1 © 2001 nokia kimmo raatikainen, mikko puuskari, juha kalliokulju, sami uskela umts overview...

1 © 2001 NOKIA Kimmo Raatikainen, Mikko Puuskari, Juha Kalliokulju, Sami Uskela

UMTS Overview

Presentation at Berkeley – Helsinki Summer School,

May 30, 2001

Kimmo Raatikainen

Principal Scientist

Nokia Research Center


Presentation Outline

• What is it?

• Standarization fora

• Radio Evolution

• UMTS Architecture

• UMTS Protocols

• QoS Issues

• Domains

• Services

• Technical Requirements

• Backup Material


What is it?

• IP multimedia and realtime services support within the UMTS system; IP Multimedia network elements in addition to Packet-Switched and Circuit-Switched domains

• Two different radio access technologies connected to the same core network: GERAN (GPRS/EDGE RAN) and UTRAN (WCDMA RAN)

– other access technologies should be enabled as well; e.g. fixed access, cable modems, WLAN, etc.

• Network architecture and elements based on Internet protocols

• Voice services on top of IP; Call control by SIP (or H.323 or…)

• Supports for further evolution towards even more IP-centric architecture and services...


Relevant fora• 3G.IP - closed forum

– Initial founding members: Operators: AT&T, British Telecom, CSELT, Rogers Cantel, Telenor

Vendors: Nokia, Ericsson, Lucent, Nortel

– Current member status: a lot of new members

• Mobile Wireless Internet Forum - open forum

– Initiators: Vodafone/Airtouch, Orange, Motorola, Cisco, etc.

• Both driving for a definition of a more IP-based UMTS system and attempting to affect standardisation bodies

– 3GPP - making the standards for UMTS Release 2000

– Tiphon - IP telephony related standardisation group within ETSI

– IETF - Internet related standards


3G Approaches

cdma2000 (IS-95+)

IS-136+ WCDMA+GSM

WCDMA+GSM 3GPP

3GPP2

3GPP (GERAN) TIA/ANSI


3GPP2 (www.3gpp2.org)

TSG AAccess Network Interface

TSG CCDMA2000

TSG NANSI41/WIN

TSG PWireless Packet Data Networking

TSG RInterface of 3GPP Radio Access Technology to 3G Core Network evolved from ANSI-41

TSG SSystems and Services Aspects

3G

PP

2 S

tee

rin

g C

om

mit

tee


3GPP (www.3gpp.org)

TSG-CNStephen HayesEricsson, USA

TSG-GERANNiels Andersen

Motorola, Denmark

TSG-RANYukitsuna Furuya

NEC, Japan

TSG-TSang-Keun ParkSamsung, Korea

TSG-SANiels Andersen

Motorola, Denmark

PCGKarl Heinz Rosenbrock

ETSI

CN WG1 GERAN WG1 RAN WG1 T WG1SA WG1



CN WG4 GERAN WG4 RAN WG4 SA WG4

SA WG5CN WG5


3GPP and 3G Schedule• First meetings held in Sophia Antipolis, France, on 7-8 December

1998

• 3GPP Releases – ‘99 specifications on March’00– 4 specifications on March'01– 5 expected on December'01

• UMTS stardardisation started 1990 in ETSI (SMG 5)

• WCDMA selected as radio interface for UMTS (FDD bands) in January 1998

– TD-CDMA selected for TDD bands

• Experimental systems already up-and-running

• Expected launch of first commercial systems in – Japan 2001 (Tokyo area), 2003 (nation wide coverage)– Europe 2002


Radio Evolution

11 Mbits/s

2 Mbits/

s

170 kbits/s

76.8 kbits/s

14.4 kbits/s

43.2 kbits/s

5.4 Mbits/s

10 Mbits/s

EDGETDMA (IS-

41)CDPD

473 kbits/s

115.2 kbits/s

GPRSGSM

(MAP)HSCSD

PDC/PDC-P

cdmaOne(IS-41)

WCDMA FDD

WCDMAHSPA

cdma2000-1X

307.2 kbits/s

WLAN802.11b

54 Mbits/s

1XEV - DO, phase 1 1XEV - DV, phase 2

HiperLAN 2

EDGE Ph. 2

GERAN

473 kbits/sReal Time IP

IEEE802.11a

WCDMA TDD

Harmonised HL2-

IEEE802.11a

standard

200kHz

5MHz

1.25MHz

30kHz

2.4 Mbits/s

2 Mbits/s

Enhanced WLAN

High Speed Downlik Packet Access

Enhanced EDGE

Local

Wid

e a

rea c

overa

ge

2Mbit/s

TD-SCDMA

Higher data rate WLAN100 Mbps

54 Mbits/s

Evolution of 3G

Future Wireless

Inter-PLMN Backbone Network

3G-SGSN3G-MSC

CS Domain

10 © NOKIA 2000 ICCS'00.PPT/ DATE / Juha Kalliokulju

3G-GGSNPS Domain

Node B

RNC

RAN

UMTS Network Architecture


UMTS Reference Architecture

Gf Gi

Iu

GiMr

Gi

Ms

Gi

R UuMGW

Gn

Gc

Signalling and Data TransferInterface

SignallingInterface

TE MT UTRAN

Gr

SGSN GGSN

EIR

MGCF

R-SGW *)

