3 g core nw

© Copyright 2000 Wireless facilities, Inc.

3G Core Network Technology Trends


Story so far

Mobile Mobile Internet Internet


Growth in MobileCommunication Services

120

240

360

480

600

720

840

960

1080

1,200

01995 1996 1997 1998 1999 2000 2001 2002 2003

Sub

scrib

ers

(in

mill

ion)

Japan(excl. PHS)

Asia Pacific(excl. Japan)

Latin America

Rest of theworld

NorthAmerica

WesternEurope


The New Telecom World …. Beyond Voice


Bundling of ServicesBundling of Services

TELECOMMUNICATIONSTELECOMMUNICATIONSCOMPUTERCOMPUTER

CONVERGENCECONVERGENCECONVERGENCECONVERGENCEInformation ContentInformation Content

Information ServersInformation Servers

Access NetworksAccess Networks

Information AppliancesInformation Appliances

COMMERCE & BROADCATERSCOMMERCE & BROADCATERS

DELIVERY TO A WIDE RANGE OF DEVICES OVER A COMMON CORE NETWORKDELIVERY TO A WIDE RANGE OF DEVICES OVER A COMMON CORE NETWORK


Converging industries

Computers& Datacom

Consumer electronics

Entertainment& Publishing

Businessmultimedia

Informationgadgets

Telecom

Homemultimedia

Information &work support

IP


CS vs PS

Today: you go through a circuit switch to get to a packet switch.Tomorrow: you’ll use a packet switch

to emulate to a circuit switch.


The strategic direction

Te

lec

om

Datacom

Mobility

2G mobilevoice

Wirelinetelephony

Mobiledata

WAN/LANdata

Voice over IP

3G(UMTS)

2G Internet

1G mobile Internet

1G Internet

3G Internet


Three important steps

Voice goes Mobile– Home / Office Zone, GSM on the Net, Number Portability– Separation of private / business usage and roles

Mobile Data kick-off– WAP (SMS/USSD), SIM TK,...– GPRS, GSM on the Net, Virtual Office,

WebOnAir, ...

New Business Concepts– GPRS - always connected, client-server, content v.s. time– UMTS Virtual Home Environment - networks opening up– Bluetooth - bridging technology, e-services– Mobile eCommerce - real time charging/billing, triple-A


Cerf’s Prediction:

By 2010, 100% of all trafficwill be packetized!

Are we ready?!


IP on Everything


It’s All About DATA!

• KEY FACTORS:- Data Access- Data Delivery- Data Integration

•WIRELESS IS JUST HOW IT GETS THERE

•THE FOCUS IS THE END-TO-END SOLUTION

Services that offer Value Added Applications and

Content are of interest to the user!...


Vision 2003!

IP Virtual Private Network (VPN)IP Virtual Private Network (VPN)

PLATFORM FOR A WIDE RANGE OF PLATFORM FOR A WIDE RANGE OF COMMUNICATIONS-BASED SERVICESCOMMUNICATIONS-BASED SERVICES

CAPACITYCAPACITY

SERVICES

SERVICES

MO

BILITY

MO

BILITY


The Future

The Battle of the access network is over, it is know called: “Harmonized single global standard with several modes”

The new cry for revolution is:“All IP-based core networks!!!”


Internet Protocol (IP)

• Routes information packets through islands of networks

• Provides addressing information to identify the source and destination


0 7 15 23 31

Version Type of service Total length

Identification Fragment offset

IP Datagram

IHL

DF

MF

Time to live Protocol Header checksum

Source address

Destination address

Options


What will IP offer?

• The convergence interface for data, voice and multimedia applications as well as fixed and mobile networks

• Opportunity for third party developers to add value to a system

• Single system architecture for residential, office, fixed, mobile environments


The Famous Questions

• Which one is better, IP or ATM?

• Wireless IP or Mobile IP? What about Cellular IP?


How does IP work?

