NTIA chief Larry Strickling has asked the FCC to delay its approval for LightSquared's mobile broadband service until the agency can conduct more tests on a new plan to reduce the network's effect on GPS service.

"NTIA supports the EXCOM' s [National Executive Committee for Space-Based Positioning, Navigation, and Timing] recommendation that additional tests be performed and recommends that the FCC continue to withhold authorization for LightSquared to commence commercial operations until all the available test data can be analyzed and all valid concerns have been resolved," Strickling wrote in a letter posted Friday to the agency's website.

LightSquared wants to deploy its network in 10 MHz of spectrum located farther away from GPS bands than its original plan, which would have set up the service in airwaves directly adjacent to spectrum used by sensitive GPS receivers. The venture-backed company scrapped its original plan after testing showed the network would have knocked out GPS service within the vicinity of its base stations.

Today marks the FCC's deadline for public comment on the plan. The agency has not said when it will make a decision on whether LightSquared will be able to move forward with its network.

Strickling says the revamped plan needs to be vetted before LightSquared can move ahead with the launch of its network.

Strickling also said his prior concerns about LightSquared's network "remain unresolved."

The NTIA has pushed the FCC to make good on its promise to delay the launch of LightSquared's network until it resolves problems with GPS interference.

The FCC has said it will not allow LightSquared to begin commercial operations until the problem is fixed and plans to consult with the NTIA before making a final decision.

FCC Chairman Julius Genachowski recently reiterated the agency's promise to ensure GPS service is protected, saying the FCC wouldn't "do anything that creates problems for GPS safety and services."

The GPS industry wants the FCC to block LightSquared from operating in spectrum near to bandwidth used by GPS receivers, claiming its revamped plan doesn't do enough to protect the service.

LightSquared has continued to sign up wholesale customers as its dispute with the GPS industry drags on. The company's latest customer is Texas-based EarthComm Solutions.

EarthComm said today it signed a multi-year wholesale deal with LightSquared to provide mobile data, voice and satellite services to customers in the southwest United States. The deal with EarthComm comes less than two weeks after LightSquared landed a similar agreement with PowerNet Global.

Sprint has also inked a deal with LightSquared, though the contract will be void if the company cannot resolve the GPS interference dispute.