Our wireless access points are going to get deployed in such a way that they
have this range
around them where their wireless transmissions reach.
Eventually, transmissions get weak enough that they can't be used and so we
sort of have
this boundary around each one of our access points.
These boundaries in this space is known as a wireless cell.
And there are a few important aspects to cells.
First of all, we actually do want wireless overlap here. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
First of all, we actually do want wireless overlap here.
The reason we want overlap is because if I'm a wireless device and I'm walking
this
direction, eventually I'm going to hit this spot where I can't really
communicate to
this access point anymore.
But imagine if the next access point was all the way over here.
Well, I would have to try to maintain that weak connection all the way until I
get to
the next cell.
And that's no good.
Instead, like I have drawn here, I can immediately connect to the next closest
access point. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
access point.
And I can very seamlessly roam ideally so that the wireless user doesn't even
notice that
we've gone from one access point to the other.
So we do want overlap, however, if we're going to overlap, then we cannot use
the same
channels.
We must use different channels for adjacent cells.
Now if I have a cell over here, could this be on channel one and this one be on
channel
one?
Absolutely.
That's a big part of our wireless design is maximizing the channel utilization WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That's a big part of our wireless design is maximizing the channel utilization
in our
wireless spaces.
Because even if I have 25 different 5 gigahertz channels, I might have 50 or
100 access points,
I'm going to have to repeat channels at some point.
Now that said, we have seen that the 5 and the 6 gigahertz spaces, these give
us a massive
number of channels.
And the reality is that we don't need that many channels, specifically 20 mega WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And the reality is that we don't need that many channels, specifically 20 mega
hertz channels.
Even if I have 100 access points in the same warehouse or building, they can't
all see
each other.
And so even with 5 and 6 gigahertz, I could start with channel 36 here and go
to 40 here
and I could use channel 36 again over on the right.
So what's the value in having so many of these channels or maybe more
accurately, could
I find a better use for these channels, all these channels that I have
available? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
available?
And the answer is yes.
I can actually use a technique known as channel bonding.
Channel bonding is going to allow me to combine my channels.
What's the value of that?
So the value is that I can get greater throughputs.
Now to understand why this works, think about a situation where maybe I'm
wanting to fire
off some model rockets. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
off some model rockets.
Maybe I'm a model rocket fan.
We build these little plastic rockets and we want to go to the park and fire
them off.
And so maybe my kids get really excited and we create dozens of model rockets
and we
want to fire them all off at once.
I don't know logistically how we do that.
But we go out to the park and we find this little spot of land.
It's a pretty busy day.
There's people over here, people over here.
But we're able to fire off, I don't know, 4 rockets at once.
That's pretty cool.
That was a lot of fun. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
That was a lot of fun.
We saw 4 rockets go off.
But we had dozens of rockets.
So it's going to take a while to fire off all of them for at a time.
Now imagine that I go on a day where it's not as busy and I'm able to get a
second plot
of land here right next to it.
Well now I can shoot off 8 rockets, assuming the same density.
So I just fired off twice as much at once using twice as much real estate.
And as you can imagine, if I could get a third and a fourth plot of land, well
now I could
actually do 16 rockets at once and I'm going to be able to burn through all of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
actually do 16 rockets at once and I'm going to be able to burn through all of
my
rockets really, really fast.
Well the channel bonding is very similar because again it comes back to this
real estate concept.
So what we're talking about here is taking 120 megahertz channel and combining
it with an
adjacent 20 megahertz channel to essentially create a 40 megahertz channel.
This single 40 megahertz channel is going to be able to send off more wireless WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This single 40 megahertz channel is going to be able to send off more wireless
signals
all at once.
And this, remember, a 20 megahertz channel allows me to take advantage of lots
of frequencies
in here.
I'm sending lots of little communications, what we call subchannels or subcar
riers within the
channel.
So I'm sending lots of signals within a 20 megahertz channel.
As soon as I add a second to 20 megahertz channel, I'm sending off twice as
many.
And as you can imagine, if I combine more together, now we're talking about an WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And as you can imagine, if I combine more together, now we're talking about an
80 megahertz
channel.
And yes, we can actually take this one step further at the time of this video
and do a 160
megahertz channel.
I say at the time of this video because we are going to see 320 megahertz
channels start
to show up.
