By Jim Palmer
Jim Palmer explains how a Wi-Fi specification’s exciting numbers don’t always translate directly into real-world application performance—and how some thoughtful reimagining of Wi-Fi architecture can unlock an entirely different kind of performance that’s worth getting excited about.
When the 6 GHz band was first released for use in Wi-Fi networks in 2020, it felt like the future had arrived. 1.2 GHz of spectrum allocation (depending on where you live) is a lot of new spectrum to utilize. The once frowned on (pre-6 GHz) practice of 80 MHz wide channels suddenly became an acceptable practice.
Everywhere I looked, I saw people proclaiming “80’s are the new 20’s!” in their excitement over all this new spectrum. The golden age of Wi-Fi was finally upon us, and many dreamed of the times when we could finally openly indulge in the practice, we all do after installing new gear – running a speed test. While there are many times we lament those who run a speed test every day and then call to ask why they didn’t get the maximum speed they read about in the spec sheet, we also love to break out the speed test apps ourselves and find out just how fast we can get our new toys to perform.
You see, running a speed test from a laptop and seeing a result come back at 5 Gbps up and down (just over the 50 percent mark of the maximum PHY rate of 9.6 Mbps for a 160 MHz wide channel running eight spatial streams) is just plain exhilarating for us nerdy types. Speed is the magic number that we all look for in each new release of hardware, right?
Now, not to pump the brakes, but it’s going to be a long time before anyone of us sees a mobile device that comes anywhere near 5 Gbps over the air, let alone the maximum PHY rate of 9.6 Gbps. We can hang that spec sheet on the wall just like the posters of supercars I used to dream about as a kid, but in the near term, that dream is not going to make it off that poster and into the real world.
The fact of the matter is there aren’t any mobile devices today that could even process data received at 9 Gbps, which would translate to downloading two average Netflix movies every second! That mind-boggling performance certainly sizzles on a spec sheet, but just like the posters of the supercars from my youth, it’s destined to stay on the wall—for the time being.
Know what doesn’t get attention? A wired connection at 10 Gbps. The IEEE standard of 802.3ae was first defined in 2002, 20 years ago! Today, people are routinely talking about getting 10 Gbps service to their houses—it’s become the standard; nothing to get excited about.
However, there is one place where 10 Gbps links (up or down) aren’t commonplace, and in hushed corners of the Wi-Fi world, they are dearly needed. That unremarkable place we don’t like to talk about is mesh networks. Deploying Wi-Fi networks using mesh is the last place a Wi-Fi professional likes to go, but in an increasing number of places, it is the only option to provide Wi-Fi service to the end users.
The thing is, mesh is highly inefficient and a waste of spectrum, with a limited number of ways to do it right and almost infinite of ways to do it wrong. To get quality backhauls, we are forced to use 5 GHz channels for the mesh connection. But, if we do that, we are forced to push all the clients to the 2.4 GHz spectrum, its 20 MHz channels and lower PHY rates.
Switching the mesh backhaul to the 2.4 GHz band allows clients to connect to the 5 GHz radios and get those higher PHY rates, but then the backhaul connection can’t support the client traffic. So, even when done right, mesh is still a messy beast.
Enter 6 GHz.
With limited client-side support of the 6 GHz band, there is one application that can use the 6 GHz channels, and the third radio in these new APs, to their full potential. That application is mesh backhaul.
Using 6 GHz as mesh backhaul is the double-decker bus of the automotive world. It’s not the supercar on the poster, but it is the utilitarian vehicle that we need today. Sure, mesh backhauls suffer from a drop of throughput at each hop, but if you can start with a 320 MHz wide channel and eight spatial streams, we have bandwidth to burn.
Let the clients keep both the 2.4 and 5 GHz spectrum to connect to and let those APs with the wired power, three radios, and eight radio chains go to work. Even without having an automated frequency control (AFC) system to allow installing 6 GHz APs outdoors, there are still plenty of places where a Wi-Fi designer can utilize 6 GHz mesh backhaul indoors—and they can utilize it today.
And those crazy corners that need coverage, but you can’t get a wired drop to them? 6 GHz mesh has you covered. Need to create a wireless bridge across a large auditorium? 6 GHz mesh backhauls. In fact, there are plenty of use cases where designers can utilize these new third radios in APs without having a single client device that supports the new spectrum.
Once AFCs come online—in early 2023 if we’re lucky—and we can deploy these new radios outdoors, this will finally present sizzling, sensational news for outdoor Wi-Fi. We simply keep the IoT and other devices on the 2.4 GHz radio, client-serving Wi-Fi on the 5 GHz radios, all of them utilizing 6 GHz as the mesh backhaul. The money savings on outdoor Wi-Fi is going to be staggering. Is it as exciting as those supercars of my youth? Nope. Not even close.
But to a Wi-Fi nerd like me, that double-decker bus is starting to look mighty attractive.
View the original article at commscope.com.
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