WASHINGTON — U.S. transportation and telecommunications officials hope to develop technical standards that would allow companies planning broadband networks using mobile satellite services frequencies to tailor their systems to avoid disrupting GPS applications.
The proposal comes amid the still-simmering controversy over, whose plans for a mobile broadband network serving North America have been upended by GPS interference concerns. LightSquared of Reston, Va., has invested some $3 billion in its satellite-terrestrial network and has a satellite in orbit, but now faces what might be an insurmountable regulatory roadblock.
U.S. Deputy Transportation Secretary John Porcari told lawmakers during a Feb. 8 hearing that his agency would work with the Commerce Department’s National Telecommunications and Information Administration (NTIA) to develop GPS spectrum standards in consultation with stakeholders in industry. The standards would be crafted so as not to affect emerging GPS applications that are vital for the economy, public safety and national security.
LightSquared’s proposed wholesale broadband service would operate in L-band frequencies adjacent to spectrum set aside for GPS navigation and timing signals, which are used for a wide variety of military and civilian applications including aviation safety. The interference issue primarily affects precision GPS units that receive signals in those adjacent bands, which the U.S. Federal Communications Commission has set aside for mobile satellite services but which LightSquared would also use to broadcast from terrestrial towers.
“In general terms, the more precise the GPS receiver — for example the avionics in an aircraft — the more that they are likely to have a wideband receiver that in fact needs to be able to listen beyond the GPS frequency,” Porcari told members of the House Transportation and Infrastructure aviation subcommittee. “Acknowledging that and building a policy around that would be, we think, a very good use of staff time and, from a policy perspective, critical to protecting GPS as an asset.”
Thomas Hendricks, senior vice president for safety, security and operations for Airlines for America, an advocacy group based here, said a government policy is needed to help federal regulatory agencies navigate GPS issues. He also said the Federal Communications Commission (FCC) should be required to consult with the National Space-based Positioning, Navigation and Timing Executive Committee (EXCOM) before taking action on an application for a terrestrial communications network that may impact GPS.
The EXCOM is a decision-making panel with representation from nine U.S. agencies with a stake in GPS. The EXCOM coordinated testing that determined last summer that the terrestrial portion of LightSquared’s proposed network would cause unacceptable interference with GPS applications. LightSquared then proposed a modified plan under which its ground stations would transmit at reduced power levels and only in its assigned frequencies that are furthest away from the GPS bands. However, testing of the new operating scheme determined that it too would interfere with critical precision GPS applications, leading the FCC to withhold approval of the company’s operating plan.
LightSquared has long maintained that the interference problem is caused not by its proposed system but by GPS receivers that rely on signals that spill outside the assigned GPS band and into frequencies set aside for mobile satellite services. Company officials say GPS receiver manufacturers have known about LightSquared’s planned service for years yet continued to produce what they characterize as faulty equipment.
Scott Pace, director of the George Washington University’s Space Policy Institute and an expert on GPS matters, said imposing standards that require GPS receivers to listen only in specifically designated GPS frequencies is not the answer.
“Receiver standards have been mentioned as a possible way of allowing higher-power emissions in bands adjacent to the GPS spectrum, or at least creating a more predictable regulatory environment for new entrants,” Pace said during the hearing. “I do not believe this will be a useful approach and would suggest instead focusing on defining GPS spectrum-protection criteria.”
Jeffrey Carlisle, LightSquared’s executive vice president for regulatory affairs and public policy, strongly disagreed, saying the onus should be on receiver manufacturers to design less-vulnerable equipment. “It ought to be resistant,” he said in a telephone interview. “And if it is a precision receiver that needs to have access to other spectrum, fine; design it in a responsible way,” incorporating filters to protect against interference.
LightSquared was not represented at the hearing despite its repeated requests to testify, according to Chris Stern, a company spokesman.
“We are dismayed but not surprised to hear today that this hearing was little more than a one-sided trial of LightSquared in absentia,” Stern said via email Feb. 8. “It is outrageous that a congressional hearing set up to examine factual issues was only focused on one side of the story — a side of the story supported by commercial GPS makers who designed faulty devices that depend on using spectrum licensed to LightSquared.”
LightSquared’s predecessor company won a license in late 2004 to deploy a nationwide network of ground-based repeaters to transmit signals in locations beyond the reach of its satellite, such as in urban canyons. Opposition from the GPS industry reached fever pitch after the company was granted conditional approval in early 2011 to offer a terrestrial-only version of its service, pending the results of testing to resolve the GPS interference question.