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Our wireless access points are going to get deployed in such a way that they

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have this range

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around them where their wireless transmissions reach.

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Eventually, transmissions get weak enough that they can't be used and so we

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sort of have

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this boundary around each one of our access points.

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These boundaries in this space is known as a wireless cell.

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And there are a few important aspects to cells.

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First of all, we actually do want wireless overlap here.
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First of all, we actually do want wireless overlap here.

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The reason we want overlap is because if I'm a wireless device and I'm walking

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this

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direction, eventually I'm going to hit this spot where I can't really

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communicate to

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this access point anymore.

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But imagine if the next access point was all the way over here.

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Well, I would have to try to maintain that weak connection all the way until I

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get to

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the next cell.

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And that's no good.

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Instead, like I have drawn here, I can immediately connect to the next closest

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access point.
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access point.

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And I can very seamlessly roam ideally so that the wireless user doesn't even

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notice that

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we've gone from one access point to the other.

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So we do want overlap, however, if we're going to overlap, then we cannot use

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the same

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channels.

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We must use different channels for adjacent cells.

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Now if I have a cell over here, could this be on channel one and this one be on

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channel

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one?

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Absolutely.

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That's a big part of our wireless design is maximizing the channel utilization
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That's a big part of our wireless design is maximizing the channel utilization

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in our

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wireless spaces.

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Because even if I have 25 different 5 gigahertz channels, I might have 50 or

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100 access points,

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I'm going to have to repeat channels at some point.

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Now that said, we have seen that the 5 and the 6 gigahertz spaces, these give

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us a massive

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number of channels.

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And the reality is that we don't need that many channels, specifically 20 mega
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And the reality is that we don't need that many channels, specifically 20 mega

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hertz channels.

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Even if I have 100 access points in the same warehouse or building, they can't

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all see

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each other.

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And so even with 5 and 6 gigahertz, I could start with channel 36 here and go

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to 40 here

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and I could use channel 36 again over on the right.

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So what's the value in having so many of these channels or maybe more

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accurately, could

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I find a better use for these channels, all these channels that I have

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available?
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available?

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And the answer is yes.

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I can actually use a technique known as channel bonding.

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Channel bonding is going to allow me to combine my channels.

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What's the value of that?

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So the value is that I can get greater throughputs.

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Now to understand why this works, think about a situation where maybe I'm

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wanting to fire

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off some model rockets.
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off some model rockets.

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Maybe I'm a model rocket fan.

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We build these little plastic rockets and we want to go to the park and fire

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them off.

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And so maybe my kids get really excited and we create dozens of model rockets

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and we

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want to fire them all off at once.

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I don't know logistically how we do that.

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But we go out to the park and we find this little spot of land.

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It's a pretty busy day.

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There's people over here, people over here.

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But we're able to fire off, I don't know, 4 rockets at once.

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That's pretty cool.

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That was a lot of fun.
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That was a lot of fun.

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We saw 4 rockets go off.

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But we had dozens of rockets.

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So it's going to take a while to fire off all of them for at a time.

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Now imagine that I go on a day where it's not as busy and I'm able to get a

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second plot

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of land here right next to it.

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Well now I can shoot off 8 rockets, assuming the same density.

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So I just fired off twice as much at once using twice as much real estate.

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And as you can imagine, if I could get a third and a fourth plot of land, well

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now I could

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actually do 16 rockets at once and I'm going to be able to burn through all of
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actually do 16 rockets at once and I'm going to be able to burn through all of

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my

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rockets really, really fast.

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Well the channel bonding is very similar because again it comes back to this

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real estate concept.

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So what we're talking about here is taking 120 megahertz channel and combining

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it with an

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adjacent 20 megahertz channel to essentially create a 40 megahertz channel.

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This single 40 megahertz channel is going to be able to send off more wireless
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This single 40 megahertz channel is going to be able to send off more wireless

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signals

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all at once.

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And this, remember, a 20 megahertz channel allows me to take advantage of lots

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of frequencies

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in here.

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I'm sending lots of little communications, what we call subchannels or subcar

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riers within the

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channel.

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So I'm sending lots of signals within a 20 megahertz channel.

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As soon as I add a second to 20 megahertz channel, I'm sending off twice as

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many.

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And as you can imagine, if I combine more together, now we're talking about an
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And as you can imagine, if I combine more together, now we're talking about an

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80 megahertz

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channel.

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And yes, we can actually take this one step further at the time of this video

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and do a 160

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megahertz channel.

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I say at the time of this video because we are going to see 320 megahertz

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channels start

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to show up.

