Modeling moving objects for location based services

As prices of basic enabling equipment like smart cell phones, hand holds, wireless modems, and GPS devices continue to drop rapidly, International Data Corp (IDC) predicts that the number of wireless subscribers worldwide will soar to 1.1 billion in 2003. Spurred by the combination of expensive new location-based infrastructure and an enormous market of mobile users, companies will roll out new wireless applications to re-coop their technology investments and increase customer loyalty and switching costs. These applications are collectively called location-based services. In this position paper we outline a novel and comprehensive model for moving objects in location based services. The model is different than other models proposed in the literature in the sense that is captures the spatial, temporal, and uncertain aspects of the location of a moving object. These aspects are captured in the concept of a trajectory. We argue that the existing prevalent model in industry, point location management, has severe drawbacks, and explain why our trajectory model solves these problems. We also outline a set of operators to access the trajectories database.