6 Basic or Additional Abbrev. System Full component name Platform Basic MSC/VLRGMSCHLRILRAUCEIRDTITRCBSCBTSOMCNMCMCSSPSCPSDPSOGBGWSSBSSOSSMobile service Switching Center/Visitor Location RegisterGateway MSCHome Location RegisterInterworking Location RegisterAuthentication CenterEquipment Identity RegisterData Transmission InterfaceTRanscoder ControllerBase Station ControllerBase Transceiver StationOperation and Maintenance CenterNetwork Management CenterMessage CenterService Switching PointService Control PointService Data PointService Order GatewayBilling GatewayAXEUnix/AXEUnixRBSTMOSMXE
7 Network Structure Cell A cell is the basic unit of a cellular system and is defined as the radio coverage given by one BS antenna system.Each cell is assigned a unique CGI.
8 Network Structure LOCATION AREA A LA is defined as a group of cells.Within the network, a subsriber’s location is known by the LA which they are in.The identity of the LA in which an MS is currently located is stored in the VLR. (LAI)
12 Network Structure PLMN SERVICE AREA A PLMN service area is the entire set of cells served by one network operatorand is defined as the area in which an operator offers radio coverage and access to its network.
13 PLMN Service AreaIIIVIMSCMSCVLRVLRMSCMSCVLRIIIIV
14 Network Structure GSM SERVICE AREA The GSM service area is the entire geographical area in which a subscriber can gain access to a GSM network.
15 Relation between areas in GSM Location AreaCellLocation AreaMSC Service AreaPLMN Service AreaGSM Service Area
16 Mobile Station GSM MSs consist of: Mobile Equipment Subscriber Identity Module
17 Functions of Mobile Station Voice and data transmission& receiptFrequency and time synchronizationMonitoring of power and signal quality of the surrounding cellsProvision of location updates even during inactive state
18 Mobile Station Discontinuous Transmission(DTX) Discontinuous reception(DRX)MS identified by unique IMEISTAR#06#
19 SIM Fixed data stored for the subscription: IMSI, Authentication Key, KiSecurity Algorithms:kc,A3,A8PIN&PUK
20 SIM Temporary network data: Location area of subscriber and forbidden PLMNsService data:language preference, advice of charge
21 KEY TERMS An MS can have one of the following states : Idle: the MS is ON but a call is not in progress.Active: the MS is ON and a call is in progress.Detached: the MS is OFF.
22 The following table defined the key terms used to describe GSM mobile traffic cases (there are no traffic cases in detached mode):ModeTermDescriptionIdleRegistrationRoamingInternational RoamingThis is the process in which an MS informs a network that it is attached.When an MS moves around a network in idle mode, it is referred to as roaming.When an MS moves into a network which is not its home network, it is referred to as international roaming. MSs can only roam into networks with which the home network has a roaming agreement.
23 Mode Term Description Active Location Updating Paging Handover An MS roaming around the network must inform the network when it enters a new LA. This is called location updating.This is the process whereby a network attempts to contact a particular MS. This is achieved by broadcasting a paging message containing the identity of that MS.This is the process in which control of a call is passed from one cell to another while the MS moves between cells.
25 MSISDN Mobile Station ISDN Number 1 to 3 digits Variable Variable CC The MSISDN is registered in the telephone directory and used by the calling party for dialing.MSISDN shall not exceed 15 digits.NDC--National Destination CodeSN--Subscriber Number1 to 3 digitsVariableVariableCCNDCSNMSISDN : not more than 15 digits
26 IMSI International mobile subscriber Identity The IMSI is an unique identity which is used internationally and used within the network to identify the mobile subscribers.The IMSI is stored in the subscriber identity module (SIM), the HLR, VLR database.
27 IMSI 3 digits MCC MNC MSIN 3 digits Not more than 9 digits NMSI IMSI : Max. 15 digitsMCC--Mobile Country Code, MNC--Mobile N/W Code, MSIN--Mobile Station Identification NumberNMSI--National Mobile Station Identity,assigned by Individual Administration.Mobile station Identification Number. It identifies the subs. In a PLMN. First 3 digit identifies the Logical HLR-id of Mobile subs.
28 Temporary Mobile subscriber Identity TMSI is a temporary IMSI no. made known to an MS at registration.The VLR assigns a TMSI to each mobile subscribers entering the VLR area.Assigned only after successful authentication.TMSI has only local significance i.e. within VLR area & controlled by the VLR.TMSI changes on location updation.TMSI is less than 8 digit.
29 MSRN Mobile Station Roaming Number The MSRN is used in the GMSC to set up a connection to the visited MSC/VLR.MSRN--is a temporary identity which is assigned during the establishment of a call to a roaming subs.CCSNNDCCC--Country Code, NDC--National Destination Code, SN– Servicing Node
30 IMEI International Mobile Equipment Identity The IMEI is an unique code allocated to each mobile equipment. It is checked in the EIR.IMEI check ListWhite ListGrey ListBlack List
36 Switching System (SS) SS7 Signalling Traffic Path MSC (PSTN) (BSS) D VLRHLRAUCCFEOtherMSCEIRAMSC(PSTN)(BSS)
37 MSC Functions Switcing and call routing Charging Service provisioning Communication with HLRCommunication with VLRCommunication with other MSCsControl of connected BSCs
38 MSC Functions Echo canceller operation control Signaling interface to databases like HLR, VLR.Gateway to SMS between SMS centers and subscribersHandle interworking function while working as GMSC
39 VISITOR LOCATION REGISTER (VLR) It controls those mobiles roaming in its area.VLR reduces the number of queries to HLROne VLR may be incharge of one or more LA.VLR is updated by HLR on entry of MS its area.VLR assigns TMSI which keeps on changing.IMSI detach and attach operation
40 Data in VLR IMSI & TMSI MSISDN MSRN. Location Area Supplementary service parametersMS categoryAuthentication Key
41 Home Location Register(HLR) Reference store for subscriber’s parameters, numbers, authentication & Encryption values.Current subscriber status and associated VLR.Both VLR and HLR can be implemented in thesame equipment in an MSC.one PLMN may contain one or several HLR.
42 Home Location Register(HLR) Permanent data in HLRData stored is changed only by commands.IMSI, MS-ISDN number.Category of MS ( whether pay phone or not )Roaming restriction ( allowed or not ).Supplementary services like call forwarding
43 Home Location Register(HLR) Temporary data in HLRThe data changes from call to call & is dynamicMSRNRAND /SRES and KcVLR address , MSC address.Messages waiting data used for SMS
44 EQUIPMENT IDENTITY REGISTER ( EIR ) This data base stores IMEI for all registered mobile equipments and is unique to every ME.Only one EIR per PLMN.White list : IMEI, assigned to valid ME.Black list : IMEI reported stolenGray list : IMEI having problems like faulty software, wrong make of equipment etc.
45 AUthentication Center (AUC) To authenticate the subs. attempting to use a network.AUC is connected to HLR which provides it with authentication parameters and ciphering keys used to ensure network security.
46 AUC FunctionsTo perform subscriber authentication and to establish ciphering procedures on the radio link between the network and MS.
47 AUC Functions Information provided is called a TRIPLET consists of: RAND(non predictable random number)SRES(Signed response)Kc(ciphering key)
48 Operations and Maintenance Centre OMC The centralized operation of the various units in the system and functions needed to maintain the subsystems.Dynamic monitoring and controlling of the network
49 Functions Of OMC -Configuration management -O&M data function-Configuration management--Fault report and alarm handling-Performance supervision/management-Storage of system software and data