Wi-Fi 7(802.11be) 기술

Spencer:

All right, looks like chat's lively. I'll just make a note at the top: We want to keep this conversational. This is obviously a very technical presentation, but we want it to be engaging as well, so having your input in the chat. We'll try and follow up with questions as we can. Both Wes and Peter can help answer whatever you guys have in mind.

So to start things off, my name is Spencer Rolfs. I'm a product manager here at Juniper and joined today by both Peter and Wes, our wizards of Wi-Fi. I'll have you both introduce yourselves for those of you that don't know. Peter, go ahead and start us off.

Peter:

Yeah, hello everyone. Welcome to this webinar. My name's Peter Mackenzie. I'm an independent Wi-Fi consultant in the UK. And that's me.

Spencer:

Awesome. And Wes?

Wes:

Okay, so hello everyone, I am Wes Purvis, and I do Wi-Fi things at Juniper Mist. I am taking a one-hour break from my paternity leave just for this webinar, so definitely excited. You know, how excited I am to talk about Wi-Fi 7 today.

Spencer:

The dedication, it's good. Well, cool, okay. So obviously today's topic is going to be a deep dive into Wi-Fi 7, so without further ado, I'll hand it over to you guys.

Wes:

Okay, so Peter, let's do it so this.

Peter:

Yeah, let's do it.

Wes:

We're kicking off our Wizards of Wi-Fi again. We did we did one for Wi-Fi 6e, four or five webinars on that, and then we're going to do a similar type of thing for Wi-Fi 7. So this is this is the first one of many.

Peter:

That's right. I'm looking forward to this series actually where I think it could be a lot of fun. And for those who are sort of tuning into to this first one, we're going to really just talk about, you know, what does Wi-Fi 7 give us today. But what we want to do over the course of this series is, as we learn more about Wi-Fi 7, as we do more testing, we're going to try and share what we learn with you over the course of this year as sort of Wi-Fi 7 deployments become—maybe start to get rolled out and we start to get more clients and learn more stuff. So, just like we did with the Wi-Fi 6 series, we're not claiming to know everything, but we're going to try and share with you the things that we've learned as we go.

Wes:

Yeah. So yeah, this first one is kind of an intro and where we are in terms of Wi-Fi 7 as an industry and then, you know, there'll be an MLO-specific one and then, you know, get into deployments and troubleshooting and that kind of stuff a little bit later on.

And just kind of as point of order, so we have chat. Keep chat going. If you have specific questions that you want us to try to tackle, put in the Q&A just because the chat goes by so quickly. The Q&A makes it a little easier, if you have, you know, a specific question that you that you would like answered, makes it easier to track for us.

So first of all, let's just kind of get into, you know, what are we getting with Wi-Fi 7. And for those of you that saw our Mobility Field Day presentation, you've already seen this part, but I like to put up the, you know, the big numbers, right. Everybody is always kind of infatuated by the big number. So you may see Wi-Fi 7, 46 Gigabits per second. It's a big number from where Wi-Fi started. It's quite impressive, right, if we're ever able to get to that kind of number, very, very impressive.

320 MHz channels, right, from 20 MHz to 320 MHz, which is 16 bonded channels. That's quite a lot.

And then you have this 4K-QAM from a modulation perspective just to put more bits on the air.

So this is how you get to that big number.

But if you kind of bring it back into reality, right, so 46 Gigabits per second, that assumes 16 spatial streams and 320 MHz channels. So both those right off the bat may not be the most relevant for the enterprise market that we live in.

So your Wi-Fi 7 APs from an enterprise perspective are likely to have a max aggregated data rate of 26. And this will be on the high-end APs that most likely support dual 6 GHz where you can have two 320 MHz channels.

But okay, let's actually break it down to, you know, what is that what is that client actually going to experience? So if we take 2 spatial streams and data rates at m13, you know, in a 20 MHz channel, that gets us a 344 Megabit per second data rate. It's quite, quite a difference from 46 Gig.

Peter:

It's quite a difference, but it's still—they are great numbers compared to, you know, where we came from.

Wes:

Correct.

Peter:

And of course throughput is going to be, you know, somewhere to do, you know, about 50 to 60% of that. But there's still—that's pretty good numbers over a wireless link. I think, you know, 20 years ago I never thought we'd get to these sort of numbers.

Wes:

Yeah. So yeah, I mean this is, this is kind of—let's bring it to reality. This is a modest bump if you get 4K-QAM, you know, what, 20%, 15 to 20% over Wi-Fi 6. But, you know, this 4K-QAM, you know, may not—you may not get 4K-QAM everywhere.

So where are we from a standard perspective, from a certification perspective? So Wi-Fi has kind of settled into every three years or so there's been a major generation. So, you know, Wi-Fi you know, 11n Wi-Fi 4, to Wi-Fi 5, to 11 AC Wave 1, to 11 AC Wave 2, to Wi-Fi 6, to 6E was about three years between. Wi-Fi 6E to Wi-Fi 7, it's kind of this half-generation, about 18 months 24 months rather than the typical three years. So, but just, you know, this is how Wi-Fi has progressed, you know. Wi-Fi 7 you'll see, you know, is 11be, also extremely high throughput from an IEEE perspective

Peter:

I think it's worth pausing a second as well when you think about that, on just how Wi-Fi is getting more and more complex as well with every addition that we get out. I remember when— back when 82. 11n first came out, thinking, oh this MIMO stuff, that's quite complex, we can, you know, send on multiple spatial streams. And now you look back at that, and you go, actually that doesn't seem that complex when you look at some of the stuff we've got now.

Wes:

The table stakes of modern Wi-Fi.

