IMS-based Presence Service with Enhanced Scalability and Guaranteed QoS for Inter-Domain Enterprise Mobility

Enterprise mobility and IP Multimedia System (IMS) corporate services are becoming of growing and growing relevance: in particular, the IMS-based presence service is starting to widely provide different kinds of seamlessly mobile services with context awareness in enterprise deployment scenarios. However, the deployment of presence-based enterprise services in wide-scale and heterogeneous wireless networks still requires to face several challenging issues. First of all, scalability and differentiated quality are considered crucial, especially under high traffic conditions and when dealing with inter-domain mobility scenarios. The paper overviews some very recent research contributions about the standard IMS presence service and novel proposals for scalability/quality optimization. In addition, we propose a novel presence service solution that presents three original extensions toward scalability and quality: i) a federated model to optimize inter-domain distribution of notification messages via locality-based aggregation, ii) a proposal of differentiated quality levels, and iii) an extension of client-side buffering for reliable delivery of presence messages even during user roaming. The prototype of the enhanced presence service has been deployed and validated, by obtaining performance results of improved scalability in terms of CPU/memory usage at infrastructure nodes and message traffic; finally, the prototype is openly available to the IMS community for possible refinement and extension.