MRF

MultimediaIP Networks

PSTN/Legacy/External

Applications &Services *)

Mm

Mw

Legacy mobilesignallingNetwork

Mc

Cx

AlternativeAccess

Network

Mh

CSCF

CSCF

Mg

T-SGW *)

T-SGW *)

HSS *)

HSS *)

Applications& Services *)

MSC server GMSC server

McMc

D C

SCP

CAP

MGWNb

Nc

Iu

Iu

R-SGW *)Mh

CAPCAP

R UmTE MT

BSS/GERAN

Gb

A

*) those elements are duplicated for figurelayout purpose only, they belong to the samelogical element in the reference model

Iu


UMTS Abbreviations – 1/3AAL2 ATM adaptation layer 2

ANSI American National Standards Institute

ARIB Association of radio industries and businesses

ASN.1 Abstract Syntax Notation One

ATM Asynchronous transfer mode

BER Bit error rate

BS Base station

BSAP Base Station application part

BSC Base station controller

BSSGP Base Station Sub-System GPRS Protocol

CC Call control

cdma code division multiple access

CDPD Cellular Digital Packet Data

CN Core network

CS Circuit switched

CSCF Call services control function

CWTS China's Wireless Telecommunications Standard

EDGE Enhanced data rates for GSM evolution

ETSI European Telecommunication standardisation

institute

FDD Frequencey division duplex

GERAN Global system for mobile communications enhanced data rates for GSM evolution radio access network

GGSN Gateway GPRS support node

GMM GPRS MM

GMSC Gateway MSC

GPRS General packet access

GSM Global system for mobile communication

GTP GPRS tunneling protocol

HLR Home location register

HSCSD High speed circuit switched data

HSS Home subscriber server

IETF Internet engineering task force

IM Internet multimedia

IP Internet protocol

ISDN Integrated services digital network

ITU International telecommunications union

LLC Link layer control

MACMedium access control

MAP Mobile application part

MM Mobility management

MGCF Media gateway control function


UMTS Abbreviations – 2/3MGW Media gateway

MPLS Multiprotocol label switching

MSC Mobile services switching center

MMS Multimedia messaging

MWIF Mobile wireless interest forum

OHG Operator harmonisation group

OSA Open services architecture

P-CSCF Proxy-CSCF

PDC Personal digital communication

PDCP Packet data convergence protocol

PDP Packet data protocol

PHB Per hop behaviour

PLMN Public land mabile network

PPP Point-to-point protocol

PS Packet switched

PSTN Public switched telephony network

QoS Quality of service

RAN Radio access network

RANAP RAN application part

RF Radio frequency

RLC Radio link control

RNC Radio network controller

RRC Radio resource control

RSVP Resource reservation protocol

SCP Services control point

SA Services and System Aspects

SDL Specification and description language

SDU Serving data unit

SGSN Serving GPRS support node

SGW Signalling gateway

SM Session managament

SMG Special mobile group

SNDCP Sub-network dependent convergence protocol

T Terminal

TCP Transmission control protocol

TD-CDMA Time division-CDMA

TDD Time division duplex

TDMA Time division multiple access

TFT Traffic flow template

TIA Telecommunications industry association

TTA Telecommunications technology association

TTC Telecommunications technology committee


UMTS Abbreviations – 3/3TSG Technnical specification group

UDP User datagram protocol

UMTS Universal mobile telecommunication system

UWCC Universal wireless communications consortium

UTRAN UMTS terrestrial RAN

VHE Virtual home environment

VLR Visitor location register

VoIP Voice over IP

WAP Wireless application protocol

WLAN Wireless local area network

WCDMA Wideband CDMA

3GPP 3rd generation partnership project

3GPP2 3rd generation partnership project 2


Control Plane Protocols

W C D M A L1

M S

M AC

R R C

M MC C SM

W C D M A L1

BS

T ransportlayers

RNC

R R C

T ransportlayers

Iub

T ransportlayers

CN

M M

C C SM

T ransportlayers

Iu

R AN AP R AN AP

M AC '

BSAPBSAPBS-RRC

U u

M ACR LC -CR LC -C

RRM

RAN protocols (Access Stratum, AS)

CN protocols (Non Access Stratum, NAS)

