Minimizing unnecessary notification traffic in the IMS presence system

Presence is an always-on service. This means that even when the user does not need presence information about his buddies, his mobile phone gets updates about their state. These updates use bandwidth on the radio network and - even more important - drain the mobile terminal´s battery. This paper suggests ways to reduce these updates within the presence part of the 3G IP multimedia subsystem (IMS) while maintaining full responsiveness of the presence service for the end user. We propose and compare three solutions to the problem. They extend the interface between the resource list server and the mobile terminal. Our methods minimize traffic on the air interface while maintaining full responsiveness for the end user. They are transparent to the presence server and the presentities, the only entities needing adaptations are the client on the user terminal and the resource list server.