IP based networks

Until very recently train operators have mainly relied on narrowband analogueue communication technologies. The rapid development of IP-based, digital broadband communication technologies is now drastically changing the industry landscape and requires a new generation of connectivity components.

For switched-technology networks, Ethernet is typically more and more used than conventional bus-technology networks mainly for bandwidth-demanding applications commonly designated as multimedia applications (e.g. CCTV, Passenger Infotainment, Internet on Board). As far as operational data is concerned the IEC 61375 standard also highlights a clear opening for the use of switched-technology networks (Ethernet).

This paves the road for merging all applications into a single switched-technology network where the network manages prioritisation between safety-critical and non-safety-critical data (Quality of Service) .

Unlike operational data, multimedia data require broadband network capabilities in particular on the backbone level of the network, Train backbones with up to 1Gbit/s and even 10Gbit/s bandwidth are already required.


Switched-technology gigabit networks

Challenge

• High-performance communication infrastructure including: Broadband connection to the outside world and Gigabit backbone network throughout the train
• Easy upgrade by use of performance-scalable connectivity components

Basis

• Ethernet-based network

Solution

• fiber optics backbone connections
• CAT7 backbone connections
• Benefits of fiber optic technology: Free from electromagnetic interference, Galvanic insulation thanks to dielectric properties

Inter-vehicle connections - a key part in the backbone

Challenge
Demanding environmental conditions

• In trains at very high speed
• Permanent movement, exposure to vibrations and shock
• Particularly high or low temperatures, moisture, detergents, dirt, UV radiation

Wired solution

• 100% tested and optimised system cables specially developed for the railway market
• Combination of optical cables, data bus, signal and power cables in one system cable
• Maintenance-free use

Wireless solution
Using antennas rather than cables means lower installation and maintenance costs, particularly for retrofitting and less effort to couple and uncouple the carriages.

The signal is often transmitted from carriage to carriage using Wi-Fi standard 802.11 a/n in the 5 GHz frequency band. This is mainly done to avoid problems between the various communication standards within a train. MIMO antennas also allow larger data volumes to be transmitted. Solutions involve:

• Space-saving directional antennas which can be fitted to the interior of the carriage using a range of installation methods.
• Dust- and waterproofed in accordance with IP67 means they are also suitable for outside installation