Sprint Eyes WiMax Backhaul

NEW YORK -- When Sprint Nextel Corp. (NYSE: S) starts to roll out WiMax in Chicago and Washington, D.C., at the end of 2007 it is also considering using the wireless technology as a cost-effective way of providing backhaul for the new broadband networks.

At the jam-packed "Backhaul Strategies for Mobile Operators" Light Reading Live show in New York City on Thursday afternoon, Ali Afrashteh, VP of access technologies for Sprint Nextel, expanded on the reasons behind the carrier's move to WiMax and how the technology also forms part of its strategy to move to "alternative" methods for linking wireless networks to wired switching centers.

The VP told the crowd at the Westin Hotel in Times Square that Sprint Nextel, the third largest wireless operator in the U.S., is currently using T1 lines for 99 percent of its backhaul tasks and "about 1 percent" uses other technologies.

"T1 is like pizza -- you order it, you get it," Afrashteh quipped. "The problem is, you order it for dinner and you get it for lunch next day, its cold, there's no topping, and there's only one store you can get it from -- and that's Pizza Hut."

Sprint Nextel is already planning to use its massive domininance in the 2.5GHz spectrum band -- the operator has 85 percent of the band in the 100 top markets in the U.S. -- to provide high-speed WiMax services across the country by the end of 2008. Afrashteh says that Sprint is very interested at looking at using the technology for backhaul as well. "Alternative backhaul is important to us."

Putting in WiMax backhaul for its so-called "4G" technology could also translate into cost savings for its legacy cellular networks over time. "Absolutely, whatever we use for our 4G we can use for iDEN and CDMA, that's part of our plan and that's how we save -- eventually," said Afrashteh.

Afrashteh stressed a couple of times during his speech that WiMax wasn't the only alternative that the operator was looking at for backhaul. A good portion of his presentation and the majority of the questions from the crowd, however, focused on the wireless metropolitan area standard.

The VP says Sprint will use a whopping 30MHz of spectrum to deploy WiMax in the two test markets at the end of 2007: "We're initially using 30MHz of spectrum [that's 3 channels of 10Mhz] -- otherwise we are worried that WiMax will not work on the edge of the cell."

The operator has so much bandwidth in the band that Afrashteh says that he is also considering using another 30MHz for backhaul. "We can use another 30MHz for backhaul -- not everywhere, but we can do that."

Compare this to the operator's current CDMA EV-DO high-speed technology, which uses a single 1.25MHz channel for voice and data transmissions, although some variants band together more channels for more horsepower. "When you want to start with the big bandwidths it is very hard to be in CDMA."

Afrashteh says Sprint needs this kind of bandwidth for access and backhaul in order to be able to start to offer mobile broadband at prices that make it attractive as a cable replacement. "People will only pay so much for mobility," he told us after the show.

It is also clear that Sprint hasn't quite settled on how it will use WiMax as a backhaul technology. Initially, Afrashteh says, the carrier is looking at using 802.16d fixed WiMax -- possibly modified to reduce packet jitter and delay -- alongside its mobile network. It may, however, move to 802.16e if the price drops as manufacturing volumes ramp up.

The company has also been examining the use of mesh for both access and backhaul on the same network. "We are testing mesh in Houston, we're doing it in Virginia, we're doing it in Kansas City," he says.

Whatever happens, the company is hoping to move -- albeit slowly -- away from its T1 habit in the next five years. Afrashteh wants to have 10 to 20 percent WiMax backhaul in the mix by then -- "particularly in the larger markets."

— Dan Jones, Site Editor, Unstrung