LightSquared Aired in Bavaria
March 3, 2011The new potential threat to GPS signals across the United States finally emerged as a topic of discussion at the Munich Satellite Navigation Summit, several thousand miles away from any near-term effects, and in front of an audience that will feel no pain — at first. But the European GNSS community is clearly concerned. Five European speakers joined one American on a panel that examined various aspects of the problem, and proposed some possible solutions, none of the simple or easy.
“The L-word has finally been spoken,” said panel moderator Gerard Lachapelle, after a briefing from Hanspeter Kuhlen, head of system evolution and regulatory affairs for Astrium GmbH of Germany. Not until a full 24 hours of the conference had passed did the prime topic on the minds of most attendees emerge in discussion. Kuhlen had identified out-of-band emissions from the mobile satellite spectrum (MSS) band as a critical challenge for GNSS generally. As for the high-powered terrestrial transmitters sought by Lightsquared, “We don’t know if it is a good idea or not. There is a lot of discussion to be done.”
Following panelists zeroed in closer on the topic. Chris Hegarty from the MITRE Corporation reminded the audience of the increasingly intense demand for spectrum among all users. Mobile services data traffic has increased by a factor of 50 over the last five years, and is projected to increase another 50-fold in the next five years.
Hegarty also pointed out something that may have passed unnoticed by many in GNSS: in March of 2010, the Federal Communications Commission (FCC) called for 500 MHz of spectrum to be found and made newly available, as part of the National Broadband Plan. In June 2010, the President Obama further directed all executive branches of government to do just that: find it! This directive included the Department of Defense and the Department of Transportation, which might otherwise have resisted attempts to enter what they consider their spectrum territory; they were firmly told to assist. In February 2011 — after the FCC granted the conditional waiver to LightSquared for ancillary terrestrial transmitters — the President reiterated his commitment.
Some in the room felt a chill as the political muscle behind this move swam more clearly into focus.
Michael Meurer from the German Aerospace Center found some potential win-win solutions, but not of them appeared easy or at all inexpensive. He outlined two main principles to get to win-win: the best possible frequency coordination between communication and navigation services, and improved interference robustness of receivers.
Lionel Ries from CNES, the French space agency, found that there will continually be different answers for the communications and navigation communities because of their divergent need. Communication demands higher throughput, wider coverage, more mobility, and interactivity. Navigation requires reliability and coverage in constrained environments, with a much less powerful infrastructure. The communities driven by the two technologies, that otherwise have been headed toward tighter integration, may finds themselves increasingly at odds with each other.
Matteo Paonni from the hosting Institute of Geodesy and Navigation, Germany Federal Armed Forces University, recommended consideration of the C-Band for navigation, although the higher power in that spectrum portion would increase satellite cost along with payload weight, but on the other hand furnish better resistance to multipath and ionospheric delay; and/or the S-Band, where China’s Compass and the Indian Regional Navigation Satellite System already are, along with a portion of MSS and the Globalstar network, as a place for a higher nav/comm convergence.
Michel Bousquet of the Institute Superieure de l'Aeronautique et de l’Espace, recommended further study of signals of opportunity, as well as a technique called cognitive radio spectrum sensing.
In the question period, it emerged that aside from aviation, there are no standards for commercial receivers. In order to complete the fast-track study mandated by the FCC, much more data, in many data sets from as many types of receivers operating under Lightsquared conditions will be necessary in order to draw any conclusions. “June 15 will be tough to get enough testing done and analyzed,” said one speaker. “Work starts tomorrow with the first meeting [on March 3].”
Five U.S. industry representatives attending the Munich conference gathered around a cell phone on speaker mode in a hotel room Thursday evening, in order to participate in that first meeting.
The U.S. GPS Industry Council (USGIC) and Lightsquared co-lead the technical working group, with co-chairs Jeffrey Carlisle, LightSquared’s executive vice-president of regulatory affairs and public policy, and Charles R. Trimble, USGIC chairman. The group is filled out up to 20 GPS/GNSS experts, further representatives from the telecomm company, and an unspecified number of technical advisors, representing “the full range of stakeholders and other affected entities, including interested manufacturers, user groups and experts in the GPS field,” according to the work plan.
"This is not a technical problem," said one working group member as he departed the Summit for the meeting. "There are technical solutions. They are just expensive — for somebody. Fundamentally, this problem is one half economic and three quarters political."
The group’s first progress report is due on March 15, and the final report is supposed to be in by June 15.
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