Jumat, 28 Desember 2007

Wireless Hitches a Ride on the Subway (NewsFactor)

Some cell-phone users were bemused a few years back when an episode of the Fox TV series 24 aired in which Jack Bower and his intrepid antiterrorist team used GPS technology to track the movements of a biological weapon riding on an underground train in Los Angeles.

Given that terrestrial cellular calls are unable to penetrate the wide expanse of concrete and earth that lies between trains underground and the sky above, viewers reasoned, then how could any space-based satellite be expected to succeed at the task?

These days, however, metropolitan subway systems are joining forces with technology providers to come up with a reliable method for delivering wireless services to their customers. Boston commuters, for example, now have the ability to use cellular phones and other wireless devices as they travel through some of Bostons busiest subway stations.

"This is a major customer service enhancement for our ridership," said Daniel Grabauskas, the general manager of the Metropolitan Boston Transit Authority. "Not only can customers make calls, send text messages, and receive T-Alerts while using the subway, they can also access the Internet and check e-mails."


Bostons MBTA wireless system was constructed by InSite Wireless, which specializes in the deployment of distributed antenna system (DAS) technology in public facilities, such as San Franciscos Moscone Center.

DAS technology expands the wireless coverage of cellular networks in much the same way as access points extend the reach of todays Wi-Fi systems. The DAS signal, which is received by small antennas scattered throughout a facility, is balanced among the antennas and then forwarded over fiber optic cables to the carrier networks.

The DAS providers make money by charging access fees to cellular providers, such as AT&T, T-Mobile, and Verizon Wireless. And the subway system operators benefit by getting a slice of the pie. In Boston, for example, the MBTA will be paid a minimum of $4 million under its 15-year license agreement with InSite Wireless.

New York Citys Metropolitan Transportation Authority has tapped Transit Wireless to equip the Big Apples 277 underground subway stations for cell phone and wireless Internet service. In exchange to landing the rights to access New York Citys underground, Transit Wireless has agreed to pay the MTA an estimated $46.8 million over 10 years.

The carriers are more than willing to pay the substantial access fees because of the dramatic rise in billable minutes they accrue from customers who otherwise would be unable to make or place calls. In Boston, for example, 312,000 riders on average travel through the core of the MBTAs subway system each weekday.


DAS has the potential to deliver benefits beyond mere convenience. Having wireless voice and data communications capabilities underground can improve safety for commuters and transit workers as well as provide emergency responders with access to critical information in the wake of a medical emergency, natural disaster, or terrorist attack.

One critical component of the proposed system slated for the Big Apple is that it can locate the precise source of a cell phone transmission and relay this information to the cellular telephone carrier, said Gary Simpson, spokesperson for Transit Wireless.

If someone calls for help from the north end of the uptown platform in a large station, for example, 911 communications centers will be able to provide police and paramedics with the exact location of the call, Simpson explained.

Suddenly, Jack Bowers prowess at wirelessly tracking the subterranean movements of biological terrorists seems right on the money.

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