Nearest surrounder searching in mobile computing environments

• Published in: International journal of communication systems Vol. 26; no. 6; pp. 770 - 791
• Main Authors: Chung, Jaehwa, Jang, Hong Jun, Jung, Kyoung-Ho, Jung, Soon-Young
• Format: Journal Article
• Language: English
• Published: Chichester Blackwell Publishing Ltd 01.06.2013; Wiley Subscription Services, Inc
• Subjects: Communication systems; Costs; Decentralized; Leaves; location-based services; Mobile computing; mobile computing environment; nearest surrounder; Position (location); Query processing; Servers; spatial query
• ISSN: 1074-5351; 1099-1131
• DOI: 10.1002/dac.2409

SUMMARYThe key issue in mobile computing environments (MCEs) is how to relieve communication congestion and provide accurate information through location‐based services (LBSs). The nearest surrounder (NS) query, used to find all visible objects around a given location, is a type of spatial query that suggests broad application base in LBS domain. However, because existing works for NS query only take into account static query points, the application of the NS query is limited to various LBSs in MCEs requiring frequent location updates. Motivated by this limitation, this paper introduces the continuous nearest surrounder (CNS) query, which uses a decentralized system framework to continuously maintain updated query results in MCEs. In this framework, the LBS server executes an initial NS query to prepare a region, termed non‐provoked polygon (NPP), defines a set of visible objects that cannot be changed. Conversely, a client caches the NPP and does not update request unless it leaves its NPP. We performed extensive experiments using synthetic and real datasets with various data cardinality, and query mobility to validate the accurate performance of the proposed strategy. The results show that the CNS algorithm outperforms NS, in terms of computation and communication costs as well as scalability.Copyright © 2012 John Wiley & Sons, Ltd. This paper introduces the continuous nearest surrounder query, which finds a set of visible object in moving query environment. To cope with computation and communication costs, continuous nearest surrounder query uses a decentralized system framework to continuously refresh query results. The server executes an initial nearest surrounder query to prepare a safe region that defines an area where the number of visible objects does not change. Client only performs angular calculations and does not place update requests unless it leaves the region.