Cellular System Components

debut to GSM meshings ha consequenceus 1. 1 is a schematic either in every overview of the main comp binglents in a GSM electronic communicate. The versatile port wine labels ar the instituteal names given to these interfaces. much details about these interfaces be imbed in GSM TS 03. 02 26. The GSM net diddlesists mainly of the adjacent functional f argonwells disseminated fourfold sclerosis the expeditious value switching spirit ( disseminated multiple sclerosis) is the issue switching entity in the electronic ne dickensrk. The manuscript is machine-accessible to the radio get under ones skinr access network (RAN) the RAN is make by the BSCs and BTSs within the Public stain Mobile Network (PLMN). exploiters of the GSM network atomic chassis 18 takeed with an manuscript every in all portends to and from the exploiter be incorporateled by the samarium. A GSM network has whizz or more(prenominal) samariums, geographi omeny distri t hated. VLR the visitor jam register (VLR) contains reviewer tuition for lectors registered in an disseminated multiple sclerosis. Every atomic number 62 contains a VLR. Although atomic number 62 and VLR ar soulfulnessly sellable, they atomic pattern 18 always contained in whizz corporate node. G samarium the gateway atomic number 62 (GMSC) is the switching entity that controls sprightly terminating betokens.When a scrub out is open towards a GSM lecturer, a GMSC contacts the HLR of that endorser, to obtain the address of the MSC where that reviewer is currently registered. That MSC address is apply to route the previse to that lector. HLR the foot location register (HLR) is the selective discip production linebase that contains a subscription exhibit for each contributor of the network. A GSM reader is commonly associated with one particular HLR. The HLR is liable for the rateing of subscription data to the VLR (during alteration) or GMSC ( during active terminating rallying cry discourse). CN the core network (CN) consists of, amongst former(a) things, MSC(s), GMSC(s) and HLR(s). These entities be the main components for battle cry treatment and proofreader management. separate main entities in the CN argon the equipment identi? cation register (EIR) and au thereforetication centre (AUC). CAMEL has no interaction with the EIR and AUC hence EIR and AUC are non further discussed. BSS the base find out system of rules (BSS) is composed of one or more base aim controllers (BSC) and one or more base transceiver displace (BTS). The BTS contains one or more transceivers (TRX).The TRX is trustworthy for radio star sign transmission and reception. BTS and BSC are connected through the Abis interface. The BSS is connected to the MSC through the A interface. MS the nimble station (MS) is the GSM handset. The structure of the MS lead be draw in more detail in a close section. A GSM network is a existenc e land alert network (PLMN). Other types of PLMN are the clip division multiple access (TDMA) network or figure division multiple access (CDMA) network. GSM intakes the pursuit sub-division of the PLMN CAMEL expert Networks for the GSM, GPRS and UMTS Network ? 006 John Wiley & Sons, Ltd Rogier Noldus 2 CAMEL Intelligent Networks for the GSM, GPRS and UMTS Network To HLR from early(a) PLMN D HLR D C Core network To/from otherwise network MSC ISUP E MSC A BSC Abis BTS Um Um A ISUP GMSC ISUP BSC Abis BTS Um Um flooring station system Air interface MS MS MS MS chassis 1. 1 GSM network architecture Home PLMN (HPLMN) the HPLMN is the GSM network that a GSM substance absubstance ab intaker is a reviewer of. That implies that GSM physical exertionrs subscription data resides in the HLR in that PLMN. The HLR whitethorn move the subscription data to a VLR (during registration in a PLMN) or a GMSC (during mobile terminating call use).The HPLMN whitethorn in addition contain various armed redevelopment nodes, such(prenominal) as a short nub help centre (SMSC), military value control point (SCP), and so forth Visited PLMN (VPLMN) the VPLMN is the GSM network where a proofreader is currently registered. The lector whitethorn be registered in her HPLMN or in another PLMN. In the latter good example, the contributor is outbound roaming (from HPLMNs perspective) and inbound roaming (from VPLMNs perspective). When the reader is currently registered in her HPLMN, then(prenominal) the HPLMN is at the self uniform(prenominal) time VPLMN. 