A key federal agency involved in testing the proposed LightSquared LTE 4G network has concluded that there is no practical way to solve interference between that network and GPS, possibly dealing a crippling blow to the startup carrier's hopes for a terrestrial mobile network.
In a memo released late today, the National Space-Based Positioning, Navigation, and Timing Executive Committee (PNT ExComm) said the nine federal agencies that make up the body had concluded unanimously that none of LightSquared's proposals would overcome significant interference with GPS (Global Positioning System).
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LightSquared last year received a waiver from the U.S. Federal Communications Commission (FCC) allowing it to operate a terrestrial LTE (Long-Term Evolution) 4G network on frequencies that have until now been devoted to much weaker satellite signals. But the FCC demanded that concerns over interference with GPS be resolved before the network could be launched.
Tests early last year found devastating interference to many GPS devices, so LightSquared modified its proposal. Further testing took place in November, and other tests had been expected to take place soon.
The PNT ExComm has been involved in testing and results analysis at the request of the FCC and the National Telecommunications and Information Administration (NTIA). The body is headed by deputy secretaries of Defense and Transportation and represents other federal agencies and departments. It is charged with coordinating federal GPS activities.
Both the original and modified proposals by LightSquared would cause harmful interference to many GPS receivers, the PNT ExComm chairmen said in the memo. The agency also said a Federal Aviation Administration analysis had concluded the network would be incompatible with aircraft safety systems.
"Based upon this testing and analysis, there appear to be no practical solutions or mitigations that would permit the LightSquared broadband service, as proposed, to operate in the next few months or years without significantly interfering with GPS. As a result, no additional testing is warranted at this time," the memo said.
In response to the memo on Friday, LightSquared slammed the testing and analysis process, repeating its earlier charge that some government entities involved are biased in favor of the GPS industry. On Thursday, the company called for an investigation of alleged conflicts of interest by members of the PNT Advisory Board, which advises the PNT ExComm. It said the vice chairman of the advisory board, Bradford Parkinson, simultaneously was on the board of directors of Trimble Navigation, a foe of LightSquared's plan.
LightSquared today also called upon the FCC and NTIA to "retake the lead" in government testing. The carrier said the PNT ExComm and PNT Advisory board had abandoned their commitment to test GPS receiver filters that LightSquared believes can solve interference with high-precision GPS devices.