While a lot of the early deployments of 5G using millimeter wave (mmWave) spectrum have focused on outdoor areas, Qualcomm is here to remind everyone that it has applications for indoor deployments as well.

Knowing that most of the mobile data traffic either originates or terminates indoors, “we do see millimeter wave is suitable for both outdoors and indoors,” said Danny Tseng, staff manager, 5G technical marketing at Qualcomm Technologies during a conference call with analysts and media on Thursday.

It isn’t the first time Qualcomm has tried to debunk myths around mmWave. For the past six months or so, Qualcomm has been talking about the challenges posed in millimeter wave spectrum and ways to overcome them, as well as the evolution of mmWave for indoor deployments. And it recently published a blog extolling the new indoor opportunities that 5G New Radio (NR) mmWave will bring.

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It’s timely, too, given that Wall Street analyst firms like MoffettNathanson are questioning whether Verizon bet on the wrong spectrum horse because of its vast mmWave holdings (a situation that is tied to the overall industry’s need for mid-band spectrum). MoffettNathanson’s own research on Verizon’s rollout in Sacramento as well as others critical of Verizon’s early 5G coverage in Chicago and Minneapolis have fed into an uptick in questions about the overall viability of mmWave and importantly, the economics of it.

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At the Brooklyn 5G Summit in New York last month, Ted Rappaport, founder and director of NYU Wireless, where groundbreaking research into mmWave technology occurred, said mmWave has a big learning curve. “It’s a whole new propagation environment and it’s a whole new deployment strategy,” he said. “It’s going to take a while for the massive engineering force to understand and adopt millimeter wave to work properly.”

In a separate interview, Marcus Weldon, corporate CTO and president of Nokia Bell Labs, said the technology is performing surprisingly well. “I think everybody was worried about signal fade,” and there was a history with earlier technology rollouts that were not commercially successful. But “I think everyone agrees you have multiple beams serving you,” he said. “I would say there are practical difficulties, but the technology works.”

At Qualcomm, engineers say the fact that mmWave does not propagate well from the outside to inside is beneficial for deploying mmWave indoors since the same mmWave spectrum can be reused indoors with limited coordination with the outdoor deployment. That opens new possibilities for mobile operators to offer private indoor mmWave networks, in addition to expanding mmWave indoors as part of their public networks.

According to Tseng, the fundamental design/technology is the same for indoors and outdoors, but there are optimizations for indoor versus outdoor, such as antenna configurations and power levels.

The same beamforming and beam-steering techniques for mmWave are used both indoors and outdoors; the only difference is the environment. For example, the outdoors requires dealing with buildings, trees, light posts and so on while indoors, there are walls and other dividers. “We use the same techniques and concepts to ensure strong, consistent connections,” he told FierceWirelessTech.

Lower bands generally propagate better than higher bands. Qualcomm has done simulations on 26/28/39 GHz, and it has found that 39 GHz doesn’t penetrate walls as well as say, 26 GHz or 28 GHz.

Tseng also said Qualcomm engineers generally think outdoor mmWave deployments will serve outdoor users, and indoor deployments will serve indoor users (thereby offloading outdoor cells at the same time).

“While it’s possible to serve some indoor users with outdoor cells, it’s limited and may not be reliable,” he said. For example, if there’s tint on a window, then the signal from the outdoor 5G mmWave antenna will attenuate. In order to have a strong indoor mmWave connection, you’d need to set up indoor stations by co-siting with existing infrastructure, such as Wi-Fi hotspots or LTE base stations.

Historically, Qualcomm has been no stranger to those who doubt the viability of new wireless technologies. But, once deployments become more mature, widespread and reliable, the criticism goes away.