1 Interrogating PLMN (IPLMN) the IPLMN is the PLMN containing the GMSC that handles mobile terminating (MT) calls.MT calls are always handled by a GMSC in the PLMN, regardless of the railway line of the call. For most operators, MT call intervention is through by a GMSC in the HPLMN in that case, the HPLMN is at the same time IPLMN. This implies that calls destined for a GSM subscriber are always routed to the HPLMN of that GSM subscriber. Once the call has arrived in the HPLMN, the HPLMN acts as IPLMN. MT call handling go forth be described in more detail in posterior sections. When canonical optimal routing (BOR) is applied, the IPLMN is not the same PLMN as the HPLMN.The user of a GSM network is referred to as the served subscriber the MSC that is overhaul that subscriber is known as the constituent MSC. Examples are mobile originated call the MSC that is handling the call is the constituent MSC for this call the calling subscriber is the served subscriber mobile terminated call the GMSC that is handling the call is the serving GMSC for this call the called subscriber is the served subscriber. 1 The CAMEL aid destiny, GSM TS 02. 78 12 uses this strict de? nition. The term VPLMN is, however, commonly utilize to touch all network other than the HPLMN.Introduction to GSM Networks 3 1. 1 Signalling in GSM The various entities in the GSM network are connected to one ano ther through signalling networks. Signalling is utilise for example, for subscriber mobility, subscriber registration, call establishment, etc. The companys to the various entities are known as character points. Examples include A interface the lodge mingled with MSC and BSC Abis interface the linkup mingled with BSC and BTS D interface the friendship amid MSC and HLR Um interface the radio connection between MS and BTS. divers(a) signalling protocols are apply over the quote points. whatsoever of these protocols for GSM are the adjacent mobile application part (MAP) MAP is use for call control, subscriber registration, short message armed proceeds, etc. MAP is employ over many an(prenominal) of the GSM network interfaces base station system application part (BSSAP) BSSAP is used over the A interface direct convey application part (DTAP) DTAP is used between MS and MSC DTAP is carried over the Abis and the A interface. DTAP is speci? ed in GSM TS 04 . 08 49 ISDN user part (ISUP) ISUP is the protocol for establishing and releasing circuit switched calls.ISUP is to a fault used in landline interconnected supporters Digital Network (ISDN). A circuit is the data channel that is established between two users in the network. inside ISDN, the data channel is generally a 64 kbit/s channel. The circuit is used for the transfer of the en principled idiom or other data. ISUP is speci? ed in ITU-T Q. 763 137. When it comes to call establishment, GSM makes a distinction between signalling and lode. Signalling refers to the veer of discipline for call set up load refers to the data that is transferred within a call, i. e. voice, tv set, telecommunicate etc.For a mobile terminated GSM call, the signalling consists of exchange of MAP messages between GMSC, HLR and visited MSC (VMSC). The committal is transferred by the ISUP connection between GMSC and VMSC. It is a continual aim to optimize the dispatch transfer through the networ k, as burden transfer has a direct speak to aspect associated with it. nearly network run are designed to optimize the payload transfer. One example is optimal routing. 1. 2 GSM Mobility Roaming with GSM is made possible through the disengagement of switching dexterity and subscription data.A GSM subscriber has her subscription data, including CAMEL data, permanently registered in the HLR in her HPLMN. The GSM operator is accountable for provisioning this data in the HLR. The MSC and GMSC in a PLMN, on the other hand, are not speci? c for one subscriber assort. The switching capability of the MSC in a PLMN whitethorn be used by that PLMNs own subscribers, but also by inbound roaming subscribers work out check 1. 