modul 3 gsm procedures
DESCRIPTION
Explain basic GSM (LAC, CI, Handover, etch)TRANSCRIPT
GSM-GPRS Operation
GSM Procedures
Module 3
Outline
Network Identity Parameters Idle Mode Operations Location Update Handover
GSM-GPRS Operation
Network Identity Parameter
Network Identification Parameters
Untuk mengidentifikasi setiap elemen jaringan pada suatu wilayah/area tertentu, GSM membuat suatu penomoran yang bertujuan untuk : Memampukan MS secara benar mengidentifikasi ID
jaringan pada saat ini,
Memampukan jaringan mendapatkan informasi secara real time keberadaan geografis sebuah MS.
Memampukan MS melaporkan secara benar informasi tentang suatu cell dan tetangganya, sehingga jaringan dapat melakukan proses handover untuk menjaga kontinuitas percakapan.
CGI MCC MNC LAC CI
LAI
CC NDC SNMSISDN
MCC MNC MSINIMSI
X1 X2 X3 X4 X5 X6 X7 X8HLR-ID
Introduction: Codes & Identities
International
Area LayananKode
National
MCC: Mobile Country Code
CC: Country Code
1 OperatorPLMNMNC: Mobile Network Code
NDC: National Destination Code
MSC / SGSN „Switch“
Location Area LALA1
LA2
LAC: Location Area Code
LAI: Location Area Identity
Cell CI: Cell Identity
CGI: Cell Global Identity
MSC-Identity
Hierarki Area
Layanan/ Kode GSM
Kode Negara & PLMN
IndonesiaCC = 62
MCC = 510 XL
INDOSAT
Telkomsel
NDC = 817,818,819MNC = 11
NDC = 855,856,815,816MNC = 10
NDC = 811,812,813,852MNC = 01
CC NDC SNSubscriber Number
MSISDNMobile Subscriber ISDN Number
MCC MNC MSINMobile Subscriber Id. No.
IMSIInternational Mobile Subscriber Identity
X1 X2 X3 X4 X5 X6 X7 X8HLR-ID
Subscriber Identities
Identifier:MSC / VLR - IdentityLAI = MCC + MNC + LACCGI = LAI + CI
MSC / VLR
MSC / VLR
MSC / VLR
MSC / VLR
MSC / VLR
LALA
LA
LA
LA
CellCell
MCC MNC LAC CI
LAI
MSC, Location & Cell Area
Cell Global Identity (CGI)
CGI MCC MNC LAC CI
LAI = Location Area Identity
ITU mengatur pengalokasian MCC. MCC Indonesia adalah 510 (decimal).
MNC diatur oleh regulator di tiap negara. LAC dikodekan secara berbeda setiap negara. Biasanya,
location area harus cukup luas. Dua atau lebih cell yang berada pada area yang sama
tidak diperbolehkan memiliki CI yang sama.
Setting CGI:
CGI• MCC = Mobile Country Code: berisi 3 digit desimal,
bernilai 000 - 999.
• MNC = Mobile Network Code: berisi 2 digit desimal, bernilai 00 - 99.
• LAC = Location Area Code :
bernilai antara 1-65535.
• CI = Cell Identity:
bernilai antara 0-65535.
Country MCC Operator MNCIndonesia 510 TELKOMSEL 01
INDOSAT 10
XL 11
China 460 CHINA UNICOM 01
CHINA MOBILE 02
Myanmar 410 MPT 00
Srilanka 403 CELLTEL 00
Role of CGI
• Informasi CGI dikirimkan secara broadcast pada setiap cell.
• Ketika MS menerima informasi sistem, MS akan meng-ekstrak informasi CGI dan menentukan cell berdasarkan MCC dan MNC yang di-spesifikasi-kan dalam CGI.
• Dalam saat yang sama, hal ini juga menentukan apakah location area-nya berubah atau tidak, kemudian menentukan apakah perlu dilakukan proses location update. Selama proses location update, MS akan melaporkan ke jaringan mengenai cell mana yang melayani dia pada saat itu.
