Transitive nearest neighbor search in mobile environments

Given a query point p, typically the position of a current client, and two datasets S and R, a transitive nearest neighbor (TNN) search returns a pair of objects (s, r)isinStimesR such that the total distance from p to s and then to r, i.e., dis(p,s)+dis(s,r), is minimum. We propose various algorithms for supporting TNN search as a kind of location-based services in both on-demand-based and broadcast-based mobile environments. In addition, we develop a novel validation algorithm that allows the clients to verify whether their TNN query answers are still valid after they moved to new positions. Finally, we conduct a comprehensive simulation to evaluate performance of the proposed TNN search algorithms