GPRS:

UMTS:

RLC BSSGP

SM

LLC

RLC

MAC

GSM RF

Relay

MAC

GSM RF L1 bis L1 bis

GTP

UDP

IP

L2

L1

GTP

UDP

IP

L2

L1

M S B S S S G S N G G S NU m G nG b

NetworkService

BSSGP

NetworkService

LLC

Relay

GMM

SM

GMM


User Plane Protocols

LLC

SNDCP

RLC

MAC

GSM RF

Relay

MAC

GSM RF

BSSGP

L1bis L1bis

Frame Relay

RLC

LLC

SNDCP

Relay

GTP

UDP/TCP

IP

L2

L1

GTP

UDP/TCP

IP

L2

L1

MS BSS SGSN GGSNUu GnGb

Frame Relay

BSSGP

L3CE

RLC

MAC

WCDMA/TD-CDMA

Relay

MAC

WCDMA/TD-CDMA

GTP

L1 L1

L2

RLC

GTP GTP

UDP

IP

L2

L1

GTP

UDP

IP

L2

L1

MS RAN 3G Serving Node 3GGateway

Node

UuGnIu

L2

IP

UDP UDP

IP

L3CE

GPRS:

3GPP:

PDCP PDCP

RAN protocols (Access Stratum, AS)


Mobile Functional Model

MessagingPoint-to-Point

DataStreamingBrow ser

Application Protocols

QoSManagem ent

Socket API

IP Protocols

PPP Packet Classifier

Link Management

M obile Phone

Bluetooth

SM/MM

W LANEDGE UMTS GPRS 99 GSM CS


R LC -U

R LC -Uentity

P D C P

M A C

W C D M A Phy

S MC C

M M(G M M )

M M

R R C

R LC -C

R LCM gm t

R LC -Uentity

R LC -Uentity

R LC -Uentity

H eader com pressionP D C PM gm t

T ransport fo rm at se t

T ransport fo rm at

P D P C ontext 1- IP v6 address- In te ractive Q oS

P D P C ontext 2- IP v6 address- B ackground Q oS

P D P C ontext 3- IP v4 address- In te ractive Q oS

Transportfo rm at com bina tion

C hanne l cod ing,in te rleaving

C ircu itS w itchedA pp l.

Data Protocol Functionality (simplified)


WCDMA/VoIP Mobile

EDGE/VoIP Mobile

UMTS Release 1999

UMTS Release 4/5

Packet side (GPRS)GGSN

SCPHLR

GMSC

3G-SGSNIu

MSC/VLRWCDMA UTRAN

BS

BS

BS

BS

RNC

RNCIur

Iub

(optional)

Circuit sidePSTN/ISDN

InternetWCDMA Mobile

NEW !

EDGE (GSM) BSS

BS

BS

BS

BS

BSC

BSC

Abis

WCDMA UTRAN

BS

BS

BS

BS

RNC

RNCIur

Iub

GGSN

SCPHLR

3G-SGSNIu

CSCFCSCF MGCFMGCF

SGWSGW

MGWMGW

PSTN/ISDN

Internet

Multimedia ServiceControl (IPTelephony)

Packet Core (GPRS) with real time services

NEW !NEW !

IP transportoption for SS7

GMSCMSC/VLR

Circuit Core

(optional)

UMTS Release'99 and Release 4/5UMTS Release'99 and Release 4/5


QoS History and Motivation • GSM served two data types: Transparent and non-transparent

• QoS profile introduced in GPRS rel'97

– precedence class, delay class, reliability class, peak throughput class, mean throughput class

• Enhanced QoS mechanisms in UMTS/GPRS rel'99

– multiple PDP contexts/PDP address, TFTs, management functions

• Rapid growth of Internet usage

– wide variety of applications

– emerging QoS

• Operator's requirements

– differentiation

– fast introduction of new services


Data Network(Internet)

Node B

RNC

3G-GGSN

3G-SGSN

Gn

IPFirewall

GnPS Domain

Iu

Inter-PLMN Backbone Network

External QoSmechanisms

DiffServ.on transport

level IP

Different channel types (dedicated/common)

AAL2connections

New issues in R5:* Interworking with external network (optional RSVP)* Policy control & bearer establishment (P-CSCF & GGSN)

3GPP R99/R4 standardized QoS


• NSAPI• TI• PDP type• PDP address• Access point requested• QoS requested• PDP configuration options

Evolution of Mechanisms to Enable QoS

PDP context, QoS

PDPaddress

(IP)

UE RAN SGSN GGSN

PDP context, QoS 2

PDP context, QoS 3

TFTTFT

Traffic Flow Template (TFT)Flow labelDS code points Source portDestination portSource addressSPI (Security Parameters Index for IPSec)Protocol number

