MIMO antennas extend the easily usable frequencies well beyond the 4.9 GHz band. The FCC took the first step with a Notice of Proposed Rulemaking. Claus Hetting of Wi-Fi Now kindly allowed me to reprint his report.

The FCC wants to introduce four new unlicensed subbands aptly named U-NII-5 to U-NII-8. In the case of U-NII-5 and U-NII-7 (a total of 800 MHz) a new scheme called AFC (‘Automated Frequency Control’) will protect some incumbent 6 GHz users (mostly point-to-point microwave links) from harmful interference, the FCC says. In these two subbands the FCC wants to allow the operation of ‘standard-power access points’ equivalent to current rules for U-NII-1 and U-NII-3 subbands.

Four new subbands and (some) new rules 

It's currently used for military radar but NTIA is looking to make it available. The work around CBRS is proving that sharing spectrum can work, even if the military is an interested party. Before using the band, you would have to check with a database to see whether it isn't reserved. 

The classic example is naval shipboard radars. A user in Iowa is unlikely to cause interference. Research in the 3550 CBRS band finds most of the U.S. is not in use. It would be natural to simply expand CBRS down another 100 MHz. 

The primary source is a blog by David Redl at NTIA, below.

These may be the first customers getting more than 10 megabits reported anywhere. Michael Davies and Richard Yu of 6Harmonics in Ottawa have sent me test data showing customers with a connection phy rate of 16-18 megabits, as well as convincing details from other deployments doing better than that. I thank Boston Consulting Group for pushing me to go beyond published reports and get these new results. The fuzzy photo below shows eight users connected to a base station using a single 6 MHz channel. They have deployments in California and North Carolina using two channels for nearly double the speed. High speed uplink is included.

They are ready with a three channel unit for even higher speeds. Yu has been working on multiple antenna systems (MIMO) for almost 20 years. I'm sure he can achieve even better throughput using more antennas. They seem to be so busy actually building the equipment they haven't had time to get the latest results up on their web site. CEO Yu, off the record, shared remarkable predictions for what they will offer within a year. 

T-Mobile CTO Neville Ray told the FCC his 600 MHz band 5G would be 19% more efficient than LTE. That's the primary 5G band T-Mobile is using across the country. In the 2500 MHz Sprint band, the increase is 52%. (Chart at left and larger below.) It is possible these numbers will prove lower in actual test. Over 80% of the 5G being deployed around the world is low and mid-band. Generally, this is 4G hardware with NR software, with speeds closer to 4G than to 5G millimetre wave. Sprint & T-Mobile will be 90%+ low and midband, little faster than LTE. 

Millimeter wave, which Verizon is deploying widely, is about three times faster than LTE in the real world. See Verizon 5G: "I'm getting speeds of 900+ Mbps downstream 200+ upstream." AT&T is deploying mmWave to hotspots in dense urban areas, but intends low and mid-band for most of the country.

Why are so many claiming 5G is five and ten times faster? Many don't realize that most "5G" since the 3GPP Great Renaming in Spring 2018 is now 4G hardware with 5G NR software, not particularly fast. Actually, the majority of 5G is mid-band, 60% to 80% slower than mmWave and not very much better than LTE. Others use out of date LTE capabilities; since 2017, "Gig LTE" is delivering speeds usually between 100 and 400 megabits. (It's more than a gig in the lab, hence the name.)

3.5, 3.7 GHz 1800. 2100. 2300. maybe even 700 can work just like LAA. Qualcomm, Verizon, and AT&T testing convincingly shows that commercial quality broadband can be delivered today over unlicensed spectrum. The telcos are targeting the Wi-Fi bands and possibly 3.5-4.2 GHz.

The same technology can be used to recover spectrum in licensed bands like 1800 & 2100, Especially in rural areas, massive amounts of licensed spectrum lie fallow. It would be enough, for example, to deliver a true gigabit of rural broadband.

Lowell was more polite, of course. Verizon didn't buy any spectrum in the last auction despite prices that were down by 50-60%. "We simply don’t need it," explains Chief Network Officer Nicola Palmer. Lowell McAdam told Morgan, "When you look at the spectrum and the cost of small cells versus the cost of spectrum in the old AWS auction sort of environment, it was clear to us that building the fiber infrastructure to densify via small cells was better than the alternative of a buying spectrum." CFO Matt Ellis explained to Craig Moffett, "Spectrum is one way that we can add that capacity, but it's not the only way," 

Technology allows adding relatively inexpensive capacity within existing spectrum faster than demand is growing. Verizon estimates the cost per bit is going down 40%/year; Telus estimates 55%. Verizon's capex has been flat to down but they now are offering new unlimited plans. McAdam expects capex to stay flat for the next decade, despite one of the largest 5G mmWave builds in the world.

US$58,680,000,000 is the value of U.S. spectrum from 3.7 GHz to 4.2 GHz based on the actual prices paid in the Italian auction. I'm putting the figure out there in the hopes of inspiring the D.C. press watchdogs to learn enough to report accurately. Unless they do, far too much will be wasted in the usual lobbyist-dominated FCC process.

That figure is a good starting point. Prices in England and Korea were lower. A merger reducing the number of telcos would reduce the proceeds by billions. I know to be careful estimating auction proceeds. The last U.S. auction came in far under the estimates. The one before was far above. Technologies like Massive MIMO and carrier aggregation dramatically reduce the need for spectrum and will have an impact.

Spectrum can seem infinitely confusing but here are some of the current highlights:

FCC Chief Technologist Henning Schulzrine startled the engineers at a high level 5G wireless event by predicting a complete turnaround in spectrum policy and licensing.

Instead of "licensing" monopoly use of spectrum, "All new spectrum would be shared." That corresponds to the opinions of nearly all impartial top engineers, but of course is heresy to lobbyists in the EU and U.S.

Shared spectrum is better, but I fear Henning is being optimistic about what the politicians will do.

"We have sufficient spectrum holdings below 1 GHz," says Chief Network Officer Nicola Palmer. "We have strong spectrum holdings in the 700, 850, 1900 megahertz (MHz)/PCS, AWS 1 and 3 spectrum bands. So why didn’t we bid on the 600 MHz spectrum? We simply don’t need it."

28 GHz is the most popular band of millimetre wave high-frequency spectrum. It was generally little used in the U.S. but now Verizon plans to pass 30 million homes in the first phase of the buildout. Europe chose 26 GHz because satellites were using 28 GHz. There is little gear available other than for 26-30 GHz. Verizon controls 800 MHz of the band in the U.S.

39 GHz, some AT&T controlled, requires 50% more antennas than 28 GHz and is not as popular. AT&T cutbacks in mmWave mean 39 GHz mostly will be on the shelf for years.

60 GHz, shared in the U.S., was developed by Intel as WiGig but didn't find a market. CCS, Facebook, Qualcomm, and others are reviving it, especially for backhaul. The FCC has allocated 14 GHz. With enough very small antennas, performance looks good.

Other bands above 15 GHz lack equipment or supporters, so are years away. The U.S. FCC is about to auction 24 GHz.

Low and mid-band

3.3 GHz to 4.2 GHz is the emerging new band, with enough available spectrum for several companies to expect the ideal 100 MHz.