Wireless lan protocols

WLANs
Wireless LAN Protocols
A wireless LAN. (a) A transmitting. (b) B transmitting.
CSMA/CA RTS/CTS
request to send / clear to send
The MACA protocol. (a) A sending an RTS to B.
(b) B responding with a CTS to A.
WLAN im Infrastruktur-Modus
The 802.11 Protocol Stack
Part of the 802.11 protocol stack.
Modulation / Multiplex
• FHSS
Frequency Hopping Spread Spectrum
• (HR-)DSSS
(High Rate) Direct Sequence Spread Spectrum
• OFDM
Orthogonal Frequency Division Multiplex
The 802.11 MAC Sublayer Protocol
(a) The hidden station problem.
(b) The exposed station problem.
The 802.11 MAC Sublayer Protocol (2)
The use of virtual channel sensing using CSMA/CA.
The 802.11 MAC Sublayer Protocol (3)
A fragment burst.
The 802.11 MAC Sublayer Protocol (4)
Interframe spacing in 802.11.
The 802.11 Frame Structure
The 802.11 data frame.
Broadband Wireless: 802.16 (Wimax)
• Comparison of 802.11 and 802.16
• The 802.16 Protocol Stack
• The 802.16 Physical Layer
• The 802.16 MAC Sublayer Protocol
• The 802.16 Frame Structure
The 802.16 Protocol Stack
The 802.16 Protocol Stack.
The 802.16 Physical Layer
The 802.16 transmission environment.
The 802.16 Physical Layer (2)
Frames and time slots for time division duplexing.
The 802.16 MAC Sublayer Protocol
Service Classes
• Constant bit rate service
• Real-time variable bit rate service
• Non-real-time variable bit rate service
• Best efforts service
The 802.16 Frame Structure
(a) A generic frame. (b) A bandwidth request frame.