WIRELESS FIDELITYWIRELESS FIDELITY

Introduction:Introduction:

Wi- fi is a wireless a local area network Wi- fi is a wireless a local area network

that uses high frequency radio signals tothat uses high frequency radio signals to

transmit and receive data over distancestransmit and receive data over distances

of a few hundred feet.of a few hundred feet.

Wi-FiWi-Fi is the wireless way to handle is the wireless way to handle networking. It is also known as networking. It is also known as 802.11 802.11 networkingnetworking and and wireless networkingwireless networking. .

Features:Features:

This uses low power microwave

radio to link one or more groups of

users together, or to provide a link

between two buildings.

It can span several kilometres point to point but cannot be used where trees are in the way as water in the leaves absorb the radio signal.

The computers connect to the The computers connect to the network using radio signals, and network using radio signals, and computers can be up to 100 feet computers can be up to 100 feet or so apart. or so apart.

802.xx:802.xx:

A common standard for wireless A common standard for wireless networking, issued by the IEEE.networking, issued by the IEEE.

IEEE 802.xx is a set of specifications for IEEE 802.xx is a set of specifications for LANs from The Institute of Electrical and LANs from The Institute of Electrical and Electronic Engineers (IEEE Electronic Engineers (IEEE

802.11802.11

802.11 defines the standard for wireless 802.11 defines the standard for wireless LANs encompassing three incompatible LANs encompassing three incompatible (non-interoperable) technologies: (non-interoperable) technologies: Frequency Hopping Spread Spectrum Frequency Hopping Spread Spectrum (FHSS), Direct Sequence Spread (FHSS), Direct Sequence Spread Spectrum (DSSS), and Infrared.Spectrum (DSSS), and Infrared.

IEEE 802.11a -- an add on to 802.11 that IEEE 802.11a -- an add on to 802.11 that applies to wireless LANs and provides up to 54 applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. Mbps in the 5GHz band.

IEEE 802.11b (also referred to as 802.11 High IEEE 802.11b (also referred to as 802.11 High Rate or Wi-Fi) -- an add on to 802.11 that Rate or Wi-Fi) -- an add on to 802.11 that applies to wireless LANS and provides 11 Mbps applies to wireless LANS and provides 11 Mbps transmission (all includes 5.5, 2 and 1 Mbps) in transmission (all includes 5.5, 2 and 1 Mbps) in the 2.4 GHz band. the 2.4 GHz band.

802.11g -- applies to wireless LANs and 802.11g -- applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band.provides 20+ Mbps in the 2.4 GHz band.

Working of Wi-fi:Working of Wi-fi:

Wireless networking at its simplest level makes Wireless networking at its simplest level makes use of the basic concept of a walkie-talkie.use of the basic concept of a walkie-talkie.

These are small radios that can transmit and These are small radios that can transmit and receive radio signals. receive radio signals.

The voice is picked up by a microphone, The voice is picked up by a microphone, encoded onto a encoded onto a radioradio frequency and transmitted frequency and transmitted with the antenna. with the antenna.

Another walkie-talkie can receive the Another walkie-talkie can receive the transmission with its antenna, decode your voice transmission with its antenna, decode your voice from the radio signal and drive a from the radio signal and drive a speakerspeaker. .

Wi-fi uses radios which are slightly Wi-fi uses radios which are slightly

different from the radios used in walkie-different from the radios used in walkie-

talkie.talkie.

There are three big differences between There are three big differences between WiFi radios and Walkie-talkies: WiFi radios and Walkie-talkies:

WiFi radios that work with the 802.11b and WiFi radios that work with the 802.11b and 802.11g standards transmit at 2.4 GHz, 802.11g standards transmit at 2.4 GHz, while those that comply with the 802.11a while those that comply with the 802.11a standard transmit at 5 GHz. Normal standard transmit at 5 GHz. Normal walkie-talkies normally operate at 49 MHz. walkie-talkies normally operate at 49 MHz. The higher frequency allows higher data The higher frequency allows higher data rates. rates.

WiFi radios use much more efficient WiFi radios use much more efficient coding techniques that also contribute to coding techniques that also contribute to the much higher data rates. For 802.11a the much higher data rates. For 802.11a and 802.11g, the technique is known as and 802.11g, the technique is known as orthogonal frequency-division multiplexing orthogonal frequency-division multiplexing (OFDM). For 802.11b, it is called (OFDM). For 802.11b, it is called Complementary Code Keying (CCK).Complementary Code Keying (CCK).

The radios used for WiFi have the ability to The radios used for WiFi have the ability to change frequencies. 802.11b cards can transmit change frequencies. 802.11b cards can transmit directly on any of three bands, or they can split directly on any of three bands, or they can split the available radio bandwidth into dozens of the available radio bandwidth into dozens of channels and channels and frequency hopfrequency hop rapidly between rapidly between them. The advantage of frequency hopping is them. The advantage of frequency hopping is that it is much more immune to interference and that it is much more immune to interference and can allow dozens of WiFi cards to talk can allow dozens of WiFi cards to talk simultaneously without interfering with each simultaneously without interfering with each other. other.

Since they are transmitting at much higher Since they are transmitting at much higher frequencies than a Walkie-Talkie, and because of frequencies than a Walkie-Talkie, and because of the encoding techniques, WiFi radios can handle a the encoding techniques, WiFi radios can handle a lot more data per second. lot more data per second.

802.11b can handle up to 11 megabits per second 802.11b can handle up to 11 megabits per second (although 7 megabits per second is more typical, (although 7 megabits per second is more typical, and 802.11b may fall back as low as 1 or 2 and 802.11b may fall back as low as 1 or 2 megabits per second if there is a lot of megabits per second if there is a lot of interference). 802.11a and 802.11g can handle up interference). 802.11a and 802.11g can handle up to 54 megabits per second (although 30 megabits to 54 megabits per second (although 30 megabits per second is more typical). per second is more typical).

