%0 Journal Article
%T Distributed Continuous k Nearest Neighbors Search over Moving Objects on Wireless Sensor Networks
%A Chuan-Ming Liu
%A Chuan-Chi Lai
%J International Journal of Distributed Sensor Networks
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/125145
%X Continuous k-nearest neighbor (CkNN) search is a variation of kNN search that the system persistently reports k nearest moving objects to a user. For example, system continuously returns 3 nearest moving sensors to the user. Many query processing approaches for CkNN search have been proposed in traditional environments. However, the existing client-server approaches for CkNN search are sensitive to the number of moving objects. When the moving objects quickly move, the processing load on the server will be heavy due to the overwhelming data. In this thesis, we propose a distributed CkNN search algorithm (DCkNN) on wireless sensor networks (WSNs) based on the Voronoi diagram. There are four features about DCkNN: (1) each moving object constructs a local Voronoi cell and keeps the local information; (2) in order to keep the reliability of system, the query message will be propagated to related objects; (3) using the idea of safe time, the number of updates is reduced; (4) an equation to estimate a more accurate safe time is provided. Last, we present our findings through intensive experiments and the results validate our proposed approach, DCkNN. 1. Introduction The mobile sensors have been widely used in recent years. For example, the smartphone, Samsung Galaxy S4, includes a barometer, thermometer, and hygrometer (to measure humidity)¡ªthe first major smartphone to do so. By using these sensors, people can easily use their mobile devices to obtain environmental information. On the other hand, the popularization of global positioning system (GPS) and the miniaturization of mobile devices, equipped with a wireless network module, make location-based services (LBSs) no longer expensive. Thus, with the combination of the mobile sensors and the GPS, more and more interesting applications and issues gradually emerged. In general, one can regard each mobile device (sensor) as a moving object in wireless mobile sensor networks. Each user (object) can use the GPS and sensors to provide the environmental information, such as location, temperature, and humidity, to the information systems which are built by the manufacturers. These systems can sink user¡¯s information and send the user¡¯s location through the mobile networks. Mobile users can immediately access the information related to the location and geographic information. Many manufacturers even provide different telecommunication services to the users, The multiple types of information services make life more convenient. For example, if a user issues a query and wants to know the temperature at a specific
%U http://www.hindawi.com/journals/ijdsn/2013/125145/