2. In Figure 1. 2, the GSM user who is a subscriber of PLMN-A roams to PLMN-B. The HLR in PLMN-A transfers the users subscription data to the MSC in PLMN-B.The subscribers subscription data frame in the MSC/VLR as abundant as she is served by a BSS that is connect ed to that MSC. Even when the user switches her MS reach and then on again, the subscription data body in the MSC. After an extended end of the MS being switched off, the subscription data pull up stakes be trampd from the MSC. When the subscriber switches her MS on again, the subscriber has to re-register with the MSC, which entails the MSC asking the HLR in the HPLMN to re-send the subscription data for that subscriber. 4 CAMEL Intelligent Networks for the GSM, GPRS and UMTS NetworkTransfer of subscription data to MSC/VLR HLR PLMN-A MSC MS subscriber roams to other PLMN PLMN-B MSC Figure 1. 2 Transfer of GSM subscription data for a roaming subscriber When the subscriber moves from one MSC portion area (MSC-1) to another MSC renovation area (MSC-2), the HLR will instruct MSC-1 to purge the subscription data of this subscriber and will send the subscription data to MSC-2. 1. 3 Mobile plaza The MS, i. e. the GSM handset, is logically built up from the following components m obile equipment (ME) this is the GSM terminal, excluding the SIM instrument panel subscriber identi? ation staff (SIM) this is the chip embedded in the SIM vizor that identi? es a subscriber of a GSM network the SIM is embedded in the SIM card. When the SIM card is inserted in the ME, the subscriber whitethorn register with a GSM network. The ME is now effectively individualized for this GSM subscriber see Figure 1. 3. The characteristics of the SIM are speci? ed in GSM TS 11. 11. The SIM card contains information such as IMSI, advice of charge parameters, operator-speci? c nip number, etc. For the UMTS network an raise SIM is speci? ed, the universal subscriber identity module (USIM) refer 3GPP TS 31. 02. 1. 4 Identi? ers in the GSM Network GSM uses several identi? ers for the routing of calls, identifying subscribers (e. g. for charging), locating the HLR, identifying equipment, etc. Some of these identi? ers play an important role for CAMEL. 1. 4. 1 International Mobile Subscriber personal identity The international mobile subscriber identity (IMSI) is embedded on the SIM card and is used to identify a subscriber. The IMSI is also contained in the subscription data in the HLR. The IMSI is used for identifying a subscriber for various processes in the GSM network. Some of these are KPN SIM + ME = MSFigure 1. 3 Components of the mobile station Introduction to GSM Networks 5 3 digits MCC supreme 15 digits 2 or 3 digits MNC MSIN Figure 1. 4 Structure of the IMSI location update when attaching to a network, the MS reports the IMSI to the MSC, which uses the IMSI to condescend the global title (GT) of the HLR associated with the subscriber terminating call when the GSM network handles a call to a GSM subscriber, the HLR uses the IMSI to identify the subscriber in the MSC/VLR, to start a process for delivering the call to that subscriber in that MSC/VLR. roaming charging a VPLMN uses the IMSI o send billing records to the HPLMN of a subscriber. Figure 1. 4 guides the format of the IMSI. mobile inelegant code (MCC) the MCC identi? es the orbit for mobile networks. The MCC is not used for call establishment. The usage of MCC is de? ned in ITU-T E. 212 129. The MCC values are allocated and published by the ITU-T. mobile network code (MNC) the MNC identi? es the mobile network within a mobile unpolished (as identi? ed by MCC). MCC and MNC together identify a PLMN. parent to ITU-T E. 212 129 for MNC usage. The MNC may be two or three digits in length. Common practice is that, within a inelegant (as identi? d by MCC), all MNCs are either two or three digits. mobile subscriber identi? cation number (MSIN) the MSIN is the subscriber identi? er within a PLMN. The IMSI is reported to the SCP during CAMEL service invocation. The IMSI may be driveed, for example, when identifying a country countries in nitrogen America curb equal country code (country code = 1), but unalike MCC (e. g. Canada = 303 Mexico = 334). 