Clearwire breaking ground on new LTE network

It’s been promising an LTE network for more than a year, but in the next three months Clearwire(s clwr) will actually deliver. Cleawire CFO Hope Cochran said Wednesday that Clearwire will begin constructing its LTE network rollout in the next two weeks and begin ramping up its build-out in the fourth quarter, FierceWireless reported.

There’s still no word on when Clearwire will make the new network commercially available to Sprint(s s) and other wholesale customers like Leap Wireless(s leap) (Clearwire won’t sell LTE services directly to consumers), but Clearwire is on track to complete its first stage by June of 2013 with 5,000 cell sites, Fierce said. That’s not a huge number, but Clearwire isn’t planning to build a ubiquitous network. Instead, it’s placing LTE cells in high-traffic urban areas, and selling that capacity to other carriers to augment their current LTE services.

The big issue for Clearwire will be devices. While Sprint has agreed to use Clearwire to give its own LTE network extra bandwidth oomph, it doesn’t yet have devices that support either Clearwire’s 2.5 GHz band or its special flavor of LTE. Clearwire has promised that dual-mode smartphones and modems supporting both the frequency-division LTE used by the rest of the country’s carriers and its own time-division LTE will be plentiful, but they’ve yet to emerge in the U.S. For instance, the recently launched Galaxy S III and the new iPhone 5 will be able to access Sprint’s LTE networks but not Clearwire’s.

Rival carriers are continuing to build out their LTE networks. This week, AT&T(s t) expanded its own LTE network to Seattle; Portland, Ore.; and Memphis, Tenn.; three of the last remaining big cities missing from its metro market 4G footprint. AT&T still doesn’t have the breadth and depth of Verizon’s(s vz)(s vod) network, which now covers 235 million people in close to 400 markets and is expanding into rural regions, but it’s now has a footprint of 72 big cities. Meanwhile, Sprint has some catching up to do. It’s deployed its network in six regional clusters

LTE image courtesy of Shutterstock user Inq