A second important advantage is that, because radio waves in this portion of spectrum travel farther, it is easier to bring wireless access into rural areas that currently aren't well served by wireless providers. This greater transmission range also means that operators would need to invest less in towers and base stations and other wireless infrastructure.

These advantages, combined with the nationwide coverage, explain why the available 700MHz spectrum is often referred to in the media as "beachfront property."

What technologies can be used in this portion of spectrum?
Virtually any wireless technology that is currently in use can also be used in the 700MHz range. That includes traditional and next-generation cellular service and other wireless broadband technologies such as WiMax.

What potential benefits could come from this auction?
Besides increased competition, the FCC decreed that the winner of the C block must make networks that use that portion of spectrum available to any device that employs compatible technology. For example, if a carrier builds an EvDO (evolution, data optimized) 3G network, any device with that technology built in will be able to access the network.

This openness will increase consumer choice. Currently, cellular operators in the United States typically limit what devices can be used on their networks and what applications can run on those devices. Because this approach gives them so much control, the incumbent carriers fought the open network provision vigorously.

Note, however, that this provision applies only to the C block. Carriers that win any of the other blocks can continue to limit access to those networks.

What other rules apply to the spectrum?
The effort to open up new spectrum to all devices was led by Google and several public-interest organizations. In addition, those groups urged the FCC to require that the winning bidders make some spectrum available, on a wholesale basis, to other carriers. That was another attempt to foster more competition among wireless carriers. However, this effort failed. The FCC refused to require winning bidders to resell some of that spectrum although, as always, that could occur voluntarily.

There are other limits on how the spectrum can be used. One notable mandate is that any network using the D block must be built to specifications particular to public safety applications and that portions of the spectrum are available for those uses. Because of the emphasis on public safety, the D-block is mandated to be available to 99.3 percent of the U.S. population by 2019.

There are limits on the other blocks, too. For instance, there are use-or-lose provisions that require wireless networks to be built out within a certain time frame or the license will be lost. This is an attempt to make sure that large companies don't buy spectrum simply to block other companies from acquiring it.

Who is bidding?
The auction has attracted some predictable bidders, some surprise bidders, and many smaller bidders. More than 260 applications to participate in the bidding process were initially submitted to the FCC. The predictable companies included incumbent telecommunications operators such as Verizon Communications and AT&T.