Fast moving high bit rate users and terminals

1. Fast moving high bit rate users and terminals Filip De Greve, Bart Lannoo, Tom Van Leeuwen, Frederic Van Quickenborne, Didier Colle, Filip De Turck, Ingrid Moerman, Mario Pickavet, Bart Dhoedt, Piet Demeester When today’s commuters in the train or in a car want to access the Internet, they see themselves restricted to simple web surfing or e-mail. Interactive multimedia services, like online gaming or video conferencing remain unavailable to them. In the core network, different solutions are possible: we can choose a fully meshed network consisting of IP routers or we could consider a cheaper solution with Ethernet switches. In this research, we consider Ethernet as the most appropriate choice for the core network because of different reasons: cost effectiveness, simplicity and bandwidth flexibility. However, the deployment of Ethernet in core networks faces problems such as low resource utilization and large recovery times after changes in the network topology or in the traffic demand. Nowadays, a lot of multimedia applications are taken for granted in fixed networks. These applications require a high level of Quality of Service (QoS) and generally are characterized by high bandwidth requirements. The challenge future and current telecom operators are facing is to examine how this quality and bandwidth can also be provided in wireless cellular networks. Today, organizations like IEEE and 3GPP are establishing specifications for new wireless technologies which have to meet the bandwidth requirements of tomorrow (e.g. UMTS and IEEE802.11g). Unfortunately, the fast mobile user, e.g. in the car or on the train, seems always to be kept in the dark: the faster they move, the more their available bandwidth decreases. Current wireless network technologies are not capable to meet the demand for high bandwidth at high user velocity. Therefore we will develop and evaluate new protocols and algorithms to address these issues. This work is situated in the current research to extend the Ethernet standard towards a true transport technology for core networks. The validation of the developed protocols and algorithms will be done in a test bed environment, existing of Click Modular Routers. Along the rail track, a high data rate is required in an extremely limited area. An efficient re-utilization of the frequency spectrum in combination with high radio frequencies (e.g. 60 GHz) seems to be very attractive. As a consequence, small cells (micro- or pico-cells) will form an essential part of the network, and this also means that a lot of antennas have to be installed along the railway. In densely populated areas, such as cities and business centers, there is an evolution towards smaller cell sizes in order to be able to satisfy the demand for high bandwidth. This however, results in a high handover frequency (a handover typically every few seconds) when the users move at vehicular speeds. To keep the whole implementation cost efficient, we will make use of Radio-over-Fiber (RoF) technology. The goal is to transfer complicated signal pro-cessing functions from the Remote Antenna Units (RAUs) to a Centralized Control Station. Mobile users usually behave in a more or less predictable way, e.g. cars driving on a highway or in a city. There does not yet exist a handoff protocol for fast mobile users in small cell sized access networks. Just like in the car scenario, fast moving users together with small cells result in a lot of cumbersome handovers. In the train scenario, we can make use of the advantage that all users move at the same speed. This leads to the use of moveable cells. In this way, it becomes possible for commuters to access the Internet and game on-line on the train. Moveable Cells Instead of having the train moving along a fixed repeated cell pattern, one might also consider a cell pattern that moves together with the train and thus avoiding (most of) the handovers. Therefore we are developing a dedicated intelligent handoff routing protocol taking into account the knowledge of the position and the trajectory of the vehicle and the topology of the access network. Our goal is to make interactive high bandwidth multimedia applications possible in the car. This moveable cell concept will be realized by reconfiguring the optical feeder netwerk (which makes use of RoF).