Suchergebnisse

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. ; This work has been funded by the Spanish MICINN through the I‐MOVING and ADAS‐ROAD projects (TEC2010‐18907 and TRA2013‐48314‐C3‐1‐R) and the Comunidad de Madrid government through the MEDIANET project (S2009/TIC‐1468).

Mobile Internet data traffic has experienced an exponential growth over the last few years due to the rise of demanding multimedia content and the increasing number of mobile devices. Seamless mobility support at the IP level is envisioned as a key architectural requirement in order to deal with the ever-increasing demand for data and to efficiently utilize a plethora of different wireless access networks. Current efforts from both industry and academia aim to evolve the mobility management protocols towards a more distributed operation to tackle shortcomings of fully centralized approaches. However, distributed solutions face several challenges that can result in lower performance which might affect real-time and multimedia applications. In this paper, we conduct an analytical and simulated evaluation of the main centralized and proposed Distributed Mobility Management (DMM) solutions. Our results show that, in some scenarios, when users move at high speed and/or when the mobile node is running long-lasting applications, the DMM approaches incur high signaling cost and long handover latency. ; This work was supported by the Government of Extremadura under Grant no. GR15099 and by the European Regional Development Fund Programme (2014–2020) and the Regional Fund, through Computing and Advanced Technologies Foundation of Extremadura (COMPUTAEX).

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. ; The work described in this paper has received funding from the Spanish Government through project I-MOVING (TEC2010-18907) and through the UP-TO-US Celtic project (CP07-015).