Physical

Network Access

IP

Transport(host-to-host)

Application

Physical

Network Access

IP

Transport(host-to-host)

Application

Communication Networks


Future Challenges for IP

“32 bits should be enough address space for Internet”

-- Vint Cerf, 1977

• QoS

•Addressing

• Wireless

• Mobility


Once we have advanced IP,what do we want to do with it?

• Establish a flexible service creation environment

• Enable quick service/application creation

• Ensure independence of access type

• Provide open interfaces to ensure a multi-vendor environment

• Maintain and enhance Global Roaming


How do we get there?

• Hybrid CS and PS networks will exist in near term

• Backward compatibility is critical

• Service transparency must exist across domains for common services


Again ...

IT’S ALL ABOUTDATA!

WIRELESS IS JUST HOW IT GETS THERE

• Broadband Wireless• Cellular mobile• Wireless LAN

+

IP +


Clients

Multi-Service Next Generation Networks

TodaySingle-service networks

LA

N (

Dat

a)L

AN

(D

ata)

Mo

bile

Mo

bile

Fix

ed T

elep

ho

ny

Fix

ed T

elep

ho

ny

Bro

adb

and

Wir

eles

sB

road

ban

dW

irel

ess

Servers

Clients

IP Backbone Network

AccessAccess

FutureMulti-service networks

Communcationi Control

Content Content

Access

Services


Evolution

HLRHLRPSTN/ISDN

MAP

HLR Internet

GPRS Node

BTSBTS

BSC

Voice Data

A Gb

MSCMSCBROADBAND / IP NETWORK

Node B

NodeB

RNC

Data

IWUIWU

PSTN/ISDN

LEGACYNETWORKS

Voice

ALL-IP BASEDALL-IP BASED NETWOKSNETWOKS

Today: You go through a CS to get to a PSTomorrow: You’ll go through a PS to get to a CS

2.5 G2.5 G 3 G3 G


What is GPRS?

•GSM is now in phase 2+, which consists of a large number of projects including improved voice coding and advance data transmission services such as high speed circuit switched data (HSCSD) and the General Packet Radio Service (GPRS).

•The General Packet Radio Service (GPRS) is a new non-voice value added service introduced in order to provide more efficient access to packet data networks from cellular networks.

•It supplements today's Circuit Switched Data and Short Message Service in GSM networks.


What is GPRS?

•Theoretical maximum speeds of up to 171.2 kbps

•Immediacy (no dial-up connection is necessary)

•Enable the Internet applications not available previously on GSM networks

•GPRS shares GSM frequency bands with telephone and circuit switched data traffic, and makes use of many properties of the physical layer of the original GSM system such asmultiple access scheme (TDMA) frame structuremodulation technique andslot structure


Tendency toward mobile IP

IP convergence

Telecommunication• Transportation• ISDN - Services• Video calls• Larger bandwith

Computer• Internet

access• Pictures• Remote LAN• e-mail• voice over IP

Media• Music• Video on

Demand• Animation• Infotainment• Advertisement

Mobility and

individual services

Mobile

IP

Why GPRS?


•GSM packet mode

•A new entity called GPRS Support Node (GSNs) is introduced to create end to end packet transfer mode within PLMN. There are two types of GSNs: the Serving GPRS support node (SGSN) the Gateway GPRS support node (GGSN)

•Designed to minimize hardware modifications on existing network elements :addition of a new hardware component in the BSS, the PCU,

which integrates most of the BSS new functions and manages RLC/MAC layers

BSC and BTS are impacted as few as possibleentirely new core network with many functionsThe HLR is enhanced with GPRS subscriber data and routing

information

GPRS: Architecture


•Provides an access to packet data networksInternetX.25

•This has driven to choices which are not « natural »e.g. ciphering is between MS and SGSN (LLC layer), standard

GSM BTS are not capable to handle ciphering with several keys for multiplexed MS on the same physical channel

•Two types of services are providedPoint to point (PTP)Point to multi-point (PTM)

