The federal government appears to have killed off LightSquared’s plan to build a nationwide mobile wireless network that would feature the 4G/long term evolution cellular standard.

Lawrence E. Strickling, administrator of the National Telecommunications and Information Administration (NTIA), wrote in a letter dated Tuesday, Feb. 14, to the FCC that there “is no practical way to mitigate the potential interference at this time” that LightSquared’s mobile broadband network would cause to existing GPS equipment that’s already in use.

LightSquared was granted conditional approval last year by the FCC to pursue a national 4G network, but the proposal has been plagued by significant technical issues.

Tests conducted since the second half of 2011, according to Strickling’s letter, have shown that LightSquared’s network would result in unacceptable interference for personal GPS devices and the critical navigation and safety systems used by the aviation industry.

The NTIA concluded that at this time “there are no mitigation strategies that both solve the interference issues and provide LightSquared with an adequate commercial network deployment.”

The NTIA mentioned that one unresolved issue related to LightSquared’s plan is that the federal government, FCC and private industry haven’t developed standards that address GPS receiver standards — except for international rules that govern aviation.

Changing these standards or retrofitting existing GPS receivers in order to eliminate the interference would take many years, although it might be possible, according to the NTIA’s analysis.

LightSquared executives have said the company spent millions of dollars to mitigate interference caused by its technology, which operates in a band of radio frequency adjacent to GPS. Concerns about frequency interference prompted the company to cut both its service’s signal strength and the size of its operable spectrum in order to create a buffer between its 4G service and GPS signals.

But the modifications apparently haven’t been enough to satisfy the federal government.

LightSquared complained last month that the government’s testing of potential GPS interference was unfair, and the company filed an ethics complaint alleging that one member of an advisory panel to the federal government had a conflict of interest.

In a blog post Monday, Feb. 13, Jeff Carlisle, LightSquared’s executive vice president for regulatory affairs and public policy, asserted that “GPS in America has become ‘too big to fail.’”

“GPS manufacturers have been selling devices that listen into frequencies outside of their assigned spectrum band — namely into LightSquared’s licensed band,” Carlisle claimed.

Some financial analysts have speculated that this week’s setback could force LightSquared into bankruptcy protection. But billionaire hedge fund manager Philip Falcone, the backer of Virginia-based LightSquared, reportedly said Wednesday, Feb. 15, that bankruptcy wasn’t in the cards.

The company could try swapping its airwave license for frequencies that are farther away from the GPS band, observers of the company’s options said.

[Read more of Government Technology’s coverage about LightSquared’s standoff with the GPS industry.]

Matt Williams  |  Associate Editor