No abstract

Vehicular ad hoc networks allow the exchange of information between vehicles to improve road safety. In addition, vehicles can be connected to the Internet through gateways placed alongside the roads, which allow drivers to use common Internet services and new applications specifically oriented to them. The European Telecommunications Standards Institute Technical Committee Intelligent Transport System has standardised the architecture and the communication protocols for an Intelligent Transport System, considering both safety applications and communications with the Internet. The GeoNetworking (GN) protocol has been designed to forward packets inside the vehicular ad hoc network taking safety requirements as the main concern. This paper analyses the GN protocol focusing on the provision of Internet connectivity to vehicles. The main contributions of this work are the identification of sources of performance losses when using the GN protocol in communications with the Internet and the proposal of different mechanisms to improve its performance in this type of communications. The evaluation of the GN protocol and the proposed improvements is conducted by means of extensive simulations.

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The IP Multimedia Subsystem (IMS) is considered as the common platform for providing a unified session control on top of various access network technologies for multimedia applications. At the same time, we are witnessing how wireless technologies become an integral part of our daily life, due to an increasing number of mobile multi-interface devices and the proliferation of wireless access networks. In this context the availability of transparent mobility management mechanisms is a key element to enhance user's quality of experience.On the other hand, context-awareness is a vital ingredient to allow mobile devices to make appropriate and timely mobility decisions. The benefits of using diverse context information (e.g., about the user, the service and the network) to manage mobility are twofold. First, the richer information is available, the more likely an intelligent decision can be taken. Second, it allows the network to assist the terminal to take mobility decisions, even up to the point of automatically initiating a mobility procedure if according to the context and user preferences this improves the user's quality of experience.In this paper we propose CATMISS, a solution to support context-aware mobility in IMS services. The solution is based on SIP signalling and makes mobility transparent for communication peers of mobile terminals. Two types of mobility are supported: a terminal changing of access network and a multimedia session being transferred from one terminal to another. The paper also describes the implementation of the solution and its deployment in an experimental platform. Experiments in this platform, with IPTV and videoconference services, are used to validate the proposal.