, "", MSC - Mobile services Switching Center - . MSC .
MSC GSM .
MSC , (), ..
, NSS:
- HLR - Home Location Register - .
- VLR - Visitor Location Register - ().
HLR "" , . IMSI , MS ISDN - Mobile Subscriber ISDN - , MS .
HLR, , VLR .
VLR MS, ( , , ).
VLR, VLR, .
HLR VLR:
- HLR , ,
- VLR , VLR . HLR VLR, . VLR , , , .
, BSS - Base Station Subsystem - . BSS BSC - Base Station Controller - , BTS - Base Transceiver Station - .
BSC BTS , .. BSC , ( - ).
OMC -Operation and
Meintenance Centre - .
.
MS .
- "", "", .
MS IMSI VLR .
IMSI ( ), , , - . IMSI VLR HLR. HLR VLR, , VLR, , " " .
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:
AuC
128- -RAND - Random number - , MS . SIM Ki ( , SIM) 32- - SRES - Signed RESult :
SRES = Ki RAND
AuC ( HLR Ki ).
SRES SRES, AuC, .
TMSI - Temporary Mobile Subscriber Identity - é () ().
TMSI .
TMSI ( , VLR MS - LA).
, MS - - IMEI, IMEI .
IMEI , EIR, "" :
- "" .
- "" IMEI, - MS.
- "" - "MS "", , .
VLR HLR , - .
. , , - .
MS , , - , - , , . "" MS (, , , ) .
10 ( 0 9). , 11 15 ( , .).
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SIM.
, 10 , ( "112"), - , IMSI (, , SIM-).
.
handover ( ).
BTS - ( BTS - "", ).
BTS - , LA - Location Area - .
LA LAI - Location Area Identity - .
VLR LA.
LAI VLR MS.
LA, , MS .
MS LA VLR / HLR , MS LA, MS .
- LA. LA VLR LAI, LA VLR, VLR HLR.
LA , .
LA MS , , .
LA , , , , LA, .
"handover" - , LA .
(
MS BTS, , MS "" ..) (, , ) . ( , , , handover).
Handover :
- BTS;
- , BSC;
- , - BSC, MSC;
- , BSC, MSC.
, - handover - MSC. , handover, MSC , BSC, MSC . MS BTS ( - 16), .
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, ( ) BSC MSC .
- handover:
- " " - Minimum acceptable performance.
, , . , , ( ), - handover.
- " " - Power budget. , ( handover).
MS, MSC, , .