A hybrid communication solution to distributed moving query monitoring systems

Location-based services is emerging as an important application area for mobile devices. Mobile users can issue location-based queries to probe their surroundings. The interested objects could be either static, such as gas stations, or moving, such as vehicles. We focus on the moving monitoring queries on moving objects. Due to the continuous nature of the query, existing solutions require the query issuer and the objects to frequently update their locations. This leads to high communication cost. We propose a hybrid solution, which employs two ways of communicating: on-demand access and a broadcast channel. We also design two different indexes: the Grid Index and the Direction Index, to facilitate data retrieval from the broadcast channel. We compare the hybrid solution to an existing distributed solution using simulation and analysis. Our solution achieves 30-60% savings in communication cost. We conclude that the hybrid solution with the is more scalable and desirable for medium-to-large-scale deployments. (C) 2010 Elsevier B. V. All rights reserved.