Technological fix driving onboard Ethernet communication

With laptop in hand you are about to set off on your train, metro, bus or tram journey home hoping to get some work done using the onboard Ethernet. What you don’t know is the sheer number of settings, any of which can fail, that make this endeavour possible. For example, when train wagons are changed a reconfiguration of the network settings is usually required. This increases rail maintenance and operating costs.

Other issues that need to be considered by train companies when installing an Ethernet include: the requirement for high-speed networks on both the train and trackside to be capable of withstanding wide temperature swings; the fact that power is not as readily available on a train as it is in a building; train cars aren't designed for large network deployments; and, it can be difficult, or impossible, to implement high-speed wireless coverage of the entire rail infrastructure.

But a number of high-tech companies are now developing innovative solutions to meet these challenges. Cisco Systems Inc., the California headquartered developer and manufacturer of networking hardware, telecommunications equipment and other high-technology services and products, recently showcased its high-speed Cisco Connected Train (CCT) solution. It integrates capabilities from multiple proprietary networks in train cars onto a new converged IP network infrastructure.

The solution provides a resilient infrastructure to deliver numerous services, like onboard safety and security (including video surveillance), passenger Wi-Fi and entertainment services, passenger information displays, and collaboration capabilities. CCT also provides a link to operations and control centre teams for communications-based train control (CBTC), positive train control (PTC) and fleet dispatch features. The CCT network is built on hardened, small form factor (SFF) switches and gateways that support consumer and business mobility features.

The onboard gateway manages seamless service transport simultaneously over multiple wide area network (WAN) connections, including both Ethernet-connected train-to-trackside radios and multiple long term evolution (LTE) cellular links. Wireless access points provide Wi-Fi connectivity to rail personnel and passengers. The network also supports comprehensive video surveillance, with a dedicated video surveillance media server on each car to store video archives from the onboard IP cameras.

In June, Lantech Communications Global Inc. unveiled a solution that also automatically detects and changes an IP address. Its Lantech Train Discovery Protocol (LTDP) enabled dynamic host configuration protocol (DHCP) server, Lantech EN50155 switches, can detect the current IP addresses and cause it to be exchanged when a vehicle is merged. LTDP can also respond to the connection failure or node failure to maintain the original IP range and maintain the remaining network function until the replacement occurs. Similarly, the configuration file is kept when the switch is swapped.

Lantech industrial Ethernet switches are also about to be implemented by a number of European bus manufacturers including Volvo, Scania AB, Mercedes-Benz and MAN Truck & Bus. Each vehicle will have an IP network installed. Explaining the technological requirements Lantech said, “A standard Bus can only provide either 24Vdc or 12Vdc for supply to additional systems, therefore these manufacturers require a perfect Ethernet switch able to meet the supply voltage and vehicle environmental requirements in particular with high voltage cramp or surge protection when engine starts. The switch needs to be able to provide PoE [Power over Ethernet] supply voltage of 48Vdc to PoE devices.”

Meanwhile in Norway, Moxa Inc. the provider of industrial networking, computing, and automation solutions has successfully developed an Ethernet backbone for the country’s railway. Moxa claims that its TN-5516 Ethernet switches “take only five to six seconds to boot,” thereby beating other manufacturer´s products. The switches have a built-in DC/AC power converter that eliminates the need for an additional external converter, saving space, time, and money. And they support PoE, which enables customers to add devices to their existing network infrastructure without purchasing more power cables or reorganizing the original network design.

In Japan, Tokyo Monorail Co. Ltd. uses components from HARTING Electronics GmbH for the Ethernet onboard network of its train series 10000. Its connector solutions bridge the distances between railway cars and/or wagons, ensuring high transmission quality. The services operate on LCD monitors and – in the case of the Tokyo Monorail 10000 series – are available in up to four languages. Han® HPR connectors are used for the outdoor and under-floor applications. The Ethernet transmission comprises IP65/67 M12 round connectors and Ha-VIS EtherRail® cables. The connectors are resistant to corrosion, heat and cold, as well as to UV radiation. They also feature excellent Electromagnetic compatibility (EMC) characteristics.

As train control systems have advanced, the requirements of train control networks have also kept pace. “Networks need to deliver a high level of bandwidth and availability in order to support CCTV, PA, alarm, and control systems all on the same network,” says Moxa. But the network must be able to perform in an unstable moving platform, which also physically changes when train carriages are rearranged. And all of this has to be achieved without overwhelming the operator with maintenance or operational burdens. However, by combining Ethernet train backbones (ETB) with Ethernet consist networks (ECN) railway operators are now beginning to achieve the sort of network performance and flexibility that they need.

 

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