' , , GSM . ' GSM . CSM ' , , . GSM (FDMA) (TDMA) . MS-BTS , . . GSM , , , , .
GSM ' (. full duplex), , (. down link), BTS MS, (. uplink), MS BTS (. 7.1). , ' , 㳿 , .
GSM : 900 1800 . 䳿 GSM: E-GSM PCN1900. ij .
GS900
GSM 900 .
25 (. 7.1b):
- - 890-915 ;
- - 935-960 .
GSM (. Frequency Division Duplex FDD). GSM900 45 .
124 200 . ֳ 1 124. ARFCN (. Absolute Radio Frequency Channel Number).
, 25 125 200 , 100 . . ( ) 124 GSM900 :
- : f = 890.0 +(0.2 )*;
- : fi = 935.0 +(0.2 )*;
- (ARCFN), 1<<124.
200 8 . , 8- . 1 16 , 8 128 . ʳ BTS , . , , GSM , 900 , . NMT900, AMPS ETACS, 124 . 7.1b.
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DCS1800
䳿 GSM900 , 124 , '. , , 900 (GSM900), , 1800. DS1800 (.Digital Cellular System).
DCS1800 (. 7.1):
- - 1710-1785 ;
- - 1805-1880 .
, 75 , GSM900. GSM900 ' DCS1800 - , DCS1800 GSM900. , .
75 375 200. GSM900, 100 , 374 , ARCFN 512 885. ARCFN DCS1800 :
- : fi=1710 +(0.2 )*(-511);
- : f= 1805 +(0.2 )*(-511);
- (ARCFN), 512<<885.
, DCS1800 , GSM900. 95 , - .
, , DCS1800 GSM900 ' . GSM900 ( , , 35), DCS1800 - , 3 . 1 , , 20 GSM900. DCS1800 20 , 320 GSM900.
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DCS ( 1 .), , GSM900. , , , , .
90- , GSM , ' (. Personal Communications Networks PCN) , , ..
a) ; b) GSM 900; c) DSC 1800.
. 7.1. GSM
, DCS1800 , , PCN. , GSM900 , DCS1800 ͳ , .
-GSM
GSM , . ֳ -GSM (. Extended fregueney GSM). GSM, 25 10 . 50. , ARCFN, -GSM, :
- : fi = 890 +(0.2 )*(-1024);
- : fi =935 +(0.2 )*(i-1024),
- (ARCFN), 975<<1023.
PCS1900
GSM , GSM - IS-95 JDC. GSM900, 1900 '. , , PCS1900 (. Personal Communication System - , , PCN), GSM, 100 , DCS1800.
7.1.2. Գ
GSM - , , ' GSM, (TDMA) (FDMA) .
-
GSM D (. Time Division Multiple Access) FDMA (. Frequency Division Multiple Access). 124 , 200, 0 7 (. 7.2). 577 ( 15/26 ). ³ , , TDMA 577 *8=4.615 . , .
, , , - (. 7.3). - (. burst). , . GSM - , . , , 0.577 , 4.038 200 , , , 4.615 , . TDMA , GSM 200 /8=25 . .
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TDMA . . 7.3 k- (k=0,l,...,7) , k- , . ' BTS-MS, , , 45 . , , (1.731 ). , . , 䳿 , .
. 7.4 , . , 577 . 1/4.615 = 216.6 .
( ) , , . , ' .
GSM , . ϳ . 7.5 ( ) (. power-versus-time template). 28 , 70 dB. ϳ 542.8 .
Գ , ' , ( 4.615 ) , ( burst) - . 7.6. GSM 3.69 , 148 , 546 . 577 , 30 . (. guard interval) 8.25 ( 8.25 ), 3.7 . GSM 156.25 .
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GSM 5 , , (. normal burst), , GSM, . GSM . .
1. (. normal burst). GSM , (. 7.7). :
- - , 57 , , ;
- (. training seguence) - e 26 , , . , , . , . ' , , , , , , . GSM ' . , . , BSC, ;
- (. Stealing Flags SF) - , . , (. ), , . ;
- (. Tail Bits TB) - 3- , . , ;
.7.2 TDMA .
.7.3 GSM -
.7.4
.7.5
.7.6 TDMA
- (. Guard Period GP) - , 30 , , 8.25 . , . ³ , , .
, , (. timing advance). .
2. ֲ (. frequency correction burst). (. 7.8) . , , - . . , . GP , .
3. Ͳֲ (. synchronization burst). ϳ . 64- , 39- TDMA, , , (BSIC), (. 7.9).
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4. (. access burst). , , . , .
TB - ; GP - ; SF -
.7.7
.7.8
.7.9
, . (. handover) . , , , , (. 7.10).
, , , , , . 68.25*3.69 252 . , , 252 *300000 /=75.5 , ( ) 37,75 . , 35 . , . 7.11. , .
5. ̲ (. dummy burst). , , , , , .
.5.2.1 , TDMA 4.615 (. 7.2), GSM . , .
. 7.12 , GSM. TDMA (. TDMA frame) - , , (. multiframe). : 26-, 120, 51-, 235 , . ( ) , ( ). 26-, , 200 / , 2 /. , 51 TDMA.
, , (. superframe), , 1326 TDMA, 6,12. 1326- 26 51, 51 , 26 . GSM , , (. hyperframe), 2048 . 2715648 TDMA, 3.5 .
TDMA , . TDMA .
.7.10
.7.11
. 7.12. GSM
1 - ( 0 2047), 2 - , ' 26- ( 0 25), - ' 51- ( 0 50). 1, 2 TDMA, SCH.
, GSM , . (.10.3.1), (.10.3.2). , .10.3.3, , .
GSM (. 7.13). ( ). . , . no- . . . 7.13 , GSM.
1. Ͳ (. Traffic CHannels). . , :
- full-rate TCH/FS (. Traffic CHannel/Full - rate Speech). 13 /. : 9.6; 4.8; 2.4 /;
- half-rate TCH/HS (. Traffic CHannel/Half-rate Speech). , 7 6/, . 4.8 2.4 /;
2 Ѳײ ( Broadcast CHannel). , . , ' :
- FCCH (. Frequency Correction CHannel). , , , .
- SCH (. Synchronization CHannel). , , . , .
- (. Broadcast Control CHnnel). (); LAC, , MNC, , . .
3. ϲͲ ˲ֲͲ (. Common Control CHannels). ' :
. 7.13. GSM
- (. Paging CHannel). , . , . , ;
- R (. Random Access CHannel). , DCCH. '. , RACH .7.1.2.3 , ' GSM () ( ). , ;
- AGH (. ess Grant CHannel). DCCH, SDCC, AGCH. , 䳺 .
4. ֲͲ ˲ֲͲ DCCH (. Dedicated Control CHannels). , '. , .
- SDCCH (. Standalone Dedicated Control CHannel). ' ( );
- SACCH (. Slow Associated Control CHannel). SDCCH. SACCH , , ' ( ). SACCH (. timing advance);
- FACCH (. Fast Associated Control CHannel). ' . , ', , , . 20- ( ) . SF .