6 GHz: The crackle, the speed - and the sobering reality
Ruckus Technologie, WiFi, WLAN
Jim Palmer explains why the exciting numbers of a Wi-Fi specification don't always translate directly into real-world application performance and how and how a thoughtful redesign of the Wi-Fi architecture can unleash a very different kind of can unleash a different kind of performance worth getting excited about. get excited about.
When the 6 GHz band was first released for use in Wi-Fi networks in 2020, it seemed that the future had arrived. arrived. 1.2 GHz of allocated spectrum (depending on where you live) is a lot of new spectrum to be used. The once (pre-6 GHz) practice of 80 MHz wide channels suddenly became acceptable.
Everywhere I looked, I saw people who, in their excitement about the new spectrum, proclaiming "80s are the new 20s". The golden age of Wi-Fi had finally arrived and many were dreamed of the time when we could finally openly indulge in the practice that we all do after installing new equipment - running a speed test. While we often complain about those complain about those who do a speed test every day and then call to ask to ask why they didn't get the maximum speed they read about in the specs. they read about in the specs, we also love to pull out the speed test apps ourselves. speed test apps ourselves and find out how fast we can get our new devices to run. we can get our new devices to run.
If you run a speed test on a laptop and get a result of and get a result of 5 Gbps up and down (which is a little over a little more than 50 % of the maximum PHY rate of 9.6 Mbit/s for a 160 MHz wide wide channel with eight spatial streams), that's just plain exciting. Speed is the magic number we all look for in every new version of hardware, isn't it? new version of hardware, isn't it?
Not to put the brakes on it now, but it's going to be a long be a long time before any of us see a mobile device that's anywhere near anywhere near 5 Gbit/s over the air, let alone the maximum PHY rate of 9.6 Gbit/s. We can hang the datasheet on our wall just like the posters of supercars I dreamed of as a child, but that dream is not but in the near future this dream will not move from the poster to the real world. into the real world.
The fact is that mobile devices don't exist today, that can process data at a speed of 9 Gbps, which is the equivalent of downloading downloading two average Netflix movies per second! per second! This incredible performance certainly makes an impression on the on the data sheet, but just like the posters of the supercars of my youth they will remain on the wall for the time being.
You know what's not being taken into account? A wired connection with 10 Gbit/s. The IEEE standard 802.3ae was first defined in 2002, 20 years ago! 20 years ago! Today, people routinely talk about it, about getting 10 Gbps service into their homes. It's become the standard. standard; nothing to get excited about.
However, there is one place where 10 Gbit/s connections. (up or down) are not commonplace and in quiet corners of the Wi-Fi world they are desperately needed. That inconspicuous place that we don't like to talk about is mesh networks. Setting up Wi-Fi networks with mesh is the last place a Wi-Fi expert likes to go, but in an increasing number of places, it is the only way to provide Wi-Fi services to end users. to end users.
The thing is that mesh is very inefficient and a waste of spectrum. waste of spectrum, with a limited number of ways to do it of ways to do it right and almost infinite ways to do it wrong. do it wrong. To get high quality backhauls we are forced to use 5 GHz channels for the mesh connection. But if we do that we are we are forced to switch all clients to the 2.4 GHz spectrum with its 20 MHz channels and lower PHY rates.
When the mesh backhaul is switched to the 2.4 GHz band, the clients can the clients can connect to the 5 GHz radios and use the higher PHY rates. PHY rates, but the backhaul link cannot support the client traffic. client traffic. Even if it is done properly, mesh is still a mess.
Now 6 GHz comes into play.
Since the 6 GHz band is only supported to a limited extent on the client side there is an application that uses the 6 GHz channels and the third radio in these new radio in these new APs. This application is Mesh backhaul.
The use of 6 GHz as Mesh backhaul is the double-decker bus of the automotive world. It is not the supercar on the poster, but it is the utility vehicle we need today. Sure, with mesh backhauls, throughput drops at every hop, but if you're using a 320 MHz wide channel and eight spatial streams, we have bandwidth to burn. we have bandwidth to burn.
Let the clients use both the 2.4 and 5 GHz spectrum for connectivity and let the APs with the wired power, the three radios and the eight radio chains. go to work. Even without an automatic frequency control system (AFC) that allows 6 GHz APs to be installed outdoors, there are still still many places where a Wi-Fi designer can use 6-GHz mesh backhaul indoors. Indoor can use - and already do so today.
And what about those crazy corners that need coverage but you can't get a wired connection to? cable connection? With 6-GHz mesh, you're covered. You need to build a wireless bridge across a large auditorium? 6 GHz mesh backhauls. In fact fact, there are many use cases where developers can leverage these new third radios in APs without having a single client device that supports the new spectrum.
Once the AFCs come online - early 2023 - and we can deploy these new radios out in the open outdoor, this will finally be sensational news for outdoor Wi-Fi. outdoor. We'll just let the IoT and other devices run on the 2.4 GHz radios and the client Wi-Fi on the 5 GHz radios, with all the Using 6 GHz as a mesh backhaul. The cost savings of outdoor Wi-Fi will be staggering. Is this as exciting as the supercars of my youth? Nope. Not even close.
But to a Wi-Fi nerd like this double-decker bus looks pretty attractive.