802.11 :
- ;
- (FHSS) 2,4 ;
- (DSSS) 2,4 .
850 , , (LED). , LAN . : , . . , ,
(FHSS)
FHSS 1 2 /. , FHSS . FHSS 2,402 2,480 79 ( ). 79 1 , FHSS , 1 , .
: 2,5 , , 6- (6 ) . , , 26. 2.2 , .
2.2 - FHSS
{0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72, 75} | |
{1,4,7,10,13,16,19,22,25,28,31,34,37,40,43,46,49,52,55,58,61,64,67,70,73, 76} | |
{2,5,8,11,14,17,20,23,26,29,32,35,38,41,44,47,50,53,56,59,62,65,68,71,72,77} |
, , , , , 6 , .
FHSS PLCP
MAC -, FHSS PLCP, PSDU ( PLCP service data unit), PLCP , PPDU (, PPDU PLCP). 2.8 FHSS PLCP.
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2.8 - FHSS PLCP
PLCP :
- Sync 80 . , 0 1, 0. , , (frequency offset) (packet timing).
- (start of frame delimiter, SFD) 16 . (0000 1100 1011 1101, ) (frame timing) .
PLCP :
- PLCP (PSDU), PSDU length word (PLW) 12 . MAC (PSDU) ;
- PLCP (signaling field PLCP, PSF) 4 . .
PLCP (PSDU) () . PSDU 2.9. (stuff symbols) 32- . (bias) , , , , , .
PLCP PMD. PMD FHSS , (Gaussian frequency shift keying, GFSK), .
2.9 - PSDU FHSS