FCC rules prohibit potential bidders such as Google from commenting on their spectrum plans in the run-up to the auction. Bidding is anonymous, but the FCC will release some information about the auctions at its auction Web page.

But several wireless industry observers have suggested that Google may not want to win the C block spectrum. Google, by getting the FCC to adopt the open-access rules and by pushing Verizon Wireless and AT&T to open up their current wireless networks to outside devices and applications, has already accomplished much of what it has wanted, Taylor said.

"I think it's fairly widely believed that [Google] doesn't really want to be the actual carrier," Taylor said. "That doesn't mean they still wouldn't buy spectrum and then work with somebody else who's a carrier."

A subcontracting arrangement with a wireless carrier would make sense for Google, she said.

Blair Levin, a telecom analyst with Stifel, Nicolaus & Co., also doubts Google will be a major player in the C block bidding. With the U.S. stock markets tanking in recent weeks, Google may not want to spend $10 billion to build a national network, he said, referring to the estimated cost.

Before the FCC set the auction rules in July, Google had also inquired about the legality of selling spectrum on a wholesale basis. The FCC ruled that such a plan would be legal.

In addition to the current wireless giants AT&T and Verizon Wireless, other companies to watch are the cable television providers, satellite TV providers and handset maker Qualcomm, Taylor said. Qualcomm and cable provider Cox were among the 214 bidders approved by the FCC this month.

Look for wireless carriers such as AT&T and Verizon to bid defensively, she said. "If the traditional mobile carriers really are the final winners of most of the spectrum, then nothing interesting happens," she said. "They don't want to see some major new entrant coming in."

Falling stock prices on Wall Street may discourage some competing bidders, with the auction coming at "precisely a bad time" for investment in a new nationwide network, Taylor said. But these auctions may be the last chance for a third nationwide broadband network, she added.

The 700MHz spectrum band carries wireless broadband signals three to four times farther than some higher spectrum bands, making it perfect for long-range broadband networks. "If you're going to build a green-field network from scratch, you want to build it at low megahertz like this," Taylor said. "If anybody was seriously considering launching a fully new competitor ... from scratch, this is the chance. There isn't going to be another one, probably."