The U.S. Federal Communications Commission won't allow LightSquared's proposed mobile broadband service to interfere with GPS signals, even though the potential interference would be caused by GPS receivers picking up signals outside of their designated spectrum, a group of FCC officials said Tuesday.
The FCC, which is now trying to decide whether to allow LightSquared's mobile broadband proposal to move forward, recognizes the importance of GPS (Global Positioning System) as a consumer service and as a service used by the military, airplanes, and other groups, the FCC officials said.
The FCC won't allow interference with GPS, one official there said. But FCC officials who briefed reporters on background Tuesday also said that a terrestrial broadband service has long been in the works for the spectrum bordering GPS spectrum. LightSquared and its predecessor SkyTerra have been planning a mobile service in the contested spectrum since 2003, the FCC officials said.
The current interference fight is over GPS receivers that would pick up interference from cell towers operating outside of GPS spectrum, FCC officials said. Although those receivers are operating in spectrum licensed by LightSquared, GPS is too important to allow interference, the officials said.
During recent interference tests, it was clear that GPS receivers were picking up interference well beyond GPS spectrum, one FCC official said.
LightSquared has asked the FCC for approval to operate a hybrid satellite- and land-based LTE (Long-Term Evolution) 4G mobile network. The company, which plans to sell its network as a wholesale service, is waiting for approval while the agency examines interference complaints from GPS groups. The Coalition to Save Our GPS, a group of vendors and users, has objected to the LTE portion of LightSquared's plan.
LightSquared had hoped to begin offering dual-mode mobile handsets this year, but FCC officials said Tuesday they had no timetable for finishing their review of the interference questions. The FCC gave LightSquared conditional approval to move forward in January, as long as its service did not interfere with GPS.
The mobile startup has scrapped one spectrum proposal for the LTE portion of its plan because of the objections. LightSquared planned to offer LTE service using spectrum between 1525MHz and 1559MHz, with its satellite service operating in part of the 1600MHz band.
GPS uses spectrum from 1559MHz to 1610MHz. Under the original LightSquared proposal, it would have used spectrum up to 1555.2MHz for LTE, but testing by U.S. agencies showed significant interference problems. The current LightSquared proposal, released in June, would use only spectrum from 1526MHz to 1536MHz for the LTE service, leaving a 23MHz buffer zone between its mobile broadband spectrum and GPS spectrum. A typical guard band between spectrum users is about 2MHz.
The GPS coalition blasted the new proposal in a July filing. "The utter failure of LightSquared's initial deployment plans to pass interference tests raises fundamental questions about the representations LightSquared made to the FCC," the coalition said. "The current strong indication is that whatever LightSquared told the FCC prior to January 2011 was highly inaccurate, to a degree that verges on negligence."
In the longer term, the FCC or Congress will have to decide whether a 23MHz guard band is good spectrum policy, FCC officials said. The LightSquared spectrum is identified as new spectrum for mobile broadband in the FCC's national broadband plan released in early 2010.
The FCC doesn't want to lose the LightSquared spectrum for mobile broadband, and it doesn't want to encourage 23MHz guard bands as demand for mobile broadband spectrum skyrockets, officials said.
Grant Gross covers technology and telecom policy in the U.S. government for the IDG News Service. Follow Grant on Twitter at GrantGross. Grant's email address is firstname.lastname@example.org.