A P2P Simulation Model to Support Mobile, Scalable Nearest Neighbor Queries for Location-based Services

With the increasing capabilities of mobile devices, there has been a growing interest in location-based services. Here we present MAPLE, a scalable peer-to-peer nearest neighbor (NN) query simulation system for mobile environments. MAPLE is designed for the efficient sharing of query results cached in the local storage of mobile peers. The most innovative aspect of the MAPLE model is its ability to either fully or partially compute location-dependent nearest neighbor objects on each host. Our novel verification algorithms enable a mobile host to locally determine whether the points of interest obtained from its peers are relevant to its own NN query solution set. Our simulation system emulates all aspects of the MAPLE model including the movement of mobile hosts on a road network and the launch and execution of location-based nearest neighbor queries. The simulation illustrates how cooperative data sharing and distributed processing among mobile peers results in a considerable reduction of the load on remote spatial database servers. Through its peer-to-peer topology, MAPLE exhibits great scalability: the higher the mobile host density, the more queries can be answered by peers.