WASHINGTON: The Federal Communications Commission is turning to the public regarding LightSquared’s request to operate in its own spectrum and not grant interference protection to global positioning systems. LightSquared filed the petition in December, imploring the commission to “confirm that commercial GPS manufacturers have no right to interference protection from LightSquared’s spectrum since they are not licensed users of that spectrum.” GPS devices operate in spectrum adjacent to LightSquared’s, but they haven’t the signal rejection capacity necessary to prevent interference from LightSquared’s proposed satellite-terrestrial broadband network.
The commission cannot grant LightSquared’s petition prima facie until the GPS interference issue is resolved, but it notes that the petition “raises general questions about the regulatory status of GPS devices.”
The FCC on Friday opened a comment period for public feedback on LightSquared’s request. The company has long argued that the GPS interference problem is with the devices themselves, and not signal bleed from its proposed network. However, LightSquared’s proposed network represents an exception to its bandwidth designation. Its L-band spectrum is licensed primarily for satellite transmissions, with allowance for an “Ancillary Terrestrial Component” to fill in gaps. LightSquared’s proposal comprises a terrestrial infrastructure of 40,000 base stations, using satellite transmissions to fill in the gaps of a nationwide LTE wireless broadband network. LightSquared had to get a waiver of the ATC from the commission before it could commence operations. The FCC granted the waiver on the condition that LightSquared not interfere with GPS operations.
“To date, the Interference-Resolution Process has not been completed,” the FCC noted Friday in opening the public comment cycle.
LightSquared’s regulatory odyssey includes a first round of tests that demonstrated significant interference with GPS operations. It then modified its plan to launch at a lower power on the half of its 20 MHz of spectrum farthest from the GPS band. Under the modification, LightSquared said that only a small fraction of high-precision devices would be affected, and these could be equipped with filters to prevent interference. Subsequent tests by a government consortium concluded that interference levels remained unacceptable and inalterable.
“It is the unanimous conclusion of the test findings by the National Space-Based PNT ExCom Agencies that both LightSquared’s original and modified plans for its proposed mobile network would cause harmful interference to many GPS receivers,” the co-chairmen of the consortium wrote on Jan. 13 to Larry Strickland, head of the Commerce Department’s National Telecommunications and Information Administration, which oversees spectrum usage. The ExCom said there was no need for further testing.
LightSquared cried foul, saying the ExCom tests were “rigged” by GPS manufacturers. The company had its own tests conducted by Alcatel Lucent, submitting results last week that demonstrated interference mitigation with the use of filters. The military is deign to use filters, however, because of the cost and the unknown impact on precision.
TV Technology contributor Charles Rhodes, formerly the chief scientist at the Advanced Television Test Center, noted that neither the government nor LightSquared’s tests pinpointed the cause of the interference. Rhodes conducted tests in his own laboratory and concluded it was caused by “nonlinear distortions in the GPS receiver low-noise amplifiers,” and that “desensitization lowers the GPS signal power while higher order intermodulation products increase the noise floor in the GPS band.”
“The relative importance of these two causes is unknown,” he stated in a filing with the commission. “It would be extremely dangerous for the FCC to proceed with final authorization... based on what is known about GPS receiver performance with one 10 MHz LTE signal at 1526-1536 MHz. Further testing is needed.”
While ExCom made the opposite recommendation more recently, the final decision rests with the NTIA and the FCC. The commission is invested in LightSquared’s success to the degree that it represents the most rapid deployment of nationwide wireless broadband--a chief goal of the Obama Administration. The FCC waiver and White House interactions with LightSquared’s financiers have riled Iowa Republican Sen. Charles Grassley. The senator is threatening to block confirmation of two commission nominees until he receives documents related to the waiver.
The FCC’s International Bureau has established a comment cycle for LightSquared’s petition on the existing docket, IB No. 11-109, which already has nearly 3,600 comments; as well as for ET No. 10-142, a more focused Report and Order dealing with terrestrial service allocations. Comments are due Feb. 27, with replies due March 13, 2012.
~Deborah D. McAdams
January 23, 2012: “LightSquared Submits Alcatel Lucent Test Results to FCC”
LightSquared continues to assert that its proposed wireless broadband system will not upset global positioning systems, citing test results from Alcatel Lucent.
January 18, 2012: “LightSquared Says GPS Tests ‘Rigged’”
“We believe the testing is invalid.”
December 21, 2011:“LightSquared Petitions FCC for Declaratory Ruling”
LightSquared today asked the FCC to confirm its right to use its own licensed spectrum, and to “confirm that commercial GPS manufacturers have no right to interference protection from LightSquared’s network since they are not licensed users of that spectrum.”
September. 21, 2011: “LightSquared Announces GPS Filter Fix”
“This interference problem is not a difficult one to solve, once you decide to solve it. We’ve begun manufacturing preproduction models and expect to have 25 available within two weeks--we are not talking in hypothetical here.”
September 15, 2011: “General Says Fixing Lightsquared Interference to Military GPS Ops Could TAke 10 Years”
Gen. William Shelton also told members of the House Armed Services Strategic Forces subcommittee the filters most recently proposed by LightSquared to eliminate interference with high-precision GPS receivers could cause other problems.
September 9, 2011: “FCC Delays LightSquared Launch”
The commission gave LightSquared approval last January for the Ancillary Terrestrial Component of its operation on the condition that it not interfere with GPS.
July 28, 2011: “LightSquared, Sprint Cut $9 Billion, 15-Year Shared-Services Deal”
Under the agreement, LightSquared will pay Sprint to deploy and operate a nationwide LTE network that hosts L-Band spectrum licensed to or available to LightSquared.
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