GPRS: Architecture


•Consists of packet wireless access network and IP-based backbone

•Shares mobility databases with circuit voice services and adds new packet switching nodes (SGSN & GGSN)

•Will support GPRS, EDGE & WCDMA airlinks

•Provides services to different mobile classes ranging from 1-slot to 8-slot capable

•Radio resources shared dynamically between speech and data services

GPRS: Architecture


VLR ExternalData

Network

GGSNSGSN

Signalling

User data

GbGn

Gr

Abis

Gs

GatewayMobility Management RoutingEncapsulation

Mobility Management Authentication Ciphering Routing Other

PLMNs

Gp

Gi

New nodes

GSM nodesMSC

GGSN

BSCBTS

HLR

Mobile data solution built upon the existing GSM Infrastructure and Mobility Management. The packet oriented transport is obtained through a modified use of GSM RF and the addition of packet switched nodes ( IP routers with addition features like GPRS specific control and SS7 interfaces) in the backbone.

GPRS Architecture

Um


GPRS Architecture

Gf

D

Gi

Gn

GbGc

CE

Gp

Gs

Signalling and Data Transfer Interface

Signalling Interface

MSC/VLR

TE MT BSS TEPDN

R Um

GrA

HLR

Other PLMN

SGSN

GGSN

Gd

SM-SCSMS-GMSC

SMS-IWMSC

GGSN

EIR

SGSN

Gn


GPRS Architecture, The GGSN

•The Gateway GPRS support node (GGSN) acts as a logical interface to the GPRS network and to external public data networks such as IP and X.25

•GGSN is connected to with SGSNs via an IP GPRS backbone network

•Routing. GGSN contains routing information for attached GPRS users.

•Mobility Management. GGSN also performs mobility management functions requesting location information from the HLR.

•Encapsulation. GGSN performs routing functions to “tunnel” Protocol Data Units (PDUs)


GPRS Architecture, The SGSN

•The SGSN is at the same hierarchical level as the MSC and is responsible for the delivery of packets to the MSs within its service area.

•Mobility Management. SGSN Keeps track of the individual MS’s location.

•Authentication. SGSN does access control

•Ciphering. Performs security functions

• Routing. Provides packet routing to and from the SGSN service area for all users in that service area.


GPRS Protocol Architecture

Relay

NetworkService

GTP

Application

IP / X.25

SNDCP

LLC

RLC

MAC

GSM RF

SNDCP

LLC

BSSGP

L1bis

RLC

MAC

GSM RF

BSSGP

L1bis

Relay

L2

L1

IP

L2

L1

IP

GTP

IP / X.25

Um Gb Gn GiMS BSS SGSN GGSN

NetworkService

UDP /TCP

UDP /TCP

Relay



•Above the network layer, widespread standardized protocols may be used.

•Between two GSNs:The GPRS Tunneling Protocol (GTP) tunnels packet data units

(PDU) through the backbone network by adding routing information;

TCP/UDP and IP are used as the GPRS backbone network layer protocols. Ethernet, ISDN or asynchronous transfer mode (ATM)-based protocols may be used below IP;

•Between the SGSN and the MSThe SNDCP maps network level protocol characteristics onto

the underlying logical link control and provides functionalities like multiplexing of network layer messages onto a single virtual logical connection, encryption, segmentation and compression;



•Between the MS and BSSThe DLL is divided into the LLC and the RLC/MAC sublayers.

The LLC provides a logical link between the MS and the SGSN. Protocol functionality is based on LAP-D

The RLC/MAC provides services for information transfer over the physical layer of the GPRS radio interface.– The RLC is responsible for the transmission of data blocks and the

backward error correction– The MAC is derived from a slotted ALOHA protocol.

The Physical layer is split up into a PLL and RFL. – The PLL is responsible for FEC, rectangular interleaving, and

procedures for detecting physical link congestion– The RFL conforms to the GSM 05 series of recommendations.



•In the Network

The LLC is split between the BSS and the SGSN. The BSS functionality is called LLC relay.

