Cross-posted from Blandin on Broadband blog,
originally prepared for Southwest Regional Development Commission.
LightSquared vs. GPS
A new wireless start-up with Minnesota connections has been in the news lately with plans to provide a unique wireless-satellite communications network that could bring ubiquitous broadband coverage to rural America for a fraction of the cost of existing, limited service. The issue? The new LightSquared network threatens to overwhelm America’s Global Position System (GPS) receivers, making the devices obsolete.
The Company and the Technology
Reston, Virginia-based LightSquared Subsidiary LLC was formed in 2010 with plans to provide a wholesale, nation-wide 4G-LTE wireless broadband network with integrated satellite coverage. The new service is built on spectrum used by two Mobile Satellite Service(MSS) sat-phone companies Inmarsat and SkyTerra, and has announced a significant network partnership with Sprint-Nextel. Forbes magazine reports that the company invested $50 million to develop new microchips to provide dual-mode wireless at a price below existing cellular service. By avoiding costs of supporting legacy voice networks, LightSquared projects to wholesale 1 gigabyte data service for about $7, compared to the $50-$60 typically charged retail 3G/4G customers today.
In January 2011, the Federal Communications Commission (FCC) issued an Order giving LightSquared conditional approval to build out a ground-based wireless network using its MSS spectrum. However, that order was subject to further testing and FCC review due to potential GPS interference.
The Issue with GPS
The federal Space-Based Positioning, Navigation & Timing (PNT) Committee has been examining potential interference by the LightSquared network with GPS receivers. They state the issue:
The base stations of the LightSquared network will transmit signals in a radio band immediately adjacent to the GPS frequencies. The GPS community is concerned because testing has shown that LightSquared’s ground-based transmissions overpower the relatively weak GPS signal from space. Although LightSquared will operate in its own radio band, that band is so close to the GPS signals that most GPS devices pick up the stronger LightSquared signal and become overloaded or jammed.
There is also concern that the FCC may approve a technical solution to the problem that requires millions of existing GPS users to upgrade or replace their devices…
The results [of PNT testing] clearly demonstrate that implementing LightSquared’s planned deployment for terrestrial operations poses a significant potential for harmful interference to GPS services.
There are basically two technical issues. First GPS signals are very weak—satellites are 12,000 miles above the Earth and operate on solar power—so receivers have been designed to be sensitive to the full GPS spectrum. This, however, means many GPS receivers also pick up adjacent frequencies. Second, LightSquared proposes to change weaker satellite signals in adjacent spectrum to much stronger ground-based 4G wireless signals, exacerbating interference. Further federal testing results, leaked in December, confirm interference with 75% of general purpose GPS receivers; however, no “significant interference” was found with cellular phones. The NTIA will next test high-precision receivers used in farm equipment and scientific instruments.
Different groups have suggested different ways to eliminate conflicts. (The Minnesota Geospatial Information Office (MnGEO) Emergency Preparedness Committee has tracked the evolving issue on their blog.) LightSquared’s position is that GPS makers were aware of potential interference and should have built better technology. The company has petitioned the FCC to re-affirm their spectrum license. LightSquared has also offered to limit initial use of spectrum closest to GPS signals and delay boosting power on ground stations.
Opponents, including The Coalition to Save our GPS, contend that LightSquared is causing the problem by changing from low-powered satellite service with limited ground stations to high-powered ground-based service. Members of the coalition include GPS makers; agricultural equipment manufacturers such as AGCO, Case New Holland, Caterpillar, and Deere & Company; and national organizations including the American Association of State Highway and Transportation Officials (AASHTO) and the National Rural Electric Cooperative Association, among many others. .
The Issue with Politics
Many media sources have touched on multiple political issues involved in the LightSquared proposal. Philip Falcone, a native of Minnesota’s Iron Range, acquired control of the company through Harbinger Capital, his New York hedge fund that is now being investigated by the Securities & Exchange Commission.
Senator Charles Grassley, an Iowa Republican, and FCC Chairman Julius Genachowski have feuded through the last year on Congressional oversight in the matter. The FCC’s National Broadband Plan specifically calls for accelerating terrestrial deployment of MSS frequencies. Questions have, however, been raised about why FCC approval was granted to LightSquared prior to testing, and also about a report that General William Shelton was pressured by the White House to change testimony to Congress in favor of LightSquared. Grassley placed holds in December on two nominees to the FCC over the issue.
LightSquared has also touted support where it doesn’t seem to be clear. For example, a September press release stated that “we received a strong endorsement of our view that LightSquared and GPS can co-exist from several of the country’s leading agricultural organizations…” including the American Farm Bureau Federation (AFBF) and National Farmers Union. However, far from endorsing the proposal, the letter referenced supports both rural broadband and precision agriculture. In testimony to the House Committee on Small Business, AFBF President Bob Stallman urged Congress to assure that “LightSquared should cover the expense of all technical fixes to the interference issue.”
-John C. Shepard, AICP
(Note: Graphic source is ‘Opening Remarks for “Spectrum Issues — A Place Where Competitors Become Colleagues?” ‘ by Chris Hegarty, MITRE contractor to Federal Aviation Administration, at U.S. Presentations from the Munich Satellite Navigation Summit, March 1-3, 2011. Illustration used on Space-Based Positioning, Navigation, and Timing (PNT) website referenced above.
Update: Public source of graphic & update on precision NOAA testing here.)