Sprint to deploy massive MIMO in six markets starting in April

Working with vendors Nokia, Ericsson and Samsung, Sprint is using massive multiple-input, multiple-output (MIMO) antennas to increase LTE capacity while setting the stage for a software upgrade to the 5G New Radio standard. Company CTO John Saw discussed the deployment plans during an interview with RCR Wireless News during Mobile World Congress 2018.

“It’s our secret weapon to getting 5G built simultaneously with 4G,” Saw said. “You need two enabling things. One is massive MIMO. I was just in a meeting with [Ericsson] to see if they can do more faster. The second thing is spectrum.” Sprint is tapping its 2.5 GHz spectrum to support the massive MIMO build.

“What we can do,” Saw said, “is we can use the Ericsson massive MIMO radios, split it physically in two, then allocate some spectrum for LTE and 5G, then simultaneously broadcast in both modes. As we add more to the 2.5 GHz, and we densify with LTE and add 5G at the same time, we call it killing two birds with one stone.”

Beginning in April the carrier will start to deploy in Chicago, Ill.; Dallas, Tex.; and Los Angeles, Calif. as its initial markets, with Atlanta, Ga.; Houston, Tex.; and Washington, D.C. to come later this year. From there, Saw said massive MIMO would reach 100 markets.

Saw said massive MIMO antennas would be added to existing towers, not the slate of new towers Sprint has planned. That’s a good thing, he said, because “I don’t have to look for new towers. We’re simply upgrading an existing tower. The idea is put massive MIMO on as many of our towers as possible.”

Massive MIMO capabilities will be available to Sprint customers using a phone with 2.5 GHz (Band 41) support, and the carrier is working with Qualcomm Technologies and device manufacturers on 5G NR support for 2.5 GHz targeted at the first half of 2019. Qualcomm’s new Snapdragon X50 includes Band 41 5G NR support.

Sprint is working with multiple vendors on its massive MIMO activation. Last year the carrier worked with Samsung to test the equipment including a trial in Suwon, South Korea. Results saw an increase in channel capacity by some 300% and a boost in cell edge performance by 200%, according to the operator.

Moving from MIMO to massive MIMO, according to IEEE, involves making “a clean break with current practice through the use of a large excess of service antennas over active terminals and time-division duplex operation. Extra antennas help by focusing energy into ever smaller regions of space to bring huge improvements in throughput and radiated energy efficiency.” The group calls out other benefits including cheaper parts, lower latency, “simplification of the MAC layer, and robustness against intentional jamming.”