PDP context, QoS 4, signalling


QoS Parameters

Yes/No

Yes/No/-

< 2048 kbps

<2048 kbps

<=1500 octets

<100 ms

5*10-2…10-6

10-2…10-5

1, 2, 3

Yes/No

Yes/No/-

< 2048 kbps

<2048 kbps

<=1500 octets

<250 ms

5*10-2…10-6

10-1…10-5

1, 2, 3

Yes/No

Yes/No/-

< 2048 kbps-overhead

<=1500 octets

4*10-3…6*10-8

10-3…10-6

1, 2, 3

1, 2, 3

Yes/No

Yes/No/-

< 2048 kbps-overhead

<=1500 octets

4*10-3…6*10-8

10-3…10-6

1, 2, 3

Conversationalclass

Streamingclass

Interactiveclass

Backgroundclass

Precedence class

Delay class

Reliability class

Peak throughput class

Mean throughput class

GPRSrel'97, '98

Delivery order

SDU formatinformation

Delivery oferroneous SDUs

Maximum bitrate

Guaranteed bitrate

Maximum SDU size

Transfer delay

Residual BER

SDU error ratio

Allocation/retentionpriority

Traffic handlingpriority

GPRS/UMTS rel'99, 4, 5


Interworking with Backbone Networks

Delivery order

SDU formatinformation

Delivery oferroneous SDUs

Maximum bitrate

Guaranteed bitrate

Maximum SDU size

Transfer delay

Residual BER

SDU error ratio

Allocation/retentionpriority

Traffic handlingpriority

DiffServ PHBExpedited forwardingAssured forwarding (some codepoints)Best effort

UMTSConversationalStreamingInteractiveBackground

mapping

mapping

ATM service classes MPLS (DiffServ & other QOS schemes)


Domain definitions


Domain and Subsystem Definitions

• CS CN domain: comprises all core network elements for provision of CS services.

• PS CN domain: comprises all core network elements for provision of PS connectivity services.

• IM CN subsystem: (IP Multimedia CN subsystem) comprises all CN elements for provision of IM services

• Service Subsystem: Comprises all elements providing capabilities to support operator specific services (e.g. IN and OSA)

• External Applications: Applications on an external Host.

• The Radio Access Network domain consists of the physical entities, which manage the resources of the radio access network, and provides the user with a mechanism to access the core network.


UMTS Service Definitions

External Application

s

PS Services(IM + PS

Connectivity Services)

CS Services

IM Services

PS Connectivity Services

An equivalent set of services to the relevant subset of CS Services


Service-related Definitions

• CS Services: Telecommunication services provided to "GSM/ISDN" clients via 24.008 CC.

• PS Connectivity Services: IP connectivity service provided to IP clients via 24.008 SM.

• IM Services: IP Multimedia Services that require support on the Call Control level carried on top of the PS connectivity services (this may include an equivalent set of services to the relevant subset of CS Services).

• PS services: The superset of IM services and PS connectivity Services.


Multimedia and speech support

• SIP or H.323 instead of cellular network specific call control

– SIP defined by IETF for IP multimedia services; to be used in the Internet

– H.323 defined by ITU; part of the H-protocol family; to be used over IP networks

• Both provide session and call establishment capabilities, among other capabilities & features

• Both probably need enhancements in order to be suitable for the mobile network environment and cellular systems


UMTS Layered Approach for the PS services

3G-3G-GGSNGGSN3G-3G-

SGSNSGSNMGWMGW

CSCFCSCF

MGCFMGCF

RSGWRSGW

TransportTransportLayerLayer

Application LayerApplication Layer

Service LayerService Layer

MRFMRF

HSSHSS

TSGWTSGW

CSCFCSCF

External IPExternal IPNetworksNetworks

Legacy MobileLegacy MobileSignalingSignalingNetworksNetworks

PSTN/PSTN/External CSExternal CS

NetworksNetworks

WLAN, DSL, Cable, etc.WLAN, DSL, Cable, etc.

RASRAS

OSA, VHE,OSA, VHE,etc.etc.