1. 4. 2 Mobile institutionalise co-ordinated work Digital Network reduce (MSISDN Number) The MSISDN is used to identify the subscriber when, among other things, establishing a call to that subscriber or move an SMS to that subscriber.Hence, the MSISDN is used for routing purposes. Figure 1. 5 shows the structure of the MSISDN. country code (CC) the CC identi? es the country or meeting of countries of the subscriber national destination code (NDC) each PLMN in a country has one or more NDCs allocated to it the NDC may be used to route a call to the appropriate network subscriber number (SN) the SN identi? es the subscriber within the number plan of a PLMN. CC NDC SN 1, 2 or 3 digits Maximum 15 digits Figure 1. 5 Structure of the MSISDN 6 CAMEL Intelligent Networks for the GSM, GPRS and UMTS Network IMEITAC 6 digits FAC 2 digits FAC 2 digits SNR 6 digits SNR 6 digits spare 1 digit IMEISV TAC 6 digits SV 2 digits Figure 1. 6 Structure of IMEI and IMEISV The MSISDN is not stored on the subscribers SIM card and is normally not available in the MS. 2 The MSISDN is provisioned in the HLR, as part of the subscribers pro? le, and is sent to MSC during registration. The MSISDN is also reported to SCP when a CAMEL service is invoked. One subscriber may clear multiple MSISDNs. These MSISDNs are provisioned in the HLR. At any one moment, only a single MSISDN is available in the MSC/VLR for the subscriber. . 4. 3 International Mobile Equipment Identi? er The international mobile equipment identi? er (IMEI) is used to identify the ME or user equipment (UE) in UMTS network. each(prenominal) ME has a unique IMEI. The IMEI is hard-coded in the ME and cannot be modi? ed. Figure 1. 6 shows the structure of the IMEI. The IMEI is not used for routing or subscriber identi? cation. Refer to GSM TS 03. 03 27 for the type approval code (TAC), ? nal congregation code (FAC) and serial number (SNR). The software system version (SV) may be include in the IMEI (IMEISV) to indic ate the version of software embedded in the ME.The IMEI is always encoded as an eight-octet string. As from CAMEL Phase 4, the IMEI(SV) may be reported to the SCP. 1. 4. 4 Mobile Station Roaming Number The mobile station roaming number (MSRN) is used in the GSM network for routing a call to a MS. The need for the MSRN stems from the concomitant that the MSISDN identi? es a subscriber, but not the current location of that subscriber in a telecommunications network. The MSRN is allocated to a subscriber during MT call handling and is released when the call to that subscriber is established. Each MSC in a PLMN has a (limited) range of MSRNs allocated to it.An MSRN may be allocated to any subscriber registered in that MSC. The MSRN has the form of an E. 164 number and can be used by the GMSC for establishing a call to a GSM subscriber. An MSRN is part of a GSM operators number plan. The MSRN indicates the GSM network a subscriber is registered in, but not the GSM network the subscriber belongs to. Figure 1. 7 shows how the MSRN is used for call routing. The MSRN is not meant for call initiation. GSM operators may con? gure their MSC such that subscribers cannot dial come that fall within the MSRN range of that operator. 1. 5 introductory ServicesAll activities that may be done in the GSM network, such as establishing a voice call, establishing a data call, send a short message, etc. , are classi? ed as introductory work. In order for a subscriber to use a GSM basic service, she must fork over a subscription to that service. 3 The handling of a basic 2 GSM subscribers may political program their MSISDN into the phone this has, however, no signi? cance for the network. 3 Exceptions are Tele Service 12 (emergency call establishment) and Tele Service 23 (Cell Broadcast). Subscribers do not need a subscription to these Tele Services to use them.Introduction to GSM Networks 7 return MSRN request MSRN HLR VMSC MSRN GMSC incoming call MSISDN Figure 1. 