When it comes to wireless communications, we can have all kinds of different
wireless devices
out there that have nothing to do with networking.
For example, we might have wireless TV remotes.
We have wireless video game controllers.
We even have things like Bluetooth that maybe sounds like it's wireless
networking, but
yeah, it's for transmitting data, but all of these things transmit data.
So when we're talking about actual wireless networking, we are going to use a
phrase that
we refer to as Wi-Fi. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we refer to as Wi-Fi.
Wi-Fi, it looks like an abbreviation, but believe it or not, it stands for
absolutely
nothing.
It was named in an era where we had this concept of audio called "hi-fi," which
stood
for "hi-fidelity," but when the organization now known as the Wi-Fi Alliance
created this
term, they didn't say, "Hey, it stands for wireless fidelity."
They just wanted it to be a marketable term, and that's what they came up with,
and it worked
as what we all used today.
Now the Wi-Fi Alliance builds the concept of Wi-Fi as a way of making a set of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now the Wi-Fi Alliance builds the concept of Wi-Fi as a way of making a set of
standards
for us to follow.
So they do standards testing, for example.
So if I have a Wi-Fi device, that means that I can communicate with other Wi-Fi
devices.
These days, we actually have numbers associated with it, for example.
As of the moment of this recording, the most recent version of Wi-Fi is Wi-Fi 6
, and kind
of this Wi-Fi 6E, which gives us access to additional frequencies for WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
of this Wi-Fi 6E, which gives us access to additional frequencies for
communication.
We also have Wi-Fi 4 and Wi-Fi 5 that came before it, and then we have old
legacy versions
of Wi-Fi as well.
But either way, this Wi-Fi standards-based testing is not itself the definition
of the
technology.
The definition of the technology is created by the IEEE, which creates our
Ethernet standards,
802.3 and all of these, and they created wireless Ethernet as the 802.11 spec. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
802.3 and all of these, and they created wireless Ethernet as the 802.11 spec.
And so we see 802.11 as the original definition of Wi-Fi networking, and then
from there we see
additional letters being added.
For example, they had 802.11 A and 802.11 B and G and AC and AX, and all these
letters and
numbers combining together is why we really prefer to just use the term Wi-Fi 6
, for example,
or Wi-Fi 5.
And when Wi-Fi 7 comes out, which is possibly out by the time you watch this, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And when Wi-Fi 7 comes out, which is possibly out by the time you watch this,
it's going
to be based on another 802.11 specification.
Now any wireless communication is going to need to choose which frequencies
that we're
going to transmit on.
So frequencies for transmission, which is usually abbreviated as TX like this,
we're going
to need to decide what frequencies to transmit on.
For example, if I have an access point and I have a wireless device here, if WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For example, if I have an access point and I have a wireless device here, if
one is speaking
a really high frequency and one is speaking a very low frequency, they can't
communicate
with one another.
They have to perfectly match the frequencies that they want to communicate on,
otherwise
they're not going to be able to hear the other person speak.
And so we have to match those frequencies, we have to decide which frequencies
we're
going to use.
And again, every wireless form of communication gets to choose which
frequencies to use, and
there are many that are available to choose from.
From a Wi-Fi perspective, we have three primary bands that are a range or a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
From a Wi-Fi perspective, we have three primary bands that are a range or a
collection of frequencies.
We have the 2.4 GHz band, and so these are our bands that we're listing out
here.
We have the 2.4 GHz band.
We have the 5 GHz band, actually let's write it down here, 5 GHz, and we have
the 6 GHz
band.
This is brand new, when I mentioned Wi-Fi 6E, that is the first time we ever WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This is brand new, when I mentioned Wi-Fi 6E, that is the first time we ever
had access
to the 6 GHz band.
Now the 2.4 GHz band, this was the original band, it was very, very small and
didn't give
us many frequencies to be able to use.
The 5 GHz band expanded on this, so we have lots of bands, but it's also very
busy, it's
borrowing a lot of frequencies that are supposed to be reserved for other
purposes.
And so it can be a little bit complicated as far as which channels we can use, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so it can be a little bit complicated as far as which channels we can use,
and that's
going to vary by region.
The 6 GHz is not only lots, and I mean lots of frequency real estate, but it
also is very
free.
It had been reserved, nothing else had been using it before Wi-Fi was allowed
to use this
space.
And so yes, we do have to decide, and this happens on a per country and per
region basis,
but ultimately when frequencies are opened up for use, that means that we can WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
but ultimately when frequencies are opened up for use, that means that we can
now use them
and otherwise they're typically reserved.