Peter

Yeah, yeah. But it is—I think as we go through this series and we start talking about troubleshooting, the complexity—while it brings its amazing—these speeds, which are definitely positive, it does bring more complexities in terms of troubleshooting, analyzing Wi-Fi, so it'll be, it'll be fun to talk a little bit about that as we—later on in this series, I think. Because it—as Wi-Fi gets more complex, I think the job of the wireless engineer gets more complex as well.

Wes:

That is true.

Okay so from the IEEE, you know, believe it or not, Wi-Fi 7—actually 80211 be—is not fully ratified from IEEE, so we're expecting to see final approval in December or end of the year from an IEEE perspective. Now Wi-Fi 7, which is the Wi-Fi Alliance interoperability program, Wi-Fi 7 is out there. That came out in January. There are Wi-Fi 7certified devices. However, 11be, the IEEE spec, is not, you know, fully ratified yet. Now that's to say, you know, most technical requirements, you know, are already finalized, but it's just interesting you think okay, Wi-Fi 7 is not actually, you know, we're still actually on the bleeding edge of Wi-Fi 7.

Peter:

Yeah, absolutely.

Wes:

So, what are the big features? Well, we've gone from 8 spatial streams to 16 spatial streams. We've gone from 160 MHz to 320 MHz wide channels. We've gone from 1024 QAM to 4096 QAM for modulation. And then, you know, probably the two biggest features—or three biggest depending on how you look at it—is the Multi-RU and preamble puncturing that enables kind of flexible channel utilization and then Multi-Link Operation. So we'll talk, you know, more in depth about all of these, but, you know, those are I think the two that, you know, at least I'm most excited about.

Peter:

Yeah, yeah.

Wes:

And then there's also, you know, there's a bunch of little stuff that we haven't included in here. There's some, you know, there's some QoS enhancements that, you know, we didn't touch on in here, but, you know, this is kind of the big—the big ticket items in Wi-Fi 7.

So let's talk about 16 spatial streams. First of all, you will not see a 16 spatial stream Mist AP, I can tell you that right now. Sorry. And you likely, you know, won't even see 8 spatial stream APs from anybody, you know, at least in the Enterprise Market.

Peter:

I think that's right. I think you've—even if you look at what's happened, you know, we had up to eight spatial streams before, but—and a few vendors did come out with eight spatial stream APs—but I believe all those APs are end of life now because they just weren't really needed. And I do think, you look at what has happened in the client market, they tend to have standardized on 2 by 2 for clients. It does seem that for at least enterprise APs, we're going to standardize on four spatial streams, 4 by 4 APs, I think.

Wes:

Yeah, I would agree with that. I think the eight stream AP, you know, was something to try and didn't—you know, the benefits of eight stream over four stream is not all that much and most of the time that AP was, you know, even split into dual five.

Peter:

Exactly. And I think that it's because you're serving two spatial stream clients, so four spatial streams really gives us enough for that, I think.

Wes:

Yep. Okay, so let's talk about 320 MHz channels. This is another one that is likely not too relevant for the enterprise market, you know, maybe point-to-point links. But in the US there's three non-overlapping 320 MHz channels, so yay, we get back to 2.4.

Peter:

Yeah, you're lucky.

Wes:

In Europe, Peter, you have one.

Peter:

Yeah, we only have one, so I don't see it being used at all to be honest. I think currently in Europe with, you know, only our sort of 500 MHz in the 6 GHz band, we're really going to be probably still using 20s and 40s, mainly, in the enterprise. There's a few cases for 80 MHz channels in the enterprise, but I think they're going to be special cases. But 160s and320s, at least in Europe, are just not really usable.

Wes:

Yeah, I mean what we've seen from a 6 GHz perspective, especially in Europe, you know, folks going down to 40s, kind of you know, most of the time, and some in some cases even 20 MHz. So in a case where, you know, right now with 6 Gig adoption where it is, you know, you have some let's say, extra headroom where you can get away with wider channels, but over time that will go away.

Peter:

Yeah absolutely.

Wes:

And so, you know, in Europe/UK, I mean, you have 500 MHz of spectrum. That's about the same as the amount of 5 Gig spectrum you have, and so if you're doing 20s and 5 Gig, you know, one 6 Gig adoption is equal to 5 Gig, you know. Realistically, you should do the same channel width in 6 Gig that you do in 5 Gig.

Peter:

Yeah, that's exactly how I view it. It's like getting the 5 GHz band again, so you're going to follow the same sort of rules you do for 5 Gig in Europe. Now there's consultations happening on the potential of opening up more spectrum, but we'll have to wait and see whether that happens or not.

Wes:

And I'll just throw in one note—if you're, you know, following along on 6 Gig, there's a concept of the Preferred Scan Channel, the PSC. And initially, you know, the recommendation from vendors was to use the PSC because we didn't fully understand client behavior. But now we, you know, have a good handle on client behavior because all the clients are out there. And, you know, we're very comfortable using non-PSCs. And so recently, as part of Mist RRM—you know, we stuck to the PSCs by default—but now if—you know, we'll still stick to them for 80 MHz, 160. But if you use 40s and 20s before, you had to manually enable all the channels, and now we'll just use, you know, PSCs/non-PSCs when you have those lower channel bandwidths. So yeah, we're kind of, that's how comfortable we are from a, you know, non-PSC perspective.

Peter:Yeah, absolutely.

