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We are witnessing in recent years growing interest for location-dependent information services among mobile users. We examine the issue of processing location-dependent queries in a mobile broadcast environment. Different from a traditional environment, mobile users are concerned with not only access latencies but also power conservation. The planar point location algorithms and conventional spatial index structures are shown inefficient. We propose a new index data structure, called D-tree, for querying location-dependent data in mobile broadcast environments. The basic idea is to index data regions based on the divisions between them. We describe how to construct the binary D-tree index, how to process location-dependent queries based on this index structure, and how to page the D-tree to fit the packet capacity. The performance of the D-tree is evaluated using both synthetic and real datasets. Experimental results show that the proposed D-tree provides a much better overall performance than the well-known existing schemes such as the R*-tree.
Date of Conference: 5-8 March 2003