Modul 3 gsm procedures
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The document discusses GSM-GPRS network operations including: 1. Network identity parameters such as MCC, MNC, LAC, CI which allow identification of network elements and location of mobile stations. 2. Idle mode operations which include cell selection, location updating, and allow mobile stations to receive system information when not in a call. 3. Location update and handover procedures which update the network on a mobile station's location area and allow calls to be maintained as a mobile station moves between cells.
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Modul 3 gsm procedures
- 2. kris.sujatmoko@gmail.com 2 Outline Network Identity Parameters Idle Mode Operations Location Update Handover
- 3. GSM-GPRS Operation Network Identity Parameter
- 4. kris.sujatmoko@gmail.com 4 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.
- 5. kris.sujatmoko@gmail.com 5 CGI MCC MNC LAC CI LAI CC NDC SNMSISDN MCC MNC MSINIMSI X1 X2 X3 X4 X5 X6 X7 X8HLR-ID Introduction: Codes & Identities
- 6. kris.sujatmoko@gmail.com 6 International Area Layanan Kode National MCC: Mobile Country Code CC: Country Code 1 OperatorPLMN MNC: Mobile Network Code NDC: National Destination Code MSC / SGSN „Switch“ Location Area LA LA1 LA2 LAC: Location Area Code LAI: Location Area Identity Cell CI: Cell Identity CGI: Cell Global Identity MSC-Identity Hierarki Area Layanan/ Kode GSM
- 7. kris.sujatmoko@gmail.com 7 Kode Negara & PLMN Indonesia CC = 62 MCC = 510 XL INDOSAT Telkomsel NDC = 817,818,819 MNC = 11 NDC = 855,856,815,816 MNC = 10 NDC = 811,812,813,852 MNC = 01 CC NDC SN Subscriber Number MSISDN Mobile Subscriber ISDN Number MCC MNC MSIN Mobile Subscriber Id. No. IMSI International Mobile Subscriber Identity X1 X2 X3 X4 X5 X6 X7 X8HLR-ID Subscriber Identities
- 8. kris.sujatmoko@gmail.com 8 Identifier: MSC / VLR - Identity LAI = MCC + MNC + LAC CGI = LAI + CI MSC / VLR MSC / VLR MSC / VLR MSC / VLR MSC / VLR LA LA LA LA LA Cell Cell MCC MNC LAC CI LAI MSC, Location & Cell Area
- 9. kris.sujatmoko@gmail.com 9 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:
- 10. kris.sujatmoko@gmail.com 10 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 MNC Indonesia 510 TELKOMSEL 01 INDOSAT 10 XL 11 China 460 CHINA UNICOM 01 CHINA MOBILE 02 Myanmar 410 MPT 00 Srilanka 403 CELLTEL 00
- 11. kris.sujatmoko@gmail.com 11 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.
- 12. kris.sujatmoko@gmail.com 12 Mobile station Base station 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 MM MM MM MM MM RRM RRM RRM FCCH SCH BCCH RACH AGCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH SDCCH Prosedur Location-Update
- 13. kris.sujatmoko@gmail.com 13 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 BCC NCC = Network Color Code BCC = Base Station Color Code
- 14. kris.sujatmoko@gmail.com 14 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.
- 15. kris.sujatmoko@gmail.com 15 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.
- 16. GSM-GPRS Operation Idle Mode Operation Parameter Example
- 17. kris.sujatmoko@gmail.com 17 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.
- 18. kris.sujatmoko@gmail.com 18 IDLE MODE OPERATION When the MS is switched ON When there is no dedicated connection To camp on the best suitable cell For MS to receive system info from the NW on DL For MS to be able to initiate a call whenever needed For 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?
- 19. kris.sujatmoko@gmail.com 19 Idle Mode Tasks PLMN selection Cell selection and reselection Location update
- 20. kris.sujatmoko@gmail.com 20 Idle Mode Operation Procedure Search 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 No No Yes Yes Yes Yes
- 21. kris.sujatmoko@gmail.com 21 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
- 22. kris.sujatmoko@gmail.com 22 IDLE MODE OPERATIONIDLE MODE OPERATION BaseStation 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 U 32 16 8 4 2 U Range 0 0 0 x x x 0 - 7 0 0 1 x x x 8 - 15 0 1 0 x x x 16 - 23 0 1 1 x x x 24 - 31 1 0 0 x x x 32 - 39 1 0 1 x x x 40 - 47 1 1 0 x x x 48 - 55 1 1 1 x x x 56 - 63
- 23. kris.sujatmoko@gmail.com 23 IDLE MODE OPERATION Base 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: f1 f2 ... Location Area Code BSC BTS BTS BTS 1 2 n
- 24. kris.sujatmoko@gmail.com 24 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 Mode ADJ (BCCH frequency list taken from adj. cell) IDLE (active MS uses the same list as MS in IDLE mode) IDLE MODE OPERATION Frequencies
- 25. kris.sujatmoko@gmail.com 25 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
- 26. kris.sujatmoko@gmail.com 26 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.
