Internet Architecture
Lecture 8:
How Wireless Connections and
WiFi Work
Assistant Teacher Samraa Adnan Al-Asadi
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Introduction
The wired world created a revolution of allowing people to
connect to the Internet. Now the unwired world the ability to connect to
the Internet wirelessly is bringing just as big a change.
The most popular way of connecting to the Internet wirelessly
is via a family of technologies called 802.11 or WiFi. There are several
different standards for 802.11, and they connect at different speeds,
including 802.11b standard, which operates in the 2.4GHz spectrum
and transfers data at a maximum rate of 11Mbps; the 802.11a standard,
which operates in the 5GHz spectrum at 54Mbps; and the 802.11g
standard, which operates in the 2.4GHz spectrum and transfers data at a
maximum rate of 54Mbps. In addition, there are other emerging
standards that transfer data at much higher rates, such as the 802.11n,
which will transfer data at rates approximately ten times faster than
802.11g.
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Introduction
To connect to the Internet this way, an 802.11 card
needs to be used in a computing device such as a laptop or
palmtop computer, and it needs to connect to a nearby
compatible wireless access point, most often called a
router. These routers can be in a home or business.
Increasingly there are also public access points, called hot
spots, which allow you to connect to the Internet from
public places such as coffee shops, hotels, and airports.
One problem with WiFi networks is that they can
be vulnerable to snoopers and hackers, who can use a
technique called war driving to get into the network.
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Introduction
There are a variety of other ways to connect
wirelessly to the Internet as well, for example by using a
satellite connection.
Satellite-access systems require that you use a
modem. The modem is used to request information from
the Internet, so when you send information through the
Internet, it goes at normal modem speeds. However, that
requested information is sent back to you at the high
satellite transmission speeds, not the slower modem
speeds. However, this means that if you're sending email,
or transferring a file to someone via FTP, that information
is sent at modem speeds, not satellite speeds.
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Introduction
When you access the Internet via satellite, you still use
a traditional PC. However, you can also get onto the Web in
other ways using new types of digital devices, most notably
palmtop devices. These little computers, sometimes called
personal digital assistants (PDAs) can literally put the Web in
the palm of your hand. You connect a modem to them and can
then get onto the Internet and send and receive email and
browse the Web with them, although as explained earlier, you
can also use them to access the Internet using WiFi technology.
An emerging technology may be the most revolutionary
wireless technology of all WiMax blankets an entire
metropolitan area with high-speed Internet access, and so
wherever you are, you can be connected to the Internet.
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How to Access the Internet via a
Satellite Connection
1* Accessing the Internet via a satellite connection
delivers information to your computer at much higher
speeds than do normal modems at 400 Kbps. To use it,
you need a satellite dish on your home in the same way
that you need a satellite dish to get satellite TV.
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How to Access the Internet via a
Satellite Connection
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How to Access the Internet via a
Satellite Connection
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How to Access the Internet via a
Satellite Connection
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How to Access the Internet via a
Satellite Connection
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How Cell Phones Access the Internet
1* The main way cellular telephones access the Internet
is through a protocol called the Wireless Access Protocol
(WAP) and its associated markup language, the Wireless
Markup Language (WML). To use WAP to access a web
page with a cellular telephone, you first need to make a
cellular phone call. When you dial a cell phone, it looks
for the nearest cellular antenna, called a base station, to
transmit the call. The phone scans nearby base stations
and locks on one that is either the closest or has the most
powerful signal.
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How Cell Phones Access the Internet
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How Cell Phones Access the Internet
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How Cell Phones Access the Internet
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How Cell Phones Access the Internet
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How Cell Phones Access the Internet
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How Cell Phones Access the Internet
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How Bluetooth Works
1* Bluetooth is a wireless technology that allows
computers, telephones, personal data assistants (PDAs),
and even home devices such as stereos and TVs to
communicate with one another. Each Bluetooth device
has a microchip embedded in it that can send and
receive radio signals. It can send both data and voice.
The radio signals are sent and received in the 2.4GHz
radio band, often referred to as the industrial, scientific,
and medical (ISM) band. Inside the chip is software
called a link controller that does the actual work of
identifying other Bluetooth devices and sending and
receiving data.
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How Bluetooth Works
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How Bluetooth Works
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How Bluetooth Works
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How Bluetooth Works
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How Bluetooth Works
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How Bluetooth Works
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Glossary
War Driving: A technique for finding WiFi networks
and attempting to access them.
Hot Spot: A public wireless access point that allows
people to connect to the Internet using WiFi technology.
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Thank you
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