In fact, because 2.4 GHz was one of the very first sets of frequencies that was
opened
up, when I say that it was the original frequency, that's great, but it was
also very, very
busy.
Lots and lots of devices out there that are non-Wi-Fi, meaning microwaves and
what I said
about earlier about wireless TV remotes and wireless video game controllers, a WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
lot of those
will use 2.4 GHz because hey, it was around back then.
And so that's going to make it a lot more difficult for Wi-Fi to coexist with
those types of
devices.
Now we can start to think of frequencies as sort of this wireless real estate.
I really like to think of it this way, because if I, for example, want to build
a home,
I might have 3 different plots of land that are available.
And I might go out and say, "Hey, I want this plot of land. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And I might go out and say, "Hey, I want this plot of land.
I want to use this plot of land."
Except guess what?
Somebody already has a house on that lot, meaning that that's already been
claimed.
I can't build a house on that same plot of land.
So I can't actually use that, but I could use one of these two.
And so I go out and I choose this and I build my house here.
And if somebody else shows up in the same space and wants to build a house
right here, well,
they're going to have to choose the last available spot. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
they're going to have to choose the last available spot.
And so they will have to build over here.
Well, frequencies the same way.
If I have 3 devices all here trying to communicate with maybe another device up
here on their
own, you know, that is all in the same physical space.
Maybe these are all in the same room.
Well, I might choose one frequency.
Let's just call it frequency one here to communicate up to this device.
Well, when this one shows up or these two show up to communicate, if they try
to communicate
on the same frequency, it's going to cause a lot of problems. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
on the same frequency, it's going to cause a lot of problems.
And that's a Roman numeral one, by the way, not a capital I.
I'm trying to count here.
So frequency one is already claimed.
So I'm going to have to use frequency two.
And that's going to have to be a different frequency.
Maybe it's a much lower frequency than frequency one.
And then same thing over here when this set shows up, if they want to be able
to communicate
freely with one another, they're going to have to choose another frequency,
which maybe
is a much higher frequency communication. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
is a much higher frequency communication.
In one physical area, once a frequency has been claimed, we really have to be
careful
about trying to use or share that.
It's usually best if we just find a new frequency that we can use because again
, each frequency
is itself the concept of real estate.
Now we can expand this further to look at the fact that when we're
communicating, when
I do a transmission and a reception, I could use a single frequency if I wanted WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I do a transmission and a reception, I could use a single frequency if I wanted
to.
I could communicate between these two devices, pick one frequency and just
transmit all of
my information on the one frequency.
The problem is that there's usually other devices around that are communicating
what happens
if these two devices are using the exact same frequency.
Well, as we're going to explore later, if we have the same frequency in the
same space,
this is going to cause problems.
This is called wireless interference. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This is called wireless interference.
And we've all, as engineers in the networking space, probably talked about or
heard of wireless
interference.
A lot of us have experienced it, sometimes even in our own houses, that we have
wireless
devices interfering with one another, and that's the same concept.
So usually, instead of saying, "Hey, we're going to use a single frequency," we
want to
use instead many frequencies.
So we're not going to use a single frequency. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we're not going to use a single frequency.
We're actually going to use many frequencies at once and spread our
communications across
those different frequencies.
So if I have a device here and a device here, I'm going to send one signal that
uses a very
high frequency, one signal that uses a lower frequency, another one that uses a
very low
frequency.
And because of wireless techniques like OFDM or DSSS, lots of these techniques
exist, I
can actually send all of these at once. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
can actually send all of these at once.
And then this wireless device that receives this will split the signals back
out and say,
"Okay, this signal represented a zero one, this signal represented a zero zero,
and this
one represented a, well, not a zero zero, but a one one or something like that,
and then
I can combine this into the data that you had sent to me."
Meanwhile, if I hit some level of interference in here, that took out, let's
say this middle WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
say this middle
one.
Well, now I don't have the zero zero, but usually I can use some wireless
techniques to
sort of reestablish what was sent there.
Again, much deeper into the wireless world than we have time to get into and
well beyond
the scope of this course, but at the same time, understand that we can actually
repair
the information, and this is why we spread our communications across multiple
frequencies
is to ensure that if we have a little bit of interference, that we don't lose WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
is to ensure that if we have a little bit of interference, that we don't lose
the entire
signal.
So this is where the concept of channels come into play.
A channel is a range of frequencies.
So essentially, I'm going to take my band, let's say this is the 2.4 GHz band,
and I can
draw out this frequency range.
This frequency range starts at about 2.4 GHz and ends at about 2.5 GHz. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
This frequency range starts at about 2.4 GHz and ends at about 2.5 GHz.
