BARCELONA -- Mobile World Congress -- T-Mobile US Inc. says that it will have higher-capacity backhaul networks deployed in specific markets before it switches to faster 3G technology across the U.S. to avoid any potential capacity crunch as speedier data downloads become possible.

The fourth-largest mobile operator in the U.S. laid out plans to deliver what could be the fastest 3G network in the country before the end of the year with an upgrade to High Speed Packet Access Plus (HSPA+) that will cover 205 million people and 271 cities.

T-Mobile USA's SVP of engineering operations Neville Ray, tells Light Reading Mobile, however, that the carrier won't offer the 21-Mbit/s service until after it has upgraded backhaul capacity in the markets it plans to launch. (See MWC 2010: T-Mob's 3G Speed Race.)

"That's really the gating factor, not the availability of radios," Ray says.

He adds that T-Mobile started the process of upgrading its backhaul over two years ago. "Once you start to move beyond 3G speeds, you've got to move on from copper and T1 lines," he elucidates.

For T-Mobile, this will mean working with "independent providers" to get fiber or microwave radios in place. "It's a mix," Ray says. While copper is the preference for T-Mobile, pragmatism and availability come into play too.

Ray says that Philadelphia was already lit up with fiber before the initial HSPA+ launch, and the rest of his markets will follow that model. This, of course, might help the smaller operator to avoid some of the data problems that befell AT&T Inc. (NYSE: T)'s network in New York and San Francisco as more and more 3G users pulled down more megabytes. (See AT&T to Spend $2B More on Wireless in 2010.)

On the coverage side, Ray says that the operator intends to have 90 percent of its existing 3G footprint blanketed with the faster stuff by year's end.

"You'll see a significant rollout in the first half of this year," he says. T-Mobile has said that it will go live on "both coasts" before general deployment is completed, but Ray wouldn't name any markets specifically.

The company intends to have a USB-based HSPA+ modem available in March. Cellphones supporting the faster technology will be available in the second half of the year.

One timeline that Ray wasn't really talking about, however, is when T-Mobile USA might move to Long Term Evolution (LTE), as AT&T likely will in 2011. Ray merely says that LTE is the "right solution" and T-Mobile will move "at the right point in time."

— Dan Jones, Site Editor, Light Reading Mobile