, , , PCF, . , .
PCF 802.11 DCF. ( 2.5).
2.5 - 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. , , . , , , ( , ).
- , . .
PCF, .
MAC
2.6, 802.11. , . :
|
|
- . ( ).
- /. , ( ), MAC. , .
- . . : , , , .
- . 4- , , 12- , , .
FC
D/I /
SC
) MAC
DS MD
MF W
RT 0
)
2.6 - MAC IEEE 802.11
- . MSDU MSDU. MSDU LLC MAC.
- . 32- .
, . 5.6, , .
- . 802.11, 0.
- . : , .
- . . 2.1.
- DS. MAC 1, .
- DS. MAC 0, .
- . 1, .
- . 1, .
- . 1, .
- . , . .
2.1 -
PS-opoc | |||
" " | |||
(F)- | |||
CF- + CF- | |||
+ CF- | |||
+ CF-opoc | |||
+ CF- + CF-opoc. | |||
( ) | |||
+ CF- | |||
+ CF-opoc | |||
+ CF- + CF-opoc |
|
|
- WEP. 1, (wired equivalent privacy WEP). WEP .
- 1, , , .
MAC.
. .
- (PS-). , . , , , .
- (RTS). , . , , , , .
- " " (CTS). . - - .
- (). , PS-opoc.
- (F)-. ; .
- CF- + CF-. CF-. , .
, . , -. .
- . . , .
- + CF-. . .
- + CF-opoc. , .
- + CF- + CF-opoc. .
. " " , , . , , . (CF-, CF-opoc, CF- + CF-opoc) , ( + CF-, + CF-opoc, + CF- + CF-opoc), .
. :
- . (Basic Service Set, BSS). , , , .
|
|
- . , .
- . BSS, BSS. , .
- . , .
- . . BSS IEEE 802.11.
- . .
- . , BSS.
- . ( ), , .
- . .
- . .
- . .