Date Added: Nov 2012
IP Multimedia Subsystem (IMS) introduces important advantages for users of LTE-femtocell heterogeneous access networks. In order to access services hosted in the IMS layer, the user has to undergo authentication procedure with the access network, followed by an authentication procedure with the IMS layer. This multi-pass authentication procedure is essential for securing IMS from malicious users, resulting in added overhead and possible quality of service degradations. The problem is further compounded when the user moves from one femtocell domain into another, which requires the authentication procedure to be repeated. To mitigate this problem, the authors present a lightweight, robust, and architecture-compatible IMS authentication protocol that implements a one-pass IMS procedure by promoting efficient key re-use for a mobile user.