MARINA DEL REY, California — Sprint this week made good on its promise to bring 5G to Los Angeles, New York City, Phoenix, and Washington, D.C. The network operator, which is in a sort of holding pattern as it awaits the outcome of its proposed merger with T-Mobile US, now has 5G service available in nine markets covering about 2,100 square miles and up to 11 million people. Sprint says its 5G network in Los Angeles covers 1.2 million people.

Sprint intended to get 5G service up and running in America’s most populated cities by the end of July. However, the carrier and its network partner Nokia postponed that launch for a few weeks to make sure the equipment, propagation, and the customer experience were in line with expectations prior to deployment. 

While that reasoning makes sense, the reality and experience on the ground is more nuanced. Sprint’s 5G network is running exclusively on the carrier's 2.5 GHz spectrum holdings, which covers more distance than the millimeter-wave (mmWave) spectrum that other nationwide operators are running 5G on today. But, Sprint also has less of that spectrum dedicated to its 5G service than those mmWave deployments and thus network speeds are lower.

At a hotel where Sprint’s regional executives assembled to showcase the operator’s 5G network in Los Angeles, a demo device reached speeds of 344 Mb/s on the downlink and 27 Mb/s on the uplink. In Los Angeles the average download speeds are in the range 200 Mb/s to 300 Mb/s, according to Sprint.

The new equipment deployed for Sprint’s 5G network is also boosting coverage and speeds on its LTE network. About 3 miles away in Culver City, a demo device provided to SDxCentral reached a download speed of almost 50 Mb/s and 8.5 Mb/s on the uplink. But that was on the LTE network. When the device grabbed a 5G signal at the same location, speeds dropped to 13.3 Mb/s on the downlink and 3.3 Mb/s on the uplink.

To be fair, this is not a review or comprehensive test of Sprint’s 5G network, but the fluctuation in coverage and speeds is what many early 5G customers experience on these networks until more radios are deployed.

The radios that Nokia is supplying to Sprint feature a massive multiple-input, multiple-output (MIMO) antenna system with 64 antennas and 64 radios directly connected in a single box that powers LTE and 5G New Radio (NR) concurrently. The operator is taking down antennas that currently power LTE in mid-band spectrum and replacing them with new units from Nokia.

“Every tower has to be hit but we don’t have to build new sites," said Mark Loarie, Sprint’s head of radio frequency engineering for the Southwest region of the country. "We don’t have to do massive structural upgrades or things like that. It’s a swap so it’s going very fast. We’ve got hundreds here in LA that are on the air and running from Dodger Stadium to Santa Monica and from Hollywood down to the 10 Freeway."

“We’re literally turning up sites every day in the L.A. metro area,” said Eamon O’Leary, Sprint’s VP of network operations for the Western region of the country. The network is running on a non-standalone 4G LTE core and the operator plans to upgrade to a distributed core for standalone (SA) 5G but hasn’t committed to a timeline for that.

“We don’t have the pure 5G standalone core today so the latencies we have today are really good and it’s going to get better once we go to the standalone 5G core,” O’Leary said.

“It’s in the works,” added Chris Melus, director of device and service network integration at Sprint. “Everybody will evolve into that next core in a standalone situation.”

Moreover, while Nokia is supplying its 5G Cloud RAN (radio access network) to other network operators, Sprint is operating on a traditional setup with system modules and the radios, explained Sandro Tavares, head of mobile networks marketing at Nokia.

“Even the customers that we have that were talking about starting with SA, especially like the Chinese [operators], they’re kind of reassessing that because before you actually have the ultra low latency IoT cases, SA’s not going to make a huge difference for you,” he said. “And actually deploying the [non-standalone] is an easier step and a faster step, so basically all of our live networks are now running in NSA mode with a 4G LTE core, but they are able to evolve to 5G core without major problems.”

Operators that are using Nokia’s 4G LTE core will eventually be able to activate new network functions and interfaces via software when they upgrade to 5G mobile core, Tavares explained. “One of the advantages that we’re going to have with a 5G core is in the ability to further distribute the network functions, so actually we’re going to have some of the network functions on the core be moved to the edge of the network.” That will enable ultra low latency IoT use cases, he added. “But yeah, it’s all software so it’s not a big deal.”

Edge computing is not in play on Sprint’s 5G network today, but the operator plans to initiate those capabilities when it activates a 5G core. Operators can deploy edge data centers to run the gateways for a 4G LTE core today, but relatively few will benefit from that in the near term, according to Tavares.

Meanwhile, software is playing a big role in Sprint’s 5G network already. There is “quite a bit” of virtualization managing the network today, explained Melus. “Pretty much the entire core we’re running on is all NFV for 5G today, so that includes our [network management card], our [IP Multimedia Subsystem], [voice-over-LTE], the messaging platforms are all virtualized. We haven’t gotten a lot into SDN, that’s sort of the next step, but where we are today everything is running virtualized,” he said.

Sprint has also been making use of time division duplex beamforming for years, but in a 5G environment it gives the operator an advantage because it provides band coherence and uses the same frequency for the uplink and downlink, Loarie explained. “This is the first time that’s been a real advantage for us,” he said, calling it a “significant differentiator for Sprint’s 5G deployment.”

Back at the hotel near the marina, Sprint also demonstrated the capabilities of its 5G network with a virtual reality experience. SDxCentral was equipped with a headset that provided a 360-degree view of the Venice Fishing Pier less than a mile away. The demo lasted a few minutes. As a member of Nokia’s team described the surroundings, the live video feed stalled at least five times and the screen went completely blank for a couple seconds.

It’s early days for 5G and Sprint says its 5G network will eventually reach average speeds at least 10-times faster than its LTE network, but coverage and reliability still leave room for improvement.