USGIC: LightSquared's backup plan won't work

Tue, 08/02/2011 - 8:00am
Maisie Ramsay, Wireless Week

The U.S. GPS Industry Council (USGIC) is throwing cold water on LightSquared's backup plan for its LTE network, which LightSquared claims will solve the GPS interference issue that threatens to derail its business.

The USGIC says a new report from a technical working group studying the issue shows LightSquared's proposal to deploy its service in 10 MHz of spectrum located farther away from airwaves used by sensitive GPS receivers "would cause harmful interference to GPS receivers and GPS-dependent applications."

"The TWG (technical working group) was unable to conclude – for any subteam
– that LightSquared 4G LTE operation on only the lower 10 MHz channel is a viable mitigation technique," the USGIC stated in a document to the FCC filed late Monday.

The USGIC stated that "nearly all" GPS receivers experienced "harmful interference" from LightSquared's LTE signal in the 1526-1536 MHz band, the airwaves it wants to use under its revised deployment plan.

The council also countered a finding that a deployment of LightSquared's network in a lower spectrum block would not affect cell phones, stating that more than 15 percent of devices tested would suffer harmful interference from LightSquared's proposed lower 10 MHz-only configuration.

"As a result, the Commission must rescind the waiver that was issued in LightSquared, and determine that terrestrial mobile broadband services cannot be provided in the MSS frequencies licensed to LightSquared," the USGIC said.

LightSquared rebutted the USGIC's interpretation of the technical working group's report, saying the GPS industry was "using an inappropriate interference threshold and an improper propagation model."

"Prohibiting LightSquared from operating terrestrially in its licensed band is not a solution," the company said, blaming the GPS industry for manufacturing poorly designed receivers prone to inference.

The FCC will not allow LightSquared to deploy its network until it resolves its potential threat to GPS service. It is not clear when the agency will make a decision on whether the company will be able to move ahead with its network plans.

The latest flap over LightSquared and GPS comes less than a week after the company inked a 15-year spectrum hosting deal with Sprint. The agreement will fall through if LightSquared is unable to obtain clearance from the FCC to deploy its LTE network.


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