UMTS Core Network - Unipa.it

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UMTS Core NetworkV. Mancuso, I. Tinnirello

GSM/GPRS Network ArchitectureRadio access networkBSSGSM/GPRS core networkVLRBTSMSGMSCBSCHLRPCUAuCSGSNEIRBTSIP BackboneGGSNdatabaseInternetV. Mancuso, I. TinnirelloPSTN, ISDNMSC

3GPP Rel.’99 Network ArchitectureRadio access networkUTRANRNCIu CSGMSCVLRBSUEMSCHLRIurUuAuCIubRNCBSSGSNEIRIu PSGnIP BackboneGGSNdatabaseInternetV. Mancuso, I. TinnirelloPSTNIubCore network (GSM/GPRS-based)

3GPP RelRel.’99.’99 Network ArchitectureRadio access networkUTRANIubRNCBSUEIurUuIubRNCBSV. Mancuso, I. Tinnirello2G 3GMS UE(User Equipment), often alsocalled (user) terminalNew air (radio) interfacebased on WCDMA accesstechnologyNew RAN architecture(Iur interface is available forsoft handover,BSC RNC)

3GPP Rel.’99 Network ArchitectureCore network (GSM/GPRS-based)MSC is upgraded to 3GMSCIu CSMSCGMSCVLRSGSN is upgraded to 3GSGSNGMSC and GGSN remainthe sameAuC is upgraded (moresecurity features in 3G)HLRAuCSGSNEIRIu PSGnIP BackboneGGSNInternetV. Mancuso, I. TinnirelloPSTNChanges in the corenetwork:

3GPP Rel.4 Network ArchitectureUTRAN(UMTS Terrestrial RadioAccess Network)Circuit Switched (CS) core networkMSCServerGMSCServerNew option in Rel.4:GERAN(GSM and EDGE RadioAccess Network)V. Mancuso, I. TinnirelloMGWSGWMGWPS core as in Rel.’99PSTNSGW

3GPP Rel.4 Network ArchitectureMSC Server takes careof call control signallingThe user connectionsare set up via MGW(Media GateWay)RANAP / ISUPSS7 MTPIPSigtranV. Mancuso, I. TinnirelloMSCServerGMSCServerSGWMGWcoreSGWMGWPS core as in Rel.’99PSTN“Lower layer” protocolconversion in SGW(Signalling GateWay)Circuit Switched (CS)network

3GPP Rel.5 Network ArchitectureUTRAN(UMTS Terrestrial RadioAccess Network)CS coreSGSNGGSNPS coreV. Mancuso, I. TinnirelloHSSInternetGERAN(GSM and EDGE RadioAccess Network)IMS (IPMultimediaSystem)MGWPSTNNew corenetwork part:

3GPP Rel.5 Network ArchitectureInterworking with thePSTN may be requiredfor some time .V. Mancuso, I. TinnirelloMGWIMS (IPMultimediaSystem)SGSNHSSGGSNPS coreInternet / other IMSCall/session controlusing SIP (SessionInitiating Protocol)CS corePSTNThe IMS can establishmultimedia sessions(using IP transport)via PS core betweenUE and Internet (oranother IMS)

New Service ConceptContent providerContent providerService providerService providerCarrier providerEnd userV. Mancuso, I. TinnirelloEnd userall want to makeprofit

OSA (Open Services Architecture/Access)OSA is being standardised, so that services provided bydifferent service/content providers can be created andseamlessly integrated into the 3G network (this is themeaning of “open” architecture)OSA means in practice:Service Creation Environment (SCE)APIAPI3G networkV. Mancuso, I. TinnirelloAPIAPI ApplicationProgrammingInterface(Standardised)

CAMEL (2G & 3G)CAMEL (Customised Applications for Mobile network EnhancedLogic) is a set of “IN” (intelligent network) type functions andprocedures that make operator-specific IN services available tosubscribers who roam outside their home network.CAMEL IN technology global mobilityCAMEL Service Environment (CSE) is a logical entity in thesubscriber’s home network which processes IN relatedproceduresCSE SCP in home networkV. Mancuso, I. Tinnirello

The IMSThe IP Multimedia SubsystemVincenzo Mancuso, PhDV. Mancuso, I. Tinnirello

The IMS The Third generation networks aim to mergetwo most valuable resources in communicationtechnology, along with local PSTN networks Cellular Networks The Internet Use packet switching, IP The IP Multimedia Subsystem or IMS is the solution to integrate allthe services that the internet provides with the cellular and othernetworks Triple Play: coordination of voice, video and dataV. Mancuso, I. Tinnirello

IMS ValueValue-added services IMS also can provide integratedservice to the user Third party developed services can be provided byoperators, thus developing value-added services Appropriate charging for multimedia sessions,according to the content and the service offeredV. Mancuso, I. Tinnirello