SCPSCP

3G RAN3G RAN


Service Architecture• Common service machinery for all access

systems• A core set of basic and supplementary

services defined: e.g., call divert, barring, pre-paid, emergency call, etc

• Open APIs (Parlay, JAIN, etc.) to support rapid, flexible and secure service creation to enable

– 3rd party application development– Vendor independence– New business models with external service

providers• OSA service architecture to support services

– Similar to current IN services– Exploiting the enhanced capabilities of IP

network (video, multimedia etc.)• Globally accessible services via CAMEL/WIN

or by direct access between terminal and application server

ApplicationApplicationServersServersFrameworkFramework

ServerServerOther ServiceOther ServiceCapability ServersCapability Servers

Service Capability Servers:Service Capability Servers:1) Message Transfer1) Message Transfer2) Call Control2) Call Control

OSAOSAParlay/Corba/IPParlay/Corba/IP

WAPWAPServerServer

Short messageShort messageservice centerservice center

WebWebServerServer

SCPSCPHSSHSS

CSCFCSCF

11 22


Multi-layered Approach to Mobility

AccessMobility

(1)

MicroMobility

CSCFHSS

NetworkLevel

Mobility

3G-SGSN

3G-SGSN

EdgeEdgeNetworkNetwork

EdgeEdgeNetworkNetwork

3G-GGSN

3G-GGSN IPv6IPv6NetworkNetwork

DSLDSL RASRAS

CableCable RASRAS

WLANWLAN RASRAS

AccessMobility

(2)

RANRAN

PSTNPSTN

IPv4IPv4(public(public

ororprivate)private)

IPv6IPv6(public(public

ororprivate)private)

Edge Router/Edge Router/FirewallFirewall

Edge Router/Edge Router/FirewallFirewall

MGCF/MGCF/MGWMGW

NetworkLevel

Mobility


Technical Requirements

• Equal or better quality for voice transmission

• Backwards compatibility vs. revolution (e.g. old phones should work in the new networks due to the large installed customer base)

• Roaming to/from legacy and UMTS R99 networks should be possible

• Interworking necessary with telephony networks, GSM & other cellular networks, IP networks, etc.

• Realtime handovers: which cases must be supported? Intra RAN, inter RAN, inter-SGSN, inter-operator, inter-GGSN, inter-system, ...

• Easy service creation and execution environment. Possible components:

– Mobile Station Execution Environment (MExE), SIM Application Toolkit (SAT), Open Service Architecture (OSA), Virtual Home Environment (VHE), CAMEL, WAP, etc.


Technical Key Issues

• Call control protocol: SIP (or H.323 or …)

• Addressing & Identifiers

• Roaming models and handovers

• Legacy networks: roaming, handovers, etc.

• New header compression algorithms, especially suited for realtime traffic: IETF ROHC

• End-to-end QoS negotiation? Enough guarantees on the call quality? Role of RSVP?

• IP version to be used

• Etc etc…


Requirements for Future All-IP Systems – 1/2• Mobility Handling

– Determined by, and optimised for, mobile terminals

• Multiservice– Common Network for real time and non real time services– Rapid, flexible and easy creation of new services

• Layered Network Functionality– For independence of access, transport, applications and

service creation– For system flexibility and future evolution

• Multiaccess & Access Independence– Several accesses including WCDMA, EDGE, WLAN, Cable

etc.– Mobility between accesses (Global IP Mobility)


Requirements for Future All-IP Systems – 2/2

• IPv6-Based

– For scalability and address space

– For mobility between accesses (Global IP mobility)

• Evolution and Legacy Support

– For utilisation of existing investments

– For service continuity

• Shared Transport and Network Management

– For cost efficiency


Background Material


Functional Elements: Call State Control Function (CSCF)

• Logical, i.e. internal, components: • ICGW (Incoming call gateway): Acts as a first entry point and performs routing of incoming

calls, Communicates with HSS, Incoming call service triggering (e.g. call screening/call forwarding unconditional) may need to reside for optimisation purposes, Query Address Handling (implies administrative dependency with other entities), Communicates with HSS

• CCF (Call Control Function): Call set-up/termination and state/event management, Interact with MRF in order to support multi-party and other services, Reports call events for billing, auditing, intercept or other purpose, Receives and process application level registration, Query Address Handling (implies administrative dependency), May provide service trigger mechanisms (service capabilities features) towards Application & services network (VHE/OSA), May invoke location based services relevant to the serving network, May check whether the requested outgoing communication is allowed given the current subscription.

• SPD (Serving Profile Database): Interacts with HSS in the home domain to receive profile information for the R00 all-IP network user and may store them depending on the SLA with the home domain, Notifies the home domain of initial user’s access (includes e.g. CSCF signalling transport address, user ID etc. needs further study), May cache access related information (e.g. terminal IP address(es) where the user may be reached etc.)

• AH (Address Handling): Analysis, translation, modification if required, address portability, mapping of alias addresses, May do temporary address handling for inter-network routing.


Functional Elements: Home Subscriber Server

• The Home Subscriber Server (HSS) is the master database for a given user. It is responsible for keeping a master list of features and services (either directly or via servers) associated with a user, and for tracking of location of and means of access for its users. It provides user profile information, either directly or via servers. It is a superset of the Home Location Register (HLR) functionality, The HSS shall support a subscription profile which identifies for a given user for example:

- 1) user identities; 2) subscribed services and profiles; 3) service specific information; 4) mobility management information; and 5) authorization information

• Like the HLR, the HSS contains or has access to the authentication centers/servers (e.g. AUC, AAA).

