"I've never seen a point in time where it's so open for innovation everywhere," AT&T Chief Technology Officer John Donovan said. The rapid growth of data traffic is forcing carriers to rethink the fundamental designs of their networks, and new technologies are emerging to help solve that traffic problem, he said. Wi-Fi, cloud-based network management and policy-based controls are among those new tools, he said.

Donovan and network heads from Verizon Wireless and Sprint Nextel disagreed about the practical value of specific technologies, but all cited the eventual need for more spectrum and current requirements to make more efficient use of current networks. Expanding capacity was one of AT&T's main motivations in .

Yet, two mobile network concepts that have drawn close attention recently received a generally cool reception from the big-carrier technology executives.

The "lightweight radio" concept, highlighted last month with announcements by Ericsson and Alcatel-Lucent, is overhyped, according to Sprint Senior Vice President Bob Azzi and Verizon Communications Executive Vice President and Chief Technology Officer Tony Melone.

Lightweight radios, such as the (antenna integrated radio) and , are designed to be much smaller and less power-hungry than current cellular base stations. The vendors hope to achieve this by centralizing some parts of the base-station gear and having the lightweight radios configure themselves. Proponents say the new radios ultimately could make cell towers unnecessary.