Between the BSS and the SGSN, the BSS GPRS Protocol (BSSGP) conveys routing and QoS related information, and operates above frame relay.

•Between the MS, BSS and the SGSN,

The same protocols are used for data transmission up to the SNDCP protocol. At the network layer, a specific mobility management protocol is required within the MS and SGSN.


GPRS in the GSM Evolution

•GPRS is part of the GSM data services evolution

GSMData

HSCSD

GPRS

EDGEEGPRS

WCDMA

1998 1999 2001

WCDMAPhase I

Evolution

9.6 kbps

9.6 - 28.8 kbps

9 - 53.6 kbps

384 kbps

144 - 384 kbps

384 - 2048 kbps

2000

Time


BSC

SGSN

GGSN

GPRS Mobility: Session Setup

PSTN/ISDN

BTS

IP

I want to do packet

Radio link established

Set up a contextTunnel created

IP Address exists!HLR

MSC

GMSC


GMSC

MSC

BSC

GGSN

SGSN

GPRS Mobility: Packet Forwarding

PSTN/ISDN

BTS

IP

163.43.42.143

Inbound packet

Allocate a few bursts and send it!

This tunnel!

This radio link!

Where is the mobile?

?

Where is the mobile?

?

HLR


GMSC

MSC

BSC

GGSN

SGSN

GPRS Mobility: Cell Reselection

PSTN/ISDN

BTS

IP

Tunnel createdRadio link establishedI’m here now

OK, new link and tunnel

Still same IP address!HLR


• A GPRS MS can operate in one of three modes of operation. The mode of operation depends on the services that the MS is attached to, i.e., only GPRS or both GPRS and other GSM services, and upon the MS's capabilities to operate GPRS and other GSM services simultaneously;

• An MS in class‑A mode of operation operates GPRS and other GSM services simultaneously;

• An MS in class‑B mode of operation monitors control channels for GPRS and other GSM services simultaneously, but can only operate one set of services at one time;

• An MS in class‑C mode of operation exclusively operates GPRS services;

GPRS, Types of Mobile Station


But in fact … by end 2003

•1 billion fixed IP nodes;

•1 billion mobile nodes;

•1 billion circuit switched high bandwidth nodes;

and:

•Millions of Bluetooth machine-to-machine communications;

• Millions of xDSL nodes with n>10 users per node.


ISP

Intranet

Internet

Packet Data Network with various radio technologies

GGSN

PSTNSGSN-GSM

W-ATM

SGSN-W-ATM

URAN SGSN-UMTS

PSTNGW

IP - backbone

Modular, main parts are independent of radio access

SGSN-D-AMPS

GGSN-corporate

IS-136

BSS


Network Evolution time plan(also as 3GPP,ETSI,etc evolve..finally)

GPRSBest effort packet data

EDGENo voice

Best effort packet data

EDGE UMTS

Real time spectrum efficient multimedia1999 2000 2001 2002 2003

GPRS with IPv4Best effort packet data

GSM voice

EDGEBest effort v4 packet data

GSM voice

UMTS with IPv4+v6Best effort packet dataCircuit switched voice

EDGE UMTS

Real time IPv6 voice and dataPhase1

Phase2


Common architecture 2003

3G Network based on the same Server/Gateway architecture for wireline & for wireless

Backbone

MGW MGW

Wireless Wireline

Media Gateway


GMSC

MSC

UTRAN

BSC

GGSN

SGSN

UMTS network overview

PSTN/ISDN

UTRAN: UMTS Terrestrial Radio Access NetworkRNC: Radio Network Controller

Node B

CS core network

UTRAN transport: ATMNew tricks: Soft Handover using IP

IP

Packet core network

HLR


Multiple Levels of Mobility

•Access level classical cellular

• Network level Mobile IP

• Application level H.323 mobility and WAP gateways


Mobility Concepts for Users

•The user does not care about it! They just want to have access at anytime, to anything and

anywhere;

• True mobility (always the best access) Depends on subscription, coverage and terminal capacity;