IMS Service Integration ProblemStatement:variousnetworks providing services have a“vertical infrastructure” no horizontal links between networks The challenge: to integrate thesenetworks and to create newapplications that would provideservicetonextgenerationnetworksV. Mancuso, I. Tinnirello

Component #1: the mediatransport After many other services,introduction of real timevoice/video on Internet The 1st problem is easy: howto transmit voice/video?IP packetsCodecRTPUDPIP RTP (Real-Time Protocol) is a protocol whichtransports an encoded multimedia stream aspieces, with a timestamp on each piece, and sendsthem using UDP/IP Any encoding is permitted for voice/video witha Codec: MP3, ACC, MPEG4, AMR Several streams (voice video) can be sent inparallel with the same timestamp The timestamp is used by the receiver to playthe voice/video in a regular way for quality RTP is the media transportV. Mancuso, I. Tinnirello

Component #2: session initiationRegistration of Betty’s phoneand address The 2nd problem is moredifficult: how to initiate thecall? how to know the IPaddress of the called phone? It is necessary to have a table which translates asymbolic name “Betty” into an IP address Each time a terminal service is put on, it mustnotify its presence to update the table So, thanks to an access to this table, it is possibleto make the address resolution : name - IPaddressRegistration of John’s phoneand address The control of the address tablecreates a tough competition V. Mancuso, I. Tinnirello

Why IMS?Solutions to make the address resolutionsMSN, Yahoo, AOL havedesigned a callingarchitecture hypercentralized: 1 tableworldwide, only 1 operatorSkype promotes a hyperdecentralized architecture:1 table per terminal withpeer-to-peer updatebetween terminals“The introduction and development ofsolution like Skype is highly significantas it alters the notion oftelecommunications operators bymaking the process fully electronic“IDATE - ART, 2004Operators dislike such approaches, so they push a wayvery similar to e-mail: centralization per domain. Thisapproach is named “Internet Protocol MultimediaSubsystem”, IMS.V. Mancuso, I. Tinnirello

IMS User IdentitiesSip:[email protected]: [email protected] SubscriberPrivate User IdentitySip:[email protected]: 88028112347Public User IdentitiesV. Mancuso, I. Tinnirello

User Identity Private identity Issued by home provider Used for AAA Saved on ISIM (not modifiable)PublicUser Identity 1PrivateUser Identity 1 Public identity IMSNormal SIP address (URI or TEL)SubscriptionIdentifies the user publiclyUser has one or more identitiesUsed for routingCan be grouped into implicit registration sets If one of the set is registered then the others are as well At least one is stored on ISIMPublicUser Identity 2»PublicUser Identity 4PrivateUser Identity 2PublicUser Identity 5PublicUser Identity 6Use a temporary identity derived from USIM during initial registration (derived fromIMSI)PIDs are then provided by the S-CSCF in its reply to the registrationV. Mancuso, I. TinnirelloImplicitlyRegistered IDSet 1ServiceProfile 2PublicUser Identity 3 In case no ISIM is provided»ServiceProfile 1ImplicitlyRegistered IDSet 2ImplicitlyRegistered IDSet 3ServiceProfile 3ServiceProfile 4

UICCUniversal Integrated Circuit Card Used to store data, including authenticationinformation Contains one or more applications SMSPhonebook SIM GSM Subscriber Identity Module USIM UMTS SIM ISIM IMS SIM Applications are independent SIM, USIM and ISIM can coexist on the same UICC but SIM cannot be used for IMS access (for security reasons)V. Mancuso, I. Tinnirello

IP Multimedia SubsystemAn enablerof newapplicationsNext-gennetworkarchitectureA standardIMSSIPVideo ClipsSports, NewsIP TransportTransport-layerAt HomeSIPOn the MoveConverged ServicesRich CommunicationsSIPSIPSIPIn the OfficeIMS is access agnostic, cost reducing, and serviceenhancingIMS gives the customer & carrier choiceV. Mancuso, I. Push-2-XLocation-Presence, Locationbased ServicesPictureMessaging,MM MessagingStreamingAudio, VideoE-mailIMGames,MusicDownloadsInteractive Services,Interactive Gaming

IMSGoals & ToolsV. Mancuso, I. Tinnirello

IMS goals Combine latest trends in tech Run fast, no time for standardization of services Mobile/Nomadic internet Create a platform for multimediaservices and their development Exploit/allow mobile packetswitching networks Not a mere circuit-switching replacementV. Mancuso, I. Tinnirello

IMS requirements Support for establishing IP MultimediaSessions Audio, video, messaging Support for mechanisms to negotiate QoS distinguish users operators want to control QoS Support for interworking with Internet with packet-switching networks Support for roaming Home and visited network Inter-operators roaming V. Mancuso, I. Tinnirello

