IEEE 802.11 Wireless LAN

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IEEE 802.11 Wireless LAN Protocol Architecture -
?????????????????? LAN ??? WAN - layer
1(Physical layer)
????????????????????
??????????????????????
???????????????????????
2
IEEE 802.11 Wireless LAN Protocol Architecture -
Layer 2 (Logical link controlLLC ????????MAC )
-Logic ?????? manag eaccess ?????? share-access
meadium -LLC ?????? serveral MAC operation
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IEEE 802.11 Wireless LAN IEEE 802 Protocol in
context
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IEEE 802.11 Wireless LAN LLC PDU in a Generic MAC
Frame Format
MAC Frame
MAC control
Destination MAC address
Source MAC address
Data
CRC
Variable
1 or 2
1
1octet
LLC PDU
DSAP
SSAP
LLC control
Information
LLC address fileds
I/G
DSAPn value
C/R
SSAP value
I/G individual/group DSAP destination service
access point C/R command/reponse SSAP source
service access point
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IEEE 802.11 Wireless LAN Logical Link
Control -???????????? link-level PDU ??????? 2
????????????????multicase, shared-medium
-??????????????????? access ?? MAC layer -
addess ??? service access points (SAPs) LLC
Service Unacknoledged connectionless service
?????????????? datagram ????????????????
guarantee connection-mode service ???????? HDLC
?? flow control ??? error control Acknoledged
connectionless service ?????????????? datagram
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IEEE 802.11 Wireless LAN Logical Protocol -????
asynchonous balanced ??? HDLC ???????????????
connection -???????? Unacknoledged connectionless
??????????? type 1 -???????? Acknoledged
connectionless ??????????? type 3
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IEEE 802.11 Wireless LAN IEEE 802.11 Architecture
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IEEE 802.11 Medium Access Control Reliable Data
Delivery ?????????????????? request to send(RTS)
?????????????????clear to send (CTS)
???????????????????? ACK ?????????????????????????
? Access Control ????? MAC algorithum
??????????? DFWMAC (distributed foundation
wireless MAC)
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IEEE 802.11 Medium Access Control IEEE 802.11
Protocol Architecture
????????? connection-tree
????????? access traffic ??? ?????
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IEEE 802.11 Medium Access Control Distributed
Coordination Function
IEEE 802.11 Medium Access Control Control Logic
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IEEE 802.11 Wireless LAN IEEE 802.11 MAC Timing
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IEEE 802.11 Wireless LAN IEEE 802.11 MAC Frame
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IEEE 802.11 Wireless LAN - ??????????????????????
??????? 3G??????????? 3GPP2 - ????????????????
??? TIA TR45.5 - ?????????????????????????????????
???????????? IS-95 ??spreading factor 4 ??? 256
???? downlink - ?????????? 20 ???????????
???????? 16 timeslot - ???? bursts ?????? 5
???????????