WASHINGTON: LightSquared continues to assert that its proposed wireless broadband system will not upset global positioning systems, citing test results from Alcatel Lucent. LightSquared filed the full Alu test results with the Federal Communications Commission on Friday, after having submitted a preliminary report about four weeks ago.
“The testing demonstrated the ability of high-precision GPS devices to be appropriately filtered so as to be able to fully reject LightSquared authorized transmissions in the adjacent spectrum band,” LightSquared’s filing states. Alu tested GPS devices from Topcon, Trimble, Septentrio and Javad with both legacy antennas and those provided by Javad, a San Jose, Calif., company contracted by LightSquared to develop an interference fix. The Javad antennas were key to interference rejection in the Alu tests.
“When subjected to LTE handset signals of up to -15 dBm at the device under test, the GPS devices connected to the modified antennas showed no C/N0 [Carrier-to-Noise] performance degradation,” Alu’s executive summary states. “When the GPS devices were connected to an unmodified antenna, various degradations were observed.”
LightSquared said the GPS receivers were subjected to power levels “which would be experienced on the ground.”
The Alu summary continues, “In addition to the testing described in the test plan, a worst case scenario of base station and handset was performed where both were transmitting at a level of -15 dBm as measured at the device under testing. On the devices tested with this condition using the modified antenna, no reduction in C/N0 was observed.”
The U.S. GPS Industry Council registered its objections to the Alu tests before the full results were filed. The group claimed the Javad antennas used in the Alu tests were “experimental units.” In a Jan. 12, 2012 letter to the FCC, the Council said, “The hurdles to making any of these prototypes commercially available are significant.” The group also expressed concern how modified antennas might affect the accuracy of high-precision GPS instruments.
LightSquared responded by saying it “stands by its assessments and will provide a thorough rebuttal to the USGIC’s claims in a subsequent filing.”
LightSquared, based in Reston, Va., has been jockeying for FCC approval to launch a hybrid terrestrial-satellite wireless broadband network in L-band spectrum for more than a year now. The FCC fast-tracked its proposal because of its walking orders from the Obama Administration to deploy wireless broadband. The commission gave LightSquared a conditional waiver to go forward as long is it demonstrated non-interference with GPS devices, which operate in the L-band spectrum adjacent to that licensed by LightSquared.
The ensuing problem was not that LightSquared’s terrestrial signals leaked into the GPS band, but rather that GPS devices have insufficient capability to reject LightSquared network signals. LightSquared modified its original launch plan to use only half of its spectrum at a lower power level, leaving what it said were only the high-precision GPS devices potentially affected by its system. The latest round of tests conducted by the National Executive Committee for Space-Based Positioning, Navigation and Timing Systems Engineering Forum indicated that the operational modification didn’t adequately prevent GPS interference. LightSquared blasted the tests as biased. (See “LightSquared Says GPS Tests ‘Rigged.’”)
LightSquared is funded with $3 billion from New York-based Harbinger Capital, founded by Phil Falcone, who’s been criticized for tying investors’ money up in the project. With payments looming for satellite deals, LightSquared has come under increasing speculation about its continued solvency. Bloomberg reported last week that Carl Icahn and two other investors purchased $300 million in debt from LightSquared bondholder Farallon Capital Management LLC. Management.
A $9 billion shared-services agreement with Sprint may also fall through at the end of this month if LightSquared can’t convince the carrier to stay on board. Sprint gave LightSquared a 30-day extension for a Dec. 31, 2011 deadline for getting FCC approval to launch. Partnering with Spring would save LightSquared the significant trouble and expense of building its own terrestrial infrastructure from scratch.
~Deborah D. McAdams
December 12, 2011: “LightSquared’s Travails Mount
LightSquared’s troubles are mounting with lawmakers and regulators lining up against the company’s proposed satellite-terrestrial LTE wireless broadband network.
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 hypotheticals 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. That condition remains intact, the FCC said, and noninterference has yet to be established to the satisfaction of the far-flung GPS community.
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.
Future US's leading brands bring the most important, up-to-date information right to your inbox
Thank you for signing up to TV Tech. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.