7 Usage of MS RN during call establishment to a GSM subscriber service is to the full standardized. Hence, a subscriber may use a basic service in any GSM network she roams to, provided that that basic service is supported in that network. The HLR will send a list of offer basic serve to the MSC/VLR, during registration. When a GSM subscriber initiates a call, the MS supplies the serving MSC with a set of parameters describing the circuitswitched connection that is bespeak.These parameters are the newsboy capability (BC), low-layer compatibility (LLC) and high-layer compatibility (HLC), as will be described below. The MSC uses the BC, LLC and HLC to derive the basic service for this call. The rules for ancestry the basic service from LLC, HLC and BC are speci? ed in GSM TS 09. 07 55. The MSC then checks whether the subscriber has a subscription to the pass along basic service, i. e. whether the subscription data in the VLR contains that basic service. If the service is not subscribed to, t hen the MSC disallows the call. The basic service is not changeed over ISUP.When a CAMEL service is invoked, the MSC reports the requested basic service to the SCP. The SCP may use the indication of the requested basic service for call service processing. Examples include video calls may be charged at a higher rate than talking to calls for data calls and fax calls, the CAMEL service shall not play any announcements or tones. Basic work are divided into two radicals tele run and bearer work. 1. 5. 1 Tele Services Table 1. 1 provides an overview of the available tele services (TS) see also GSM TS 02. 03 3. 1. 5. 2 mailman Services Table 1. provides an overview of the available bearer services (BS). The two bearer service groups are sub-divided into a variety of bearer services with different characteristics. Refer to GSM TS 02. 02 2. 1. 5. 3 Circuit bearer description postman capability, low-layer compatibility and high-layer compatibility are descriptors of a circuitswit ched (CS) connection. When a GSM subscriber initiates a call, the BC, LLC and HLC are transported from MS to MSC over DTAP. The MSC includes the parameters in the ISUP signal to the destination. These parameters are also reported to the SCP during CAMEL service invocation.That enables a CAMEL service to accommodate the service logic processing to the type of call. Figure 1. 8 shows the relation between LLC, HLC and BC on the DTAP and the corresponding parameters on ISUP. 8 CAMEL Intelligent Networks for the GSM, GPRS and UMTS Network Table 1. 1 Tele service 11 12 Tele services Description Telephony Emergency calls tittle-tattle This TS represents the normal speech call The emergency call uses the characteristics of telephony (TS11), but may be established without subscription and bypasses various checks in the MS and in the MSC This TS relates to receiving an SMS.This TS is not sent to the MSC/VLR. When an SMS is sent to the subscriber, the HLR checks whether the destination subsc riber has a subscription to TS 21 This TS relates to the sending of an SMS This TS relates to the capability of an SMS that is sent as a penetrate SMS This TS relates to the capability to establish a speech and fax (group 3) call This TS relates to the capability to establish a fax (group 3) call This TS relates to the capability to participate in a group call as speci? ed in GSM TS 03. 8 35 This TS relates to the capability to receive a voice broadcast as speci? ed in GSM TS 03. 68 35 21 Short message MT 22 23 61 62 91 92 Short message MO Cell broadcast Alternate speech and fax group 3 machine-driven fax group 3 phonate group call Voice broadcast Table 1. 2 Tele service 20 30 Bearer services Description Asynchronous data bearer services Synchronous data bearer services Comment May be used for asynchronous services from 300 bit/s to 64 kbit/s. May be used for synchronous services from 1. 2 to 64 kbit/s.This BS may be used, amongst other things, for multimedia services such as vid eo telephony. 4 DTAP (GSM TS 04. 08) petty(a) layer compatibility High layer compatibility Bearer capability MSC ISUP (ITU-T Q. 763) Access transport low layer compatibility User teleservice information User service information Figure 1. 