• HSS structure:

– User Mobility Server (UMS): it stores Service Profile for the Multimedia domain and stores Service Mobility or Serving CSCF related information for the users. UMS might also generate, store and/or manage security data and policies (e.g. IETF features). UMS should provide logical name to transport address translation in order to provide answer to DNS queries.

– 3G HLR: A UMTS HLR enhanced to support Release 2000 access specific information.


Functional Elements: HSS structure

HOME SUBSCRIBER SERVER

3G HLR

CSCF

Cx

SGSN GGSN

Gr

Gc

USER MOBILITY SERVER

AAA Location Server(e.g. LDAP)

DNS

R-SGW

Mh

MSC Server GMSC Server

D

C


Functional Elements: Transport Signalling Gateway

• This component in the Rel 4/5 network is PSTN/PLMN termination point for a defined network.

– Maps call related signalling from/to PSTN/PLMN on an IP bearer and sends it to/from the MGCF.

- Needs to provide PSTN/PLMN <-> IP transport level address mapping.


Functional Elements: Roaming Signalling Gateway

• The role of the R-SGW described in the following bullets is related only to roaming to/from 2G/R99 CS and GPRS domain to/from R00 UMTS Teleservices domain and UMTS GPRS domain and is not involving the Multimedia domain.

- In order to ensure proper roaming, the R-SGW performs the signaling conversion at transport level (conversion: Sigtran SCTP/IP versus SS7 MTP) between the legacy SS7 based transport of signaling and the IP based transport of signaling. The R-SGW does not interpret the MAP / CAP messages but may have to interpret the underlying SCCP layer to ensure proper routing of the signaling.

- (For the support of 2G / R99 CS terminals): The services of the R_SGW are used to ensure transport interworking between the SS7 and the IP transport of MAP_E and MAP_G signalling interfaces with a 2G / R99 MSC/VLR


Functional Elements: Media Gateway Control Function

• This component is PSTN/PLMN termination point for a defined network.

- Controls the parts of the call state that pertain to connection control for media channels in a MGW.

- Communicates with CSCF.

- MGCF selects the CSCF depending on the routing number for incoming calls from legacy networks.

- Performs protocol conversion between the Legacy (e.g. ISUP, R1/R2 etc.) and the R00 network call control protocols.

- Out of band information assumed to be received in MGCF and may be forwarded to CSCF/MGW.


Functional Elements: Media Gateway• This component is PSTN/PLMN transport termination point for a defined

network and interfaces UTRAN with the core network over Iu.

• A MGW may terminate bearer channels from a switched circuit network and media streams from a packet network (e.g., RTP streams in an IP network). Over Iu MGW may support media conversion, bearer control and payload processing (e.g. codec, echo canceller, conference bridge) for support of different Iu options for CS services: AAL2/ATM based as well as RTP/UDP/IP based.

- Interacts with MGCF, MSC server and GMSC server for resource control; Owns and handles resources such as echo cancellers etc.; May need to have codecs.

• Tailoring (i.e packages) of the H.248 may be required to support additional codecs and framing protocols, and support of mobile specific functions


Functional Elements: Multimedia Resource Function

• This component:

- performs multiparty call and multimedia conferencing functions. MRF would have the same functions of an MCU in an H.323 network.

- Is responsible for bearer control (with GGSN and MGW) in case of multi party/multi media conference

- may communicate with CSCF for service validation for multiparty/multimedia sessions.


Functional Elements: (G)MSCs, (G)MSC servers

• MSC server: comprises the call control and mobility control parts of a GSM/UMTS MSC and is responsible for the control of mobile originated and mobile terminated CS Domain calls. It terminates the user-network signalling (04.08+CC+MM) and translates it into the relevant network – network signalling. The MSC Server also contains a VLR to hold the mobile subscriber's service data and CAMEL related data.

• MSC server controls the parts of the call state that pertain to connection control for media channels in a MGW.

• Gateway MSC Server: The GMSC server mainly comprises the call control and mobility control parts of a GSM/UMTS GMSC.

• MSC: A MSC server and a MGW make up the full functionality of a MSC as defined in 23.002

• Gateway MSC: A GMSC server and a MGW make up the full functionality of a GMSC as defined in 23.002


Release 5: Basic IMSConfiguration

IM Subsystem

CSCFMGCF

Gi

HSSCx

IP MultimediaNetworkds

MGW

T-SGW R-SGW

PSTN

Mc

Mh

Gi

Mg

Mm

MRF

Gi

Mr

Gi

Legacy mobilesignalling Networks

CSCF

Mw

MsBGCF

MiMj

Mk


Proxy-CSCF• Proxy-CSCF (P-CSCF) is the first contact point within the IM subsystem. Its address is

discovered by “Procedures related to Local CSCF Discovery ”. The P-CSCF behaves like a proxy (as defined in RFC2543). The functions performed by the P-CSCF are:

– Forward the SIP register request received from the UE to an I-CSCF determined using the home domain name, as provided by the UE.

