Ligado Networks sent lawmakers a letter this week indicating some Defense Department officials supported the company's plan for deploying a terrestrial fifth-generation (5G) wireless network in the L-band and disagreed with the official Pentagon position that the network will cause "harmful interference" to GPS signals.
The June 18 letter, delivered to leaders of the House and Senate Commerce committees, comes as the Commerce Department's National Telecommunications and Information Administration asks the Federal Communications Commission to reconsider its decision to approve Ligado's network plan. The Pentagon has vociferously denounced the FCC's decision, led by DOD Chief Information Officer Dana Deasy.
Ligado's letter includes a copy of an email from a "high-ranking official" in the office of the DOD CIO sent to Ligado executives shortly after the FCC in April announced its approval of the company's plan. The official's name is redacted.
"The unanimous, bipartisan vote by the FCC is keenly obvious proof to any who are truly informed or were honest assessors of the engineering and regulatory soundness of this final determination, albeit so very long in arriving," the official wrote.
The email contends that the military operates mostly on its own section of GPS spectrum that is well outside the band closest to Ligado's licensed spectrum.
In the June 18 letter, Ligado Executive Vice President Valerie Green writes it was "well known" inside the Pentagon in 2018 that the DOD CIO's office concluded the company's spectrum plan "presented no potential for harm to the U.S. Military's GPS devices."
The letter also includes 2018 emails between Air Force and Navy officials discussing Ligado's proposal. The emails show Air Force officials warning that the DOD CIO office and NTIA planned to support Ligado's network. Air Force officials argued against abandoning the "1 dB carrier-to-noise ratio" limit for measuring GPS interference, while a Navy official disagreed with carrying that metric forward.
NTIA and DOD are now arguing that the 1 dB metric should be upheld, while the FCC said it based its decision on more appropriate "performance-based" metrics.
"The evidence also shows that there was disagreement inside DOD about the adequacies of 1 dB as a metric and some DOD officials internally urged the DOD to abandon that view," Green writes.
A Pentagon spokesman declined to comment on the emails, but said, "the department remains opposed to the Ligado proposal."
The FCC's approval of Ligado's network has drawn the ire of lawmakers on the House and Senate Armed Services Committees, respectively, who back the arguments that it poses an unacceptable risk to both military and civilian GPS signals.
However, the House and Senate commerce committees have oversight of spectrum and the FCC, and the leaders of those panels have not definitively ruled for or against the FCC's decision.
Meanwhile, in June 8 letters responding to senators' questions, FCC Chairman Ajit Pai defended the commission's decision, but assured them the FCC will consider several petitions to reconsider the Ligado order.
"Let me assure you that we will give full consideration to the issues raised in compliance with the law and the Commission's rules," Pai wrote.