Continuous Expansion: Efficient Processing of Continuous Range Monitoring in Mobile Environments

Abstract

Continuous range monitoring on moving objects has been increasingly important in mobile environments. With the computational power and memory capacity on the mobile side, the distributed processing could relieve the server from high workload and provide real-time results. The existing distributed approaches typically partition the space into subspaces and associate the monitoring regions with those subspaces. However, the spatial irrelevance of the subspaces and the monitoring regions incurs the redundant processing as well as the extra communication cost. In this paper, we propose continuous expansion (CEM), a novel approach for efficient processing of continuous range monitoring in mobile environments. Considering the concurrent execution of multiple continuous range queries, CEM abstracts the dynamic relations between the movement of objects and the change of query answers, and introduces the concept of query view. The query answers are affected if and only if there are objects changing their current query views, which lead to the minimum transmission cost on the moving object side. CEM eliminates the redundant processing by handling the updates only from the objects that potentially change the answers. The experimental results show that CEM achieves the good performance in terms of server load and communication cost.