withoutlocalization technology, it can’t to transfer and perceive information, it is the basis of targettracking and routing technology. So it is critical to the study of the node localization technology.For the better use of WSN, node localization algorithm must be considered to determine energyconsumption, cost, time complexity etc.At present, most localization algorithms are based on the study of range-based algorithm andrange-free algorithm. The former has high localization precision, but it require additionalhardware equipment costs, it is not suitable for large scale wireless sensor network; Although thelocalization precision of the latter algorithm is relatively low, it does not need to measure distancethat it has low cost and energy consumption, it is suitable for large scale WSN.This paper is mainly focused on range-free algorithm, the concrete work is as follows:(1)APIT algorithm is relatively simple in two-dimensional space, in the case of high nodedensity environment，it is not prone to error. This paper presents an improved algorithm byanalysis. The main idea of the algorithm is using judging of angle when determine whether theunknown nodes in the interior of a triangle, and judge the node position using summation ofangle. Results of the simulation experiments show that this algorithm can reduce errors andimprove the positioning accuracy in the relatively spare node density environment, and withincreasing of node density, the positioning accuracy of improved algorithm is higher thanclassical algorithm.(2)The three-dimensional DV-Hop algorithm is usually using linear distance when estimatethe distance between two points by analysis, but the actual distance is usually curve distance, so itis prone to error. This paper presents an improved algorithm which is the three dimensionalA-DV-Hop algorithm, the average hop distance is improved. The average hop distance ofunknown node is replaced by the average value of average hop distance of unknown node toanchor node and unknown node to the nearest anchor node. The experiment shows that thealgorithm can improve the localization accuracy.(3)When the distance of unknown nodes and anchor nodes is farther, cumulative error islager. This paper presents an improved algorithm which is three dimensional LH-DV-Hop algorithm, when calculate distance, anchor nodes do not participate in the calculation whichoutnumber hop threshold. Results of the simulation experiments show that the improvedalgorithm can reduce the positioning error and improve accuracy without increasing costs.