IEEE 802.11
IEEE (Institute of Electrical and Electronics Engineers) 802.11 1990 . , 2,4 , 1 2 /. 7 , 1997 802.11. IEEE 802.11 WLAN , .
IEEE 802.11, : IEEE 802.11a, IEEE 802.11b, IEEE 802.11g IEEE 802.11n.
IEEE 802.11
, IEEE 802.11 802, MAC (Media Access Control) LLC (Logical Link Control). 802, 802.11 , MAC, LLC LAN
LLC | LLC | |||||
MAC | PCF | |||||
DCF | ||||||
802.11 | 802.11a | 802.11b | 802.11g | 802.11n | ||
2,4 FHSS 1 / 2 / | 2,4 DSSS 1 / 2 / | 5 OFDM 54 /c | 2,4 DSSS CCK 11 /c | 2,4 OFDM 54 /c | 2,4 5 OFDM 600 /c | |
3. IEEE 802.11
, , . MAC, MAC .
802.11
802.11 MAC :
DCF (Distributed Coordination Function);
PCF (Point Coordination Function).
DCF
, DCF. (Carrier Sense Multiple Access with Collision Avoidance, CSMA/CA). CSMA/CD, . , . - , - , .
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DCF . 802.11 . - , .
.4. DCF
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CSMA/CD, , 802.11 . N , , . , .
802.11 2346 , RTS- 20 , CTS- 14 . RTS- CTS- , , RTS- CTS- , . RTS- CTS- . , , , RTS- CTS-.
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. . , , . , , DCF.
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PCF
, , , PCF, . , .
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PCF 802.11 DCF. .
6. PCF DCF
, :
(Short IFS, SIFS);
PCF (PIFS);
DCF (DIFS).
DCF , , , DIFS. IFS DCF DIFS , .
SIFS , CTS- , .
PIFS , SIFS, , DIFS. PIFS DIFS . , , . , , DCF , , . , , . , DIFS DCF.
PCF. , , . , , , ( , ).
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PCF, .
MAC-
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7. MAC IEEE 802.11
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+ CF- | |||
+ CF-opoc | |||
+ CF- + CF-opoc. | |||
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+ CF-opoc | |||
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