Similar to the developments in the United States focused at freight trains, passenger trains are expected to see some major enhancements for safety and service in the coming decade. Technology now exists and requisite standards are evolving to greatly enhance computerized features for passenger trains.
The first stage of this evolution is for the creation of communication channels that connect the trains to the supporting infrastructure. From a wayside (along the rail route) perspective, we are seeing four major communication channels develop. These wayside train communication channels are:
- 220 MHz Private Wireless
- Long Range Wi-Fi
- Public Cellular Networks
- High Speed Satellite Links
220 MHz Band
The 220 MHz band (218 MHz to 222 MHz) has become the default channel for smart train control. It has the advantage of excellent coverage in the range of 30 to 45 kilometres albeit at a very narrow channel and therefore minimal data rates. This spectrum is in high demand, so multiple users will exist within the crowded spectrum plan. The plan for railway use is in the upper portion of the band from 220 MHz to 222 MHz. This band is flexible in that the channel plan can be for simplex or duplex and the channel bandwidth can be configured from 2.5 kHz to 12.5 kHz in incremental steps and in concert with other users on a first come, first served basis and also based upon spectral efficiency. Coordination within 120 km of the USA – Canada border is required with specific channels assigned to each country.
The channels in the table below are available for the exclusive use by the Railway Association of Canada within the geographical area consisting of a corridor bounded by 70 km on each side of railway lines. Railway Association of Canada frequencies may be used for fixed and land mobile services beyond this geographical area according to this SRSP-512 (Standard Radio, Standard Practice – 512) , provided that the Railway Association of Canada is protected within their geographical area of operation bounding the railway lines.
Note: Base station frequencies are paired with mobile station frequencies, which are 1 MHz higher.
These channels are identified for the Railway Association of Canadian order to be interoperable with those of the Association of American Railroads (AAR) in the United States. It should be noted that, the use of these channels in the coordination zone is subject to the interim sharing arrangement between Canada and the United States for the band 220-222 MHz. They may be used by Canada within 120 km of the border under the conditions described in Section 220.127.116.11 of this SRSP. With such limited data rates available in this spectrum, the expectation is that only command and control and telemetry of the train will be possible. There is not enough data rates for much more than this core application. At 12.5 kHz channel bandwidth, the data rate will likely only be 8 to 12 kbps. With intelligence within the train’s engine, this data rate can trigger braking and reduce speed commands, share location, speed, and direction data, and a few other simplistic features. It cannot accommodate high demand applications like passenger Wi-Fi.
There are many new developments in the IEEE 802.11 standards that will greatly improve the use of Wi-Fi technology for wayside communications (railside installed communication towers to moving trains). Distances are growing much longer for these next generation commercial radios now measured in kilometres compared to the consumer products still measured in meters; so long range coverage along the wayside is now both practical and cost effective. Tunnels within the communication channel permit separation of the passenger and rail operations traffic, with hardened security solutions to protect all data traffic. Hand-offs between access points is now available for ultra low convergence of about 50ms, which will provide data flows that are acceptable for almost all passenger and rail operation applications today.
Wi-Fi designed specifically for rail installations offers ruggedized housings with swappable modules and redundant power supplies. These systems are protected from radio and electro-mechanical interference and able to operate from -40°C to 60°C. These DC powered metal housings are compact and can be remotely managed for diagnostics and remote troubleshooting. Some models are already compliant with AAR Standard S-9401 and EN-50155. The USA AAR standards will likely be adopted by Canada too.
Ruggedized Lilee Systems Wi-Fi Terminal
The use of GPS to lock radios permits synchronous operation of the disparate systems on various networks and trains with precise coordination and location capabilities. The internal carriage radios can lock to the secondary cellular networks if the source primary Wi-Fi signal is lost. This carrier sourcing capability will be seamless and permit automated selection of the best sources. It allows the lowest cost and best availability for rail routes that link urban centres via rural territory.
In many locations in North America, the penetration of 4G LTE cellular networks is popular and readily available. Often, these consumer cellular networks overlap with rail routes well. But, it is not unusual to have rail routes run through areas with poor or no cellular coverage. So, cellular coverage can be sporadic. Likewise, one cellular network may not adequately cover all rail routes and the use of multiple carriers may be necessary.
Similar to the Wi-Fi connection described above, the cellular networks can be used to connect the train and then the cellular data rate can be rebroadcast using Wi-Fi within the carriages for passenger Wi-Fi interconnectivity.
Multiple cellular signals can be aggregated with channel bonding to increase data handling capacity. The LTE physical layer can support high throughput data delivery at speeds up to 350 kph and even 500 kph in rural areas. State-of-the-art implementations of LTE have the capability to support at least 200 active data users per 5 MHz of bandwidth in a cell, which will further increase in LTE-Advanced. A typical passenger train in Canada may see a maximum of just 90 kph, so this is well within the LTE performance range. As high speed trains are evolving and becoming popular worldwide as a new means of transportation, the consideration of connectivity to high speed trains is becoming important. The famed Shinkansen bullet trains in Japan (300 kph), the Chinese high speed railway system (165kph; expected to reach 350 kph in the near future), and the Eurostar (175 kph to 334 kph) are extremely successful examples in use, with a number of others being under construction or preparation. If the rail operator can secure an Access Point Name (APN) services from the wireless carriers, then they could further isolate their commercial traffic from consumer traffic and provide a better standard for trusted and reliable service.
In order to bring ubiquitous broadband to fast moving trains in order to deliver entertainment and internet access to passengers, along the entire rail route, sometimes terrestrial connections are just not sufficient for the job. That is when satellite connections come into play and they can deliver in dark territories where other networks cannot provide adequate coverage or where the costs to deploy these terrestrial networks is cost prohibitive. To support the high data rates required for broadband, high frequency bands (Ku-Band / Ka-Band) are used to minimize space segment costs and reduce operational expenses.
For mobile SATCOM applications tracking antennas are used to maintain the line of sight (LOS). The image below shows a flat panel piezoelectric antenna suitable for train use.
A Russian railway company needed a solution for broadband communication on its long train routes, servicing primary business passenger routes. These routes of over 1,000 km with travel times up to 16 hours go through uninhabited areas, small villages and cities year round, operating in extremely cold temperatures. Travelling businessmen need to be able to access the Web at a minimum transmission rate of 2 Mbps / 0.5 Mbps of unlimited traffic. A low profile satellite antenna was used with a ruggedized receiver to provide a robust service. In Canada, we can expect to make use of similar solutions outside populated urban settings.
Whatever the communication need, it is now possible to provide contiguous high speed data communications to fast moving trains. For many regions of North America, it will take a combination of these solutions to provide a uniform and consistent coverage. Passengers will grow to rely on these network connections, therefore, maximum uptime is critical for passenger satisfaction and to provide a competitive advantage for rail operators compared to other forms of travel. No one solution will fill every need, therefore an array of solutions is deemed necessary based upon the region of Canada where the passenger trains operate.
About the Author:
Michael Martin has more than 35 years of experience in broadband networks, optical fibre, wireless and digital communications technologies. He is a Senior Executive Consultant with IBM Canada’s GTS Network Services Group. Over the past 11 years with IBM, he has worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He was previously a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN:TSX). Martin currently serves on the Board of Directors for TeraGo Inc (TGO:TSX) and previously served on the Board of Directors for Avante Logixx Inc. (XX:TSX.V). He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) and on the Board of Advisers of four different Colleges in Ontario as well as for 16 years on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section. He holds three Masters level degrees, in business (MBA), communication (MA), and education (MEd). As well, he has diplomas and certifications in business, computer programming, internetworking, project management, media, photography, and communication technology.