Nearest Neighbor Queries in a Mobile Environment

Nearest neighbor queries have received much interest in re cent years due to their increased importance in advanced database ap plications However past work has addressed such queries in a static setting In this paper we consider instead a dynamic setting where data objects move continuously Such a mobile spatiotemporal environment is motivated by real life applications in tra c management intelligent navigation and cellular communication systems We consider two ver sions of nearest neighbor queries depending on whether the temporal predicate is a single time instant or an interval For example nd the closest object to a given object o after minutes from now or nd the object that will be the closest to object o between and min utes from now Since data objects move continuously it is ine cient to update the database about their position at each time instant Instead our approach is to employ methods that store the motion function of each object and answer nearest neighbor queries by e ciently searching through these methods