ATLANTA -- What became obvious at the Light Reading Live wireless backhaul conference, here, is that there no way for any carrier to use just one technology for backhaul.

"One size doesn't fit all," was the well-worn mantra of speakers at Thursday's sold-out show. Both of the day's carrier keynoters -- Yiannis Argyropoulos, principal member of technical staff at AT&T Inc. (NYSE: T) and Kenneth Robinson, manager of network security at U.S. Cellular Corp. (NYSE: USM) -- espoused a nuanced approach to deploying the multiple technologies that focused on finding the right technology for the right cell site.

The background story of the move from 3G to 4G will involve making sure that a multitude of technologies can support anticipated major increases in data traffic without adding significantly to capex or opex bills.

Among the main technology options in connection are Metro Ethernet and Ethernet connections; pseudowire gateways; DSL; microwave wireless links; fiber; and new technologies like WiMax. The trick for carriers is to implement the option that allows them to maximize capacity while keeping costs down.

For U.S. Cellular's Robinson, part of the answer is Metro Ethernet. "The real advantage from an opex perspective is going to be Metro Ethernet to the cell tower," he told the capacity crowd at the Hyatt Regency. Metro Ethernet can match the speed and capacity of four T1 lines for less money, he said.

He admitted, however, that it makes more sense for the operator to install such equipment in urban areas where the initial installation is cheaper, rather than "a cornfield in Iowa."

AT&T's Argyropoulos was less enthused by Metro Ethernet, saying that he still wasn't convinced that costs could be kept under control. AT&T, however, is taking an agnostic approach to backhaul, so he didn't rule anything out.

Except WiMax. Interestingly, none of the speakers at the event had much good to say about WiMax as a transport option, particularly because it's considered too wasteful to use scarce 802.16 spectrum in the background when it could be making money on the access side.

Nonetheless, all the operators will need to figure out a cost-effective patchwork of backhaul technologies as they move from networks that send users' phones 100 Kbit/s of data to systems that can pump out megabits of data.

"We are definitely looking at LTE and MIMO," Argyropoulos told the crowd, referring to next-generation 3G GSM-based networks and data-boosting antenna array technology, respectively.

As for the "why" behind all this, the reason for any carrier to boost data speeds for any carrier is to offer more mobile-phone applications that they can pay for. "Voice isn't going to be a cash cow anymore. The only way to grow revenue is through data," says U.S. Cellular's Robinson.

— Dan Jones, Site Editor, Unstrung