660 Category: Location and Context Awareness Monitoring and Tracking Moving Objects in Mobile Environments Dragan Stojanović University of Nis, Serbia Slobodanka Djordjevic-Kajan University of Nis, Serbia Apostolos N. Papadopoulos Aristotle University, Greece Alexandros Nanopoulos Aristotle University, Greece Copyright © 2007, Idea Group Inc., distributing in print or electronic forms without written permission of IGI is prohibited. INtroductIoN Advances in mobile and ubiquitous computing, wireless com- munications and mobile positioning have given a rise to a new class of mobile information systems and services, called location-based services (LBS) (Schiller & Voisard, 2004). Such services, like feet management, cargo tracking, child- care, tourist services, transport management, traffc control and digital battlefeld rely on the tracking of the continuously changing positions of entire populations of moving objects. LBSs are becoming ubiquitous. A traffc service may inform its users about traffc jams, traffc accidents and weather situations that are expected to be of relevance to the service user. A friend fnder service may inform each user about the current whereabouts of friends. Other services may monitor and track the positions of emergency vehicles, police cars, security personnel, hazardous materials, or public transport. A more advanced location-based game service may allow a group of users to play and try to surround and catch “hostile” players. Monitoring and tracking moving objects require continuously registering the positions of mobile objects, and at any instance in time to know whether those objects are within the specifed area, or a specifed distance from known mobile/static objects, or which are its k nearest neighbors (k- NN). To provide monitoring and tracking of moving objects in mobile application environments, it is highly desirable and sometimes critical for the service effciency to provide ac- curate results to these requests and update them in real time, whenever moving objects enter or exit the regions of interest, or become the closest neighbors to the objects of interest. Monitoring and tracking LBS applications require data- base and application support to model and manage moving objects in both database and application domains. Such services must also provide effcient processing of continuous queries over moving objects. In contrast to regular queries that are evaluated only once, a continuous query remains active over a period of time. At any time there will be a number of continuous queries simultaneously running at the server. Each of these queries needs to be periodically re-evaluated as the objects and/or queries move. A major challenge for this problem is how to provide effcient processing of continu- ous queries with respect of CPU time, I/O time and network bandwidth utilization. The architecture of the monitoring and tracking LBS system is given in Figure 1. Figure 1. The architecture of monitoring and tracking LBS Server Workstation Laptop GPS/Galileo Mobile clients/ objects Base station Location update Location update Monitoring and tracking Monitoring and tracking Monitoring and tracking Continuous query Continuous query Continuous query