05 UMTS Architecture

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UMTS Networks 1 Andreas Mitschele-Thiel, Jens Mckenheim 19-Oct-10

UMTS System Architecture

and Protocol ArchitectureOverview on overall system architecture

UMTS network architecture and elements

Mobile station High-level functions UMTS domains and strata UMTS/GPRS protocol architecture

References: Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks Architecture, Mobility and

Services. 2nd edition, Wiley 2005 Ch 5.1: Core Network Architecture Release 3 Ch 5.4&5.5: Core Network Architecture Release 4 and 5 Ch 6: UMTS Terminal

Walke, Althoff, Seidenberg: UMTS Ein Kurs. J. Schlembach Fachverlag, 2001 3GPP TS 23.002: UMTS network architecture (CN and AN entities) and procedures 3GPP TS 23.101: General UMTS architecture 3GPP TS 23.060: GPRS, Service Description

3GPP TS 21.101/21.102/21.103: List of standards for Release 3, 4 and 5, respectively 3GPP TR 21.905: UMTS vocabulary and abbreviations


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UMTS/GSM Network Architecture

GPRS Core

(PacketSwitched)

SGSN

GGSN

Internet

GSM

RAN

Base station

Base stationcontroller

Base station

Base station

UTRAN

Radio network controller

node B

node B

node B

MSC

ISDN

GSM Core

(Circuitswitched)

HLR AuCEIR

GMSC


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UMTS System Architecture

UMTS Subscriber Identity Module (USIM): subscriber-specific data support of authorized access to network

Mobile Station (MS): radio interface service control and user interface

Radio Access Network (RAN): radio-specific functions

Core Network (CN):radio-independent functions transport mobility management subscriber data service control

datanetworks

ISDN

network

mobilenetwork

USIM


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Public Land Mobile Network (PLMN)

Definition:

a network established and operated by an administration to provideland-based mobile telecommunications services to the public

a PLMN may be regarded as an extension of a network (e.g. an ISDN)

a PLMN consists of a collection of MSC areas within a commonnumbering plan (e.g. same National Destination Code) and a commonrouting plan

PLMNs are independent telecommunications entities

Source: 3GPP 23.002-5.5.0


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U M T S N e

t w o r k

A r c

h i t e c

t u r e

B a s

i c C o n

f i g u r a

t i o n ,

R e

l e a s e

3

BSS

BSC

RNS

RNC

CN

Node B Node B

A IuPS

Iur

Iub

Uu

MSC SGSN

Gs

GGSN GMSC

GnHLR

Gr

GcC

D

E

AuC H

EIR

F Gf

GiPSTN

IuCSGb

VLR B

Gp

VLR G

BTS BTS

Um

RNC

Abis

MSC

B

PSTNPSTN

cell S o u r c e :

3 G P P 2 3

. 0 0 2 - 3 . 4 . 0

C i r c u

i t s w

i t c h e

d C N

P a c k e t s wi t c h

e d C N

GSMRAN

UTRAN


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Mobile-services Switching Centre (MSC)

An exchange performing all the switching and signalling functions (CSonly) for mobile stationsMSC controls mobile-originated and mobile-terminated CS calls

Functions call management mobility management (handling attach and authentication) subscriber administration

maintenance of charging data (for radio network usage) CS data services (FAX, modem) supplementary call services (call forwarding, etc.) SS7-based signaling

Main difference to an exchange in a fixed network: deal with mobility (e.g.location registration, handover)

Gateway MSC (GMSC) Provides interconnection between the UMTS core network and external

PSTN/ISDN networks

Source: 3GPP 23.002-3.5.0


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GPRS Support Node (GSN)

GSNs constitute the interface between the radio access network and thefixed networks for packet switched services (similar to MSC for CS calls)

Serving GSN (SGSN)

session management mobility management subscriber database management (interface with HLR) maintenance of charging data (for radio network usage)

IP-based transport of user data between SGSN and the UTRAN IP- or SS7-based signaling transport

Gateway GSN (GGSN)

gateway for UMTS packet service to external data networks (e.g. theInternet) IP interface towards SGSN performs user data screening and security

maintenance of charging data (for external data network usage)

Source: 3GPP 23.002-3.5.0


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Home Location Register (HLR)

