International specialists have joined a chorus of voices urging the U.S. Federal Communications Commission (FCC) to indefinitely delay the launch of commercial service on LightSquared Subsidiary’s 4G/LTE1 wireless broadband network (see “LightSquared on Track”).
The opponents’ position as of mid-2011 was informed by multiple independent research programs that demonstrated harmful interference to global positioning system (GPS) receivers, an unacceptable risk without adequate mitigations. In late January, the FCC had granted the company a waiver of rules, enabling network buildout to proceed on the condition that harmful interference to GPS receivers would be mitigated satisfactorily.
In June, the International Civil Aviation Organization told the FCC that “the potential disruption to aviation use of GPS caused by the LightSquared system would have a far-reaching impact on current and future aviation operations” and urged the commission to ensure that the U.S. commitment to provide vital GPS standard positioning service worldwide “is not unintentionally jeopardized by the introduction of the LightSquared system.”
The International Air Transport Association expressed strong opposition and alarm that “interference to GPS signals will directly impact the U.S. Next Generation Air Transportation System (NextGen)” and urged the FCC “to take all necessary steps to ensure that GPS service provision is not compromised in any way by the LightSquared system.”
In July, the FCC heard from more non-U.S. interest groups. The Directorate General for Enterprise and Industry, European Commission, said that a European Space Agency analysis found that when aircraft fly into the United States, LightSquared would pose a grave threat to operators equipped with European Geostationary Navigation Overlay Service receivers and, by 2014–2015, could degrade reception of signals from the Galileo satellite constellation. The European Positioning, Navigation and Timing Industry Council added that members also had deep concern about aircraft and vessels traveling to the United States while receiving signals from Russia’s Global Navigation Satellite System and China’s Beidou-2, or Compass, navigation system.
The FCC’s primary data collection effort for the LightSquared proceeding, called the Technical Working Group (TWG), was led jointly by LightSquared and the U.S. GPS Industry Council. In parallel, the U.S. Federal Aviation Administration (FAA) appointed RTCA Special Committee 159 (SC-159), Global Positioning System, to study LightSquared network effects on GPS receivers, and the National Telecommunications and Information Administration (NTIA) directed the National Space-Based Positioning, Navigation and Timing Systems Engineering Forum to perform similar research.
The engineering forum’s June 1 report to the NTIA recommended that “LightSquared should not commence commercial services per its planned deployment for terrestrial operations in the 1525–1559 MHz MSS band due to harmful interference to GPS operations.”
Since ASW’s previous story about LightSquared, the FCC opened a new public comment-rebuttal period, closing Aug. 15, to consider the TWG’s findings and LightSquared’s modified proposal. The FCC said in its announcement, “The [TWG effort] identified significant technical issues related to potential LightSquared operations [i.e., the 1545.2–1555.2 MHz channel] most proximate to the band used by GPS. … The tests demonstrated potentially significant interference between LightSquared operations in the upper portion of the band and various GPS receivers.
The tests also identified some interference issues in the lower 10 MHz portion of the band. The overall conclusion of the testing is that transmissions in the upper 10 MHz channel — the channel nearest to the 1559–1610 MHz GPS band — will adversely affect the performance of a significant number of legacy GPS receivers.
“LightSquared indicates its willingness to operate at a lower power than permitted by its existing FCC authorization; agree to a ‘standstill’ in the terrestrial use of its upper 10 MHz frequencies immediately adjacent to the GPS band; and commence terrestrial commercial operations only on the lower 10 MHz portion of its spectrum [1526–1536 MHz], and to coordinate and share the cost of underwriting a workable solution for the small number of legacy precision measurement devices that may be at risk.”
In the TWG’s June 30 final report, its Aviation Sub-team said, “All three phases of the currently proposed LightSquared deployment plan are incompatible with aviation GPS operations absent significant mitigation, and would result in a complete loss of GPS operations below 2,000 ft above ground level over a large radius from the metro deployment center. For the originally defined LightSquared spectrum deployment scenarios, GPS-based operations are expected to be unavailable over entire regions of the country at any normal operational aircraft altitude.”
RTCA SC-159 on June 16 issued its report to the FAA. In part, the committee said, “The study concludes that the current LightSquared terrestrial authorization would be incompatible with the current aviation use of GPS, however, modifications could be made to allow the LightSquared system to coexist with aviation use of GPS. … From an aviation perspective, LightSquared upper channel operation should not be allowed.”
Jeffrey Carlisle, executive vice president, regulatory affairs and public policy, LightSquared, said in the TWG report’s recommendations, “It is inescapable that it is [GPS device manufacturers’] disregard for [FCC] policies regarding immunity of receivers to transmissions in nearby frequency bands that is the source of the technical problem. … Transmissions in the [1526–1536 MHz channel] will not adversely affect the performance of over 99 percent of GPS receivers. … LightSquared is optimistic that further analysis … will support the consistency of LightSquared lower channel operation with FAA performance standards.”
Note
- The term 4G refers to fourth-generation mobile broadband; LTE means long-term evolution, an advanced protocol.