【Lynda高精度字幕由CGSUB.COM独家发布】 - When it comes to internet connectivity,
you really only have two choices.
Now, those two choices are called
good old Cellular WANs and WiMax.
Now, these are two fairly similar technologies
in that both of these technologies use the same cell towers
for both of their access points,
in essence, if you wanna call it that.
Now, what's interesting here is that,
well, start with WiMax because he's kind of cool.
WiMax is a extension of the good old Wi-Fi networks
that we see all over the place, the 802.11 Standard.
Wi-Fi is based on the 802.16 Standard
which instead of having a few hundred feet of range,
this has a range,
well, cell towers are in essence about 35 miles apart,
and so this has a range around a little over 17 miles.
What makes these nice is that
we're not leaning on towers being all over the place,
we can just use the existing cell phone towers
and we can install our wireless access points
onto these towers and get WiMax.
WiMax is pretty good.
It runs fairly quickly in the
multiple megabits per second.
The downside to it is like any wireless technology,
it's susceptible to where you actually place this box
and all those types of things.
The thing that's kind of cool about this though
is that this particular company, Clear Communications,
provides these boxes to you,
you take this box and put it in your house,
you plug it in,
and if you want to you can actually connect, I believe,
right, you can see there's an RJ45 connection there.
But what's actually kind of cool about these
is that not only do they let you plug in
but they also act as a little Wi-Fi network.
It sends and receives, on the internet,
on the 802.16 Standard,
but then it'll actually become a little hotspot.
And using regular old Wi-Fi wireless,
everybody can connect to it
and can get on the internet that way.
So, that is WiMax.
It's pretty good, it's been around for a while.
It's never had quite the penetration that the
WiMax folks would like
but it's certainly out there and it's pretty fast.
The alternative WiMax is good old Cellular WANs.
The thing you need to appreciate about cell phones
is that this entire technology
was developed only to carry voice, not data.
Over the years,
there have been a number of data-carrying standards
that have come up to try to take this technology
and start letting it send data.
It's very complicated so to make life easier,
the cell companies came up with these terms called
first generation, second generation and such
and they would say "1G, 2G, 3G,"
and right now we're in a 4G world.
These are just marketing terms so they're highly imperfect.
In fact, you'll even see things like
"This is 2.5G" and stuff like that.
The bottom line is, for the Network+,
there's really only two types
of data transfer technologies you need to be aware of.
The first one is called HSPA.
HSPA runs in the single megabit per second kind of range
and it would be considered a 3G technology
but it's been improved and now we have an HSPA+
which is running in the multiple megabits per second range
and it's considered a 4G technology.
What's interesting is that
a new technology, it's only been around now,
it came out in around 2009 so it's just been a few years,
called LTE is now coming predominant.
LTE runs in the tens of megabits per second range
and most the time when you see people touting 4G technology,
they're talking about LTE.
Now, the nice thing is that if you're gonna run these,
first of all, you're gonna have some kind of device.
For WiMax, you invariably have some kind of box like this
or a lot of times you'll see a little USB connector
that you can plug into a laptop.
They always think in terms of mobility
with wireless technologies.
Now, with a cell phone,
things are gonna be a little bit different,
and we tend to use the word tethering.
When we're tethering, what we're doing is we're
taking the signal that's coming in and out of our cell phone
and then we're connecting to other devices
and sharing that connection.
There's really two ways to do a tether.
The more old school way is for me to take my device,
turn tethering on and then I'll usually plug something in
and run it into my laptop or whatever it might be.
Another way we're seeing it done more and more today
is wireless.
And in that case, it's kinda like that WiMax device in that
it's connecting through the cellular WAN on this side
but on the same token, it turns your phone into a
wireless hotspot
and allows people to connect to your phone
via a wireless network.
The important thing I need you to appreciate
for the Net+ Exam
is number one, WiMAx is on the 802.16 Standard,
whereas, cell phones have a huge plethora of standards
and they hide it under these "G" terms
to make your life easier.
There are hundreds of standards for cell phones
but for the Network+, just remember two,
HSPA er HSPA+
and LTE.
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