Satellite-based Aircraft Tracking Joins C-band Fight on WRC-15 Agenda

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PARIS — International radio-frequency regulators on April 2 agreed to address satellite-based global commercial aircraft tracking when they meet in November to allocate spectrum at a conference that will also decide whether frequencies currently reserved for satellite services will be opened to terrestrial broadband wireless networks.

Ending an 11-day meeting in Geneva to prepare for the month-long World Radiocommunication Conference (WRC-15) set for Nov. 2-27, the International Telecommunication Union (ITU) said that, as of now, there is no need for WRC-15 to address the recent flurry of regulatory submissions on mega-constellations of satellites providing global Internet service.

In a press briefing, Francois Rancy, director of the ITU’s Radiocommunication Bureau, said ITU members wrestled for years with the spectrum-sharing issues associated with hundreds — now, potentially thousands — of satellites in low Earth orbit using the same frequencies as ground-based networks and geostationary satellites in higher orbit.

Francois Rancy ITU
“We’ve been ready for 20 years,” Francois Rancy, director of the ITU’s Radiocommunication Bureau, said regarding the plan by several companies to implement mega-constellations. Credit: ITU/V.Martin

“We’ve been ready for 20 years,” Rancy said when asked if ITU was prepared to deal with the half-dozen proposed constellations — in C-, Ku- and Ka-band — that have placed initial spectrum reservation applications at the United Nations agency.

Rancy said WRC conferences of the ITU’s 193 member nations took up nongeostationary-orbit telecommunications satellites in 1995, 1997, 2000 and 2003. Rancy, who had been in the thick of those battles as part of France’s National Frequencies Agency, said no more new regulatory ground need be plowed. “We are fully ready for the ITU to welcome them,” he said of the proposed Internet constellations.

ITU governments earlier this year made clear that they wanted action at WRC-15 to make it impossible for a large commercial jetliner to disappear from view, as was the case with Malaysian Airlines Flight 370 in March 2014.

The International Civil Aviation Organization (ICAO) of Montreal has asked that WRC-15 extend an existing regulatory regime related to the 1090-megahertz spectrum, used for a terrestrially based aircraft navigation service called Automatic Dependent Surveillance-Broadcast, or ADS-B, to satellites.

Mobile satellite services providers Inmarsat of London and Iridium Communications of McLean, Virginia, have been sparring over this point for the past couple of years. Iridium backs an ADS-B solution; Inmarsat has appeared to resist it, saying Inmarsat’s current technology, already on thousands of aircraft, is enough to do the job. Inmarsat has also suggested that ADS-B needs further testing before it is adopted.

Inmarsat’s argument, around its edges, is also that Iridium’s second-generation constellation, to start launching this year, is ultimately a less stable platform for global airline tracking because Iridium’s long-term financial health is unclear.

“We support the expeditious finalization and adoption of the [Global Aeronautical Distress and Safety System] concept as part of the solution for safer skies,” Inmarsat External Affairs Senior Vice President Christopher McLaughlin said in an April 2 statement. “Inmarsat can deliver a solution now that meets ICAO’s recommendations for an easily implementable global flight tracking service.”

In the press briefing, Rancy said that while some nations had reservations about what technologies should be used for global flight tracking, the issue would be put to WRC-15 delegates.

ICAO has called on WRC-15 to introduce ADS-B-enabled global flight tracking “as a matter of urgency.”

Iridium said it would decline to comment on the just-completed meeting’s results on flight tracking.

Rancy said tests of ADS-B should be completed in May, in time for the ITU to issue a clear recommendation to WRC-15.

Meanwhile, telecommunications satellite operators have been fighting terrestrial mobile broadband operators for years to keep the satellite sector’s exclusive use of C-band spectrum between 3.4 and 4.2 gigahertz. A victory for the satellite sector in 2007 was diluted by the decision of several dozen nations to open at least part of this spectrum to terrestrial networks within their borders.

The same issue will be front and center at WRC-15.

Rancy conceded it will likely be a contentious debate and declined to step into the issue beyond saying that cellular backhaul poses a dilemma for terrestrial broadband. Cellular backhaul uses a satellite signal from a remote base station to connect to the grid for remote regions. Many of these cellular-backhaul services thus depend on the same C-band spectrum that the terrestrial networks want to use.

Satellite operators, as they did in 2007, are telling WRC-15 delegations that C-band satellite transmissions, which are relatively weak, will be drowned out if there is a terrestrial wireless broadband network in the vicinity. The two cannot coexist, these companies say.

Terrestrial broadband networks “would be shooting themselves in the foot” by eliminating the satellite service, Rancy said.

Without handicapping the WRC-15 decision, he said some portions of the C-band at issue could be subject to compromise.

The use of C-band is particularly widespread in tropical regions because C-band signals are less susceptible to attenuation by rain than higher-frequency bands including Ku- and Ka-band. Rainstorms can leave the higher frequencies “less available for certain services,” he said.