Updated Aug. 31 at 10:25 a.m. to include comments from Boeing.
WASHINGTON — An aeronautical communications service meant to improve aircraft safety while on the ground at airports could cause unacceptable interference to Globalstar’s satellite system, according to Boeing.
In an Aug. 18 filing to the U.S. Federal Communications Commission, Boeing cautioned that the service rules for the Aeronautical Mobile Airport Communications System, or AeroMACS, as proposed by the WiMAX Forum don’t adequately ensure protection of transmissions from Globalstar’s Earth-to-space satellite links.
“Although Boeing supports the deployment of AeroMACS at major airports throughout the United States, Boeing believes that it is premature for the Commission to propose service rules for AeroMACS, particularly pursuant to the minimalist framework proposed by the WiMAX Forum,” Boeing wrote.
AeroMACS is a wireless broadband technology based on a WiMAX standard, billed as a means to improve information sharing and data communications on airport surfaces for aircraft and support vehicles. Regulators at the International Telecommunication Union’s 2007 World Radiocommunication Conference designated spectrum from 5,091 MHz to 5,150 MHz for AeroMACS and Aeronautical Mobile Telemetry (AMT) flight tests on a global basis. WiMAX submitted its FCC rule-making petition for AeroMACS in March.
Boeing wrote that while the FCC gave AeroMACS priority over AMT within the spectrum, the agency should ensure interference mitigation “that minimizes transmissions towards space.”
“[A] significant issue exists with respect to the manner in which AeroMACS can protect the Earth-to-space feeder links for the Globalstar [mobile satellite services] system, which also operates in the 5091-5150 MHz band,” Boeing wrote. “The protection framework adopted by the ITU effectively requires that the total aggregate power from all AeroMACS installations must not exceed interference thresholds for the feeder link receivers on the Globalstar spacecraft. As experts on AeroMACS have recognized, this restriction places ‘a significant limitation on the total system capacity of AeroMACS’ and the deployment of AeroMACS systems without first adequately addressing this issue ‘will eventually lead to a saturation of AeroMACS capacity.’”
Covington, Louisiana-based Globalstar operates a constellation of 24 second-generation satellites in low-Earth orbit to provide mobile satellite services.
In an Aug. 26 email, Globalstar’s general counsel and vice president of regulatory affairs, Barbee Ponder, told SpaceNews that Globalstar worked with aeronautical interest groups leading up to WRC-2007 “and came to an amicable agreement regarding the amount of interference that we would accept from all aeronautical services in the 5091 to 5150 MHz band.”
“That aggregate interference limit was agreed to be no more than 6 percent, with [Aeronautical Radio-Navigation Service] accounting for no more than 3 percent, AMT accounting for no more than 1 percent, and the balance which would include AeroMACS accounting for not more than 2 percent,” he said.
When ARNS is absent, Ponder said AeroMACS is allotted up to 5 percent interference, keeping the total interference level to Globalstar’s licensed Earth-to-space feederlinks under 6 percent.
“This agreement is memorialized in Recommendation ITU-R M. 1827, as modified in 2015. In any proceeding regarding this band, aeronautical interests, as well as the FCC, should abide by this ITU recommendation,” he said.
SpaceNews contacted the WiMAX Forum, which said that beyond Boeing’s filing, the organization has had no contact with the Globalstar community.
“We are not aware that they have any issues or concerns with the Petition,” a spokesperson said Aug. 28.
Boeing told SpaceNews Aug. 30 that the company’s role as a satellite manufacturer “is incidental to our advocacy for ensuring that AeroMACS systems are appropriately designed to avoid interference with satellite systems operating in the same spectrum.”
Of Boeing’s $482 billion backlog, the vast majority — $423.4 billion — comes from building and supporting commercial aviation, according to the company’s second quarter 2017 financial results. By comparison, Boeing Network & Space Systems, where satellite orders are counted, represented a backlog of $4.5 billion as of June 30.
“Boeing has a clear and significant interest in aviation safety as demonstrated by our support for the Aeronautical Mobile Airport Communications System,” Boeing said.