LightSquared to Propose Initial Lower L-Band Use for Wireless Service
LightSquared will propose initially only using the lower 10 MHz of the L-band spectrum the company has access to as a way to deal with interference problems with GPS services, it said Monday. The proposal, which includes the acceleration of a LightSquared agreement with Inmarsat, would allow LightSquared to begin service further away from spectrum used by the GPS industry. LightSquared made the decision after “early test results indicated that one of LightSquared’s 10MHz blocks of frequencies poses interference to many GPS receivers,” the company said. The GPS industry has expressed concerns over such plans in the past (CD June p9).
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LightSquared will float the proposal in more detail in a coming working group report that is due at the FCC July 1, Executive Vice President Jeff Carlisle said in an interview. Some of those details will have to be worked out cooperatively with the group, he said. The deadline for that report was recently pushed back (CD June 17 p13). LightSquared previously made an agreement with Inmarsat that would allow LightSquared to access contiguous L-band spectrum. That agreement was recently changed to give LightSquared access to lower band more quickly, Carlisle said.
Testing has demonstrated that LightSquared service in the lower part of the band largely won’t interfere with GPS service, “with the exception of a limited number of high precision GPS receivers that are specifically designed to rely on LightSquared’s spectrum,” the company said. “In its original plan, LightSquared planned to move into this other frequency block as its business grew over the next two to three years."
Precision GPS interference may continue to be a stumbling block for the proposal, despite being a very small portion of the GPS industry as whole, said a satellite industry executive. Many precision GPS services use an FCC-authorized augmentation band that extends into the L-band. It remains unclear to what extent service in that lower-band has been properly tested, said the executive. Carlisle said LightSquared is willing “to step forward” and to make sure that the precision receivers will continue service. Eventually, precision GPS services will also be able to rely on much more stable service arrangements than what exists today, he said. In some cases, coordination among the spectrum users will necessary, he said.
LightSquared said it will use the initial launch period to work with the FCC, NTIA and other “relevant U.S. government agencies and commercial GPS users, to explore mitigation possibilities and operational alternatives that will allow LightSquared to continue to expand its business.” LightSquared will also modify its FCC license to lower the power limit of base-station transmitters, a “good-faith effort” that will reduce the power levels to 1.6 kW, said Carlisle. LightSquared was always planning to use that power level, but others were concerned it would eventually deploy service with a higher power level, as it was authorized to do by its current commission license, Carlisle said.
The GPS industry was largely unswayed by the new plan. “This latest gambit by LightSquared borders on the bizarre,” said Jim Kirkland, general counsel of Trimble. He’s a founder of the Coalition to Save Our GPS, a group aimed at preventing GPS interference from LightSquared. “Last week LightSquared unilaterally delayed filing of the study report that culminated months of intensive work to evaluate interference to GPS, because they purportedly needed two more weeks to analyze the results. Days later, well before the report is scheduled to be filed, LightSquared unilaterally announces that it has found a ’solution.’ LightSquared’s supposed solution is nothing but a ‘Hail Mary’ move. Confining its operation to the lower MSS band still interferes with many critical GPS receivers in addition to the precision receivers that even LightSquared concedes will be affected. The government results submitted to date already prove this, and the study group report will also confirm this. It is time for LightSquared to move to out of the MSS band."
Meanwhile, a more substantial governmental report on testing from the National Space-Based Positioning, Navigation, and Timing Systems Engineering Forum was released. The report, which wasn’t part of the working group effort, had been previously released in a more condensed form. “Initial test results demonstrated that some applications (e.g. aviation) were able to operate with little to no degradation when only a 5 or 10 MHz channel (1526.3-1531.3 MHz or 1526-1536 MHz) in the lower portion of the MSS spectrum was utilized for the LightSquared broadcast,” the report said. “However, for other applications, GPS loss of function still occurs at unacceptable distances to LightSquared towers. Use of only the lower portion of the L-band MSS spectrum is not one of the planned Phases for the LightSquared Network evolution so only limited testing has been conducted under this scenario.”