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.
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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: An International Journal. 03/2014; 41(4):1294-1300.
Article: Broadcast-Based Spatial Queries.[Show abstract] [Hide abstract]
ABSTRACT: Indexing techniques have been developed for wireless data broadcast environments, in order to conserve the scarce power resources of the mobile clients. However, the use of interleaved index segments in a broadcast cycle increases the average access latency for the clients. In this paper, the broadcast-based spatial query processing methods (BBS) are presented for the location-based services. In the BBS, broadcasted data objects are sorted sequentially based on their locations, and the server broadcasts the location dependent data along with an index segment. Then, a sequential prefetching and caching scheme is designed to reduce the query response time. The performance of this scheme is investigated in relation to various environmental variables, such as the distributions of the data objects, the average speed of the clients and the size of the service area.Journal of Computer Science and Technology 01/2005; 20:811-821. · 0.48 Impact Factor
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ABSTRACT: Due to the personal portable devices and advances in wireless communication technologies, Location Dependent Information Services (LDISs) have received a lot of attention from both the industrial and academic communities. In LDISs, 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 LDISs using a Voronoi Diagram. We introduce a new NN search method, called the Exponential Sequence Scheme (ESS), to support NN query processing in periodic broadcast environment. This paper aims to provide research directions towards minimizing both the access latency and energy consumption for the NN-query processing.Journal of Computer Science and Technology 01/2007; 22:131-134. · 0.48 Impact Factor