And that's thanks largely to the fact that we have the 6 gigahertz space.
So do we just use all 160 megahertz channels these days when we why bother WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So do we just use all 160 megahertz channels these days when we why bother
using the smaller
channel size?
Believe it or not, the answer is no.
In fact, in most corporate environments, we're probably looking at 40 megahertz
.
And these days with the super high density wireless deployments, we actually
still see
the use of 20 megahertz channels.
The downside to these larger channels is we end up getting fewer of those
channels within
a non from a non overlapping perspective.
For example, in the 5 gigahertz space, we said that we had about 25 of these 20 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For example, in the 5 gigahertz space, we said that we had about 25 of these 20
megahertz
channels.
When I combine adjacent channels together, I have a whole lot less of these 40,
80 and 160
megahertz channels.
In fact, I have the ability to only deploy six of the 80 megahertz channels and
only two
of the 160 megahertz channels because I can't quite combine all of those 80
megahertz
channels together.
There are a couple that aren't perfectly adjacent to one another.
And again, they do have to be adjacent.
Let's insert that in here.
I'm going to combine adjacent channels, which means they not only have to be WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'm going to combine adjacent channels, which means they not only have to be
channels right
next to each other within the band, but we can't combine channels that exist in
two different
bands.
So can I create a non overlapping design with two channels?
Absolutely not.
In fact, it can be challenging to create a decent design that only uses six of
these.
Furthermore, if there's a little bit of interference in this space here, notice
that this 80 and 160
megahertz channel, these are going to have to wait.
For whatever this device is to stop communicating for them to be able to WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For whatever this device is to stop communicating for them to be able to
transmit.
Whereas the 40 megahertz can transmit any time.
It makes it a little more agile.
It can communicate more often.
So we have to be careful about just assuming that bigger is necessarily better
when it comes
to these channels.
Now worth noting as well from a designation perspective, see a lot of different
ways of
designating bonded channels.
Usually if we're going to bond two channels together, we usually put a plus
there.
If I'm going to bond channel 36 with channel 40, for example, I'll say it like WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
If I'm going to bond channel 36 with channel 40, for example, I'll say it like
this.
You might occasionally see somebody describe this as a channel 38 kind of
situation, but for
the most part, it's going to look like this.
Furthermore, think about the fact that in the 2.4 gigahertz space, if I want to
combine channels
1 and 6, that gets me a 40 megahertz channel.
But what am I going to do with channel 11 over here?
I mean, that leaves me with 20 megahertz.
If I wanted to create a 6 plus 11, then I am overlapping on channel 6 as we see WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
If I wanted to create a 6 plus 11, then I am overlapping on channel 6 as we see
.
So we can't actually use bonded channels effectively in the 2.4 gigahertz space
.
Now when it comes to our access points and the capabilities, access points can
actually
support multiple radios.
And this is a very good thing because we have a lot of devices out there that
support 2.4
gigahertz.
We have some of my devices that support 5 gigahertz and a lot of devices that
will support both. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
will support both.
And we want to make sure we can communicate with all of these.
And so I don't want to have to deploy 2.4 gigahertz, access point and a 5 giga
hertz access
point.
Instead, I can deploy an access point that has 2 radios, which now is going to
have additional
antennas in all likelihood.
There are some antennas that can support both.
But either way, we are transmitting out on 2.4 and 5 gigahertz.
Furthermore, when we look at Cisco APs, Cisco has some monster access points
with tons of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
with tons of
antennas sticking out and internal antennas, external antennas.
And we can actually find that it supports a 2.4 gigahertz radio and a 5 giga
hertz radio.
And another 5 gigahertz radio and a 6 gigahertz radio.
We say, why does that have 2 5 gigahertz radios?
Well, to support 2 different channels.
I could put this on channel 36 and this on channel 40.
And now that's going to allow me to support more stations and more wireless
clients because
I'm servicing essentially 2 overlapping cells that aren't causing interference WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'm servicing essentially 2 overlapping cells that aren't causing interference
with one
another.
So this is going to be very important for us when it comes to our high density
wireless
designs because we're going to want to try to support as many stations as
possible in
a relatively confined space and being able to support multiple bands and
multiple even
channels on a single access point, whether bonded or unbonded, either way is
going to be very
useful to us in those designs.