The FCC said yesterday it is requiring LightSquared to conduct more testing before it can deploy its LTE network to ensure GPS won't be harmed by the hybrid satellite-terrestrial mobile broadband service.

The move was not unexpected, as several government agencies, including the Defense Department, have expressed concerns about potential GPS interference caused by the network and have repeatedly asked the FCC to stop the service from going live until more testing could be done to show the issue is resolved.

"Additional targeted testing is needed to ensure that any potential commercial terrestrial services offered by LightSquared will not cause harmful interference to GPS operations," the FCC said Tuesday.

The agency's order indicated LightSquared is making progress to address the interference issue, which has threatened to derail its plans to launch a wholesale LTE network.

Testing of LightSquared's first deployment plan, which would have installed the network on bandwidth directly adjacent to spectrum used by GPS, showed significant interference problems. The tests prompted LightSquared to change its plans, and the company now plans to deploy its network in 10 MHz of spectrum farther away from GPS bands.

The FCC said the new plans "showed significant improvement," but concerns remain.

"The results thus far from the testing using the lower 10 MHz showed significant improvement compared to tests of the upper 10 MHz, although there continue to be interference concerns, e.g., with certain types of high-precision GPS receivers, including devices used in national security and aviation applications," the FCC said. "Additional tests are therefore necessary."

The company has also pledged to limit the power of its on-ground transmissions to no more than -30 dBm until 2015 and will address interference with satellite-augmented GPS by providing a long-term satellite signal near the top of the MSS downlink band.

"LightSquared is grateful that the FCC acknowledged today the significant improvement achieved by LightSquared's decision to move to new spectrum for the launch of its 4G LTE broadband network," a company spokesman said in an e-mail statement. "The FCC's request for additional testing is consistent with the letter filed by NTIA with the FCC today, establishing a path forward for LightSquared through further targeted testing."

LightSquared is working with the NTIA on testing for GPS used in cell phones and personal navigation devices. Results from the tests are expected to be completed by Nov. 30. The NTIA recommended the next few months of tests be limited to consumer devices, leaving LightSquared to work separately with other government agencies to resolve interference with high-precision GPS receivers.

LightSquared squared off with government agencies about the GPS interference issue at a hearing last week before the House Science Committee. Several lawmakers said they wanted LightSquared to find a way to deploy its network but did not want the service to move forward if it affected GPS. Some also expressed skepticism about the company's ability to resolve the problem.