Home (primary) data base in charge of the management ofmobile subscribersBasic information: International Mobile Subscriber Identity (IMSI)

CS subscription information one or more Mobile Subscriber International ISDN number(s)

(MSISDN) PS subscription information

zero or more Packet Data Protocol (PDP) address(es) permission for GGSN to dynamically allocate PDP addresses for a

subscriber location information enabling the charging and routing of calls towards

the MSC or SGSN where the MS is registered (e.g. VLR Number)

Other information: teleservices and bearer services subscription information service restrictions (e.g. roaming limitation)

parameters attached to supplementary services

Source: 3GPP 23.002-3.5.0


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Visitor Location Register (VLR)

(Secondary) data base supporting the management of mobilesubscribers currently located within its VLR area

Motivation: minimize load for HLR (i.e. of the primary data base)

Tasks: control MSs roaming in an MSC assigned to it exchange information with HLR to allow the proper handling of calls

Information maintained by VLR (for call handling):

International Mobile Subscriber Identity (IMSI) Mobile Station International ISDN number (MSISDN) Mobile Station Roaming Number (MSRN)

Temporary Mobile Station Identity (TMSI), if applicable location area where the mobile station has been registered the last known location and the initial location of the MS supplementary service parameters attached to the mobile subscriber

(received from the HLR)

Source: 3GPP 23.002-3.5.0


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Authentication Centre (AuC)

Stores data for each mobile subscriber to authenticate the International Mobile Subscriber Identity (IMSI) to support ciphering of the communication over the radio path

The AuC transmits the data needed for authentication and ciphering viathe HLR to the VLR, MSC and SGSN which need to authenticate a mobilestation

AuC is associated with an HLR, and stores an identity key for each mobilesubscriber

The AuC communicates solely with its associated HLR (H-interface)

Source: 3GPP 23.002-3.5.0


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Equipment Identity Register (EIR)

Logical entity storing the International Mobile Equipment Identities (IMEIs)

Equipment is classified as white listed: serie number of equipment

grey listed: equipment tracked by network

black listed: barred equipment

unknown to EIR

Source: 3GPP 23.002-3.5.0


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Other CN entities

SMS Gateway MSC (SMS-GMSC) gateway between Short Message Service Center and PLMN deliver SMSs from service center to MS

SMS Interworking MSC (SMS-IWMSC) gateway between PLMN and Short Message Service Center deliver SMSs from MS to service center

Interworking Function (IWF)

associated with MSC supports interworking of PLMN with fixed networks, e.g. ISDN, PSTN,

PDN (protocol conversion)

Border Gateway (BG)

PS gateway to other PLMNs firewall functionality

Charging Gateway Functionality (CGF) collects charging records from SGSNs and GGSNs

Source: 3GPP 23.002-3.5.0

o


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Radio Network System (RNS)

Provide access to the UMTS terrestrial radio interface

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

UTRAN

Radio Network Controller (RNC) (Radio) mobility management Management of radio resources

Base Station (Node B) Radio coverage of cells Physical layer processing


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Mobile Station (MS)

ITU-T RecommendyerUE

Mobile Equipment (ME)MobileTermination(MT)

RT

AF

Cu

AccessNetwork

UuTerminalEquipment(TE)

USIM

Mobile Equipment (ME)radio transmissionand application

Terminal Adaptation Functions (TAF)(service dependent) mapping of terminal requests on

network capabilities

flow control/rate adaptations

Terminal Equipment (TE)support for end-to-endapplicationfunctions necessary forthe operation of theaccess protocols by theuser, e.g. a labtop

UMTS Subscriber IdentityModule (USIM)user identitycontains data and proceduresto unambiguously and securely

identify itself

Mobile Termination (MT)

functions for radio transmissionand management of the radiointerface, e.g. the handset

Mobile station (MS)/User Equipment (UE)physical equipment used bya PLMN subscriber

o


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High-level Functions (PS Domain)Network Access Control

Provide means by which a user isconnected to a telecommunicationnetwork

Registration

Association of Mobile ID with theuser's packet data protocol(s) andaddress(es) within the PLMN, andwith the user's access point(s) to theexternal PDP network

Authentication and AuthorisationIdentification and authentication ofthe service requester, and thevalidation of the service request type

Admission ControlCheck available network resourcesrequired to provide the quality ofservice (QoS)