Wes:

Okay, 4K-QAM, this is another—so I think you know, the 16 spatial stream, the 320 MHz, really not all that relevant. 4K-QAM I think is probably, you know, the first one that becomes, you know, relevant where we can see, you know, tangible benefits from. Now—

Peter:

Yeah, I think that's right. I think it's got a lot of—I think this is one that you're going to see sort of instantaneous tangible benefits from as well, you know, while I think some of the things we're going to talk about later, like, Multi-Link Operation, it's going to take a bit of time to figure out how that works, and client compatibilities. I think this is something that should be potentially a benefit from the get-go. Especially given, I think, a lot of modern sort of density-based designs tend to have access points fairly close to the users, which is something we've been sort of preaching for a while, is place your access points as close to the user as possible in wireless design. I think as you get these sort of higher density designs where, you know, you've got APS above desks or maybe you're in a meeting room and there's an AP above the table you're sat at, so you're only a couple of meters from the AP and you're in the same room as it, I think this should be fairly achievable.

Wes:

Yeah, I think—well, okay, so first of all, I mean, you need a pretty strong signal.

Peter:

You do, yeah. Yeah.

Wes:

And so that will be the challenge is, you know, can you get a good enough signal? And, you know, we've seen, you know, sort of, generation over generation—you know, remember back to 11 AC, people, you know, 256 QAM, oh you'll never get that, and then, you know, 1024, right? So it's that, that same kind of mentality of, you know, yes, you need a strong signal, but it's—we've seen, it's attainable. And especially, you know, to your point of designs are getting, you know, denser and denser and the AP is getting closer to the client, you know, you're likely to see 4K-QAM, you know, in good conditions.

Peter:

Yeah, absolutely and, you know, things, like, I know some people are now putting APs underneath desks, so and then, you know, the AP can literally be a meter or a meter and a half from your client. So I think that's where you're going to see these sort of data rates said to be coming to their own. Obviously, if you're not in the—the AP is in the room next door to you and you've got a wall between you, you're probably not going to achieve this. So—

Wes:

Right. Okay. Hey did I go out of focus, by the way?

Peter:

Yeah, but you're back.

Wes:

All right. So preamble puncturing. So let's say, you know, we want to use wider channels but, you know, we're worried about interference. Preamble puncturing is, in theory, a way to be able to use wider channels in the presence of interference. Now, there's kind of a big, you know, contingent here where your client has to be Wi-Fi 7 to be able to, you know, understand the puncture, right, because it's advertised in beacon. And so, you know, if—you know, before you get to, you know, good adoption of Wi-Fi 7, this likely is not to have, you know, that big of an impact. But if you get to somewhere where you have a lot of Wi-Fi 7 clients, yeah, then maybe this is a viable thing to be able to, you know, to use the wider channel when you can and if you have, like, a persistent interference, you know, this just kind of works around it.

You know, I think there's a lot of questions to figure out over time of like, you know—and this will kind of be some of the, you know, tweaking that vendors do—but, you know, how quickly do you react to an interference when it comes up, when it goes away, you know, how do clients react? And, you know, from testing it, I think we've seen different behaviors from different clients. And, you know, some clients need a reassociation to, you know, take advantage. Some will do it dynamically. But yeah, this is one of those that has potential, but there's some things to work out and definitely needs client adoption.

Peter:

Yeah, that's my feeling with it, is it's going to be interesting to see, you know, how it—sort of, how the clients are going to do this and how the devices are going to do it. Are they going to—you know, at the slightest bit of interference are they going to start puncturing the channel? Or is that interference going to have to be there for a while? And how long will they keep the channel punctured before they go back to it being unpunctured if the interference goes away? So I feel there's still quite a lot of questions over this technology in terms of how it'll actually be implemented. So it'll be interesting to see what happens.

Wes:

Okay, so then related in terms of, you know, more efficient use of the channel, is Multi-RU. So in Wi-Fi 6, you know, we have OFDMA and we can split up the channel into the different sub-carriers, the resource units, and, you know, a client can be allocated a resource unit. That gets you to a point where you may not fully utilize the channel based on the allocation.

With Wi-Fi 7, a client can have multiple RU allocations to be able to, you know, basically the AP can fully fill up the channel. So this is just kind of a nice, you know, nice efficiency improvement, you know, when OFDMA is used.

Peter:

That's right. I'm fairly excited about Multi-RU, actually. I think it's—because when I did a lot of testing with OFDMA something I found when looking on sort of spectral traces was often you did have bits of the channel that weren't used. And you think, well is that really good spectral efficiency when there’s, like, used and not being used, compared to one client using the full, you know, the full channel and the full spectrum. So I think this could really—that definitely increases the sort of efficiency of OFDMA. And, you know, the big selling point of OFDMA is it's meant to be more efficient. So I feel this would be a really nice little, you know, add-on to that, really, which should improve things.

Wes:

Okay, so let's take a pause and look at the Q&A real fast. Is the cost of labor to swap Wi-Fi 6E APs worth it? Oh, okay, let's come back—we'll come back to that one at the end. It's a worthwhile discussion to have.

Okay next one. Does wireless—does this bring wireless as a true reliable option for the data center infrastructure? I would say no.

Peter:

No.

Wes:

The old rule is, you know, if it doesn't move, wire it up. I think that, you know, that continues.

Peter:

I think that still exists, yeah.

Wes:

Then, will we see significant regulatory reduced max transmit power for 6 GHz band like we see in U-NII-3 channels for 5 Gig and some of the EU countries? So U-NII-3 in EU, if I recall, is 25 mW short-range device. The transmit power of 6 Gig in Europe in the low power indoor mode is higher than that. And, if I recall, it’s, like, 10 dBm per MHz. I know it's different between UK and EU, but the 6 Gig power is higher than the U-NII-3 power.

Peter:

Yeah 10 DB per MHz. I think if we get the sort of, the very low power outdoor that's going to be 25 mW Europe.

