Wi-fi (ppt) by Mayank Saxena


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this ppt i represent in my clg wrkshop INSPIRE-2012

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Wi-fi (ppt) by Mayank Saxena

  1. 1. WiFiIs for “Wireless Fidelity” By-Mayank Saxena WiFi 1
  2. 2. What is Wi-Fi? Wi-fiis a wireless technology that usesradio frequency to transmit data throughthe 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. WiFi 2
  3. 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. WiFi 3
  4. 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. 4
  5. 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 WiFi 5
  6. 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 WiFi 6
  7. 7. Wi-Fi network services Distributionand integration Association, re-association, and disassociation Authentication and deauthentication Providing privacy. WiFi 7
  8. 8. Do I need any license to use 802.11 device ?  No , 2.4 GHz and 5.0 GHz are public available frequency !!! WiFi 8
  9. 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. WiFi 9
  10. 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. WiFi 10
  11. 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. WiFi 11
  12. 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 , ….) WiFi 12
  13. 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 WiFi 13
  14. 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) WiFi 14
  15. 15. Summary of required features anddifficulties... 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) WiFi 15
  16. 16. Acknowledgment WiFi 16
  17. 17. 802.11/802.16 WiFi 17
  18. 18. Diff.bw Bluetooth & Wi-Fi WiFi 18
  19. 19. WiFi 19
  20. 20. WiFi 20
  21. 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! WiFi 21
  22. 22. Thankyou…! WiFi 22