The IHMAS Project


Recent advances in wireless client devices and multimedia communications have motivated relevant standardization efforts, such as the IP Multimedia System (IMS) to support session control, mobility, and interoperability in all-IP next generation networks. One of the most challenging issues in IMS-based solutions is service continuity during handoffs, i.e., the capacity to maintain service provisioning and avoid flow interruptions when clients roam through different wireless APs by minimizing or eliminating handoff delays and packet losses, especially during vertical handoffs among different wireless technologies.


The purpose of the IMS-compliant Handoff Management Application Server (IHMAS) infrastructure is to provide effective support for IMS-compliant fast vertical handoff and dynamic multimedia content tailoring. IHMAS significantly differs from state-of-the-art work by combining the following original technical aspects:

  • IHMAS is proactive. It predicts vertical handoffs at clients and exploits handoff predictions to proactively start SIP-based session reconfiguration (REGISTER/INVITE messages) over the target AP while continuing to receive multimedia data from the old AP.
  • IHMAS adopts an application-layer approach for session adaptation. It adjusts service provisioning by applying application-level content adaptation techniques and seamlessly integrates with existing tools and applicative protocols, e.g., Asterisk server and RTP-over-UDP.
  • IHMAS grants low session adaptation latencies. It guarantees low adaptation times, even during most challenging vertical handoffs, thanks to our proactive application-layer approach.
  • IHMAS is a real and ready-to-deploy IMS-based solution. It is the first proposal in the field fully compatible with IMS; it can interwork, without the need of any intervention or modification, with already deployed IMS implementation.

In the context of the IHMAS project, we are also tackling IMS scalability/quality optimization issues by focusing on IMS Presence Service (PS) and its use for the development of mobile enterprise services. Our original contribution includes various extensions aimed to optimize inter-domain distribution of PS notification messages towards presence-based enterprise services that have to be deployed and seamlessly accessed from different and geographically distributed IMS domains. For more information please refer to the IHMAS PS optimizations section.