Wes:

Yes, very low power, yes, correct.

Peter:

That that's going to be 25 mW, but for the just the indoor it's going to actually be more.

Wes:

Yeah. Does Wi-Fi 6E support multi-RU? Technically yes, but it's an optional feature of Wi-Fi 6, so you may—clients may or may not understand it today.

And has preamble puncturing been ratified? Is it supported feature? It is part of Wi-Fi 7, or 11be. Not ratified yet, but will be shortly by IEEE.

Okay so then that takes us to Multi-Link Operation, which I think is the biggest feature of Wi-Fi 7. This is what I'm most excited about. And I think probably if you ask anybody, this is what they would say. And, you know, if we just take a second to kind of stop and think of, you know, the past couple generations of Wi-Fi, the biggest feature, right? So in Wi-Fi 6, OFDMA. And you know, in 11ac I would argue Multi-User MIMO even though that turned out to be a dud. But, you know, you kind of have, is Multi-Link Operation going to be more, like, OFDMA, which has been useful and is actually seen in real life, or be more, like, Multi-User MIMO, which is a dud and is not, you know, there's overhead, and you don't really see it in the real world outside of a lab.

Peter:

I think that's a fair question to ask really. So and I think that that's some of the things we can consider, isn't it, as we go through this webinar series. I think maybe let's just pause and say what is Multi-Link Operation? Just in case. Because basically Multi-Link Operation is taking the multiple frequencies that we've got, so 2.4 GHz, 5, and 6, and being able to—and generally, if you think about an AP, a tri-band AP, they've got three radios. And it's the ability for a client to make connections to all of those three radios at the same time. That's what we're talking about when we're talk about Multi-Link Operation. And then there's a number of different ways we can use those three links.

Wes:

And sort of—and, you know, there's different advantages or use cases also of the Multi-Link Operation. And so one is, you know, to use kind of the different links for increased reliability. So, you know, basically picking a link that can, you know, if this link is busy let me go to a different one, and that can increase my reliability and also lower my latency.

Peter:

Absolutely.

Wes:

The concept of, you know, data aggregation, which is sending, you know, across multiple links simultaneously in kind of, like, lag form we'll say, but to be able to split the traffic across the links to, you know, combine the throughput to get higher aggregate throughput.

And then last is sort of a redundancy, to be able to send a duplicate over multiple links so that way, you know, in, you know, in critical environments or harsh environments, you know, you kind of ensure that your data transfer gets through. This can also have the effect of lowering latency because the frame that makes it first will be received and forwarded out on the wire of the AP.

Okay, so we have, you know, this is the why and what MLO will do. Let's talk a little bit about the how. So in MLO you'll hear lots of terms and lots of lots of acronyms that are frankly a little confusing. And it took me a little while to kind of get to the most simple, but the most simple is there's two types of MLO. You have link switching where, you know, the client will switch—only, you know, operate on one band at a time and switch between the two, or three potentially depending on the client, whatever.

Peter:

It's basically making a choice, isn't it, which band to use with link switching. So it can it can have a connection, if you want to think of it like that, what we call a link to each radio, but then which one it's going to use, it can choose at any one time. So, and of course—

Wes:

And the AP can make the same decision, and the client can make the same decision of which links it wants to use for what.

Peter:

And and of course this only needs a single radio in the device to do that. That radio can just switch. So we tend to use that term, the multi-link single radio, because the client only needs one radio. And it's going to choose which link based upon how busy the channel is, or whether there's interference, or errors, it can choose which link it wants to use.

Wes:

Peter, we lost your video.

Peter:

Oh.

Wes:

OK, so there's a couple flavors of link switching, which I'll come back and talk about. And then you have the multi-link concurrent, which means that, you know, operating on multiple links concurrently. So link switching, multi-link concurrent, right, those are your two flavors at the most basic level. And then you'll hear the technical terms of Multi-Link Single Radio, MLSR, so remember that, Multi-Link Single Radio. And that's just what it sounds, like, multi-link, but I have a single radio on the—on my device.

Now we can see you.

And then for the Multi-Link Concurrent, MLMR, that's Multi-Link Multi-Radio. And so it's actually, you know, the terminology once you, you know, understand is pretty simple. It just, you know, can be confusing at first. So you have Multi-Link Single Radio (MLSR), Multi-Link Multi-Radio (MLMR), and then in these there's a there's different flavors of them.

So the most basic type of MLO is Multi-Link Single-Radio, where I'm a client, I may only have one radio or one radio core, and so therefore I can only—I can maintain my multiple connections, but I can only operate on one band at a time and I have to switch, you know, basically time, you know, time-switching between the bands.

Peter:

That's right. Yeah, it's going to say, I think this is the best band, so I'm going to use that one for a period of time until I've decided by some algorithm that another band is better.

Wes:

Yeah. And then what we've seen is more common than MLSR is something called Enhanced MLSR (EMLSR). And this is the ability of a client device to be able to take its radio—let's say it's a 2 by 2 client, split that 2 by 2 into two 1 by ones and listen on two links at the same time. And then it can—there's a signaling, there's an RTS signaling mechanism, to actually say, all right from—the AP is like, all right, I'm going to I'm going to transmit on link one, set up link one. The client goes to 2 x 2 to do the transmission, and then it goes back into the dual 1 by 1 and then, you know, the client's ready to transmit something it goes into the 2 by 2 mode on link zero, you know, whatever, right. So this is actually what we we've seen, most devices at a minimum support EMLSR, where, you know, they're basically splitting the radio into, you know, two 1 by 1 chains, listening, and then there's a signaling to determine which band is actually going to get transmitted on.