• The way to get there Hidden and seamless across different access technologies


UMTS Basic Configuration

BSS

BSC

RNS

RNC

CN

Node B Node B

A IuPS

Iur

Iubis

USIM

ME

MS

Cu

Uu

MSCSGSN

Gs

GGSNGMSC

GnHLR

Gr

GcC

D

E

AuCH

EIR

F Gf

GiPSTN

IuCSGb

VLRB

Gp

VLRG

BTSBTS

Um

RNC

Abis

SIM

SIM-ME i/f or

MSC

B

PSTNPSTN

cell

• The basic configuration is a PLMN supporting GPRS and the interconnection to the PSTN/ISDN and PDN;

• Interface Iu, Iur and Iubis are defined in the UMTS 24.4xx series;

• Interfaces B, C, D, E, F and G need the support of the support of the Mobile application Part of the signaling system No 7 to exchange the data necessary to provide the mobile service.


Working Assumptions

The phase 1 UMTS/Release ‘99 standards should provide the capability to support:

• a core network based on an evolved 2G MSC and an evolved SGSN;

• an optionally evolved Gs interface;

• mobile IPv4 with Foreign Agent care-of address to end users over the UMTS/GPRS network, where the Foreign-Agent is located in the GGSN;

• UMTS/IMT2000 phase 1 (release 99) network architecture and standards shall the operator to choose between Integrated and Separated core network for transmission (including L2);

• the UMTS standard shall allow for both separated and combined MSC/VLR and SGSN configurations;

• separate the L3 control signaling from the L2 transport (do not optimize L3 for one L2 technology);

• future evolution may lead to the migration of some services from CS-domain to the PS-domain without changes to the associated higher-layer protocols of functions.


Iu Interface

Iu-PS

AAL5

ATM

UDP/IP

GTPUser plane

AAL5

ATM

UDP/IP

GTPUser plane

• UTRAN shall support two logically separate signaling flows via Iu to combined or separate network nodes of different types (MSC and SGSN);

• the protocol architecture for the User Plane of the Iu interface towards the IP domain shall be based on the same principles as for the (evolved) Gn interface;

• One or several AAL5/ATM Permanent VCs may be used as the common L2 resources between the UTRAN and the ‘IP domain’ of the CN.

Protocol architecture for the Iu user plane toward the IP domain


Charging Functionality

Charging functionality is located at the 3G-SGSN, on the other hand only RNC can identify the actual packet volume successfully transferred to a UE. In order for 3G-SGSN to provide the volume based charging for IP domain, the system shall support the following procedure over Iu interface:

• RNC indicates the volume of all not transferred downlink data (discarded or forwarded to 2G-SGSN) to the 3G-SGSN so that the 3G-SGSN can correct its counter. Partially transferred packets are handled as not transferred;

• RNC delivers to the 3G-SGSN the discarded of forwarded volume accumulated over an implementation dependent time and not per discarded or forwarded packet;

• the 3G-SGSN can ask RNC to provide the volume of buffered downlink data to correct its counter at any time the 3G-SGSN wants.


Iu Control Plane

RANAP

MTP-3bCTP

(module SCCP/MTP3 users)

SAAL-NNI IP

SCCP

RANAP protocol stack option

• for transport of RANAP messages over Iu an SCCP protocol shall be used for both packet and circuit switched domains;

• in the circuit switched domain SCCP messages shall be transported on a broadband SS7 stack comprising MTP3b on top of SAAL-NNI;

• in the packet switched domain the UMTS standard shall allow operators to chose one out of two standardized protocol suites for transport of SCCP messages: broadband SS7 stack comprising MTP3b

on top of SAAL-NNI; IETF CTP protocol suite for MTP3b users

with adaptation to SCCP, fully compatible with IP.


