BARCELONA—Sprint is preparing to launch 5G smartphones early next year, CTO John Saw said at a Mobile World Congress roundtable here in Barcelona.

When asked about whether we should expect to see smartphones announced for Sprint's upcoming 2.5GHz, 5G network at MWC 2019, Saw said, "I think that's about the right timeframe. It's an aggressive timeframe, and we do need to get the network upgraded."

Yesterday at MWC, Sprint announced its first six 5G cities. The first three will be Atlanta, Chicago, and LA, Saw said, and the next three will be Washington D.C., Houston, and Dallas. Sprint chose those cities because they have a lot of customers in each one, a "critical mass" of 2.5GHz cell sites, and sufficient spectrum to pull off its spectrum plan, Saw said.

All US carriers have been trying to one-up each other with 5G announcements here at MWC. Yesterday, T-Mobile said it's working on getting 30 cities up and running by the time those smartphones arrive next year. Verizon says it will have 5G fixed wireless for homes in Sacramento this year, and AT&T will launch later this year with a puck, or wireless hotspot.

While the basic 5G standard is now set and the MWC halls are full of 5G network equipment, we're still waiting on 5G consumer devices. Samsung showed off a working Verizon home modem and a prototype tablet at the show. We've heard that Netgear will have a version of its M1 hotspot for AT&T, which will have Qualcomm X24 4G and X50 5G modems side by side, but phone makers won't be ready for 5G until next year.

Like T-Mobile, Sprint is focused on smartphones rather than hotspots (which AT&T is doing) or home internet access (which Verizon is doing.) But unlike T-Mobile, Saw said Sprint sees an opportunity in 5G hotspots and connected PCs a little further down the road.

"It's not going to be a hotspot, it's going to be a phone, because that's what customers want," Saw said. "We will, over time, develop hotspots, mini MiFis, and we will also develop connected PCs."

Sprint's plan is to use Nokia's massive MIMO cell sites—which have 128 antennas—to split its relatively broad array of 2.5GHz spectrum into 4G and 5G sides. Sprint has 120-160MHz of 2.5GHz spectrum in most of the country, Saw said; 60MHz will be used for LTE, and 60-100MHz will initially be used for 5G. 5G will just about double the capacity per cell sector on Sprint's towers, although the real-life speeds consumers get will be based on the capabilities of their phones.

Also, unlike T-Mobile and Verizon, Sprint still relies heavily on 2G for its voice network. The company has been behind its competitors in switching customers to voice-over-LTE, and Saw said that's because Sprint wanted to make sure LTE coverage was good enough. "The plan is to start turning up [VoLTE markets] towards the end of the year," Saw said.