Peter:

That's right. So basically as a transmitter you can transmit on whichever band you want, and the device listening will listen on both bands, and whichever they hear, like, the RTS on, they know they can switch to 2 by 2 and receive the data. So I think it's worth it. It's still classed as a single radio because it's a single MIMO radio, a 2 by 2, but remember in a MIMO radio you've got two spatial streams. And a spatial stream is basically a radio and antenna. So it can split those and listen on the two frequencies for that initial control frame and then whichever it hears it on, that's the band it's going to use. So it can literally dynamically switch for every transmit opportunity which band it's transmitting on.

Wes:

Yeah, this can be on a per-frame level. Okay, so then there's the in the Multi-Link Concurrrent (MLMR). You basically have three flavors, but the most common flavor will be this STR, Simultaneous Transmit Receive. Right, so this is this is kind of, like, the Holy Grail. This is, like, I can aggregate over, you know, multiple links, I can transmit over multiple links at the same time, I can receive over multiple links at the same time. However, this requires the most sophisticated client, right? You need, like, an excellent RF design, you know, think of—if you think of APs and, you know, it's relatively recent that we've supported, like, dual 5GHz on APs, right, to support multiple radios in the same band, you know, on the AP. And, you know, we have the luxury of space, relatively speaking, on a client—or, on an AP. Think about a client, you know, a mobile phone, where space is at a premium, size is a premium, battery is a premium, so you really need, like, a very sophisticated RF design to support the Simultaneous Transmit Receive, especially if you want to do STR with the 5 and 6 Gig band at the same time. And we'll get into a little bit of this nuance a little bit later. And remember we're going to have a dedicated MLMR webinar, so we're keeping at relatively high level here, so—

Peter:

Yeah. I think at a high level a way to understand what we mean when we say simultaneous transmit and receive, it means that on both links, on both bands, it could be receiving on one and transmitting on the other. And to do that it basically just needs to have really good filtering between those bands. Otherwise, you're going to get what we call in-device co-existence interference between the two bands, so that—that's what we're really trying to do here.

Wes:

Yeah and I see that in the chat, you know, full duplex and client flexibility. Yeah I mean so, you know, I think depending on how, you know, your definition of full duplex, you know, if you can transmit on one link and receive on another, it kind of sounds, like, full duplex. Now, there's I think some caveats with that.

Peter:

I think there's definitely caveats with that, but yeah. And there is, we should mention, there is a mode, which I'm not sure whether we'll see or not, which is called NSTR—which is yeah, the ability to non-simultaneously transmit and receive. And in that, they coordinate so you transmit at the same time and you receive at the same time. So we'll have to wait and see what devices actually end up supporting and doing.

Wes:

And this is because, you know, TX—if you transmit and receive, that's the most difficult thing to do because your transmit can overpower your receiver.

Peter:

That's right.

Wes:

You need strong isolation there.

And then there's the last one, which I think will be the least common, which is Enhanced MLMR where you can have different number of spatial streams per link and reallocate your spatial streams to different links. I don't, you know—we may get there in future generations of clients, and—but that's not all that common.

OK, so then let's get into what are we seeing today? And so, if you if you go buy an MLO AP and an MLO client, you will see it connect on multiple links. That, that has been rock solid. Like every MLO client that I've seen, every MLO AP, you will see multiple links. So thumbs up, you can show your boss, yep, Wi-Fi 7 is making a difference. Now the question is, is there actually any benefit? Are we seeing a benefit? Are we, you know, are we actually seeing the data traverse multiple links? That is not as clear cut and really varies by the client.

So okay, so this is just one connected on 5 Gig and six Gig this is a Windows output. It actually, you know, shows the, you know, the bands that it's connected on. I don't think this aggregate link speed is actually correct. It's only showing a single band aggregate speed, but, you know, you can at least see, yep multiple links. And then if you go into the command prompt and do the, you know, netsh, you know, WLAN, it gives you a little bit more detail in terms of which links—the BSSIDs of those links, the MAC address that you're using, the BSSID of the links, the signal strength, channel, band, bandwidth, so—

Peter:

And this information is going to be quite useful when you start getting to looking at packet captures and doing troubleshooting because you're going to want to know the MLD AP MAC address, BSSID, but you're also going to want to know the local link MAC addresses as well, so—

Wes:

Yeah. And so there there's a question around who decides which links to send the traffic on, and it depends on if it's downlink or uplink traffic. So if it's downlink, the AP decides. If it's uplink, the client decides which link to send on. And, you know, actually in, like, Android has published some pretty detailed documentation around the use of MLO, and actually the applications can determine to some extent the type of MLO. Like, is it is it redundancy? Like, do I send, you know, multiple links at the same time? Do I aggregate, you know, do I go for lower latency? And Android actually recommends for users priority 6 and 7, always do duplication. So, you know, there's a lot of nuance and I think this is an area of opportunity where we're at the very beginning of MLO, and the client side and the AP side need to figure out the most efficient scheduling of the multiple links.

Peter:

But it's—effectively, it's the transmitter that makes a decision, isn't it?

Wes:

Yes the transmitter makes the decision, correct.

Peter:

Which is similar to many other things in Wi-Fi.

Wes:

Yep. Here is Android. Android—this device is actually a Pixel 9, which is by far the best MLO device that I've seen. The Pixel 9 actually connects on three bands, three links simultaneously. It does STR on two of the bands and EMLSR on one of the bands. So this is a, you know, good device. Here's—the right side is a—if you turn on the developer tools and turn on the Wi-Fi debug, you get this kind of output. And it, you know, it mentions the MLO and which links you're connected to, and your MAC address, the BSSID, you know, per-link kind of stuff.