Mobilestation
Basestation
Category Logical Channel
SYNC CHANNEL INFORMATION
Carrier sine wave
SYSTEM INFORMATION TYPE3
CHANNEL REQUEST
IMMEDIATE ASSIGNMENT
LOCATION UPDATING REQUEST
AUTHENTICATION REQUEST
CIPHERING MODE COMMAND
CIPHERING MODE ACK
LOCATION UPDATING ACCEPT
TMSI ALLOCATION COMPLETE
AUTHENTICATION RESPONSE
CHANNEL RELEASE
RRM
RRM
RRM
RRM
MMMMMM
MM
MM
RRMRRM
RRM
FCCH
SCH
BCCH
RACH
AGCH
SDCCH
SDCCHSDCCH
SDCCH
SDCCH
SDCCH
SDCCH
SDCCH
Prosedur Location-Update
BSIC (Base Station Identity Code)
Para sistem GSM, masing-masing BTS dialokasikan suatu kode “color code” yg disebut base station identity code (BSIC).
Jika pada suatu saat, sebuah MS dapat menerima BCCH TRX dari dua cell pada saat yang bersamaan dan memiliki nomor kanal yang sama, maka MS akan membedakan dua cell tersebut berdasarkan BSIC.
NCC bernilai 0-7. BCC berilai 0-7.
BSIC NCC BCCNCC = Network Color Code
BCC = Base Station Color Code
BSIC = NCC and BCC
In the connection mode (during conversation), the MS must measure the signals in the adjacent cells and report the result to the network.
As each measurement report sent by the MS can only contain the contents of six cells, so it is necessary to control the MS so as to only report the information of cells factually related to the cell concerned. The high 3 bits (i.e. NCC) in the BSIC serve this purpose.
The BCC is used to identify different BS using the same BCCH in the same GSM PLMN.
BSIC Configuration Principle
CBA
FED
In general, it is required that Cells A, B, C, D, E
and F use different BSIC. When the BSIC resources are not enough, the cells close to each other may take the priority to use different BSIC.
GSM-GPRS Operation
Idle Mode Operation Parameter Example
The Purposes
Secondly, the parameters related to idle mode operation must be specified.
Idle mode signalling is directly relevant to LA design, and dedicated mode signalling is relevant to measurement reporting, HOC, and POC.
When the mobile station is in idle mode, it needs some information from the network in order to know the right frequencies, and find the right cells and channel configuration.
IDLE MODE OPERATION
When the MS is switched ONWhen there is no dedicated connection
To camp on the best suitable cell
For MS to receive system info from the NW on DLFor MS to be able to initiate a call whenever neededFor the NW to be able to locate the MS when there is a MT call/SMS
When?
Why?
Why to camp on a specific cell?
Idle Mode Operation ProcedureSearch all the RF channels , take samples during
3-5 s and calculate averages. And put them in ascending order with respect to signal level.
Then tune to the strongest RF channel.
Search for the frequency correction burst in that carrier in order to varify if it is a BCCH carrier
Camp on the cell
Try to synchronize to the carrier and read the BCCH data.
Is it a BCCH carrier?
Is it a correct PLMN ?
Is the cell barred?