Adding a Wi-Fi to your PC:Adding a Wi-Fi to your PC:

One of the best things about WiFi is its simplicity.One of the best things about WiFi is its simplicity.Steps:Steps:Buy a 802.11a, 802.11b or 802.11g network card. 802.11g Buy a 802.11a, 802.11b or 802.11g network card. 802.11g

has the advantage of higher speeds and good has the advantage of higher speeds and good interoperability on 802.11b equipment. interoperability on 802.11b equipment.

For a laptop, this card will normally be a PCMCIA card that For a laptop, this card will normally be a PCMCIA card that you slide into a PCMCIA slot on your laptop. Or you can you slide into a PCMCIA slot on your laptop. Or you can buy a small external adapter and plug it into a USB port. buy a small external adapter and plug it into a USB port.

For a desktop machine, you can buy a PCI card that you For a desktop machine, you can buy a PCI card that you install inside the machine, or a small external adapter that install inside the machine, or a small external adapter that you connect to the computer with a USB cable. you connect to the computer with a USB cable.

Install the card Install the card

Install the drivers for the cardInstall the drivers for the card

Find an 802.11 Find an 802.11 hotspothotspot

Access the hotspot. Access the hotspot.

What is a hot spot?What is a hot spot?

A hotspot is a connection point for a WiFi A hotspot is a connection point for a WiFi network. It is a small box that is hardwired network. It is a small box that is hardwired into the Internet. The box contains an into the Internet. The box contains an 802.11 radio that can simultaneously talk 802.11 radio that can simultaneously talk to up to 100 or so 802.11 cards. There are to up to 100 or so 802.11 cards. There are many WiFi hotspots now available in many WiFi hotspots now available in public places like restaurants, hotels, public places like restaurants, hotels, libraries and airports. You can also create libraries and airports. You can also create your own hotspot in your home, as we will your own hotspot in your home, as we will see in a later section. see in a later section.

Configuring WiFi

On the newest machines, an 802.11 card will On the newest machines, an 802.11 card will automatically connect with an 802.11 hotspot and a automatically connect with an 802.11 hotspot and a network connection will be established. As soon as you network connection will be established. As soon as you turn on your machine, it will connect and you will be able turn on your machine, it will connect and you will be able to browse the Web, send email, etc. using WiFi. On older to browse the Web, send email, etc. using WiFi. On older machines you often have to go through this simple 3-machines you often have to go through this simple 3-step process to connect to a hotspot: step process to connect to a hotspot:

Access the software for the 802.11 card -- normally there Access the software for the 802.11 card -- normally there is an icon for the card down in the system tray at the is an icon for the card down in the system tray at the bottom right of the screen. bottom right of the screen.

Click the "Search button" in the software. The card will Click the "Search button" in the software. The card will search for all of the available hotspots in the area and search for all of the available hotspots in the area and show you a list. show you a list.

Double-click on one of the hotspots to connect to it. Double-click on one of the hotspots to connect to it.

WiFi Security:WiFi Security: WiFi hotspots can be open or secure. If a hotspot is WiFi hotspots can be open or secure. If a hotspot is

open, then anyone with a WiFi card can access the open, then anyone with a WiFi card can access the hotspot. If it is secure, then the user needs to know a hotspot. If it is secure, then the user needs to know a WEP keyWEP key to connect. to connect.

WEP stands for Wired Equivalent Privacy, and it is an WEP stands for Wired Equivalent Privacy, and it is an encryption system for the data that 802.11 sends encryption system for the data that 802.11 sends through the air. WEP has two variations: 64-bit through the air. WEP has two variations: 64-bit encryption (really 40-bit) and 128-bit encryption (really encryption (really 40-bit) and 128-bit encryption (really 104-bit). 40-bit encryption was the original standard but 104-bit). 40-bit encryption was the original standard but was found to be easily broken (see this page for an was found to be easily broken (see this page for an explanation). 128-bit encryption is more secure and is explanation). 128-bit encryption is more secure and is what most people use if they enable WEP. what most people use if they enable WEP.

Advantages of Wi-fi:Advantages of Wi-fi: Unlike packet radio systems, Wi-Fi uses Unlike packet radio systems, Wi-Fi uses

unlicensed radio spectrum and does not require unlicensed radio spectrum and does not require regulatory approval for individual deployers. regulatory approval for individual deployers.

Allows LANs to be deployed without cabling, Allows LANs to be deployed without cabling, potentially reducing the costs of network potentially reducing the costs of network deployment and expansion. Spaces where deployment and expansion. Spaces where cables cannot be run, such as outdoor areas cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs. and historical buildings, can host wireless LANs.

Wi-Fi products are widely available in the Wi-Fi products are widely available in the market. Different brands of access points and market. Different brands of access points and client network interfaces are interoperable at a client network interfaces are interoperable at a basic level of service. basic level of service.

Competition amongst vendors has lowered Competition amongst vendors has lowered prices considerably since their inception. prices considerably since their inception.

Wi-Fi networks support roaming, in which a Wi-Fi networks support roaming, in which a mobile client station such as a laptop computer mobile client station such as a laptop computer can move from one access point to another as can move from one access point to another as the user moves around a building or area. the user moves around a building or area.

Many access points and network interfaces Many access points and network interfaces support various degrees of encryption to protect support various degrees of encryption to protect traffic from interception. traffic from interception.

Wi-Fi is a global set of standards. Unlike cellular Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi client works in different carriers, the same Wi-Fi client works in different countries around the world. countries around the world.

THANK YOUTHANK YOU