Regions Northern Virginia

LightSquared addresses interference concerns

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Print this page by Heather B. Hayes

Reston-based LightSquared is set to become the first company in the country to provide a nationwide 4G wireless broadband network that relies on satellite and terrestrial technology. The network is scheduled for a commercial launch in three test markets by the end of the year.

The company will sell its service as a wholesaler through retailers like Best Buy and wireless and broadband competitors such as LEAP Wireless, which will allow device, application and service developers to create products for customers. The 4G speeds will enable mobile users to enjoy faster data uploads and Internet surfing capabilities.

“It’s a huge deal,” says Jeff Carlisle, LightSquared’s executive vice president for regulatory affairs. “We’re offering a function and a capability that no one else is really bringing to the market.”

First, however, company officials must satisfy concerns over whether its network will interfere with Global Positioning System (GPS) signals and disrupt the operation of GPS devices used in public safety systems and jet flight controls as well as car navigations systems.

The potential for interference stems from the fact that one part of the spectrum utilized by the LightSquared network lies close to the area used by GPS devices.

The company has addressed potential transmission problems by installing filters on its base stations, which transmit signals from cell towers. “Instead of your signal gradually tapering off into GPS, the filter cuts it off like a wall, so we’re not sending any energy into the GPS units that could cause any sort of interference,” Carlisle says, noting that the filters adhere to a strict set of requirements demanded by the GPS Industry Council.

That solution was developed in 2004 when the company received authorization from the Federal Communications Commission to build and provide its new integrated service.

Last September, however, the GPS industry came up with another concern: A small group of GPS devices could be sensitive to signal transmissions from the LightSquared spectrum. If the devices overreach and pull signals from LightSquared’s band, the GPS devices could fail.

To alleviate those concerns, LightSquared now is co-chairing a working group that includes engineers from major GPS and wireless firms, as well as U.S. defense, public safety and aviation agencies. Testing will begin this spring, and LightSquared will submit a final report to the FCC in mid-June with recommended measures for mitigating any interference for different types of receivers.

“You’ve got everybody you would want looking at this issue,” Carlisle says. “We’re moving forward with it, and there’s been a high level of cooperation.”

LightSquared, which has more than 300 employees, will invest more than $7 billion to build out the network. 

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