Is C1>0
Tune to the next highest RF channel which is not
tried before
No
No
NoNo
Yes
Yes
Yes
Yes
locationAreaId
• ncc (Network Colour Code) 0 … 7• bcc (BTS Colour Code) 0 … 7
bsIdentityCode
cell-ID 0 … 65535
Parameter Value
trainingSequenceCode 0 … 7
IDLE MODE OPERATION ID's and ID Codes
• mcc (Mobile Country Code) 0 … 999• mnc (Mobile Network Code) 0 … 99• lac (Location Area Code) 0 … 65535
Cell Global Identity MCC + MNC + LAC + CI
IDLE MODE OPERATIONIDLE MODE OPERATIONBaseStation Identity Code (BSIC)BaseStation Identity Code (BSIC)
• BSIC is a combination of NCC and BCC
• Reported in Measurement Results to BSC
• Can be listed in Hex or Decimal
NCC (0...7) BCC (0...7)4 2 U 4 2 U32 16 8 4 2 U Range0 0 0 x x x 0 - 70 0 1 x x x 8 - 150 1 0 x x x 16 - 230 1 1 x x x 24 - 311 0 0 x x x 32 - 391 0 1 x x x 40 - 471 1 0 x x x 48 - 551 1 1 x x x 56 - 63
IDLE MODE OPERATIONBase Station Colour Code
MNC = Operator e.g Telkomsel
MCC = Country e.g Indonesia
LAC 1 = Jakarta LAC 2
LAC 3 LAC 4
f1
f2
f3
f1
f1
bcc = 1
bcc = 2
bcc = 3
Neighbour list of f3:f1f2...
Location Area Code
BSC
BTS BTS BTS
1 2 n
initialFrequency 1 ... 124 GSM 900 512 … 885 GSM 1800
512 … 810 GSM 1900
Parameter Value
bCCHAllocation-ID 1 ... 128 in GSM
bCCHAllocationList 1 ... 124 in GSM ( max. 32 freq. for all bands)
idleStateBCCHAllocation 0 (BCCH list is taken from the adjacent cell) 1 ... 128 (number of the BCCH list used)
measurementBCCHAllocation Dedicated ModeADJ (BCCH frequency list taken from adj. cell)IDLE (active MS uses the same list as MS
in IDLE mode)
IDLE MODE OPERATION Frequencies
plmnpermitted 0 ... 7
Parameter Value
NOTE This parameter is confusing. It’s not used for network selection. It’s used AFTER a network has been selected so that only measurements from one PLMN are reported
IDLE MODE OPERATION PLMN Selection
Two Modes Automatic Manual
Three Types of Lists Preferred Found Forbidden
IDLE MODE OPERATION Cell Selection in Idle Mode
Two methods:a) Normal cell selection
b) Stored list cell selection (opt)
If no suitable cell found with method b) then a) is tried.
• timerPeriodicUpdateMS 0.0 ... 25.5 (hours)• allowIMSIAttachDetach Yes/No
Parameter Value
IDLE MODE OPERATION Location Update
MS => MSC / VLR Mobile Station switched ON
No IMSI Attach / Detach Same Location Area => No Location Update Different Location Area => Location Update
Change of the Location Area Location Area under the same MSC / VLR Location Area under another MSC /VLR => HLR will be updated
Service is rejected (MS unknown in VLR) Time Periodic (MS -> MSC/VLR)
GSM-GPRS Operation
Procedures
Location Update Handover
LAI =2620533
MS
BTS
BCCH:CGI =
26205A64B...
LocationRegistration/
Update
• Location Registration: initial MS registration in PLMN• Location Update• no LU during connection!
requestLocation Update
3 types of Location Update:• normal• periodic• with IMSI attach
Intra-cell
BSCBTS
f 1, TS 1
f 2, TS 2
Intra-BSS
BSC
BTS
BTS
MSC
Handoverperformed
Intra-MSC
MSC
BSS
BSS
Inter-MSC
MSC - BMSC - A
MSC - C
basic
subsequent
MSC
Handoverperformed
Handover
Measurement:connection quality & strength:
strength of serving BTS &surrounding BTSs
HandoverDecision
MS
Measurement:connection quality & strength,distance measurement (TA)
BTS
Measurement report
Timing Advance,Power control
BSC
HOdecision
Measurement value processing(averaging, limit values,..)
Evaluation list(suitable BTSs for HO...)
Initiation of HO type
HandoverBSC/MSC
Measurementreport
GSM-GPRS Operation
End of Section 3
GSM Procedures