Monday, March 24, 2008

Railway wireless options

A news report has questioned if Australian railways should adopt the European GSM-R digital radio system, or Tetra. GSM-R is an adaption of the GSM phone system for railways. Tetra (TErrestrial Trunked RAdio) is a European developed digital trunked radio system. Tetra has the advantage of being used more widely than just for railways, but is no more technically  advanced than GSM-R.

Both SGM-R and Tetra have advantages and disadvantages. Neither is designed for high speed data transfer comparable to 4G mobile  phone networks, but this is not a requirement for a railway system. One problem is the need to install infrastructure. Unless the wireless network is shared with other suers (such as police and other emergency services), they a whole network has to be installed and paid for just for the railway. This applies to both GSM-R and Tetra, but there are more likely to be other government Tetra users to share the cost.

An alternative would be for the railways to use public 4G wireless mobile phone and other data networks (particularly WiMax). Railways have tended to want to use their own dedicated communications network, however, if multiple public networks were used this might provide sufficient reliability. In any case the telecommunications companies are likely to be keen to provide access to their services for railway passengers and so install the needed equipment in tunnels and other locations the signals would not normally reach. There would be little extra cost in providing railway communications. These could also be used for other equipment, such as level crossing signals.

Some railways are using WiFi for signaling, but this would generally apply only to small, dense, metro systems, due to the need for a base station every few tens of metres.

Railways are installing new GSM-R networks, such as China's use of GSM-R for its network. Railways are using 4G networks, such as Australian Rail Track Corporation (ARTC) is to use Telstra's NextG 4G mobile phone network for 10,000km of rail line in regional Australia.
THE State Government's promised rail communications system upgrade has come under attack, with claims the $80 million project is set for cost blow-outs because of outdated technology.

The upgrade of the Metropolitan Train Safety Communications System, announced in May 2006, is designed to allow drivers to communicate directly with each other in the event of emergencies such as track intruders or accidents.

The Government favours GSM-R technology, a variant of the GSM system used for most non-3G mobile phones. Technical experts describe this as a second-generation technology and point out that the IT world is already using third-generation (3G) technology.

The Age understands the Government plans to use the GSM-R on the phone spectrum bought after the collapse of One.Tel in 2001. But that licence expires by 2015....

The London Underground, Paris, Madrid, Berlin and many train networks throughout Asia have progressed to the more modern TETRA system, which is said to be more cost effective in metropolitan areas. ...

Many suburban train drivers have told The Age they have been forced to use their own mobile phones to fill "dead spots" in the current radio system.

From: Railway project cost blow-out fears, Mathew Murphy and Clay Lucas, The Age, March 22 2008

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