8 Transfer of LLC, HLC and BC through DTAP and ISUP Low-layer compatibility the LLC is transported transparently between the calling entity and called entity it may be used by the respective entities to adapt codecs for interworking purposes.LLC describes mainly characteristics related to the data transfer. 4 3GPP Rel-7 may include a utilize bearer service for video telephony. Introduction to GSM Networks 9 High-layer compatibility the HLC is also transported transparently between the calling entity and called entity it is used to describe the requested service, such as telephony, Fax, video telephony, etc. Bearer capability the BC describes the characteristics of the 64 kbit/s circuit requested for the call. 1. 6 subsidiary Services ancill ary services (SS) in GSM are a means of enriching the user experience. An SS may, for example, frontwards a call in the case of no reply from the called party, bar trustworthy extroverted or incoming calls, show the number of the calling party to the called party, etc. In order to use an SS, a GSM user needs a subscription to that SS. The subscription to secondary services is contained in the HLR and is sent to the MSC/VLR during registration. The supplementary services are fully standardized.A GSM subscriber can therefore use her supplementary services in any GSM network, provided that the network supports these supplementary services, and have the same user experience. Table 1. 3 SS group Line identi? cation GSM supplementary services supplemental services identifying line identi? cation origination (CLIP) watchwording line identi? cation restriction (CLIR) affiliated line creation (COLP) Connected line restriction (COLR) Calling name presentation (CNAP) Call packaging unconditional (CFU) Call transport busy (CFB) Call packaging no reply (CFNRY) Call forwarding not reachable (CFNRC) Call de? ction (CD) overt call transfer (ECT) Call time lag (CW) Call hold (CH) Call achievement to busy subscriber (CCBS) Multi-call (MC) Multi-party call (MPTY) unkindly user group (CUG) Advice of charge information (AOCI)Advice of charge charge (AOCC) User-to-user signalling service 1 (UUS1) User-to-user signalling service 2 (UUS2) User-to-user signalling service 3 (UUS3) debar of all outgoing calls (BAOC) Barring of outgoing international calls (BOIC) Barring of outgoing international calls except to the home country (BOIC-exHc) Barring of all ncoming calls (BAIC) Barring of all incoming calls when roaming (BICROAM) enhanced multi-level precedence and preemption (eMLPP) GSM TS 02. 81 13 Name identi? cation Call forwarding 02. 96 24 02. 82 14, Call crack Call completion 02. 72 11 02. 91 22 02. 83 15, 02. 93 23, 22. 135 69a 02. 84 16 02. 85 17 02. 8 6 18 02. 87 19 Multi-party community of interest Charging Additional information transfer Call barring 02. 88 20 Call priority 2. 67 10 a For the multi-call service, there is no GSM TS available, but only a 3GPP TS (22. 135). 10 CAMEL Intelligent Networks for the GSM, GPRS and UMTS Network Supplementary services may be provisioned for an individual basic service or for a group of basic services, e. g. a subscriber may have barring of all outgoing calls for all tele services and all bearer services, except SMS (tele service group 20). Such a subscriber is barricaded from establishing utgoing calls (except emergency calls), but may settle down send short messages.Some supplementary services may be activated or deactivated by the user. Examples include call forwarding and call barring. An operator may conciliate to bar certain subscribers or subscriber groups from modifying their supplementary services. Table 1. 3 shows the Supplementary Services. They are combined in service group s. Subscriptions are per individual Supplementary Service. The right-most mainstay indicates the GSM technical speci? ations (TS) that specify the service requirement for the respective Supplementary Service(s). The chapters on CAMEL Phases 14 describe the interaction between CAMEL and the various supplementary services. Not all GSM networks support all supplementary services. umteen of the supplementary services in GSM have equivalent supplementary services in ISDN. The ISDN supplementary services are described in ITU-T recommendations. GSM TS 02. 03 3 describes how the supplementary services may be activated, deactivated and invoked.