– Forward SIP messages received from the UE to the SIP server (e.g. S-CSCF) whose name the P-CSCF has received as a result of the registration procedure.

– As part of processing of the request and before forwarding, the P-CSCF may modify the Request URI of outgoing requests according to a set of provisioned rules defined by the network operator (e.g. Number analysis and potential modification such as translation from local to international format.)

– Forward the SIP request or response to the UE.

– Detect an emergency call and select a S-CSCF in the visited network to handle emergency calls.

– The generation of CDRs.

– Authorization of bearer resources and QoS management and Security issues are FFS.


Interrogating-CSCF• Interrogating-CSCF (I-CSCF) is the contact point within an operator’s network

for all connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator’s service area. There may be multiple I-CSCFs within an operator’s network. The functions performed by the I-CSCF are:

• Registration: Assigning a S-CSCF to a user performing SIP registration (see section on Procedures related to Serving CSCF assignment); Cryptography mechanisms may be used by I-CSCF to hide the S-CSCF when S-CSCF name is provided to the P-CSCF in the Visited network

• Session Flows: Route a SIP request received from another network towards the S-CSCF; Obtain from HSS the Address of the S-CSCF; Forward the SIP request or response to the S-CSCF determined by the step above;

• Charging and resource utilisation: Generation of CDRs.

• In performing the above functions the operator may use I-CSCF to hide the configuration, capacity, and topology of the its network from the outside

• Editor’s Note: Additional functions related to inter-operator security are for further study.


Serving-CSCF• Serving-CSCF (S-CSCF) performs the session control services for the endpoint. It

maintains session state. Within an operator’s network, different S-CSCFs may have different functionalities. The functions performed by the S-CSCF during a session are:

• Registration: Acts like a Registrar defined in the RFC2543, i.e. it accepts Register requests and makes its information available through the location server (eg. HSS).

• Session flows: Session control for the registered endpoint's sessions; Interaction with Services Platforms for the support of Services;

– On behalf of an originating endpoint (i.e. the originating subscriber/UE); Forward the SIP request or response to the I-CSCF

– On behalf of a destination endpoint (i.e. the terminating subscriber/UE): Forward the SIP request or response to a P-CSCF for a MT session to a home subscriber within the home network, or for a subscriber roaming within a visited network where the home network operator has chosen not to have an I-CSCF in the path; Forward the SIP request or response to an I-CSCF for a MT session for a roaming subscriber within a visited network where the home network operator has chosen to have an I-CSCF in the path.

• Charging and resource utilisation: Generation of CDRs.

• Security issues are FFS


BGCF• The S-CSCF, possibly in conjunction with an application server, shall determine

that the session should be forwarded to the PSTN. The S-CSCF will forward the Invite information flow to the BGCF in the same network.

• The BGCF selects the network in which the interworking should occur based on local policy

• If the BGCF determines that the interworking should occur in the same network, then the BGCF selects the MGCF which will perform the interworking, otherwise the BGCF forward the invite information flow to the BGCF in the selected network. The MGCF will perform the interworking to the PSTN and control the MG for the media conversions. Receipt of SIP

invite

S-CSCF determines ifthe session is to be continued in IM CN

or in GSTN?

Continue withSIP routing

BGCF selects network

BGCF selects &forwards

the signallingto the MGCF

BGCF forwardssignalling tothe selected

network

Same network

To GSTN via Network

Other networkContinued viaIM CN subsystem


Identities• Private User identities

- Every IM subsystem subscriber shall have a private user identity. The private identity is assigned by the home network operator, and used, for example, for Registration, Authorization, Administration, and Accounting purposes. This identity shall take the form of a Network Access Identifier (NAI) as defined in RFC2486. Note: It is possible for a representation of the IMSI to be contained within the NAI for the private identity.

- The Private User Identity is not used for routing of SIP messages

• Public user identities

– Every IM subsystem subscriber shall have one or more public user identities [Ref 22.228]. The public user identity/identities are used by any user for requesting communications to other users. Note: For example, this might be included on a business card.

– Both telecom numbering and internet naming schemes can be used to address users depending on the Public User identities that the user’s have.

– The public user identity/identities shall take the form of SIP URL (as defined in RFC2543 and RFC2396) or E.164 numbers.


