Instructor: Let's talk about cellular,
because most of us have a smartphone in our pocket
and we use cellular every day to connect
to the wide area network known as the internet.
Now, when we talk about cellular,
this includes not just our smartphones though,
but also our tablets,
dedicated cellular modes for corporate networks
or cellular wireless access points known as hotspots.
There is a wide range of cellular technologies in use,
including 2G, 3G, 4G, LTE, and 5G.
When you hear someone talking about G like 4G or 5G,
they're basically talking about which generation
of cellular technology is being used by a cellular modem
in that smartphone or other device.
Basically, for any of these devices to connect
to a cellular network,
they have to have an embedded cellular modem
that supports one or more of these different technologies
and the associated frequencies for them.
Now, the very first cellular networks we had
which we now call 1G,
were developed all the way back in the 1980s.
These 1G phones communicate using a frequency
of 30 kilohertz and had a bandwidth
of about 2 kilobits per second or 2,000 bits per second.
So we really were pushing a lot of data
over these 1G handsets.
Instead, they were dedicated to providing voice calls
for the most part.
As time went on,
cell phones moved into their second generation
known as 2G during the late 1990s.
2G devices communicate over a GSM network
using the 1,800 megahertz frequency ban.
The big difference here, is that 2G devices
ran over a digital network, they use multiplexing,
and therefore, it was able to start using data
in addition to just providing phone calls.
Now, the data here, wasn't super-fast.
Here in 2G we're talking about speed similar to
a dialup modem.
Usually in the range of 14.4 kilobits per second
to 64 kilobits per second, using GPRS,
which is the General Packet Radio Service.
In fact, when I started my very first company back in 1999,
I had a 2G Motorola flip-phone that I used.
And I was able to tether my laptop to that phone
and dial up to connect to the internet.
And that way, I could email invoices to my clients
once I left their office using this low speed connection.
Now 2G gave us a lot of benefits for cellular devices
even though the speeds here for data were rather limited.
2G devices were the first to have SMS and text messaging,
as well as the ability to do international enrollment,
conference calling, the use of the internet
while away from our computers and other things like this.
The next evolution we had in 2G
was the introduction up EDGE
or the Enhanced Data Rates for GSM Evolution.
This brought our speeds up to about 1 megabit per second
for most modern 2G devices,
like the very first iPhone that was released in 2008.
The third generation of cellular saw the release of 3G
with faster data speeds.
At a minimum, 3G networks must support
144 kilobits per second to be called 3G.
But most devices were faster than that.
And they supported speeds around 384 kilobits per second,
if you're moving in a car
or up to 2 megabits per second
if you're walking or standing still.
To provide these faster speeds,
3G devices used a wider frequency band
with frequencies ranging from 1.6 gigahertz
all the way up to 2 gigahertz within the 3G spectrum,
depending on where you lived in the world.
When it comes to 3G,
there are three different technologies that you might find.
WCDMA, HSPA and HSPA-plus.
WCDMA is the Wideband Code Division Multiple Access
which uses the UMTS standard,
it could reach data speeds up to about
2 megabits per second.
This is the slowest of the 3G technologies.
As an improvement to WCDMA,
there was HSPA or the High Speed Packet Access Standard.
This could reach speeds at up to 14.4 megabits per second.
This is sometimes referred to as 3.5G by the industry.
Then over time, that wasn't fast enough.
So we went to HSPA-plus, High Speed Packet Access Evolution.
This brings us speeds up to about 50 megabits per second
and is often referred to as 3.75G.
Now after that, we got to our fourth generation.
This gave us 4G with even faster speeds
and the introduction of using MIMO,
which is Multiple Input Multiple Output technology.
With 4G, we could get speeds of up to
100 megabits per second
while driving or up to 1 gigabit per second
for fixed stationary size or modems with a large antenna.
4G devices even used a wider frequency band than the others
covering frequencies from 2 to 8 gigahertz
depending on the implementation in a given country.
Now, when 4G first came out it was often called 4G LTE
or 4G Long-term Evolution.
These devices could reach speeds
up to about 100 megabits per second.
Now over time, there is an improved version of LTE
known as LTE-A or LTE Advanced.
This is an advanced version of LTE
that add even more capabilities and increased speeds
of 2 to 3 times of that, of regular LTE
and under perfect conditions
with a stationary cellular modem,
it could get up to speeds of 1 gigabit per second.
Our fifth generation of cellular is called 5G.
And again, it has faster speeds and more capabilities.
5G is actually relatively new
and it just began deployment back in 2019.
5G devices bringing enormous improvement
over previous generations devices.
With 5G, it's possible to reach speeds
up to 10 gigabits per second using high-band 5G frequencies.
Now, this is one of the biggest differences with 5G
over the older generations.
With 5G, we actually split it up
into three different frequency bands.
There's low-band, mid-band and high-band frequencies.
Now low-band frequencies are between 600 and 850 megahertz
and they provide us with speeds
of 30 to 250 megabits per second.
The benefits of using this low-band frequency range
is that it has a longer range
and can cover an area similar in size
to the older 4G networks.
The mid-band frequencies operate between
2.5 and 3.7 gigahertz.
This higher frequency band is going to support
higher data rates of 100 to 900 megabits per second,
but each cellular tower now covers less area
than the low-band or 4G towers could.
As of 2021, most 5G deployments
are actually being done using this mid-frequency towers,
because it provides a good balance of coverage
with those higher speeds.
Now, the third frequency range we have
is known as the high-band frequencies,
and these operate between 25 and 39 gigahertz.
This much higher frequency band
is going to support extremely high speeds
in the gigabit per second range.
Now, the challenge here is that these frequencies
operate in the millimeter waveband
and this causes the range of these towers
to be much, much smaller.
Also, because the smaller millimeter waveband
the signal is easily blocked by walls, windows
and other objects.
For this reason, there is not a lot
of high-band deployments going on quite yet.
So far, we're seeing these deployed near areas
where there's a lot of people expected to be
in one small area, such as the sports stadium,
and amusement park or convention centers.
All right, I just gave you
a lot of facts and figures about cellular
and all the different generations of cellular technology,
and you're probably wondering,
do you need to memorize the speeds and frequencies
for each and every one?
And the answer is no, you don't.
Instead, you need to know that the higher the G such as 4G
is higher than 3G,
this would mean that the newer standard
and it has increased speeds.
It also is important to remember that 5G
comes in three different bands,
low-band, mid-band, and high-band.
As you go upward in the bands, you get faster speeds,
but you decrease your coverage area.
For this reason, most 5G deployments
are going to use that mid-band frequency I spoke about,
leading to better coverage and pretty high speeds.