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And that's thanks largely to the fact that we have the 6 gigahertz space.

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So do we just use all 160 megahertz channels these days when we why bother
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So do we just use all 160 megahertz channels these days when we why bother

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using the smaller

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channel size?

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Believe it or not, the answer is no.

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In fact, in most corporate environments, we're probably looking at 40 megahertz

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.

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And these days with the super high density wireless deployments, we actually

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still see

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the use of 20 megahertz channels.

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The downside to these larger channels is we end up getting fewer of those

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channels within

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a non from a non overlapping perspective.

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For example, in the 5 gigahertz space, we said that we had about 25 of these 20
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For example, in the 5 gigahertz space, we said that we had about 25 of these 20

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megahertz

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channels.

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When I combine adjacent channels together, I have a whole lot less of these 40,

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80 and 160

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megahertz channels.

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In fact, I have the ability to only deploy six of the 80 megahertz channels and

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only two

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of the 160 megahertz channels because I can't quite combine all of those 80

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megahertz

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channels together.

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There are a couple that aren't perfectly adjacent to one another.

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And again, they do have to be adjacent.

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Let's insert that in here.

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I'm going to combine adjacent channels, which means they not only have to be
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I'm going to combine adjacent channels, which means they not only have to be

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channels right

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next to each other within the band, but we can't combine channels that exist in

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two different

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bands.

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So can I create a non overlapping design with two channels?

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Absolutely not.

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In fact, it can be challenging to create a decent design that only uses six of

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these.

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Furthermore, if there's a little bit of interference in this space here, notice

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that this 80 and 160

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megahertz channel, these are going to have to wait.

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For whatever this device is to stop communicating for them to be able to
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For whatever this device is to stop communicating for them to be able to

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transmit.

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Whereas the 40 megahertz can transmit any time.

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It makes it a little more agile.

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It can communicate more often.

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So we have to be careful about just assuming that bigger is necessarily better

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when it comes

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to these channels.

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Now worth noting as well from a designation perspective, see a lot of different

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ways of

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designating bonded channels.

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Usually if we're going to bond two channels together, we usually put a plus

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there.

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If I'm going to bond channel 36 with channel 40, for example, I'll say it like
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If I'm going to bond channel 36 with channel 40, for example, I'll say it like

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this.

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You might occasionally see somebody describe this as a channel 38 kind of

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situation, but for

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the most part, it's going to look like this.

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Furthermore, think about the fact that in the 2.4 gigahertz space, if I want to

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combine channels

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1 and 6, that gets me a 40 megahertz channel.

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But what am I going to do with channel 11 over here?

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I mean, that leaves me with 20 megahertz.

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If I wanted to create a 6 plus 11, then I am overlapping on channel 6 as we see
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If I wanted to create a 6 plus 11, then I am overlapping on channel 6 as we see

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.

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So we can't actually use bonded channels effectively in the 2.4 gigahertz space

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.

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Now when it comes to our access points and the capabilities, access points can

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actually

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support multiple radios.

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And this is a very good thing because we have a lot of devices out there that

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support 2.4

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gigahertz.

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We have some of my devices that support 5 gigahertz and a lot of devices that

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will support both.
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will support both.

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And we want to make sure we can communicate with all of these.

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And so I don't want to have to deploy 2.4 gigahertz, access point and a 5 giga

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hertz access

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point.

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Instead, I can deploy an access point that has 2 radios, which now is going to

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have additional

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antennas in all likelihood.

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There are some antennas that can support both.

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But either way, we are transmitting out on 2.4 and 5 gigahertz.

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Furthermore, when we look at Cisco APs, Cisco has some monster access points

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with tons of
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with tons of

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antennas sticking out and internal antennas, external antennas.

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And we can actually find that it supports a 2.4 gigahertz radio and a 5 giga

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hertz radio.

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And another 5 gigahertz radio and a 6 gigahertz radio.

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We say, why does that have 2 5 gigahertz radios?

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Well, to support 2 different channels.

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I could put this on channel 36 and this on channel 40.

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And now that's going to allow me to support more stations and more wireless

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clients because

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I'm servicing essentially 2 overlapping cells that aren't causing interference
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I'm servicing essentially 2 overlapping cells that aren't causing interference

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with one

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another.

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So this is going to be very important for us when it comes to our high density

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wireless

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designs because we're going to want to try to support as many stations as

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possible in

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a relatively confined space and being able to support multiple bands and

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multiple even

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channels on a single access point, whether bonded or unbonded, either way is

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going to be very

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useful to us in those designs.