New Reference points (1)

• Cx Reference Point (HSS – CSCF): the transfer of data between the HSS and the CSCF. When a UE has registered with a CSCF, the CSCF can update its location towards HSS. This will allow the HSS to determine which CSCF to direct incoming calls to. On this update towards the HSS, the HSS sends the subscriber data (application related) to CSCF. For a MT call, CSCF asks the HSS for call routing information.

• Gm Reference Point (CSCF – UE): allow UE to communicate with the CSCF e.g.

- Register with a CSCF,

- Call origination and termination

- Supplementary services control


New reference points (2)• Mc Reference Point (MGCF – MGW): describes the interfaces between

the MGCF and MGW, between the MSC Server and MGW, and between the GMSC Server and MGW. It has the following properties:

- full compliance with the H.248 standard.

- flexible connection handling which allows support of different call models and different media processing purposes not restricted to H.323 usage.

- dynamic sharing of MGW physical node resources. A physical MGW can be partitioned into logically separate virtual MGWs/domains consisting of a set of statically allocated Terminations.

- dynamic sharing of transmission resources between the domains as the MGW controls bearers and manage resources according to the H.248 protocols.

– The functionality across the Mc reference point will need to support mobile specific functions such as SRNS relocation/handover and anchoring. It is expected that current H.248/IETF Megaco standard mechanisms can be applied to enable this.


New reference points (3)

• Mg Reference Point (MGCF – CSCF): The Mg reference point is based on external specifications, e.g. H.323 or SIP

• Mh Reference Point (HSS – R-SGW): supports the exchange of mobility management and subscription data information between HSS and R99 and 2G networks. This is required to support Release 2000 network users who are roaming in R99 and 2G networks.

• Mm Reference Point (CSCF – Multimedia IP networks): an IP interface between CSCF and IP networks. This interface is used, for example, to receive a call request from another VoIP call control server or terminal.

• Mr Reference Point (CSCF - MRF): Allows the CSCF to control the resources within the MRF.

• Ms Reference Point (CSCF – R-SGW): This is an interface between the CSCF and R-SGW.


New reference points (4)

• Mw Reference Point (CSCF – CSCF): The interface allows one CSCF (e.g. home CSCF) to relay the call request to another CSCF (e.g. serving CSCF).

• Nc Reference Point (MSC Server – GMSC Server): Over the Nc reference point the Network-Network based call control is performed. Examples of this are ISUP or an evolvement of ISUP for bearer independent call control (BICC). In the R’00 architecture different options for signalling transport on Nc shall be possible including IP.

• Nb Reference Point (MGW-MGW): Over the Nb reference point the bearer control and transport are performed. The transport may be RTP/UDP/IP or AAL2 for transport of user data. In the R00 architecture different options for user data transport and bearer control shall be possible on Nb, for example: AAL2/Q.AAL2, STM/none, RTP/H.245.


New reference points (5): CAP towards SCP

• This includes the interfaces from the SGSN to the SCP, from the MSC Server to the SCP, and the GMSC Server to the SCP.

DOCUMENTTYPE 1 (1)

Nokia Research CenterTypeYourNameHere TypeDateHere

CAPTCAPSCCP

M3UA MTP-3BSCTP (1) SAAL

Narrow-band SS7

IP (2) ATM(2) STM (2)


New reference points (6): MAP-based

• This includes the interfaces from the GGSN to the HSS (Gc reference point), from the SGSN to the HSS (Gr reference point), from the GMSC Server to the HSS (C reference point), and the MSC Server to the HSS (D reference point).

• The MAP based interfaces may be implemented using MAP transported over IP, or MAP over SS7.

• MAP can be transported on the same protocol stacks as CAP


New reference points (7): Iu ref point• This is the reference point between UTRAN and the R00 core

network. This reference point is realized by one or more interfaces:

- Between UTRAN and SGSN, transport of user data is IP based.

- Between UTRAN and SGSN, transport of signalling is based on IP or SS#7.

- Between UTRAN and MGW, transport of user data is based on different technologies (e.g., IP, AAL2), and includes the relevant bearer control protocol in the interface.

- Between UTRAN and MSC server, transport of signalling is based on IP or SS#7.

• When the Iu_cs is ATM based, then the protocols used can be based on R99 protocols or an evolved version. When Iu_cs is IP based, new IP transport related protocols need to be added as part of the Iu protocols. It shall be possible to have R99 Iu interface with MSCs compliant to R99 specifications in the network. It shall be possible to have a R99 CS domain with R99 Iu_cs reference point coexisting with a R00 Iu reference point.

1 © 2001 nokia kimmo raatikainen, mikko puuskari, juha kalliokulju, sami uskela umts overview...

Documents

nokia kimmo raatikainen

juha kalliokulju

mikko puuskari

denmark tsg

sami uskela 3gpp2

gpp 3gpp2

sami uskela relevant

ipbased umts system