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Congress addresses GPS interference threat

Jan 4, 2012 — by LinuxDevices Staff — from the LinuxDevices Archive — views

A 4G-LTE network currently being built by LightSquared will interfere with the operation of GPS receivers, or so critics maintain. But provisions in a a defense spending bill signed by President Obama at the end of 2011 now require the Federal Communications Commission (FCC) to resolve all concerns before approving the service, according to this analysis by eWEEK's Wayne Rash.

LightSquared is a Reston, Va.-based company that, in its own words, is "building the only national 4G-LTE open wireless broadband network that incorporates nationwide satellite coverage." The firm has entered into an agreement with Sprint Nextel to provide terrestrial connectivity, and also launched a Boeing-built satellite into geostationary orbit over North America in November 2010.

The company's plans have been tarnished, however, by the fact that the frequencies allocated to it are directly adjacent to those employed by GPS receivers. Critics such as the "Coalition to Save Our GPS" have charged that as a result, the LightSquared service could disrupt critical services.

Now, buried deep within the 500-page-plus National Defense Authorization Act of 2012 is a series of requirements that specify exactly what LightSquared must do before the FCC can authorize operation of the satellite- and terrestrial-based Long-Term Evolution (LTE) wholesale data service.

The provision, which appears under the Space Activities section of the defense funding bill, prohibits the FCC from permitting any operations that interfere with the military use of GPS in any way. The NDAA, which was signed into law on Dec. 31, 2011, by President Obama, is best known for the controversy surrounding the detention of suspected terrorists.

However, bills such as these typically cover a lot of ground, and the NDAA is no exception. What's notable in this bill is that both the House and Senate versions of the bill contained restrictions on GPS interference, and in this case the Conference Committee adopted the strictest provisions of each.

The language of the bill is very specific. "The Federal Communications Commission shall not lift the conditions imposed on commercial terrestrial operations in the Order and Authorization adopted on January 26, 2011 (DA 11-133), or otherwise permit such operations, until the Commission has resolved concerns of widespread harmful interference by such commercial terrestrial operations to covered GPS devices."

In this case, covered GPS devices means basically anything used by the military.

In addition to the prohibition of approval, the law also imposes a requirement that the FCC make available to the appropriate House and Senate committees the final Working Group report as mandated by the FCC. It is the Working Group that conducts the interference testing intended to demonstrate to the FCC that the LightSquared system does not interfere with GPS, or if it does interfere, to what extent.

The most recent version of the Working Group report, released late in 2011, showed significant interference with GPS.

The legislation also requires the FCC to report to Congress the commission's final decision regarding whether or not to permit commercial operations of the type LightSquared is proposing. If the FCC decides to permit such operations, it must explain to Congress how it resolved any concerns regarding GPS interference.

In addition to the reporting requirement from the FCC, the NDAA also requires that the Secretary of Defense assess the ability of GPS devices to operate without interference and to determine if commercial operations are interfering with the military's ability to use GPS.

If interference is found, the Secretary of Defense must report to Congress the nature and severity of the interference, circumstances under which the interference occurs, and how this might affect the national security interests of the United States. The Secretary of Defense is also required to report on how the interference will be eliminated or mitigated, and the cost of such plans.

Onerous burdens

While the NDAA doesn't specifically prohibit LightSquared's planned LTE network, it puts a number of onerous burdens on both the FCC and the Secretary of Defense. More importantly, it prohibits the FCC from allowing operation of the LightSquared LTE network unless it can prove that it won't interfere with the needs of the Department of Defense. This factor, along with the frequent reporting requirement, means that there's a powerful incentive for the FCC to carefully ascertain that LightSquared has completely solved the interference problems.

Note that there's a cost factor in the reporting requirement. What this means is that if interference is found, then the military must determine how much it will cost to either fix all of those GPS units in use or find some other way to eliminate the problem.

Considering the limitation on the defense budgets with the end of the Iraq war and the war in Afghanistan winding down, it's unlikely that the Defense Department will have the money for a massive repair or swap of GPS receivers.

"Included in the bill is the provision I authored with Rep. Loretta Sanchez which will prohibit the FCC from granting LightSquared final approval for its proposed network unless the FCC can resolve the significant harms the LightSquared network creates for the Department of Defense," Rep. Michael R. Turner, R-Ohio, told eWEEK. "According to the recently completed round of government tests, which did not even look at DoD receivers, LightSquared falls well short of meeting that threshold. Let's not lose sight of what the most important thing is in the debate about LightSquared's network — the safety of our men and women in uniform."

All of this means the FCC can't approve LightSquared's plans unless there simply isn't any interference, since the DoD isn't going to accept a plan where it must spend millions out of its shrinking budget to fix what currently isn't broken. This puts the solution outside of the realm of LightSquared's lobbyists, and squarely into the realm of technical solutions.

What's more, it's pretty clear that Congress isn't interested in appropriating any money to pay for fixing or upgrading GPS receivers that belong to the military. Because of the way the Defense Department appropriations work, the DoD can't simply take the money from some other project, but even if it could, its budget is getting very tight, so it's unlikely that it would be done in any case.

The bottom line is that LightSquared has basically one choice if it wants to operate its network. It must show to the satisfaction of the Working Group, the FCC and Congress that it does not interfere with GPS at all.

If it can't do that, then the FCC can't grant approval and LightSquared can't operate. The other side of the coin is that if LightSquared finds a way to solve the military's issue to the satisfaction of Congress, then it will have solved the problem for civilian and commercial users of the global GPS system.

Via a Dec. 13 blog posting, LightSquared posted a video demonstrating that high-precision GPS receivers can co-exist with its network signals when they are fitted with modified antennas. However, the company made no reference to the massive installed base of GPS devices, whether civilian or military.

LightSquared claims modified GPS receivers will not be affected by its network
(click to play)

Wayne Rash is a Senior Analyst for
eWEEK Labs and runs the publication's Washington bureau.

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