The Federal Communications Commission is preparing to turn out the lights on LightSquared's proposed $14-billion national 4G broadband network, following findings from a key technical committee that "there is no practical way to mitigate potential interference" with the nation's GPS systems.

The FCC will open a comment period today on the recommendation from the National Telecommunications And Information Administration that the launch of the network should be killed.

“NTIA, the federal agency that coordinates spectrum uses for the military and other federal government entities, has now concluded that there is no practical way to mitigate potential interference at this time," said Tammy Sun, a spokeswoman for the FCC, in a statement about the NTIA letter.

"Consequently, the Commission will not lift the prohibition on LightSquared," she said, adding that the FCC's international bureau is therefore proposing the FCC vacate the conditional waiver and suspend indefinitely LightSquared’s authority to proceed with the development of the terrestrial system in the mobile satellite band.

Virginia-based LightSquared obtained a waiver from the FCC a year ago to build and operate what its terrestrial 4G network in the mobile satellite band, but the waiver had the condition that LightSquared first had to prove the system would not interfere with GPS in neighboring frequencies.

Opponents in the GPS industry strongly maintained that LightSquared system could not meet that standard and that existing GPS would be seriously, even dangerously compromised. LightSquared argued that filters and better GPS receiver design could mitigate what interference there was.

After a year of protests and technical evaluations, the NTIA has agreed with LightSquared's opponents. In a letter dated Feb. 14, it formally advised the FCC that LightSquared's proposal cannot pass the test, and recommends the waiver be withdrawn.

Sun added that the interference concerns raised during the process have revealed roadblocks to expanding the opportunities of mobile broadband, and particularly, "it has revealed challenges to removing regulatory barriers" that restrict the use of the mobile broadband spectrum—which includes receivers that pick up signals from neighboring bands.

"There are very substantial costs to our economy and to consumers of preventing the use of this and other spectrum for mobile broadband," Sun added. She called on Congress, the FCC, other federal agencies, and private sector stakeholders to work together to reduce barriers and free up spectrum to expand mobile broadband opportunities.

"Part of this effort should address receiver performance to help ensure the most efficient use of all spectrum to drive our economy and best serve American consumers,” Sun said.