- 27. kris.sujatmoko@gmail.com 27 • 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)
- 30. kris.sujatmoko@gmail.com 30 LAI = 2620533 MS BTS BCCH: CGI = 26205A64B... Location Registration/ Update • Location Registration: initial MS registration in PLMN • Location Update • no LU during connection! request Location Update 3 types of Location Update: • normal • periodic • with IMSI attach
- 31. kris.sujatmoko@gmail.com 31 Intra-cell BSCBTS f 1, TS 1 f 2, TS 2 Intra-BSS BSC BTS BTS MSC Handover performed Intra-MSC MSC BSS BSS Inter-MSC MSC - BMSC - A MSC - C basic subsequent MSC Handover performed Handover
- 32. kris.sujatmoko@gmail.com 32 Measurement: connection quality & strength: strength of serving BTS & surrounding BTSs Handover Decision MS Measurement: connection quality & strength, distance measurement (TA) BTS Measurement report Timing Advance, Power control BSC HO decision Measurement value processing (averaging, limit values,..) Evaluation list (suitable BTSs for HO...) Initiation of HO type Handover BSC/ MSC Measurement report
- 33. GSM-GPRS Operation End of Section 3 GSM Procedures
Editor's Notes
- {"27":"MODIFIED\nWhen the MS is switched on, the action taken by the location updating process is :\na) SIM present and no LU needed (because of the status of the stored LAI and "attach" flag): The MS is in the update state UPDATED;\nb) SIM present and LU needed: A LU request is made;\nc) No SIM present: The MS enters the update state Idle, NO IMSI.\nFurthermore, an LU request indicating Normal Location Updating is also made when the response to an outgoing request shows that the MS is unknown in the VLR.\nThe timer for the Periodic Location Updating is broadcast by the Nw in the System Info 3 within the CCCH description. This timer is T3212.\nA timer in the MS is started randomly and when it reaches T3212 a Periodic LU is required.\nPeriodic Location Update is a compromise between the load in terms of signalling between the MS and the VLR (!) for frequent periodic LU and the risk of the MS not being reached in case of a MTC if for some reason the information in the VLR looses its validity or is lost.\nThe BCCH will contain an indicator indicating whether or not IMSI attach/detach operation is mandatory :\nallowIMSIAttachDetach\nWhen IMSI attach/detach operation applies, a MS shall send the IMSI detach message to the network when the MS is powered down.\nWhen the MS returns to the active state, the MS shall perform an LU request indicating IMSI attach, provided that the MS still is in the same location area. If the location area has changed, an LU request indicating Normal Location Updating shall be performed.\n","16":"","5":"","33":"","22":"","11":"","28":"","17":"","6":"","23":"TWO SLIDES TOGETHER\n","12":"","1":"","29":"","18":"New\nSummary:\nWhen an MS is switched on, it attempts to make contact with a GSM public land mobile network (PLMN). The particular PLMN to be contacted may be selected either automatically or manually. The MS looks for a suitable cell of the chosen PLMN and chooses that cell to provide available services, and tunes to its control channel. This choosing is known as "camping on the cell". The MS will then register its presence in the registration area of the chosen cell if necessary, by means of a location registration (LR), GPRS attach or IMSI attach procedure. If the MS loses coverage of a cell, it reselects onto the most suitable alternative cell of the selected PLMN and camps on that cell. If the new cell is in a different registration area, an LR request is performed. If the MS loses coverage of a PLMN, either a new PLMN is selected automatically, or an indication of which PLMNs are available is given to the user, so that a manual selection can be made. \n","7":"","24":"InitialFrequency is a TRX parameter that defines the ARFCN in use for that TRX. The problem is when the Cell uses RF Hopping. In that case in fact the frequency is a sort of reference to be used when hopping is disabled.\nBcchAllocationId defined in the BSC, identifies one of 128 lists of frequencies that can be defined in the BSC. \nBcchAllocationListdefined in the BSC, contains a list of ARFCNs, with a maximum of 32 frequencies. They are interpreted by the MS as BCCH frequencies to listen to.\nIdleStateBcchAllocation BTS parameter specifies which set of BCCH frequencies, the MS should listen to.\nMeasurementBcchAllocation specifies if in dedicated mode the MS should use the real list of neighbour or the list of BCCH defined for the idle mode.\n","13":"","2":"","30":"","19":"New\nSo the Idle mode tasks are three.\n","8":"","25":"The MS leaves a PLMN if \na) the user decides so \nb) the serving PLMN cannot give coverage anymore\nThe Home PLMN is always a priority PLMN to select.\nFORBIDDEN PLMN's LIST\nThe set of PLMN where the MS can make roaming is changing all the time. Therefore the information is dynamically handled in the SIM based on the attempts to register in the PLMN.\nWhen the MS finds a new PLMN it may try to register into it the NW rejects the attempt and the PLMN is inserted in the list.\nFOUND PLMN's LIST\nIn manual mode the Mobile scans the GSM band and the list of the PLMNs found is presented to the user, independently from the PLMN being forbidden or not. Then the user can choose one of the PLMN and try the registration.\nPREFERRED PLMN's LIST\nIt's a list of PLMN (at least 8) stored in order of priority in the SIM. The selection of the PLMN in automatic mode will consider the PLMNs of the FOUND LIST and sort them according to the PREFERRED LIST provided that they are not in the FORBIDDEN LIST.\nThe PREFERRED LIST can be created by the Operator and then modified by the subscriber. \nPLMNpermitted is a parameter defined in GSM 05.08 par. 7.2 as a bitmap of 8 bits to select the NCC of the cells that can be measured and reported by the MS in dedicated mode.\n","14":"","3":"","31":"","20":"","9":"","26":"New\nStored list is the list of the BCCH frequencies used in the NW. Maybe achived during the previous contact with that PLMN?????\n","15":"","4":"","32":"","21":"We first mention about the Ids and ID codes which are very important for the identification of network elements.\nAnd frequencies.\nSLIGHTLY MODIFIED\nNetwork Colour Code and Base Station Colour Code form the BSIC and are transmitted on the SCH channel . They are decoded by the MS. Note that they are both coded with 3 bits, but in some cases the 6 bits are put together, thus creating some problems of decoding.\nE.g. BSIC 6,3 = 110 , 011 => 110011 = 51\nFor Broadcast and and common control channels, the Training Sequence Code must be equal to the BCC (GSM 05.02 paragraph 5.2.2)\n","10":""}