11-04-2013, 02:50 PM
WiFi Networking
WiFi Networking.ppt (Size: 509.5 KB / Downloads: 170)
WiFi
WiFi is the wireless way to handle networking.
It is also known as 802.11 networking.
The big advantage of WiFi is its simplicity.
You can connect computers anywhere in your home or office without the need for wires. The computers connect to the network using radio signals, and computers can be up to 100 feet or so apart.
Outline for Today
The next slides, we will discuss the basic technology that makes WiFi networking possible.
Then we will discuss the hardware you need to create a WiFi network, and help you understand how to set up and access a WiFi hotspot in your home.
Finally, we will look at a demonstration by Dimitri Demergis.
Wireless Networking Standards
WiFi refers to the protocols that allow wireless networking.
These protocols are codified in standards.
Standards are mutually agreed upon rules adopted by the industry on how the wireless networks operate.
There are several standards that enable wireless local area networks (WLANs).
802.11 Suite
Since then, several new extensions have been added to the core 802.11 protocols.
The most relevant of these additions are: 802.11a, 802.11b, and 802.11g.
Next time, we will look at this core protocol (802.11) and these three expansions in more detail.
Walkie-Talkie Network
If you want to understand wireless networking at its simplest level, think about a pair of $5 walkie-talkies that you might purchase at Wal-Mart.
These are small radios that can transmit and receive radio signals.
Recall, when you talk into a Walkie-Talkie, your voice is picked up by a microphone, encoded onto a radio frequency and transmitted with the antenna.
Another walkie-talkie can receive the transmission with its antenna, decode your voice from the radio signal and drive a speaker.
Simple walkie-talkies like this transmit at a signal strength of about 0.25 watts, and they can transmit about 500 to 1,000 feet.
We wish to consider how these walkie-talkies can be used to communicate between the two computers.
WiFi’s Radio Technology
The radios used in WiFi are not so different from the radios used in $5 walkie-talkies.
They have the ability to transmit and receive.
They have the ability to convert 1s and 0s into radio waves and then back into 1s and 0s.
There are major differences, of course.
802.11b, 802.11a, and 802.11g
802.11b was first to reach the marketplace. It is the slowest and least expensive of the three. 802.11b transmits at 2.4 GHz and go up to 11 Mbps.
802.11a was next. It operates at 5 GHz and can handle up to 54 Mbps.
802.11g is a mix of both worlds. It operates at 2.4Ghz (giving it the cost advantage of 802.11b) but it has the 54 megabits per second speed of 802.11a. It is also backward compatible to 802.11b.
Most WiFi cards nowadays are capable of all three of these radio technologies.
Adding WiFi to Your Computer
One of the best things about WiFi is how simple it is.
Many new laptops already come with a WiFi card built in -- in many cases you don't have to do anything to start using WiFi.
It is also easy to add a WiFi card to an older laptop or a desktop PC.
Adding WiFi to an Older Computer
Buy a 802.11a, 802.11b or 802.11g network card.
For a laptop, this card will normally be a PCMCIA card that you slide into a PCMCIA slot on your laptop. Or you can buy a small external adapter and plug it into a USB port.
For a desktop machine, you can buy a PCI card that you install inside the machine, or a small external adapter that you connect to the computer with a USB cable.
Install the card
WiFi Security
WiFi hotspots can be open or secure.
If a hotspot is open, then anyone with a WiFi card can access the hotspot.
If it is secure, then the user needs to know a WEP key to connect.
WEP stands for Wired Equivalent Privacy
WEP
WEP has two variations: 64-bit encryption (really 40-bit) and 128-bit encryption (really 104-bit).
40-bit encryption was the original standard but was found to be easily broken.
128-bit encryption is more secure and is what most people use if they enable WEP.
For a casual user, any hotspot that is using WEP is inaccessible unless you know this WEP key.
Alternate Setup using a Wireless Router
If you are setting up a network in your home for the first time, or if you are upgrading, you can buy a Wireless Access Point Router.
This is a single box that contains:
1) a port to connect to your cable modem or DSL modem,
2) a router,
3) an Ethernet hub,
4) a firewall and
5) a wireless access point.
You can connect the computers in your home to this box either with traditional Ethernet cables or with wireless cards.
WiFi Range
Regardless of which setup you use, once you turn your Wireless Access Point on, you will have a WiFi hotspot in your house.
In a typical home, this hotspot will provide coverage for about 100 feet (30.5 meters) in all directions, although walls and floors do cut down on the range.
Even so, you should get good coverage throughout a typical home. For a large home, you can buy inexpensive signal boosters to increase the range of the Hotspot.