Okay, and then let's—I want to show what does MLO look like? So I mentioned you won't always see MLO from the client, right? So depends on the client, depends on the AP, depends on the traffic type. And the, you know, the most reliable client that I've seen from an MLO perspective is the Pixel 9. Like, I had one Windows client who was connected on 5 Gig and 6 Gig. 5 Gig 40 4MHz, 6 Gig 160. And for some reason it was transferring only on the 5 Gig 40 MHz. Right, I was doing a speed test. So, I mean that's not the most efficient. I actually would have had a better experience had I been only single band, right, connected on 6 Gig. So there's definitely these kind of, you know, improvements that need to be made but, you know, it's at least interesting or encouraging to see, you know, the clients link up, you know, by themselves.

So this is Pixel 9, 6 Gig band, you know, there's really nothing going on. On the 5 Gig band, there's also, you know, really nothing going on. And then if I start a speed test, I see transmissions on 5 Gig and then if we wait a sec, we'll switch over to 6 Gig and also see transmissions. So, great, this is, you know, simultaneous trans, you know, transmit over 5 Gig and 6 Gig, which is really cool to see.

Peter:

Yes, nice to see it working.

Wes:

Go back to 5 Gig see the same thing. If we wait one second, the speed test will go from downlink to uplink, so it's transferring—it's changing to uplink right here, and then it's starting its uplink. So we're seeing transmissions on 5 Gig, and then switch over to 6 Gig, also seeing transmissions on 6 Gig. Right, so this is, you know, there's MLO happening here. Now this isn't—you know, I didn't do a packet capture to kind of, you know, see exactly what's going on, but, you know, high level, you know, we're seeing MLO. We'll do the packet level kind of stuff in the follow-on MLO webinar, but I at least want to show you MLO can happen. Now this is kind of the best case. Not all devices are like this.

Peter:

And we're also seeing the sort of speed you were getting, throughput, there as well.

Wes:

Yeah, correct. Yeah, I wasn't so concerned with, you know, the throughput. I, you know, if I wanted to see the throughput improvement, I would have gone to 20 channels and, you know, I have a Gig link at home, right.

Peter:

Right okay.

Wes:

You know, to see the, you know, additive benefits. So okay so then that kind of takes it to where are we with an MLO perspective?

So you know, many of the Wi-Fi—let's say, I think all the Wi-Fi 7 devices out there that support MLO, they will actually link on multiple bands. Whether or not you see transmissions across multiple bands is a totally different story.

And so, from a Windows perspective, you have to have Windows 11, you have to have Windows 11 24H2, which is not fully available yet. You know, if you have, like, I think you need a co-pilot Windows laptop. If you have that, then you have this version. Or else you need to get into the Windows Insider program. But once you do, that version of Windows supports Wi-Fi 7, you'll see the multiple links and, you know, all the output that I showed.

There's really three main Windows clients out there. There's the Intel BE200, which only supports EMLSR. There's the Qualcomm Fastconnect, which supports both MLMR and EMLSR. There's a third Media Tech, I didn't include it in here because it's Media Tech. But yeah, so yeah, Windows has added support.

Same on Android, the, you know, first seen in Android 13, but Android 14 adds, you know, kind of better, you know, more robust. It actually uses the multi-link, the MLD as a calculation in its throughput calculation for roaming decisions, so if you have, like—it uses the aggregate of the links, which is cool.

When you get to the different client types, this is where you start to see a lot of the nuance. So many of the, let's say, first set of Wi-Fi 7 devices actually do support Simultaneous Transmit Receive, but they only do it on 2.4 plus either 5 Gig or 6 Gig, which is—the benefits to me are questionable, and that's because it requires the least amount of filtering, right, if you need—you don't need as sophisticated as an RF design on the client. Now frankly, I was a little surprised to see, you know, the STR support at all on the mobile devices, but what's mostly—what's out there is the 2.4 plus 5 or 6, which I think is meh.

The Pixel 9 actually supports simultaneous on 5 and 6, which is awesome. So from what I've seen, the Pixel 9 will connect on all three bands. It does simultaneous on two of the bands and then EMLSR on one of the bands. And if you look at—this is the—from the Pixel 9 website, it actually lists out 2 by 2 plus 2 by 2. so it has you know—it's only one radio, but it's actually two radio cores on there.

Peter:

And I think that's one of the things that has surprised me really when we first started looking at MLO, I was very skeptical whether mobile devices would support Multi-Link Multi-Radio just because you've got that extra power needed to support the 2 by 2 plus 2 by 2, the two, you know, the extra radio. Because obviously, you know, mobile phone manufacturers typically try and keep battery consumption as low as possible because you want your mobile phone battery to last at least a day, don't you, before you have to charge it. So I was quite—I'll say, I'm pleasantly surprised to see these devices supporting it.

Wes:

I agree. I agree. I mean, to me the dirty little secret is this 2.4, you know, plus 5 or 6, right, not, you know, not the 5 plus 6, which you would, like, to see for the STR. But the newer devices and the higher end devices I think are starting to support that. So if you, like, if you go to Qualcomm website and look at this client, you'll see something called HBS, High Band Simultaneous. And then Broadcom has a similar type of feature, you know, where they've actually put in this, the filtering to be able to support it.

Yeah, okay. Now Apple, you know, there's nothing out there. Apple does have an announcement next week for iPhones. Who knows what will come there.

And then if you're curious, go google Android MLO, and it actually does a very good job of walking through the MLO capabilities on Android, like, a very well-written, detailed document.

OK, and then the last piece of MLO is just to talk a little bit about the—just the functionality of how, you know, how it works a little bit under the covers. Again, we'll go more in depth on a dedicated MLO webinar. But just high level, there's now two MAC layers.

