WiFi (Wireless Fidelity) is a wireless technology that uses radio waves to provide wireless internet access in local areas. It allows devices to connect to the internet without being physically connected with cables. The first wireless products using this technology were introduced in 1991 under the name WaveLAN. WiFi operates in the 2.4GHz and 5GHz radio bands and allows devices to connect within a range of around 100 feet from an access point. It provides wireless internet access through WiFi hotspots that can be either open for public use or secure networks requiring a password. The 802.11 WiFi standards have continued to evolve with improvements to speed and security.

1. WiFi
Is for “Wireless Fidelity”
By-Mayank Saxena
WiFi 1

2. What is Wi-Fi?
 Wi-fiis a wireless technology that uses
radio frequency to transmit data through
the air.
 Vic-Hayes has been called the "father of Wi-Fi".
 The first wireless products were under the name
WaveLAN was introduced in1991.
 Wi-Fi allows you to use your computer or other
device to connect to the internet from anywhere
there is a Wi-Fi access point (often known as a
hot Spot.
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3. 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.
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4. What is the goal of 802.11 standard ?
 To develop a Medium Access Control (MAC)
and Physical Layer (PHY) specification for
wireless connectivity for fixed, portable and
moving stations within a local area.
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5. Wi-Fi Standards…
Standard Speed Freq band Notes
802.11 2 Mbps 2.4 GHz (1997)
802.11a 54 Mbps 5 GHz (1999)
802.11b 11 Mbps 2.4 GHz
802.11g 54 Mbps 2.4 GHz
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6. Range and Performance
 Performance decreases as distance
increases
 802.11a
Indoor 40-300 feet
Outdoor – 100 to 1000 feet
 802.11b
Indoor 100-300 feet
Outdoor 400 – 1500 feet
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7. Wi-Fi network services
 Distributionand integration
 Association, re-association, and
disassociation
 Authentication and deauthentication
 Providing privacy.
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8. Do I need any license to use 802.11 device ?
 No , 2.4 GHz and 5.0 GHz are public
available frequency !!!
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9. WiFi Security
 WiFi hotspots can be open or secure.
 If
a hotspot is open, then anyone with a
WiFi card can access the hotspot.
 Ifit is secure, then the user needs to know
a WEP key to connect.
 WEP stands for Wired Equivalent Privacy.
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10. WiFi Security (Conti…)
 WEP is an encryption system for the data
that 802.11 sends through the air.
 Encryption system prevents any non-
authorized party from reading or changing
data.
 Specifically, it is the process of encoding
bit stream in such a way that only the
person (or computer) with the key (a
digital sequence) can decode it.
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11. Wi-Fi Security(conti…)
 WEP ( wired equivalent privacy) 64/128 bits
Using RC4 algorithm, almost permanent key, very week
security, able to crack by collecting statistic
Current security level for 99.9% products on the market.
 TKIP (temporal key integrity protocol )
Used RC4 algorithm with with a 128-bit "temporal key"
but changes temporal keys every 10,000 packets and key
dependes on address and sequence number.
Will be required to obtain WiFi certification from 09/01/03
 AES (Advanced Encryption Standard )
New, much more stronger encryption, protect against hacker frames
in insertion. Need hardware accelerator. Optional feature.
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12. Frames types and subtypes
 Three types of frames:
 Control
(ACK,RTS,CTS ,Power Save …)
 Management
(Beacon,Probe Request ,Probe Response,
Association request , Association response …)
 Data
(Data, Null Data, Data_CF_Ack , ….)
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13. How to connect a wi-fi device…?
• Stations (STA)
– any wireless device BSS2
• Access Point (AP)
– connects BSS to DS
– controls access by STA’s
ESS1
• Basic Service Set (BSS)
– a region controlled by an AP
– mobility is supported within a
single BSS AP2
• Extended Service Set (ESS) AP3
DS
– a set of BSS’s forming a virtual
BSS
– mobility is supported between
AP1
BSS’s in an ESS
STA3
• Distribution Service (DS)
STA1
– connection between BSS’s BSS3
BSS1
STA2
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14. Two types of access to air
 DCF (distributed coordination function )
means everybody can speak and try
to get air : 100% on the market
 PCF (point coordination function)
means ONE point coordinator (BOSS)
who will allowed you to speak
(like in bluetooth)
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15. Summary of required features and
difficulties...
 Features
 High speed operation (PHY only)
 Fair access (DCF, PCF)
 Time-bounded access (PCF)
 Flexible configuration (BSS, IBSS)
 Security (WEP)
 Mobility support (ESS)
 Low power (PS)
 Difficulties
 Hidden terminals (RTS/CTS)
 Capture (CSMA/CA, ACK)
 Noise and interference (ACK, frag)
 Limited spectrum (licencing, PHYs)
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16. Acknowledgment
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17. 802.11/802.16
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18. Diff.bw Bluetooth & Wi-Fi
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19. WiFi 19

20. WiFi 20

21. Conclusion…
The IEEE standards
group that oversees
Wi-Fi technology has
just approved a brand
new next-gen Wi-Fi
802.22 technology
that could allow your
home network to
span up to 60 miles!
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22. Thankyou…!
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