Date Added: Mar 2011
Continuous queries are often employed to monitor the locations of Mobile Objects (MOs), which are determined by sensing devices like GPS receivers. In this paper, the authors tackle two challenges in processing Continuous Range Queries (CRQs): coping with data uncertainty inherently associated with location data, and reducing the energy consumption of battery-powered MOs. They propose the concept of spatiotemporal tolerance for CRQ to relax a query's accuracy requirements in terms of a maximal acceptable error. Unlike previous works, their definition considers tolerance in both the spatial and temporal dimensions, which offers applications more flexibility in specifying their individual accuracy requirements. As they will show, these tolerance bounds can provide well-defined query semantics in spite of different sources of data uncertainty.