WIRELESS NETWORKS
Wireless coverage for public transport On The Right Track? By Phil Sorsky, VP of Wireless Sales in Europe, CommScope
From keeping up-to-date with work on the move to downloading films onto the latest tablet, customers expect their wireless devices to work perfectly no matter where they are or what services they are attempting to access. Subscribers now consider mobile
Phil Sorsky discusses the challenges facing wireless coverage on public transport.
connectivity an indispensable utility and demand instant access to a range of resources including e-mail, instant messaging, multimedia content and voice and video calling. If such services are not available, operators not only miss out on revenue opportunities but their customers may become frustrated by the lack of connectivity and potentially look elsewhere. Crowded commuter trains and metro
systems are a familiar sight in many cities, particularly those with thriving business and commercial centres. Yet, it has become an anomaly of modern life that commuters, who crave wireless communications for personal and business use during their journeys, are left completely unconnected for up to several hours a day - leaving a largely untapped revenue opportunity for operators.
As government initiatives advocate using public transport and its ability to reduce our carbon footprint, the potential revenue opportunities will only increase. In addition, rising fuel prices, congestion charges and increasing traffic levels mean that public transport can often be a quicker and cheaper alternative, especially in highly populated urban areas. Unfortunately, the usual features
of urban public transport systems are often the enemy of dependable wireless coverage. Operators face the challenge of providing wireless coverage in what amount to high-speed Faraday cages, sometimes deep underground or running through many kilometres of tunnels.
Overground Trains Even for trains aboveground, perfect coverage along the track often does not translate to wireless connectivity inside the train. The metallised windows of high-speed trains can dramatically reduce wireless signal penetration into train carriages, resulting in patchy coverage and an increase in dropped
calls. Even the pure velocity of high- speed trains complicates matters, as wireless signals must be rapidly handed- off between base-stations as the train moves along its route. If this process is not managed correctly, it can result in dropped calls or interrupted data connections. Additionally, the wireless communications systems in such trains must support the complexities of rapidly changing outdoor signal levels of the various mobile networks involved. Above ground, this lack of
connectivity can be overcome by fitting in-train repeaters, which transmit and receive wireless signals to passenger’s handheld devices, recovering the high penetration loss caused by the carriage’s metalised structure to the signal coming from outside. For example, such repeaters have provided a solution on high-speed trains running between Beijing and Tianjin in China, and were specifically installed to cope with heavy usage from visitors to the 2008 Olympic Games. This method was used by Telecom
Italia to provide the Trenitalia Frecciarossa high-speed train line with wireless coverage. The use of these in-train repeaters also improves the power efficiency of the base stations that are providing coverage alongside the track, resulting in an overall increase of the data transfer speed for the wireless devices on board. Wireless coverage is now supported on all 60 trains travelling this route at speeds of up to 350 kilometres per hour.
Underground Trains Users of overground trains are only part of the whole commuter market. Residents of the world’s busiest cities are also often frustrated by the lack of connectivity in their underground or subway systems, preventing them from checking emails and making important calls from their mobiles whilst travelling between home, the office and business meetings. Again, a technical solution is available, but many underground networks have yet to deploy wireless communications systems. The technology required to
Perfect coverage along the the track does not guarantee connectivity inside the train. 18 NETCOMMS europe Volume II Issue 3 2012
facilitate wireless communications in underground networks differs from that of overground trains. Usually RF repeaters must be fitted in each station
www.netcommseurope.com
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