Message Screening A screening function with filtering outunauthorised or unsolicited messages(firewall)

Packet Terminal Adaptation

Adaptation of data packets suitablefor transmission across the packetdomain network

Charging Data Collection

Collection of data necessary tosupport subscription and/or trafficfees

Operator Determined BarringLimitation of the service provider'sfinancial risk with respect to newsubscribers or to those who have notpromptly paid their bills by restrictinga particular packet-switched service


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High-level Functions (PS Domain)Packet Routing and Transfer

Determining and using the routefor transmission of a messagewithin and between the PLMN(s)

Relay

Forwarding of data received fromone node to the next node in theroute

RoutingSelection of the transmission path

for the "next hop" in the routeusing the destination address ofthe message

Address Translation and MappingConversion of one address to

another address of the same ordifferent type, i.e. to convert anexternal network protocoladdress into an internal networkaddress

Encapsulation/Decapsulation Addition/removal of address and controlinformation to a data unit for routingpackets within and between the PLMN(s)and between the SGSN and the MS

TunnelingTransfer of encapsulated data unitswithin and between the PLMN(s) fromthe point of encapsulation to the point ofdecapsulation

A tunnel is a two-way point-to-point path Compression

Optimisation of radio path capacity Ciphering

Preservation of the confidentiality of userdata and signalling across the radiochannels

Mobility Management Keep track of location of MSRadio Resource Management

Management of radio resources


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UMTS Functional Entities: Domains

Domain: grouping of physical entities of the system

User Equipment (UE) Domain

Access Network(AN) Domain

Core Network(CN) Domain

Infrastructure Domain

Cu

MobileEquipmentDomain

USIMDomain

HomeNetwork

Domain

TransitNetworkDomain

Uu Iu

[Zu]

[Yu]

Serving Network(SN) Domain

Source: 3GPP 23.101-4.0.0

Air InterfaceRadio AccessNetwork (RAN)


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Functions of the UMTS DomainsInfrastructure domain Access network (AN) domain: functions specific to access technique Core network (CN) domain: functions independent of access technique

Access network domain physical entities managing the resources of the access network

provides the user with a mechanism to access the core network domainServing network (SN) domain part of the CN domain to which the AN domain that provides the users access is

currently connected responsible for routing calls and transport user data/information from source to

destination provides CN functions that are local to the users access point (i.e. SN changes

when the user moves)Home network (HN) domain

provides CN functions that are conducted at a permanent location regardless ofthe location of the users access point (i.e. does not change due to user mobility) contains user-specific data and is responsible for management of subscription

information handle home-specific services, not offered by the serving network domain

User Services Identity Module domain (USIM) related to the home network domain by subscription


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Functional Communication betweenUMTS domains

Source: 3GPP 23.101-4.0.0

USIM

MT - AN

MT/ME AccessNetworkDomain

ServingNetworkDomain

HomeNetworkDomain

AN - SN

Access Stratum

MT - SN

Serving Stratum

USIM - HN

SN - HN

Home Stratum

MT - SNUSIM - MT

Transport Stratum

USIM - MT

Transport of user data andnetwork control signalling error correction and recovery encrypt data over the radio interface

and in the infrastructure part adaptation of data to use the supported

physical format transcoding of data to make efficient

use of, e.g. the radio interface

Parts of infrastructure, user equipment andprotocols specific to the access technique provides services related to the transmission

of data over the radio interface andthe management of the radio

interface

Protocols and functions toroute and transmitdata/information (useror network generated) fromsource to destination

Protocols and functions related to the

handling and storage ofsubscription data andpossibly home networkspecific services

functions related to subscriptiondata management, customer care,including billing and charging,

mobility management andauthentication

functions to allow domains otherthan the home network domain toact on behalf of the home network

Strata concept: grouping of functions grouping of

respective protocolso


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Functional Communication betweenUMTS domains

Source: 3GPP 23.101-4.0.0

End-to-end protocols andfunctions which make use of servicesprovided by the home, serving andtransport strata and infrastructure tosupport services and/or value addedservices.The functions and protocols within theapplication stratum may adhere toGSM/UMTS standards such as MExE ormay be outside the scope of the UMTSstandards.

