LightSquared submits GPS interference testing plan to the FCC

LightSquared submitted to the FCC its testing plans designed to determine where interference may occur between LightSquared's L-band spectrum and GPS receivers and how it can be resolved. A GPS industry group has indicated it does not consider the tests legitimate and is going to work with the U.S. Department of Transportation on separate tests.

LightSquared is requesting that the FCC  transfer control of spectrum licenses to the new LightSquared that is emerging from bankruptcy protection. Separately, LightSquared has contracted with Dennis Roberson and Associates, a consulting firm that specializes in spectrum and RF measurements and analysis, to conduct the tests.

In a filing with the FCC, LightSquared said the testing process is underway and will "collect supporting data to establish the impact on Key Performance Indicators (KPIs) that a GPS device user may experience when L-band LTE downlink and uplink signals are present." The tests will place an "emphasis is on real world expected LTE signal levels including temporal and spatial variations in signal levels." Additionally, "signal to noise ratios in the form of reported C/N0 values and other GPS receiver data will also be collected."

The tests will cover several GSP device categories, including "aviation (certified), aviation (non-certified), general location and navigation, cellular, high precision and timing."

Roberson will test 10 MHz bandwidths of spectrum for the LTE signals to be used in the KPI measurements. Downlink spectrum will be tested in the 1526-1536 MHz and 1545-1555 MHz bands, and potentially the 1670-1680 MHz band. Uplink spectrum will be tested in the 1627.5-1637.5 MHz and 1646.7-1656.7 MHz bands.

"As we have indicated previously, Roberson & Associates is commencing a clear and comprehensive test of whether LTE wireless broadband in midband spectrum causes actual harm to GPS devices.  We have made repeated requests for input from industry stakeholders, but after years of indecision and inaction, it is time to move forward," LightSquared spokeswoman Ashley Durmer told FierceWireless. "As the company emerges from bankruptcy, it's committed to discussions governed by facts, not anecdotes. For too long, the facts have been kept in the shadows, and decisions by business and government must be made in the sunlight of facts."

Durmer said the testing results are expected in the fall, "and that data will enable all government agencies to make timely decisions grounded in consumer welfare. The whole wireless industry will benefit from this decisiveness."

Earlier this month the GPS Innovation Alliance, a group formed in 2013 to promote the interests of the GPS industry, told the FCC that it essentially considers the testing being conducted by Roberson to be duplicative.

The group said it "does not support duplicative testing and wishes to make clear that it will focus its technical efforts on the government assessment of adjacent-band compatibility issues that is currently being conducted by the Department of Transportation. If and when LightSquared submits technical analyses for the record, GPSIA will comment at that time."

LightSquared initially launched in 2010 with the goal of building a nationwide wireless LTE network that other companies could use in order to offer their own services to customers. The company signed up around 40 wholesale customers to the plan. However, LightSquared entered bankruptcy protection in May 2012 after the FCC revoked its conditional license to operate because of unresolved concerns that LightSquared's planned LTE-based network in the L-band would interfere with GPS receivers. LightSquared vigorously contested that move.

To mitigate GPS interference concerns, in the fall of 2012, LightSquared submitted a request to the FCC to combine the 5 MHz it uses for satellite service at 1670-1675 MHz with frequencies in the 1675-1680 MHz band, currently used by National Oceanographic and Atmospheric Administration (NOAA) weather balloons. The company would share the NOAA spectrum rather than gain exclusive rights to it. LightSquared would then agree not to deploy a terrestrial network in the 1545-1555 MHz downlink part of the L Band.

For more:
- see this FCC filing

Related articles:
LightSquared still jousting with GPS Innovation Alliance over interference testing
LightSquared, Trimble to seek settlement over GPS interference disputes
LightSquared, GPS Innovation Alliance spar over spectrum, power levels, interference and more
LightSquared to GPS industry: Work with us on interference testing or stop complaining
LightSquared hires advisers to help overcome GPS industry concerns
LightSquared could target first responders, transport and energy industries with new service

Article updated Aug. 26 at 2:45 p.m. ET to reflect that the Roberson tests are not tied to LightSquared getting control of the spectrum licenses. 

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