More WiFi Spectrum

There is more WiFi spectrum on the way due to the US Court of Appeals for the District of Columbia that rejected a legal challenge from the Intelligent Transportation Society of America and the American Association of State Highway and Transportation Officials that had asked to vacate the FCC’s 2020 order to repurpose some of the spectrum that had been reserved for smart cars.

The spectrum is called the 5.9 GHz band and sits between 5.85 GHz and 5.925 GHz. The FCC had decided to allocate the lowest 45 MHz of spectrum to WiFi while allowing the upper 30 MHz to remain with the auto industry.

The process will now begin to make the transition to WiFi. The FCC had originally given the auto industry a year to vacate the lower 45 MHz of spectrum. The FCC is likely going to have to set a new timeline to mandate the transition. The FCC also needs to rule on a waiver from the auto industry to redeploy technology using the Cellular Vehicle-to-Everything (C-V2X) technology from the lower to the higher frequency band. This is the technology that most of the industry is using for testing and deploying self-driving vehicles.

The lower 45 MHz of the new spectrum sits adjacent to the existing WiFi 5.8 GHz spectrum. Combining the new spectrum with the existing band is a boon to WISPs, which now get a larger uninterrupted swath of spectrum for point-to-multipoint broadband deployment. During the early stage of the pandemic, the FCC gave multiple WISPs the ability to use the 5.9 GHz spectrum on a trial basis for 60 days, and many of them have been regularly renewing that temporary licenses since then.

When the FCC announced the resolution of the lawsuit, the agency issued a press release discussing the benefits touted by WISPs for using the new spectrum. Some of them claimed to see between a 40% and 75% increase in throughput bandwidth. This was mostly due to less congestion on this spectrum, which is rarely used. There was little or no interference during the last year. The spectrum also provided a clear path for wireless backhaul between towers. Of course, once this is made available to all WISPs, it’s likely that much of this benefit will disappear as everybody starts vying to use the new spectrum. But it is an increase in bandwidth potential, and that has to mean higher quality wireless signals.

This spectrum will also be available for home WiFi. However, it takes a lot longer for the home WiFi industry to respond to new spectrum. It means upgrading home WiFi routers but also adding the capability to use the spectrum to the many devices in our homes and offices that use WiFi. Everything I’m reading says that we are still years away from seeing widespread use of the 6 GHz WiFi spectrum, and this new bandwidth will likely be rolled out at the same time.

This was an interesting lawsuit for several reasons. First, the entities filing the court suit challenged the FCC’s ability to change the use of spectrum in this manner. The court decision made it clear that the FCC is fully in the driver’s seat in terms of spectrum allocation.

This was also a battle between two large industries. The FCC originally assigned this spectrum to the auto industry twenty years ago. But the industry was slow to adopt any real-world uses of the spectrum, and it largely sat idle, except for experimental test beds. There is finally some movement toward deploying self-driving cars and trucks in ways that uses the spectrum. But even now, there is still a lot of disagreement about the best technology to use for self-driving vehicles. Some favor the smart road that uses spectrum to communicate with vehicles, while the majority opinion seems to favor standalone smart-driving technology in each vehicle.

Between this order and the 6 GHz spectrum, the FCC has come down solidly in favor of having sufficient WiFi spectrum going into the future. It’s clear that the existing bands of WiFi are already heavily overloaded in some settings, and the WiFi industry has been successful in getting WiFi included in huge numbers of new devices. I have an idea that we’ll look back twenty years from now and say that these new WiFi spectrum bands are not enough and that we’ll need even more. But this is a good downpayment to make sure that WiFi remains vigorous.

The FCC Releases Needed Spectrum

The FCC made two moves in the last week concerning spectrum. Chairman Ajit Pai announced intentions to vote later this month to release the entire 1,200 MHz band of 6 GHz spectrum for unlicensed usage. They also awarded special temporary authority for 33 WISPs to use 45 MHz out of the 5.9 GHz band to boost rural fixed broadband during the COVID-19 crisis.

It’s expected that the recommendation for the 6 GHz spectrum will be approved unanimously by FCC Commissioners. This announcement is huge news. This would increase the bandwidth available for WiFi by almost a factor of 5. The WiFi band already carries far more data than any other swath of spectrum and this bolsters WiFi for the next few decades. The order proposes to uses for the new spectrum. The entire 1,200 MHz of frequency would be released for indoor usage at low power. 850 MHz of the band would be released at standard power levels and can be used outdoors in hot spots and for point-to-multipoint fixed wireless networks.

The cellular carriers have been lobbying hard to have some of the bandwidth sold as licensed spectrum. Instead, the FCC order would allocate it all to public use, but allows anybody, including the cellular carriers to use the spectrum subject to automated frequency coordination. That’s the system that senses existing use of the spectrum before allowing a second interfering use. The cellular carriers might elect to use this spectrum heavily, on an as-needed basis, in urban areas, but likely won’t bother in rural areas – freeing this bandwidth mostly for rural broadband usage.

This is big news because until this announcement there was still the possibility that some of the spectrum would be allocated to a licensed auction. The Chairman did say that he was considering making this all public spectrum a year ago, but a decision was never official until now. This is big news for the whole WiFi industry as well, since any spectrum allocated to licensed spectrum would have been off-limits for indoor WiFi use. As I’ve written in other blogs, this new spectrum, along with the introduction of WiFi 6 technology means a massive upgrade in capability for home and office WiFi performance. This should enable multiple simultaneous large-bandwidth uses of bandwidth within the home or office without interference. WiFi 6 also uses techniques that cut down on interference from neighboring hotspots.

The second action by the FCC is interesting. They granted special temporary authority to 33 rural WISPs to use 45 MHz of the 5.9 GHz spectrum for the next 60 days. This will allow these WISPs to beef up rural bandwidth during the COVID-19 crisis. The WISPs report that they are seeing a 35% increase in traffic volumes along with a requests for more bandwidth due to students and employees suddenly working from homes.

The extra bandwidth will allow these ISPs to boost bandwidth since they use software-defined radios that already work in the nearby 5 GHz WiFi spectrum band. I would expect the FCC to continue the temporary use of the spectrum if shelter-in-place extends in some places past the 60-day window.

These temporary uses of the spectrum might presage a more permanent use of this spectrum band. The 5.9 GHz spectrum was set aside many years ago for vehicle-to-vehicle communications. The self-driving and assisted driving vehicle technology has advanced much more slowly than originally anticipated, plus some car manufacturers are using a different spectrum solution for communicating from car to car. The FCC was already considering splitting the spectrum band and cutting the amount of spectrum available to vehicles in half, with the rest likely going to public auction. The cellular carriers claim that they still only have half of the mid-range spectrum they need to support full deployment of 5G, and the FCC seems likely to grab this spectrum for that purpose.