Sprint Sees Path to Future Technologies with TDD Flexibility

While all other U.S. operators are still using Frequency Division Duplex (FDD), Sprint has turned the page to focus on Time Division Duplex (TDD) in a move executives said will give it a leg up in the run up to 5G.

At CTIA 2016 earlier this month, Sprint COO Gunther Ottendorfer and Vice President of Technology Innovation and Architecture Ron Marquardt said Sprint’s decision to move to TDD has both allowed it to cover more people and take advantage of the inherent flexibility in the system.

“We couldn’t cover as many people with 20 by 20 FDD channels,” Marquardt said. “We couldn’t pair the spectrum to match the Band 7 definition and cover as many people. So, for us, we got better coverage and there’s a lot you can do in TDD that you can’t do in FDD for the future in terms of beamforming, for example.”

Ottendorfer explained that FDD systems use 50 percent of a carrier’s spectrum for downlink and 50 percent for uplink – and those numbers can’t be changed. With TDD, however, Ottendorfer said carriers can adjust that balance which in turn can be an advantage for rolling out new technologies on the network.

Ottendorfer said Sprint currently uses beamforming technology on its 2.5 GHz spectrum. The technology allows the carrier to better reach its customers on the edge of the network, he said.

“I wouldn’t say that you can’t (roll out new technologies) in FDD but it’s much easier in TDD where you actually understand the channel because you’re using it for both directions,” Marquardt said. “And that lets us grow to add these features we’ve been talking about.”

Thanks to the adoption of TDD in other places around the world, including in major markets like China, Ottendorfer and Marquardt said Sprint has also managed to secure an ecosystem advantage.

“We don’t have to worry about whether a particular device manufacturer is going to want to include it because there are just more customers out there for that (Band 41) than any other,” Marquardt said.

But Sprint execs aren’t the only ones tooting the carrier’s horn over its use of TDD.

In a June note, Wells Fargo analyst Jennifer Fritzsche noted Sprint’s use of TDD as an asset that will become more important as networks move toward 5G in the coming years.