Iu User Plane

RLC

MAC

L1

GTP-U

BSSGP

ATM

L2

L1

UDP/IP

L2

L1

UDP/IP

Uu Iu Gn GiUE RNS 3G-SGSN 3G-GGSN

GTP-UGTP-U

UDP/IP

RLC

L1

AAL5

ATM

UDP/IP

GTP-U

MACAAL5

• the standard shall support that the user data flows transported over the Iu reference point to/from the ‘IP domain’ shall be multiplexed on top of common L2 resources;

• if the Iu data transport bases on ATM PVCs then the Iu IP layer provides the Iu network layer services;

• a tunneling protocol is used on top of the common L2, this tunneling protocol corresponds to an evolution of the user plane part of the GTP protocol used in GPRS put on top of UDP/IP;

• the user data plane in the UMTS network is made up of two tunnels: a first IP/UDP/GTP tunnel between RNC and 3G SGSN on Iu; a second IP/UDP/GTP tunnel between GGSN and 3G SGSN on Gn.


Data Retrieve Between GPRS and UMTS

G G S N

2 G -S G S N

S R N C

UE

R L CL L C

3 G -S G S N

D a t a r e t r i e v e v i a 3 G -S G S N v i a t w o G T Pp i p e s

D a t a R e t r i e v eI n t h e u s e r p l a n e

G P R S / U M T SH a n d o v e rS i g n a l l i n g

R A N A P

G T P - c

• since some parameters transported by GTP-c are CN related only, it is necessary to terminate GTP-c signaling exchanged with the 2G-SGSN in the 3G-SGSN and to use RANAP signaling on Iu between 3G-SGSN and SRNC;

• as charging of the retrieved data is to be carried out at 3G-SGSN, data exchanged between SRNC and 2G-SGSN are handled by the 3G-SGSN to ensure that: 3G-SGSN can increment charging counters

for user data sent from 2G-SGSN to SRNC; 3G-SGSN can decrement charging counters

for user data sent from SRNC to 2G-SGSN avoiding that such data are charged twice.


GTP-u

AAL5

IP

UDP

ATM

GTP-u

L2

IP

UDP

L1

SRNC 3G-SGSN 2G-SGSN

GTP-u

L2

IP

UDP

L1

GTP-u

AAL5

IP

UDP

ATMIu Gn

User Plane Protocol Stack for Data Retrieve Between GPRS and UMTS


SRNC

GGSN

SRNC

UE

RLCRLC

3G-SGSN 3G-SGSN

data retrieve via 3G-SGSN

User data stream

RNSAPSignalling

SRNSRelocationSignalling

GTP-c

RANAPRANAP

User Data Retrieve in UMTS

• there are two kind of signaling: core network: corresponds to signaling

exchanged on Gn between 3G-SGSNs during the first phase of resources for the SRNC relocation;

access network: corresponds to signaling for RLC protocol between SRNC and UE. This can be done over Iur when the source SRNC actually hands-over the role of SRNC;

• the user plane for data retrieve between two RNCs is based on GTP-u/UDP/IP, the GTP connections are terminated in the source SRNC and the target SRNC.


User Plane Protocol Stack for Data Retrieve in UMTS

GnIu Iu

GTP-u

AAL5

IP

UDP

ATM

L2

IP

L1

GTP-u

AAL5

IP

UDP

ATM

SourceSRNC

3G-SGSN 3G-SGSN TargetSRNC

L2

IP

L1

AAL5

IP

ATM

AAL5

IP

ATM


Two Iu signalling connections (“two RANAP instances”)

UTRAN

3G SGSN

HLR

3G MSC/VLR

UE

CS servicedomain

Two CN service domains

One RRC connection

UTRAN withdistributionfunctionality

PS servicedomain

Common subscription data base

CS state PS state

PS state CS state

CS location PS location

Separate Core Network Architecturefor UMTS


Integrated Core Network Architecturefor UMTS

Two Iu signalling connections “two RANAP instances”

UTRAN

HLR

UMSC

UE

CS servicedomain

Two CN service domains

One RRC connection

UTRAN withdistributionfunctionality

PS servicedomain

Common subscription data base

CS state PS state

PS state CS state

CS location PS location