Peter:

Yeah, yeah, that's exactly right. We've got two MAC layers to deal with. That upper MAC layer, which is going to be—which is going to be the MAC address, which ties the MAC addresses together. So you'll have a physical sort of lower MAC layer, which is tied to each radio. So there'll be one for your 2.4, your 5 Gig, and your 6 Gig, and it's going to create a link on each of those radios with the AP, or the AP with the client. And then you're gonna have an upper layer MAC address, which will be the same.

So obviously, if you think about MAC-layer communications, when we're having a conversation or we've got an association, we have a MAC address that associates—that's what uniquely identifies a client. So that would be—think of that as your upper-layer MAC and then for that upper-layer MAC, it could have multiple physical links to the AP, and they will be identified with the lower-layer MAC addresses.

Wes:

Yeah, and here's kind of a different view of that, right, where you have your multi-link device, there's the MAC address for the MLD, whether that's the AP or the client, and then each link on each side there's a different MAC address. So the—basically, when the client connects, it's supposed to already have learned about all the links. And at the time of association, it can—it actually does the association on one band. So it picks one of the bands, it does its association, like, normal. In the association request, you'll see this multi-link element. And in the multi-link element, it basically sets up the MLO. It says, hey this is my multi-link address. On each of the links, this is going to be my address. And, you know, it exchanges the keys. And then the client can just go start transmitting on the other links after that. There's accompanying association response where the AP will set up the links as well. Say hey, this is my MLD address, these are my link addresses, so the client knows. And yeah, it'll make troubleshooting—especially if you're at packet level—much more fun.

Peter:

It'll make it—it'll make it more interesting. I'm thinking we're going to need more columns in Wire Shark. You're going to need to have your MLD device, which you may want to filter on if you want all traffic going to one client. But then you'll also want to see the two different links because maybe you're having an issue on one link and not the other. So it'll make it interesting.

Wes:

Yep.

Peter:

For sure.

Wes:

The question around what format will the MAC—you know, the lower MACs—be in. And it'll vary by client. I think most commonly you'll see random MAC, locally administrated MAC. In Android, they basically say you can do whatever you want, but, you know, you should—here's, you know, something that you can consider, you know. It'll always be a unicast MAC, and then, you know, it could be—you know, it could be global or it could be local. I think, you know, most commonly, just because it's more MAC addresses, you'll see it as local.

Peter:

Yeah, and I think as we go to our MLO webinar, when we when we do our next one on this topic, we'll try and go into a bit more detail and maybe have a few more protocol traces to show you.

Wes:

Yeah, yeah, exactly. This is—this is just to wet your whistle. It can get pretty deep.

All right then, not strictly Wi-Fi 7 or 11be, but the Wi-Fi Alliance Wi-Fi 7 program included some additional security enhancements. So to be a Wi-Fi 7 certified device, you have to support both beacon protection and AKM 24 with Hash-to-Element for WPA3-Personal.

So beacon protection—and these aren't strictly new, but they're just mandatory now. So beacon protection is an integrity check of a beacon so that, you know, a client can more easily, you know, figure out if something spoofed. And then the AKM 24 is, you know, a higher-level encryption with, you know, different key derivation. And then the HTE for, you know, you know, better resistance to things like cracked. So yeah, you'll see these from client devices. It's unknown if these will introduce interoperability concerns with previous generations, but yeah, just something to consider that there's additional security, enhanced security requirements for Wi-Fi 7devices.

Peter:

I think probably you're going to—if you're seeing compatibility issues, it's probably more likely to be on 2.4 and 5 Gig where we've got other devices.

Wes:

Agree.

Peter:

But it'll be interesting to see if any of the Wi-Fi 6E clients have an issue. I suspect not, but, you know, I guess we'll see that in time.

Wes:

So we just went through all this Wi-Fi 7. I want to look through what we just talked about through the lens of 6 GHz because we just went through, or are still going through, this migration to 6 GHz Wi-Fi. So if we're, you know, two years, you know, we're two years and change into 6 GHz Wi-Fi. We're just cracking 20 to 30% client adoption. So Wi-Fi 7 will have to go through this same adoption curve. So, you know, your Wi-Fi 7 clients, you know, will take years, you know, basically to get to meaningful adoption.

So here's one example where we had a public event, 18,000 clients in this particular screenshot, and 4,000 were on 6 Gig, which we thought was really awesome. Here's a kind of smaller office environment, 65 clients. 12 of them on 6 Gig. Another office environment, 3500 clients. A thousand of them on 6 Gig. So you know, we are seeing 6 Gig adoption, but just remember Wi-Fi 7 will have to do the same thing.

Peter:

Yeah yeah, it's definitely gonna take time, isn't it?

Wes:

Yeah. Yeah, like, we're—I mean, we're just at the point, like, 6 Gig Wi-Fi—this is, you know, my local grocery store. I went in and, you know, connected to guest Wi-Fi, and I was pleasantly surprised to see I was on 6 Gig. So, you know, it—6 Gig, you know, we were, I think we, you know, we all kind of had concerns of, you know, how is how is roaming going to work, is the RNR going to work, and all that stuff kind of figured itself out and works well. We're on that same kind of trajectory with Wi-Fi 7. You know, there's definitely things still to figure out, and it will need deployments to figure out what, you know, what sort of the rough edges are with Wi-Fi 7. But, you know, we'll get there just like we did with 6 Gig Wi-Fi. But it will take time for that to happen.

You know, here's an example. I just—I find this really cool, where there's—this is an AP where there's more 6 Gig clients, 45, than there are 5 Gig clients, 41. So, you know, we're—you know, in some environments, we actually have seen the shift where 6 Gig outnumbers 5 gig.

