Bidding in a government auction of airwaves has now topped $34 billion in a sign of the increasing demand for mobile broadband. That's more than three times the $10.5 billion reserve price the Federal Communications Commission had put on the six blocks of airwaves, which total 65 MHz. Prices will likely rise even further as the auction has no predetermined end date. Citi equity research analyst Michael Rollins said in a recent note, 'We believe the auction is reinforcing the value of mid-band spectrum and could lead the national carriers to incur a greater investment cost for spectrum resources and capacity than we currently estimate for AWS-3 spectrum. The strong bidding activity is likely being driven by bids from the larger national carriers, AT&T and Verizon.'