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Presented by:
Bart Lannoo, Didier Colle, Mario Pickavet, Piet Demeester

Abstract

Broadband access in a train environment is a topic which requires still a lot of research. It is especially the combination of fast moving users and high data rates which is still difficult to realize. In our proposed network architecture, we will make use of a reconfigurable Radio-over-Fiber network, which implements a moveable cell concept. By means of a case study, we will evaluate the total concept.

Introduction

It is not inconceivable that, in the near future, an internet connection or streaming video will become widely accepted on a train. The government will more and more promote public transport to decrease the number of nasty traffic jams. Furthermore, if time spent on the train can be applied usefully, this would be an extra stimulus for the commuters to choose the train as a daily means of transport. Thus, it would be nice that the “train of the future” were equipped with an internet connection which offers all sorts of multimedia applications to its passengers.

To realize such a connection, we will have a need for a wireless network which provides a lot of these services to fast moving users and simultaneously also at high data rates. Up till now, the combination of high bandwidth and fast moving users is not very evident. On one hand, there exist a lot of wireless networks which offer a high bandwidth to stationary users (e.g. in some cities, there are so-called hotspots which already provide wireless broadband access). On the other hand, mobile users at high speed can also set up a connection (e.g. GSM, UMTS) to a network such as internet, but the corresponding bandwidth will be insufficient to make use of the current broadband applications.

Our intention is to design a wireless network that can offer high data rates to mobile users at high speed. The network will contain a central control station, which is connected to a number of Remote Antenna Units (RAUs) via an optical fiber using Radio-over-Fiber (RoF) technology. In the next paragraph, the RoF technology itself and especially its benefits will be explained. Then, the structure of the proposed RoF network is described in some more detail. The design will be based in particular on a smooth handover concept between the different RAUs and will make use of moveable cells. Finally, we will consider a case study of a typical train scenario and also make a short calculation about the required capacity in this case. These requirements will be compared with the achievable capacity by our proposed network architecture.