IMS requirements (cont’d) Support for user activity control policies imposed by the operator (general policies and per-user policies) accomplish to service agreements Support for fast service creation don’t require service standardization Standardize service capabilities instead Support for multiple access Not only GPRS, UMTS IP is independent on lower protocol layersV. Mancuso, I. Tinnirello

Protocols in IMS 3GPP reuses protocol developed by otherstandards development organizations ETSI (European Telecommunications Standard Institute) IETF (Internet Engineering Task Force) ITU-T (International Telecommunications Union - Telecommunications) 3GPP interacts with standardsdevelopment organizations as for thedevelopment of existing and newprotocols Protocols RTP for media transport Session control protocols AAA protocols OtherV. Mancuso, I. Tinnirello

Session Control Protocol SIP (Session Initiation Protocol, byIETF- RFC2821) Protocol to establish and manage multimedia sessionover IP SIP borrows some design principles from SMTP andHTTP Does not differentiate the user-to-network interface fromthe network-to-network interface (unlike BICC andH.323) It follows the client-server model Text-based protocol Easy to debug, extend and reuse for service buildingV. Mancuso, I. Tinnirello

AAA protocol: DIAMETERone protocol for many interfaces Authorization What service can be used?DiameterClient ApplicationDiameterServer Application Authentication Are you really who you say youare? AccountingSession ManagementSession ManagementRouting ManagementRouting Base ProtocolBase Protocol DIAMETER––––by IETF RFC3588Evolution of RADIUSBase protocolDiameter applications Diameter applications used to customize/extend the base protocol for different interfaces, environments, andapplications E.g.: interact with SIP session setup (Authorization and Authentication) E.g.: interact with the billing subsystem to control accounting E.g.: interact with routing entitiesV. Mancuso, I. Tinnirello

IMS ArchitectureV. Mancuso, I. Tinnirello

New services for mobileand fixed networks Open, standardised, operator friendly, NGNmultimedia architecture for mobile and fixed services Based on SIP, DIAMETER and COPS controls Supports legal interception, localisation, PSTN interworking, etc.Access IndependentApplicationsInternet3G mobileWLANWiMAXDSLFibreEthernetIMS PlatformPSTNIP transportV. Mancuso, I. TinnirelloMGW

Functions and nodes IMS standardizes functions IMS does NOT standardize nodes The IMS Architecture is a collection offunctions linked by standardizedinterfaces A function can be implemented through one or more nodes Multiple functions can share a node Commonly a function per nodeV. Mancuso, I. Tinnirello

A standard architecture forservice IPIP NetworkGGSNPSTN/PLMNCPEV. Mancuso, I. Tinnirello

Access to IMSThe user can connect to an IMS network invariety of ways, all of which use thestandard Internet Protocol (IP) for packetswitching e.g., IMS terminals can register directlyon an IMS network e.g., mobile phones, personal digital assistants (PDAs) and computers even when they are roaming in another network or country (the visitednetwork) The only requirement is that they can use IPv6 (also IPv4 in early IMS)and run SIP user agentsV. Mancuso, I. Tinnirello

Other access examples Fixed access- e.g., Digital Subscriber Line (DSL), cable modems, Ethernet Mobile access e.g., W-CDMA, CDMA2000, GSM, GPRS Wireless access e.g., WLAN, WiMAX Other phone systems like plain oldtelephone service (POTS -- the oldanalogue telephones) or PSTN, H.323and non IMS-compatible VoIP systems,are supported through gatewaysV. Mancuso, I. Tinnirello

IMS functional elementsV. Mancuso, I. Tinnirello

Infrastructure of SIP Proxies(media do not traverse the IMS.)V. Mancuso, I. Tinnirello

IMS Functional Elements Session Management (SIP) Routing Databases Network Interoperability Elements Services and Support Components Charging ComponentsV. Mancuso, I. Tinnirello

Nodes/Functions in the IMS User databases HSS (Home Subscriber Server) SLF (Subscriber Location Function) SIP servers CSCF (Call/Session Control Function) AS (Application Server) MRF (Media Resource Function) MRFC (MRF Controller) MRFP (MRF Processor) BGCF (Breakout Gateway Control Function) PSTN/CS gateways, decomposed into: SGW (Signaling Gateway) MGCF (Media Gateway Controller Function) MGW (Media Gateway) Charging collection functionsV. Mancuso, I. Tinnirello

Databases (HSS,SLF) HSS is an evolution of the HLR (HomeLocation Register) of GSM Contains the user-related subscription data (e.g., location,authorization and authentication information) More than one HSS is possible If #HSS 1 SL