GPS Innovation Alliance Responds to Latest Lightsquared Comments

Figure 1. LightSquared propagation models can underestimate interference by more than a factor of 100 (>20 dB). Two-ray models accounting for ground reflections show LightSquared signals at levels 6 dB above free space predictions several miles out. (Figure from August 2011 GPS World.)

The GPS Innovation Alliance has responded to recent media reports on LightSquared’s position regarding the testing of the compatibility of terrestrial broadband and GPS.  

LightSquared is asking the GPS industry to participate in new tests on interference between LightSquared’s spectrum and GPS receivers or waive its right to complain, according to a lawyer representing LightSquared.

Following is the GPS Innovation Alliance’s response:

“The GPS Innovation Alliance (GPSIA) supports a consensus-driven process, including all government and non-government stakeholders, to clearly identify and address remaining technical issues raised by LightSquared proposals to repurpose mobile satellite spectrum for terrestrial broadband use.

“The technical challenges posed by these proposals are formidable, as evidenced by the conclusions of multiple U.S. government entities. Specifically, the U.S. Departments of Defense and Transportation and the NTIA have all found in the last several years that LightSquared’s proposals have significant potential to interfere with GPS.

“Contrary to LightSquared’s recent suggestions, this is not simply a private matter between three GPS companies and LightSquared, but is important to all GPS users who rely on this critical technology every day. The Department of Transportation has sponsored an ongoing effort to assess adjacent band issues, and the GPS industry is actively engaged with the FCC, DOT and other government stakeholders to drive consensus around next steps. 

“While we welcome the participation of LightSquared consultants, any further analysis of the technical issues should be informed by input from all of the relevant stakeholders, rather than the one-off efforts of an interested party.”

In a filing last week with the FCC, LightSquared listed 28 different GPS receivers and related devices that it wants to test for interference with its terrestrial mobile broadband service. The devices include certified and non-certified aviation receivers and avionics equipment, general location, cell phones and 13 different high-precision clocks and receivers.