Device makers, however, feared that GPS signals would suffer the way a radio station can get drowned out by a stronger broadcast in a nearby channel. The problem is that sensitive GPS receivers, designed to pick up relatively weak signals from space, could be overwhelmed by high-power signals from as many as 40,000 LightSquared transmitters on the ground. LightSquared planned to transmit on a frequency adjacent to that used by GPS.
After conducting tests, the NTIA said Monday that it found interference with dozens of personal-navigation devices and aircraft-control systems that rely on GPS.
The agency said that new technology in the future might mitigate the problems, but it would take time and money to replace GPS equipment already used extensively in the U.S. The NTIA, a branch of the Commerce Department, also said adjustments to LightSquared's network could cost billions of dollars and might not solve all of the problems.
Virginia-based LightSquared had no immediate comment Tuesday.
LightSquared had hoped to compete nationally with super-fast, fourth-generation wireless services being rolled out AT&T, Verizon Wireless and other traditional wireless companies. It hadn't planned to sell directly to consumers. Rather, it would have provided network access to companies including Leap Wireless, parent of the Cricket phone service, and Best Buy, which planned to rebrand the service under its own name.
Making more airwaves available has been one of the FCC's top goals. Wireless companies have been clamoring for greater ability to feed consumers' appetites for movies, music and games on a variety of mobile devices.
FCC spokeswoman Tammy Sun said the experience with LightSquared "revealed challenges to maximizing the opportunities of mobile broadband for our economy."