The GSOC model would give government agencies the "right incentive structure," White said.

Others at the forum questioned whether reallocating government spectrum was the right move. Some government agencies may not use their spectrum all the time, but agencies like the U.S. Department of Defense need priority access to spectrum at critical times, said Matthew Hussey, a legislative assistant specializing in telecom issues for Senator Olympia Snowe, a Maine Republican.

Many government agencies, including the DOD, will see their spectrum needs increase in coming years, not fall, he added.

Instead of forcing government agencies to give up spectrum, the FCC and other policymakers should also focus on ways to share spectrum and other technologies that make better use of existing spectrum, Hussey said. "We have to make sure we meet the demands of all spectrum users," he said. "Reallocation ... alone isn't going to solve the problem, because that's a zero-sum game."

Kathleen Ham, vice president of federal regulatory affairs for T-Mobile USA, praised Genachowski's plan to target 500MHz of spectrum for mobile broadband. T-Mobile is "very supportive" of the FCC's efforts, she said.