A Hybrid Location Model with a Computable Location Identifier for Ubiquitous Computing

Location modeling and representation are crucial technologies for context-aware applications. In this paper, we present a novel location model combining the virtues of both the hierarchical and coordinate location models, and we introduce a computable location identifier, namely Aura Location Identifier (ALI). We then describe how the Aura space service uses this hybrid model to handle spatial queries for contextaware applications. Asimple example of such a query is a range query, e.g. "select name from printer where distance(location, 'ali://cmu/wean-hall/floor3/3100-corridor#(10,10,0)') < 10", where "location" is an attribute representing the location of printers. Finally, we discuss how we extended the PostgreSQL database system to provide direct support for spatial SQL queries at the database level. These extensions improve performance and increase flexibility for context-aware applications.

[1]  Barry Brumitt,et al.  Topological World Modeling Using Semantic Spaces , 2001 .

[2]  Michael Stonebraker,et al.  Inclusion of new types in relational data base systems , 1986, 1986 IEEE Second International Conference on Data Engineering.

[3]  Christian Becker,et al.  Location Models from the Perspective of Context-Aware Applications and Mobile Ad Hoc Networks , 2002, Personal and Ubiquitous Computing.

[4]  Fritz Hohl,et al.  Nexus - an open global infrastructure for spatial-aware applications , 1999 .

[5]  Frank Dürr,et al.  On location models for ubiquitous computing , 2004, Personal and Ubiquitous Computing.

[6]  David Garlan,et al.  Project Aura: Toward Distraction-Free Pervasive Computing , 2002, IEEE Pervasive Comput..

[7]  Ulf Leonhardt,et al.  Supporting location-awareness in open distributed systems , 1998 .

[8]  Asim Smailagic,et al.  Location sensing and privacy in a context-aware computing environment , 2002, IEEE Wirel. Commun..

[9]  Michael Stonebraker,et al.  The POSTGRES next generation database management system , 1991, CACM.

[10]  Svetlana Domnitcheva,et al.  Location Modeling: State of the Art and Challenges , 2001 .

[11]  Paramvir Bahl,et al.  RADAR: an in-building RF-based user location and tracking system , 2000, Proceedings IEEE INFOCOM 2000. Conference on Computer Communications. Nineteenth Annual Joint Conference of the IEEE Computer and Communications Societies (Cat. No.00CH37064).

[12]  Peter Steenkiste,et al.  Providing contextual information to ubiquitous computing applica-tions , 2002 .

[13]  Fritz Hohl,et al.  Next century challenges: Nexus—an open global infrastructure for spatial-aware applications , 1999, MobiCom.