The Federal Communications Commission is about to vote on a proposed rule that would add more room for Wi-Fi, freeing up space for things like pairing it with 5G. The immediate plan is to add 45 MegaHertz to the unlicensed radio bands above the area that’s now used for 5 GigaHertz Wi-Fi. This would effectively add two more channels in the 5.9 GHz band to the existing frequencies used for Wi-Fi.
Unlicensed radio bands, or spectrum, refers to a range of radio frequencies that don’t require a radio station license or a radio operator’s license from the FCC. Uses include Wi-Fi, Bluetooth and microwave ovens. But the uses go far beyond that.
Here we are, two decades later, and the situation can at best be described as ‘promise unfulfilled.’
There’s been some controversy about this plan because those frequencies are currently allocated for automotive use. The idea is that cars and trucks would use radio signaling to let other vehicles know their intentions and their actions. Such communications could dramatically ease traffic flow and reduce accidents.
Unfortunately, the car and truck makers haven’t done much with those bands beyond a few experimental trials, largely in truck platooning, which is a practice in which several trucks travel as one, controlled by the lead truck.
The FCC, which does not want valuable spectrum lay fallow, has decided that at least some of these frequencies, which have essentially been unused for the last 20 years, should be added to the unlicensed spectrum where it can be used for things like Wi-Fi.
But there’s more to it than just a couple of Wi-Fi channels. The next step that the FCC has planned really could lead to vast new horizons of unlicensed spectrum, including Wi-Fi.
Cries of Anguish
The American Automobile Association stresses the need for traffic safety in a statement sent by email. “AAA supports preserving the entire 5.9GHz band for transportation safety communications. With more than 36,000 people killed in motor vehicle traffic crashes on U.S. roadways in 2018, vehicle-to-everything (V2X) technologies have the potential to connect vehicles, infrastructure, and people to support a safer transportation system.”
Those concerns are echoed by the American Trucking Association in a letter to the FCC. “Maintaining the full breadth of seven channels in the 5.9GHz spectrum for DSRC (dedicated short range communications) is essential towards enabling a wide deployment for V2X that accommodates all vehicle types, road users and infrastructure operators thereby fostering the innovation in V2X applications that will facilitate the safe and efficient movement of people and goods.”
20 Years and little action
“Back in 1999, the FCC allocated 75 megahertz of spectrum in the 5.9 GHz band for a service called Dedicated Short-Range Communications. Commonly known as DSRC, this technology was intended to enable ubiquitous transportation and vehicle-related
communications,” said FCC Chairman Ajit Pai in a speech on November 20, 2019. “But results haven’t matched that intent. Here we are, two decades later, and the situation can at best be described as ‘promise unfulfilled.’ DSRC has evolved slowly. It’s not widely deployed. And in the meantime, a wave of new transportation communication technologies has emerged.”
In the view of the FCC, those new technologies, including a cellular-based method of vehicle communications based on 5G technologies, holds great promise and would demand far less bandwidth. As a result, the FCC will be voting on its plan to siphon off part of the spectrum previously planned for vehicle communications.
Executive Branch disagreement
The US Department of Transportation, as you might expect, is less than totally thrilled about the FCC’s plans to take back some of the vehicle spectrum. It’s made its opposition known to the FCC and as was mentioned in recent Congressional hearings. But DoT doesn’t really have much sway with the FCC, and its opposition isn’t likely to change things.
What will happen is that the FCC will adopt its report and order at the meeting on December 12, 2019, and set a date for the new rule to take effect. At that point, unlicensed users can start operating in the 5.9 GHz frequencies. Note that this does not necessarily mean that the automotive uses of the same frequencies have to stop, only that unlicensed uses, such as WiFi, can start.
Because this change to 5.9 GHz is broadly supported by the FCC commissioners, passage is all but certain. When it takes effect, the change will mostly be felt as wireless carriers move into the unlicensed spectrum shared by Wi-Fi. There, you can start seeing LTE over Wi-Fi, allowing your phone to roam wirelessly as it moves between wireless signals outside and Wi-Fi inside.
The bigger prize
Chances are you won’t notice the presence of the additional 45 MHz of bandwidth that’s being added to the unlicensed spectrum. It may show up when you get phone calls inside, but that’s about it. But you will notice what comes next.
The 5.9 GHz frequencies are really a stepping stone for a vast allocation of unlicensed frequencies at 6 GHz.
The FCC has already announced a 1200 MHz bandwidth allocation for unlicensed uses starting just below 6 GHz, and covering a huge area above 6 GHz. This is a big enough spread of frequencies to allow really fast communications. While 5 GHz WiFi can now support a gigabit connection, the new frequencies will support much more than that, perhaps an order of magnitude more.
Exactly how the massive 6 GHz resource will be used remains to be seen. There’s still work to be done and the FCC still has to approve the details before the vote can be taken.
Meanwhile, back on the highway, advocates for the continued use of the 5.9 GHz band for vehicle communications are going to find themselves with a smaller slice of this spectrum for their dedicated use. In the near term, this won’t affect them since they aren’t using it anyway.
In the longer term, the change will require the transportation users to find more efficient ways to use spectrum. Given that the previous use cases were based on technology that’s two decades old, this is certainly possible. When that happens, highway use will eventually become safer and more efficient, but only after a large portion of vehicles on the road are equipped to handle it.