Peter:

Yeah, that's cool.

Wes:

So that takes us I think to the last slide, which is do we need a Wi-Fi 7, or like, based on where we are now, like, how do we feel about Wi-Fi 7? So this is kind of how I think about it—and Ben, I'll get back to your question of, you know, is the labor, you know, is it worth it to swap to Wi-Fi 7?

And so like, you know, Wi-Fi 7 is here. There's no doubt about it, right? There's products out there, there's clients out there, but the overall adoption is minimal. And it will take a couple years just like we saw with 6 Gig to get meaningful adoption. You know, even now we're still at only 20 to 30% 6 Gig adoptions. And then you know, the technology itself is relatively immature. You know, most of the vendors out there that are shipping, you know, MLO as a beta future, you know, as an early access feature. So and some of these, you know, some of the things that we've seen can be fixed with software and will be fixed with software, right? Like the MLL scheduling of which link do I actually transmit something on, or how do I reconfigure one of my links, like, if I need to change channels due to RRM, for example. Like, that stuff can be fixed in software.

But there are other things that, you know, are limited by the hardware. Right. The Simultaneous Transmit Receive, where on many of the devices you can only do that with 2.4 and 5 or 2.4 and 6, right—you can't do 5 and 6, which in my opinion is, you know, a little bit of a limitation and, you know, probably makes the EMLSR more useful. So I think, you know, for most people who have not, you know, adopted Wi-Fi 6E, just adopting 6 GHz Wi-Fi is the next logical move. That will have an immediate impact, we know works, and, you know, getting 6 Gig clients, you know, you'll see a boost. We've done this now at many of our customers where, you know, they were out of 5 Gig capacity, they moved to 6 Gig, you know, we were able to refresh some of their clients to 6 Gig, and life is good. The additional 1200 MHz of spectrum in the US and 500 in Europe is just a game changer.

And then it was, you know—it should also be noted that Wi-Fi 7 APs need more power. The MLO doesn't come for free. And so, you know, these things—you know, most of the high-end APS will need BT for full functionality. You know, some of the mid-range and lower end could operate fully on AT, but likely, you know, BT, you know, is what you should think about for planning.

Peter:

Yeah I think that's right. I think the way I look at it is, you know, a lot of these things are going to sort of have to—we're going to have to see how it actually behaves when it's deployed and deployed at scale. I think with the Multi-Link Multi-Radio, you know, it gives us one of two things: Either we get more throughput or we—by sending different things on both links—or we get more reliability by sending redundant data, the same data, on both links.

So, I think it's just a little bit of a correction of what is it, what do we need? Do we need that additional throughput, at the moment? And I think in a lot of cases, a lot of use cases, we don't actually need the additional throughput because by using the additional throughput you're also using up two channels. And one of the things, especially if you think about, like, high density environments, where actually what we want to do is split our users across lots and lots of channels—so by actually effectively taking up two channels by one device sending on both, that might not actually always be what we want. So I think it's probably going to depend environment by environment what's needed.

I also think—but I think when we look at the redundancy requirements of Multi-Link Multi-Radio, so when we're sending redundant data, I do think that could potentially be useful in highly critical environments. So I instantly think about warehouses, where maybe you've got things, like, picking operations going on, where any sort of delay in the transmission, even if it can be literally a few seconds of delay, that can actually cause over an entire shift, maybe, someone's pick rate to go down. And therefore the entire warehouse—if that's happening across everyone's radio—maybe becomes less efficient. So I think having a more reliable link where actually I send the same—I don't need a lot throughputs—I send the same on both links and two frequencies, if that makes it more reliable and means I have a lot less latency, like, latency issues due to busy mediums or interference, I think that could potentially provide a lot of improvements in those type of environments.

Wes:

Yeah, I agree. I mean, I think there's—there are definitely use cases, you know, for multi-link. You know, I kind of, like, the idea—you know, in just generally the idea of, if you have usage in one band, the client can just go to another band, right? It doesn't have to think about roaming. It's already connected and can say hey, is this other band free? Like, in theory that sounds really awesome, like, you know, to be able to use, you know, hop between 5 Gig and 6 Gig, you know, to lower the, you know, the chances of, you know, of a collision or, you know, of somebody else that's transmitting at the same time. And you know, it remains to be seen whether that, you know, pans out, but I think, you know, kind of the early indications are there is potential for that.

Peter:

Yeah, I think that is the early indications. And I think a little bit like OFDMA, you're going to find the devices are supporting this and using it, you know, as Wi-Fi 7 goes out. So it will be—it'll just be interesting to see, I think, how it scales. And also, I think that's what's going to be interesting, is how much control we'll potentially have over some of these features.

Wes:

Yeah, I mean at least what Android says, you know, the app will be able to control some of it, which is interesting. So yeah, there could even be, you know, some application-level, you know, improvements that people can make.

Peter:

Yeah absolutely and again, just going back to my warehouse environments, a lot of mobile devices used in warehouse operations are actually—you look at the Zebra devices—they're all based on Android operating systems, so I wonder if they could take, you know, make use of some of that configure on the client device.

Wes:

Okay, we are 5 minutes over. I think we can we can probably call it here. So, thank you everyone for joining. This is again the first of our Wi-Fi7 Wizards of Wi-Fi webinar series. There will be more of these, so stay tuned. And if you are someone who is interested in Wi-Fi 7, maybe check back with us in a couple of weeks, wink-wink, and, you know, we'll catch you next time.

Peter:

We will do. Thank you, everyone.

Wes:

Allrighty, thank you.