Backbone for the Digital Railway

Author: Malcolm D'Cruz
Co-author: David Lim
Reserve paper
Railways are always increasing the number of network services to cope with emerging technologies. The success of Communication Based Train Control (CBTC) depends on the ability of the backbone communication system to guarantee high bandwidths and reliability. Thus the traditional role of railways as a network operator is gradually moving towards a service provider for both internal as well as external clients.
The quick fix solution that railways currently adopt is to deploy parallel networks over the communication backbone system to cope with the demand of emerging technologies like Video Analytics in Closed Circuit Television Cameras (CCTV), Long Term Evolution 4G digital radio and CBTC. This basically means adding a new box each time a new network service is required and the funding comes on top of the operational costs for maintaining the railway in the form of capital expenditure for an Information and Communications Technology (ICT) refresh.
The drawback with hardware-based solutions is that they rapidly reach end of life and require a reiteration of the design-integrate-deploy cycle with little or no revenue benefit and require operational outages for deployment of changes or upgrades. Passenger railway operators are not profit driven, the "no-revenue benefit" factor doesn't really appeal to them instead passenger railways are more worried about public relations and the impact caused by prolonged or unexpected outages. Therefore minimizing impacts to the operating systems and the railway overall is more appealing to passenger rail operators.
The challenge for backbone railway communication networking is to have a common platform for all network services whilst being ready for emerging technologies like CBTC.
Telecom service providers are faced with the same set of problems every time there is a new network service to be launched, the most common problems are high equipment costs of parallel networks, increased power consumption by addition of new hardware, space issues for retrofitting new hardware, longer deployment times means reduced lifecycle benefits of the hardware, since the technology becomes obsolete by the time the hardware is deployed.
To address these issues, Telecom service providers have embraced the virtualisation trend in information technology to perform network functions which are traditionally provided by hardware such as routers and switches.
The aim of this paper is to show how Software Defined Networks (SDN) adopted by telecom service providers as a common platform for all network services can benefit the railway networking environment to cope with constantly emerging technologies.