Adaptive schemes for location update generation in execution location-dependent continuous queries

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jss.2005.07.015 Byline: Kam-Yiu Lam (a), Azgur Ulusoy (b) Keywords: Location-dependent continuous queries; Location update; Moving object database; Location management Abstract: An important feature that is expected to be owned by today's mobile computing systems is the ability of processing location-dependent continuous queries on moving objects. The result of a location-dependent query depends on the current location of the mobile client which has generated the query as well as the locations of the moving objects on which the query has been issued. When a location-dependent query is specified to be continuous, the result of the query can continuously change. In order to provide accurate and timely query results to a client, the location of the client as well as the locations of moving objects in the system has to be closely monitored. Most of the location generation methods proposed in the literature aim to optimize utilization of the limited wireless bandwidth. The issues of correctness and timeliness of query results reported to clients have been largely ignored. In this paper, we propose an adaptive monitoring method (AMM) and a deadline-driven method (DDM) for managing the locations of moving objects. The aim of our methods is to generate location updates with the consideration of maintaining the correctness of query evaluation results without increasing location update workload. Extensive simulation experiments have been conducted to investigate the performance of the proposed methods as compared to a well-known location update generation method, the plain dead-reckoning (pdr). Author Affiliation: (a) Department of Computer Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (b) Department of Computer Engineering, Bilkent University, Bilkent, Ankara 06800, Turkey Article History: Received 27 January 2004; Revised 1 July 2005; Accepted 15 July 2005 Article Note: (footnote) [star] This work described in this paper was supported by a research grant from the Research Grant Council of Hong Kong Special Administration Region, China [Project No. CityU 1076/02E].