In the middle here, we have these channels, and the channel is itself a range.
For example, this group of channels here is part of channel one.
And then we have another group of channels here, or group of frequencies called
channel
two.
And you might notice, well, wait a second, they overlap all of these
frequencies in here,
and that is actually true.
So we probably are going to want to look at whatever channel, if I say, well, WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we probably are going to want to look at whatever channel, if I say, well,
this is channel
three, and this is channel four.
Eventually, we're going to get to a channel that starts here and ends over here
.
And in the 2.4 GHz space, that would be channel six.
And the last channel over here is channel 11, giving us in the 2.4 GHz space,
three non-overlapping
channels.
And as you might imagine, these non-overlapping channels are going to be the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And as you might imagine, these non-overlapping channels are going to be the
ones that we want
to use for wireless communications, because if I put a wireless communicator
here, and,
you know, maybe two devices like this and two devices like this, and they're in
the same
physical space, and I'm on channel one here and channel two here, there's a lot
of overlap
of these individual signals in here.
And as a result, there's going to be a lot of interference when they're trying
to communicate
with one another.
So we like to choose the non-overlapping channels. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we like to choose the non-overlapping channels.
Now each one of these channels represents roughly 20 MHz.
And I say roughly because 2.4 GHz bands a little weird, it uses 22 MHz.
The other bands use 20.
And so just from an estimate perspective, it's about a 20 MHz channel.
And as we see here, if we do some math 2.4 to 2.5 GHz gives us about 100 MHz,
we don't
get all of that space.
And so, you know, out of the 100 is actually a significant chunk of that space. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so, you know, out of the 100 is actually a significant chunk of that space.
And so we actually end closer to 2480.
We also have some, you know, channels that we can't use in there.
And so for the most part, this is why we see that we've got three of these 20 M
Hz channels.
Again, there are 22 MHz in this space, which is where we lose some amount of
that as well.
If there are truly 20 MHz, maybe we could have squeezed a 5th non-overlapping
in there.
But this is why I again come back to this concept of real estate.
These plots of land right here, I can kind of see them here with these channels WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
These plots of land right here, I can kind of see them here with these channels
.
Each one of these channels is a plot of land.
It's wireless real estate.
If I deploy an access point here on channel 1, it's claiming all of channel 1
in that same
physical space.
So I could deploy another access point here that communicates here, but look at
all the
overlap.
Well, okay, so from a wireless perspective, I need to choose a channel that isn
't going
to cause interference. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
to cause interference.
And so maybe I'll choose channel 6 for this access point.
I'm building my house on a completely different plot of land, even though I'm
in the
same physical space.
So this is where the analogy breaks down because real estate is a physical
concept, whereas
this is a radio frequency concept that helps us describe what's happening in
the same
physical space.
So as we see, we don't get a lot of these 20 MHz channels out of the 2.4 GHz
band.
What's going on with 5 GHz and 6 GHz? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
What's going on with 5 GHz and 6 GHz?
Well with 5 GHz, notice we don't have a point in here.
We're not saying 5.1 GHz or anything like this.
We have a lot of real estate inside of the 5 GHz space, but even that said, we
don't get
all of it.
I mentioned there's a lot going on in there.
We get roughly half of it, so we can estimate about 500 MHz of that that we get
.
And if we do some quick math there, 500 divided by the 20, and we get about 25 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And if we do some quick math there, 500 divided by the 20, and we get about 25
channels.
Which is way more than the 3 that we get with our 2.4 GHz space.
And yet we say it's about 25 because depending on where you live in the world,
maybe you'll
get 25, maybe you'll get 20, maybe you'll get 16.
It just depends on the regional authorities and which channels have been made
available
for Wi-Fi use.
The 6 GHz space on the other hand is very large and relatively unused.
And we actually get up to 59 of these 20 MHz channels inside of the 6 GHz space WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And we actually get up to 59 of these 20 MHz channels inside of the 6 GHz space
.
It's an absolutely massive space.
It's like breaking new ground, discovering new land in the wireless world.
And it's been absolutely huge what we're capable of doing with this 6 GHz space
.
It's just a matter of making sure our wireless devices can actually communicate
at 6 GHz.
For right now, most of our devices are going to be communicating either on 2.4 WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
For right now, most of our devices are going to be communicating either on 2.4
GHz or 5 GHz.
But as we see more and more devices adopting 6 GHz, we're going to have a lot
more freedom
to be able to deploy the wireless networks that we want because we're not
limited as much
by our channel space.