LightSquared argues the problem is that GPS receivers are poorly designed and are receiving signals from outside their designated frequency bands. The GPS industry says its receivers are too sensitive to filter out the powerful signals from LightSquared's cell towers on nearby frequencies.
The FCC granted LightSquared a conditional waiver to move forward last year, but officials now say the company will have to fix the interference problem before receiving final approval to launch its network.
In his letter, Conyers argued that LightSquared would expand wireless broadband access and increase competition in the wireless industry.
"The U.S. wireless sector is in need of increased competition," Conyers wrote, noting that there are only four national carriers, with AT&T and Verizon controlling about 60 percent of the market.
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"Millions of Americans, especially in rural areas, lack even a single adequate wireless broadband option, with little hope on the horizon unless new providers enter the market," he wrote.
LightSquared plans to sell access to its network wholesale to other companies, providing an alternative to the four national wireless carriers.
The company has until mid-March to secure regulatory approval or it risks losing a multibillion-dollar contract with Sprint.
Some Republicans have questioned whether the FCC and the White House have shown inappropriate favoritism to LightSquared. Sen. Chuck Grassley (R-Iowa) has vowed to block President Obama's two FCC nominees unless the agency releases internal records on its review of the company.
The White House and the FCC have denied giving any special treatment to LightSquared, but expanding broadband access has been a top priority of both agencies.
In a separate letter sent last December, GOP Reps. Cliff Stearns (Fla.) Brian Bilbray (Calif.), Devin Nunes (Calif.) and John Campbell (Calif.) said they believed a solution to the interference problem is possible, and urged Genachowski to "quickly move forward on a solution."
Stearns's support for LightSquared is noteworthy: as the chairman of the Energy and Commerce Committee's Oversight subcommittee, Stearns has led the congressional probe of the White House loan guarantee for failed solar firm Solyndra.