Broadcasting and Prefetching Schemes for Location Dependent Information Services.
ABSTRACT The results of location-dependent queries(LDQ) generally depend on the current locations of query issuers. Many mechanisms,
such as broadcast scheme, prefetching scheme, or caching scheme have been developed to improve system performance and provide
better service for location dependent information services(LDISs). However, the client’s mobility may lead to inconsistency
problems. In this paper, we introduce the broadcast-based LDIS scheme(BBS) in the mobile computing environment. In the BBS,
broadcasting data items are sorted sequentially based on their location and the server broadcasts the location dependent data(LDD)
without additional indices. Then we present a data prefetching scheme and OBC(Object Boundary Circle) in order to reduce the
client’s tuning time. The performance for the proposed scheme is investigated by various environmental variables such as distributions
of the data items, average speeds of the clients and the size of the service area.
- [Show abstract] [Hide abstract]
ABSTRACT: Researchers have studied the various index structures and query processing algorithms to support efficient spatial queries in wireless communication environments. However, most previous studies have focused on server-side methods. In a server-side method, the server executes queries from individual clients and then relays the results. In our proposed method, the server transmits an index called DGI (Distributed Grid Index), and the client examines the received index to process spatial queries. The proposed index structure and search algorithm support efficient spatial queries in a wireless broadcast environment, shortening query search times.Expert Systems with Applications 03/2014; 41(4):1294-1300. · 1.85 Impact Factor
Conference Paper: Location-Based Caching Scheme for Mobile Clients.[Show abstract] [Hide abstract]
ABSTRACT: The Voronoi Diagram(VD) is the most suitable mechanism to find the nearest neighbor(NN) for mobile clients. In NN query processing, it is important to reduce the query response time, since a late query response may contain out-of-date information. In this paper, we study the issue of location dependent information services(LDISs) using a VD. To begin our study, we first introduce a broadcast-based spatial query processing methods designed to support NN query processing. In further sections, we introduce a generic method for location-dependent sequential prefetching and caching. The performance of this scheme is studied in different simulated environments. The core contribution of this research, resides in our analytical proof and experimental results.Advances in Web-Age Information Management, 6th International Conference, WAIM 2005, Hangzhou, China, October 11-13, 2005, Proceedings; 01/2005
- [Show abstract] [Hide abstract]
ABSTRACT: Most current research on Location-Based Services (LBSs, for short) assumes point-to-point wireless communication, where the server processes a query and returns the query result to the user via a point-to-point wireless channel. However, LBSs via point-to-point wireless channel suffer from a tremendous amount of traffic and service requests from the user and thereby result in poor performance. In this paper, we present broadcast-based spatial query processing algorithms designed to support k-NN (k-Nearest Neighbor) and range queries via a wireless network. The task of the query processor is to selectively monitor the wireless broadcast channel, when the data items are disseminated by the server, according to their locations. Experiments are conducted to evaluate the performance of the proposed algorithms. Comprehensive experiments illustrate that the presented algorithms are highly scalable and are more efficient than the previous techniques in terms of both access time and energy consumption. Keywordsdistributed databases-indexing methods-information storage and retrieval-spatial databases and GISJournal of Computer Science and Technology 25(2):330-346. · 0.48 Impact Factor