When we talk about using a wireless network today,
we're often talking about one that
is the IEEE LAN/MAN Standard from the 802.11 Standards
Committee.
This committee is in charge of maintaining
all of the standards for wireless communication
on our local area networks, and they
create new versions of these standards all the time.
If you see the trademark that says Wi-Fi,
we are referring specifically to these 802.11 standards,
and the Wi-Fi Alliance is a group
that handles the interoperability testing
for all of the devices that need to connect to an 802.11
network.
In October of 1999, the very first 802.11 standards
were released.
We released 802.11a and 802.11b.
The 802.11a standard operates in the 5 GHz range, although,
in special situations, there are other frequencies that
you're able to use.
But the vast majority of 802.11a will always be at 5 GHz.
This 802.11a standard operates at 54 megabits per second,
which was quite a bit more than the 802.11b standard that was
released at the same time.
802.11b is a different standard operating at 2.4 GHz.
And a good rule of thumb is that if something
is operating at 2.4 GHz, and you compare that
to something operating at 5 GHz, that you
can calculate about one-third the range of these 2.4 GHz
technologies.
This is obviously a rule of thumb,
because there are so many different variables involved
in determining what the range of a wireless network might be.
And in the case of 802.11a, we don't commonly see this
standard in use on today's networks.
Also, in October of 1999, the 802.11b standard was released
effectively at the same time.
This standard, though, operates at 2.4 GHz,
and it operates at a speed of 11 megabits per second.
Obviously, much slower than the 54 megabits per second seen
with 802.11a.
But because this operates at 2.4 GHz,
those frequencies tend to bounce off of other objects that may
be around us, which is a bit different than 802.11a,
where those objects tend to absorb those higher
frequencies.
Unfortunately, there are more devices using these 2.4 GHz
range frequencies.
Things like baby monitors, cordless phones,
microwave ovens, and Bluetooth all use frequencies
within the 2.4 GHz range.
Obviously, the 802.11a and 802.11b standards are
relatively old, being released in October of 1999.
So you don't commonly see those two standards operating today.
In June, 2003 the IEEE introduced a new version
of 802.11 called 802.11g.
This is effectively an upgrade to 802.11b.
It operates in the 2.4 GHz range, just like 802.11b,
but it operates at a higher speed--
54 megabits per second, effectively matching the same
speed as 802.11a.
This is also backwards compatible with 802.11b.
So many 802.11g access points allow you to set
a compatibility mode where both B and G devices can connect
to that same access point.
Unfortunately, at 2.4 GHz, you have those same problems
with a limited amount of frequencies that are available,
and a large number of devices that want
to use those same frequencies.
In October of 2009, the IEEE introduced a new standard
called 802.11n.
We are retroactively referring to this as Wi-Fi 4.
This inversion is an update to 802.11g, 802.11b, and 802.11a.
And unlike the previous standards,
you're able to use 802.11n in either 2.4 GHz frequencies,
or 5 GHz frequencies.
And you can use larger channel widths
to be able to transfer more data at one time.
Because of that, we're able to get maximum throughputs of this
802.11n to range around 600 megabits per second,
if you're using that 40 MHz mode,
and you're using four separate antennas on your access point,
and the remote device.
This 802.11n also introduces a new technology called MIMO that
stands for multiple input, multiple output.
With MIMO, we can increase the number of transmit
and receive antennas to be able to send
more information across the wireless network
at the same time.
In January of 2014, the IEEE introduced 802.11ac,
or what we are now calling Wi-Fi 5.
This added a number of improvements over 802.11n,
the first being that it operated exclusively in the 5 GHz range.
There are many more frequencies available
in the 5 GHz range, which means it's much less crowded,
and there's less interference that you
would have to deal with.
There's also much larger bandwidths that you can use
in this range, and 802.11ac can use up to 160 MHz of channel
bandwidth.
The 802.11ac standard also allows for bonding of channels,
which means you can transmit much more data across
the wireless network.
There's also a denser signal modulation,
which really means that we're able to send
much more information over a shorter amount of time.
And 802.11ac, we introduced a new type of MIMO called
a multi-user MIMO, and you can have up to eight multi-user
MIMO downlink streams in 802.11ac.
This is twice as many streams as we saw previously in 802.11n,
and it increased the total possible throughput
for an 802.11ac network to around seven gigabits per
second.
In February of 2021, the IEEE introduced 802.11ax,
or what we are calling Wi-Fi 6.
This is the successor to 802.11ac.
It operates at both 5 GHz and 4 GHz channel ranges,
and it can use channel widths ranging between 20
MHz, all the way up to 160 MHz.
And 802.11ax, you can have 1.2 gigabits per second per
channel, which seems to be a relatively small increase
in throughput until you realize that this is a bidirectional
speed, because of the new signaling available
in 802.11ax, and you can now have eight bi-directional
multi-user MIMO streams providing much more throughput
for the wireless network.
This version of wireless technology
is designed for high-density environments,
and it uses a new signaling type.
It's able to send this information very efficiently
to a large number of people at the same time.
This is referred to OFDMA, or the Orthogonal Frequency
Division Multiple Access.
This is very similar to the signaling
you might see with a cellular communication
where you're communicating to many hundreds of devices
all from one single antenna, allowing for a very
high-density communication.
Here's our summary of those six standards you need to know.
The 802.11a is a 5 GHz technology,
does not use any type of multiple input multiple output,
and has a maximum theoretical throughput of 54 megabits per
second.
802.11b operates at 2.4 GHz.
Also, does not use MIMO, and has a maximum throughput
of 11 megabits per second.
802.11g is also a 2.4 GHz technology,
does not have any type of multiple input multiple output,
and operates at 54 megabits per second.
802.11n can operate on either 5 GHz or 2.4 GHz frequencies,
and can use multiple input multiple output with four
separate streams.
The maximum theoretical throughput for a single stream
would be around 150 megabits per second,
making the total throughput for 802.11n to be 600 megabits per
second.
802.11ac operates in the 5 GHz frequency band.
It allows for multi-user MIMO when
you're downloading information using a maximum of eight MIMO
streams.
Each one of those streams can operate at roughly 867 megabits
per second, making the total maximum theoretical throughput
on 802.11ac to be 6.9 gigabits per second.
802.11ax operates in either the 5 GHz or 2.4 GHz range,
and supports bi-directional MIMO that's in both download
and upload multi-user MIMO over eight total streams.
Each one of those streams can support roughly 1,200 megabits
per second, with a total maximum theoretical throughput
of 9.6 gigabits per second.