GSM, FDMA TDMA, 3G CDMA. CDMA. . . , CDMA . . , . CDMA m , ( ). 64 128 . , 1, . , 0, (.. , - ). . , 010011, 1 010011, 0 - 101100.
, CDMA . GSM, , CDMA DSSS (Direct Sequence Spread Spectrum). CDMA . 1, 100 , (1) , 1/.
, , .. 0. , . (3,-2,4) (-2,3,3) : (3,-2,-4)* (-2,3,3) = -6-6+12=0. (1,2,3) (4,2,-6)- ( -10), (1,2,3) (4,2,-3) ( -1), .. . .
, . , (+1,-1,+1,+1,-1,+1,+1,+1,-1,-1,-1) , .. , 11. ( 11- , ) ( ) 1. , .
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4
+1 | -1 | +1 | +1 | -1 | +1 | +1 | +1 | -1 | -1 | -1 | |
-1 | +1 | +1 | +1 | -1 | -1 | -1 | +1 | -1 | +1 | +1 | 4 |
-1 | -1 | +1 | +1 | +1 | -1 | -1 | +1 | +1 | -1 | -1 | -1 |
, , . . . , . , , . , . CDMA , , . , , . , CDMA . CDMA.
CDMA .
, , . CDMA : k=010011 k=110101. d = 1, Bd=0. -1, +1. d =+1, Bd=-1. . , ( ). .
, .
-1 | +1 | -1 | -1 | +1 | +1 | ||
+1 | -1 | +1 | -1 | +1 | |||
* | -1 | +1 | +1 | -1 | -1 | +1 |
, Ak Bk . As =Ad *Ak = +1 * (-1, +1, -1, -1, +1,+1) =(-1,+1, -1, -1, +1, +1). , : Bs = Bd * Bk = -1 * (+1, +1, -1, +1, -1, +1) = (-1, -1, +1, -1, +1, -1).
, . , , =s + Bs =(-2, 0, 0, -2, +2, 0). . , : * = (-2, 0, 0, -2, +2, 0) * (-1, +1, -1, 1, +1, +1) = 2 + 0 +0 + 2 + 2 + 0 = 6. 0, . , .. * = (-2, 0, 0, -2, +2, 0) * (+1, +1, -1, +1, -1, +1,) = - 2 + 0 + 0 2 2 + 0 = - 6. , .
. , , , . , , . , (+6, -6) , , , . , 0 1, - . , . , , ? , , . = As + 5* Bs = (-1, +1, -1, -1, +1, +1) + (-5, -5, +5, -5, +5, -5) = (- 6, - 4, + 4, - 6, + 6, -4). , : * = - 6 4 4 -6 - 6 4 = -30. , , . : * = 6 4 4 + 6 + 6 4 = 6. , (-30 +6). 30 , +6 : -30 +6 . : - , , . , CDMA . , CDMA.
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, , , . , .
23.2.2. TDMA/FDMA CDMA
TDMA/FDMA CDMA , [79]. TDMA/FDMA:
;
;
. GSM .
TDMA/FDMA:
1. . TDMA/FDMA . , , , , ( );
2. . / , .
CDMA:
, . CDMA IS-95 115,2 / ;
. . . CDMA , , TDMA/FDMA;
. CDMA / , .
CDMA:
;
. - CDMA , ;
CDMA , TDMA/FDMA. CDMA , .