IEEE 802.11 wifi
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The document discusses the components and architectures of wireless networks. It describes basic service sets (BSS) which can be either ad-hoc or infrastructure networks, and extended service sets (ESS) which connect multiple BSS through a distribution system. It also outlines the 802.11 protocol stack and frame formats, including the frame control field and address fields.
![BASIC SERVICE SET [BSS]
AD HOC NETWORK INFRASTRUCTURE NETWORK](https://image.slidesharecdn.com/ieee802-11wifi-121008124459-phpapp01/85/IEEE-802-11-wifi-6-320.jpg)
![EXTENDED SERVICE SET [ESS]
DISTRIBUTION SYSTEM
BSS BSS BSS](https://image.slidesharecdn.com/ieee802-11wifi-121008124459-phpapp01/85/IEEE-802-11-wifi-7-320.jpg)
IEEE 802.11 wifi
- 4. Network Components Wireless Stations Access Point
- 5. Types of Architectures Basic Service Set Extended Service Set Stationary or Mobile Distributed System wireless stations Uses LAN to connect Optional Central Base Central Stations form Station Basic Service Sets
- 6. BASIC SERVICE SET [BSS] AD HOC NETWORK INFRASTRUCTURE NETWORK
- 7. EXTENDED SERVICE SET [ESS] DISTRIBUTION SYSTEM BSS BSS BSS
- 8. TYPES OF STATIONS NO Transition BSS Transition ESS Transition
- 11. 802.11 define 3 classes of frames : DATA CONTROL MANAGEMENT
- 13. FRAME CONTROL
- 14. PROTOCOL VERISION 0 : current version
- 15. 00 : Management frame 01 : Control frame 10 : Data frame 11 : Unspecified
- 16. Control (01)- RTS (1011) CTS (1100) ACK (1101)
- 17. ToDS- 1: frame is addressed to AP for forwarding it to DS 0: other frames FromDS- 1: frame coming from DS 0 : other frames
- 18. 1 : When there are more fragments 0 : Sent fragment is last
- 19. 1 : Frame is retransmitted 0 : Frame is transmitted for the first time
- 20. 1 : Station in in sleep mode 0 : active mode
- 21. 1 : indicates that the sender has additional frames
- 22. 1 : frame body is encrypted 0 : not encrypted
- 23. 1 : frames transmitted in order 0 : not transmitted in order
- 24. Data, Management frame : defines duration of transmission Control frame : defines ID of frame
- 25. Address1 : next device Address2 : Previous device Address3 : final destination if not defined by addr1 Address4: original source if not defined by addr2
- 26. CASE 1: ToDS : 0 FromDS :0 CASE 2: ToDS : 0 FromDS :1
- 27. CASE 3: ToDS : 1 FromDS :0 CASE 4: ToDS : 1 FromDS : 1
- 28. Sequence field (16 bits) has 2 subfields: 1. Fragment no.(4 bits) 2. Sequence no.(12 bits)
- 29. It can transmit frame with max payload of 2312 bytes
- 30. Its is 32bits field containing 32 bits CRC
- 31. MANAGEMENT FRAME
- 32. CONTOL FRAMES RTS FRAME CTS FRAME ACK FRAME