Location-based Information Access in Pervasive Computing Environments

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Location-based Information Access in Pervasive Computing EnvironmentsLocation-based spatial queries (LBSQs) refer to a set of spatial queries that retrieve information based on the current locations of the users. Due to the unrestricted mobility of users in the pervasive computing environments, the LBSQs is distinct from the traditional spatial queries. For example, a traveller may issue a query "find me the three nearest restaurants". The answer to this query is dependent on the location where the traveller receives the query results. The goal of this research project is to investigate new ways of indexing and caching spatial data to support processing of LBSQs in pervasive computing and to validate the methods obtained from this project via analysis, implementation, and simulations. The emphasis of the project is on methods that are particularly suitable for wireless data broadcast. A list of LBSQs, including point query, window query, nearest neighbor (NN) search, k nearest neighbor (KNN) search, continuous nearest neighbor (CNN) search, spatial join, and complex queries is studied in this project. Fundamental issues faced by all the spatial indexes and caching schemes (such as large index search space, large index size, linear streaming property of wireless data broadcast, continuous movement and requests of mobile users, and cache replacement/invalidation) are tackled. This research result will have significant impacts on advancing the fields of spatial databases and pervasive computing. The proposed research activities will be closely integrated with the PI's educational goals and activities at both of the undergraduate and graduate levels. The developed techniques and experimental data will be made available in a timely manner by means of a website and publication in multi- and interdisciplinary conferences, workshops, and journals. In addition, scientific and engineering presentations will be given to the broader community, including the public or industry, where possible. Finally, the results and experiences obtained in this research have many possible applications in location-based services, e.g., those based on the recently announced SPOT technology and directband network. Publication, technical reports, software and experimental data can be accessed at the project web site http://www.cse.psu.edu/pda/LBSQ