Time-optimized user grouping in Location Based Services

Abstract

We focus on Location Based Services (LBSs) which deliver information to groups of mobile users based on their spatial context. The existence (and non-trivial lifetime) of groups of mobile users can simplify the operation of LBS and reduce network overhead (due to location updates and application content flow). We propose an incremental group formation algorithm and an optimally scheduled, adaptive group validation mechanism which detects and further exploits spontaneous formation of groups of mobile users. The advantages of application simplification and network load reduction are pursued. Through the proposed mechanism the LBS server (back-end system) monitors representatives of formed groups, i.e., group leader, and, in turn, disseminates location-dependent application content to group members. We first introduce an incremental group formation algorithm for group partitioning and identification of group leaders. We elaborate on the mechanism which adopts the Optimal Stopping Theory in order to assess the group persistence through evaluation of compactness and coherency metrics. We compare the performance of the proposed scheme with that of existing mechanisms for moving objects clustering and quantify the benefits stemming for its adoption.