Distributed Processing of Spatial Alarms: A Safe Region-Based Approach

Spatial alarms are considered as one of the basic capabilities in future mobile computing systems for enabling personalization of location-based services. In this paper, we propose a distributed architecture and a suite of safe region techniques for scalable processing of spatial alarms. We show that safe region-based processing enables resource optimal distribution of partial alarm processing tasks from the server to the mobile clients. We propose three different safe region computation algorithms to explore the impact of size and shape of the safe region on network bandwidth, server load and client energy consumption. Concretely, we show that the maximum weighted perimeter rectangular safe region approach outperforms previous techniques in terms of performance and accuracy. We further explore finer granularity safe regions by introducing grid-based and pyramid-based representation of rectilinear polygonal shapes using bitmap encoding. Our experimental evaluation shows that the distributed safe region-based architecture outperforms the two most popular server-centric approaches, periodic and safe period-based, for spatial alarm processing.