SPQI: An efficient index for continuous range queries in mobile environments

This paper explores the problem of efficient processing of continuous range queries (CRQs) over a large number of moving objects, each of which continually retrieves the moving objects that are currently within a geographic query region of interest. In order to keep the result of CRQs up-to-date, the moving objects should continually communicate with the server to report their current locations. However, this increases the server workload and entails a huge amount of communication cost when the number of the moving objects and CRQs becomes enormous. In this paper, we adopt the approach of leveraging available memory and computational resources of the moving objects to remedy such problems. To this end, we propose a novel query indexing structure, referred to as the space partitioning query index (SPQI), which enables the server to efficiently cooperate with the moving objects for processing CRQs. SPQI greatly improves the overall system performance in terms of server workload and communication cost. Through a set of comprehensive simulations, we verify the superiority of SPQI.