TEMT - AN

MT AccessNetworkDomain

ServingNetworkDomain

TransitNetworkDomain

AN - SN

Access Stratum

TE - MT MT - SN

Serving Stratum

Application Stratum

Application

Transport Stratum

RemoteParty

MobileEquipment

Domain

o


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UMTS Protocol Architecture

References: Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks Architecture, Mobility

and Services. Wiley 2001, Ch. 5.1 Walke, et al: UMTS ein Kurs, Ch. 5 (air interface only)

3G TS 23.060: GPRS, Service Description

We will focus on the packet switched mode here


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User Plane Bearer Services Overview

TE MT UTRAN CN IuEDGENODE

CNGateway

TE

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External Bearer Service

UMTS Bearer Service

Radio Access Bearer Service CN Bearer Service

BackboneBearer Service

Iu Bearer Service

Radio Bearer Service

UTRA

FDD/TDDService

Physical

Bearer Service


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Bearer Services Analogy with PublicTransportation

TE MT UTRAN CN IuEDGENODE

CNGateway

TE

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External Bearer Service

UMTS Bearer Service

Radio Access Bearer Service CN Bearer Service

BackboneBearer Service

Iu Bearer Service

Radio Bearer Service

UTRA

FDD/TDDService

Physical

Bearer ServiceTaxi:Wohnung Bushaltestelle

Zu Fu zum Taxi

Bus:Bushaltestelle - Bahnhof

Bahn:Bahnhof - Bahnhof

Taxi und Bus im Verbund(Taxiruf im Bus)

Taxi, Bus und Bahn im Verbund:single ticket, single reservation,same service everywhere

Taxi mit Fahrer Bus mit Fahrer

For each bearer: specific attributes (delay,

bandwidth, guarantees, etc.

specific reservationmechanism


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MS-RNS-SGSN-GGSN Control Plane

UDP

L2L1

IP

L2L1

IP

UDP

Gn or Gp

GSN GSN

GTP-C GTP-C

RLC

RRC

L1

GMM /SM / SMS

RRC

MAC

ATM

RANAP

AAL5

Relay

ATM

AAL5

3G SGSNRNSMSIu-PsUu

RLC SCCP

SignallingMAC

L1

Signalling

RANAP

SCCP

GMM /SM / SMS

o


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MS-RNS-SGSN Control PlaneGMM(GPRS Mobility Management):

GMM supports mobility management functionality such as attach, detach,security, and routing area update

SM (Session Management): SM supports PDP context activation and deactivation

SMS supports short message serviceGTP-C (GPRS Tunneling Protocol for Control plane): establish, manage and release GTP tunnels

RANAP(Radio Access Network Application Protocol):

transport of higher-layer signalling handling of signalling between the 3G-SGSN and UTRAN management of the GTP connections on the Iu interface

RRC (Radio Resource Control):

Information Broadcast (AS and NAS) RRC connection management (setup, release, reconfiguration) Radio Bearers management (setup, release, reconfiguration) Management of radio resources for the RRC connection RRC connection mobility functions

Paging/notification Source: 3GPP 23.060-4.1.0


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MS-RNS-SGSN-GGSN User Plane

L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP

3G-SGSNUTRANMSIu-PSUu Gn Gi

3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Source: 3GPP 23.060-4.1.0


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L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP


3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Source: 3GPP 23.060-4.1.0

GTP-U (GPRS Tunneling Protocol for User plane): tunneling of user data between UTRAN and the 3G-SGSN tunneling between the GSNs in the backbone network

encapsulation of all PDP PDUs


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L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP


3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Source: 3GPP 23.060-4.1.0

PDCP (Packet Data ConvergenceProtocol):

provides protocol transparency (wrtthe underlying radio-interfaceprotocols) for higher-layer protocols

support for e.g., IPv4, PPP and IPv6(easy introduction of new higher-layer protocols)

compression of control information(header compression)

no user data compression in Iu mode(because the data compressionefficiency depends on the type ofuser data)


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L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP


3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Source: 3GPP 23.060-4.1.0

RLC (Radio Link Control):RLC protocol provides logical linkcontrol over the radio interfaceThere may be several simultaneousRLC links per MS; each link is identifiedby a Bearer Id

MAC (Medium Access Control):MAC protocol controls the accesssignaling (request and grant)procedures for the radio channel


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05 UMTS Architecture