In recent years, collinearity theory is widely used in large-scale sensor network. When the anchor nodes are located at almost a straight line, the collinearity phenomenon will happen and usually cause negative influence on positioning accuracy. From detailed analysis of the relation between DV-Hop localization error and the collinearity, we proposed to select the anchor nodes which can meet the condition of hop count threshold and collinearity to participate in the localization procedure. Since there is uncertain situation that the anchor node's region is hard to be decided for the sensor nodes in one hop area, Voronoi diagram is adopted to divide the sensor network into several regions. Then, we can get the anchor node information in each Voronoi polygon. With this information and the collinearity condition, we can estimate the unknown node's position with relatively higher accuracy. Compared with the traditional DV-Hop and collinearity algorithm, our proposed algorithm can get better positioning accuracy in both homogeneous network and anisotropic network. Recently, wireless sensor network (WSN) is widely used in many fields such as disaster rescuing, environment monitoring, and target tracking. As a fundamental issue in sensor network, the node localization technology has become one of the research hot spots in WSN fields [1, 2] . According to distance measurement method, the sensor network localization is divided into two categories including range-based localization and range-free localization. The former mainly consists of time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA), and received signal strength (RSS) positioning. Range-free localization methods mainly consist of centroid algorithm, DV-Hop algorithm, amorphous algorithm, and APIT algorithm. Based on the range-free localization mechanism, unknown node's location can be acquired with little consideration of environmental factors because it is unnecessary to calculate the actual distance or angle. The accuracy can meet the requirement for most of wireless sensor network applications, while reducing the requirement of node hardware and the cost greatly [3] . As a typical range-free localization method, DV-Hop algorithm has no extra requirement for WSN nodes and is characterized by such advantages as simple realization, low cost, and small payment. This paper proposes a new method based on DV-Hop algorithm and Voronoi diagram (VNC-DV-Hop, Voronoi diagram-based NC-DV-Hop). We utilize Voronoi diagram to divide the network into several areas and then calculate the groups of anchor nodes conforming to threshold condition. Best sensor node groups are selected to localize the unknown nodes. This method has more advantages in calculation complexity and better position estimation in sensor network, including homogeneous network and anisotropic network. The rest of the paper is organized as follows. Section 2 briefly introduces related research. Section 3 analyzes the errors and collinearity of DV-Hop localization algorithm. In Section 4, the Voronoi diagram and the proposed algorithm are investigated. Section 5 reports simulation experiments with different sensor networks. Finally, Section 6 concludes the whole paper.
Zhang et al. REF proposed to select the anchor nodes that can meet the condition of hop count threshold and collinearity to participate in the localization procedure to obtain better positioning accuracy in both homogeneous networks and anisotropic networks.
Improved Normalized Collinearity DV-Hop Algorithm for Node Localization in Wireless Sensor Network
International Journal of Distributed Sensor Networks
Computer Science