1

Cellular networks evolution: Cellular networks evolution: from 2G to 3Gfrom 2G to 3G

CEENet 2004: Wireless and Mobile Networking

Budapest (Hungary)

August 20th, 2004August 20th, 2004

Sami TabbaneSami Tabbane

2

SummarySummary

2G networks architecture2G networks architecture

2,5G evolution towards third 2,5G evolution towards third generationgeneration

3G services and evolution3G services and evolution

ConclusionsConclusions

3

I. 2G networks I. 2G networks architecturearchitecture

4

GSM GSM basic basic network network architecturearchitecture

.. < > ^ ... . . .

BTS

BTS

BSC

TRAU

MSC/VLR

PSTN

HLR A

Abis

SS7 Network

EIR

BSS

NSS

5

BTSBTS Radio transmission/reception

management (modulation/demodulation, equalisation, interleaving ...)

Physical layer management (TDMA transmission, SFH, coding, ciphering ...)

Link layer management (LAPDm)

Received signal quality and power measures.

6

BSCBSC

Radio resource management: channel allocation, BTS measures processing, BTS and MS power control, handover ...

Interfaces management: with the MSC (gathers the traffic towards the MSC) and with the BTSs.

7

MSCMSC Management of the communications between the

mobiles and the fixed network. Handover management. Interconnection with the

fixed network (switching features). Management of the visiting

users with the VLR. GMSC function (Gateway

MSC): gateway for the calls

coming/going towards an external network.

8

HLR/VLRHLR/VLRHLR (Home Location Register)

Subscribers database:

- Subscription data: IMSI, MSISDN, subscription type (restrictions, supplementary services, ...)

- Location information: mobile VLR number.VLR (Visitor Location Register)

Data: IMSI, MSISDN, TMSI, MSRN, subscription type, location area, ...

9

Suscriber Identity ModuleSuscriber Identity Module

Informations: subscriber identity, password (PIN), subscription informations (authorized networks, call restrictions, …), security algorithms, short numbers, last received/dialled numbers, last visited location area, ...

SIM card + GSM terminal = access to GSM services.

10

GSM sGSM services characterizationervices characterization

GSM = circuit switched-based technology.

2 types of services (ISDN based classification):

Bearer services: Telecommunications services offering transmission capabilities (bitrate, BER, synchronous/asynchronous mode ...) between network access points.

Teleservices: Telecommunications services offering capacities taking into account the terminal equipment (telephone, SMS, ...).

11

Some GSM bearer servicesSome GSM bearer servicesBearer service Target

networkOffered throughputs (bits/sec)

3.1 kHz External to the PLMN

Asynchronous data circuit duplex

PAD circuit asynchronous access

Synchr data circuit duplex.

Alternate speech and data

Speech followed by data

Synchronous packet data duplex

ISDN

PSTN, ISDN

PSPDN

PSTN, ISDN

PSTN, ISDN

ISDN, PSTN

PSPDN

300 to 9600

300, 1200, 1200/75, 2400, 4800, 9600

Idem

1200, 2400, 4800,

9600

2400, 4800, 9600

12

GSM teleservicesGSM teleservices

Radiotelephone. Emergency calls.Short message service.Fax. ...- Supplementary services:Calling number identification. Call waiting,Call transfer (on non reply, unconditional, on

busy, ...)Conference call, Closed user group

...

13

II. 2,5 G evolution II. 2,5 G evolution towards 3Gtowards 3G

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High Speed Circuit High Speed Circuit Switched Data (HSCSD)Switched Data (HSCSD)

Objective: High bitrates radio bearers.

Introduced in phase 2+ (1997).

Use several time slots per mobile (up to 6).

Bitrates: 19.2 ; 28.8 ; 28.4 ; 48 ; 56 and 64 kb/s.

Asymetric configurations (n slots on the uplink and m slots on the downlink).

Problem: Circuit-switched (cost + capacity).

15

Customized Applications for Mobile Customized Applications for Mobile network Enhanced Logic (CAMEL)network Enhanced Logic (CAMEL)

Intelligent network concept CAMEL defines an architecture and mechanisms based on IN.

Separation:

-1- Applications and Services specific features (SCP: Computers for services provision + SMP: Management point for data of one or several SCPs),

-2- Applications comon processing (SSP: Switch for service access)

Objective: Allow roaming subscribers to use their services even though these are specific to their operator.

16

CAMEL services introductionCAMEL services introduction

.. < > ̂... . . .

BTS

BTS

BSC

TRAU

MSC/VLR

PSTN

HLR A

Abis

IN Plate-form

SS7 Network

EIR

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SIM ToolkitSIM Toolkit

Principle: The SIM card can initiate actions on the terminal.

Objectives: Allow exchanges between the network and the SIM through SMSs (without displaying them) Value-added services provision.

Examples:

- Reservation in a restaurant (send a menu by the network, manages user choices and the SIM card sends back the reservation in an SMS).

- Menus management (kiosk services ).

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General Packet Radio General Packet Radio Service: 2,5 GService: 2,5 G

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Introduction of packet-switchingIntroduction of packet-switching

Packet switching advantagesPacket switching advantages Transmission of non-periodic and bursty

data (e.g.: mails),Frequent small packets (e.g.: telematic,

billing and micro-payments),Large but unfrequent packets (e.g.: ftp).

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GPRS principlesGPRS principles

Higher bit-rates per TCH (9.05 ; 13.4 ; 15.6 ; 21.4 kb/s),

Higher bit-rates with up to 8 time slots per user,

Channel sharing by active terminals,

Separate allocation of uplink and downlink channels, Separate packet transmission network between the BSC and external packet transmission networks: GSS (based on SGSN and GGSN).

21

GGSN (GGSN (Gateway GPRS Support NodeGateway GPRS Support Node)) FunctionsFunctions

Routing: IP router which supports dynamic or static routing, Security: Ciphers the communications towards or from the

mobiles. Mobility management: Use of routing areas. Handover

management between the BSCs and other SGSNs. Authentication: At Attach and inter-SGSN RA updates. Sessions management: At each session, the SGSN activates a

PDP (Packet Data Protocol) context. Billing: Production of the CDRs according to the quantity of

information and the session duration (attachment, duration of active PDP context).

SMS: Supports the Gd interface for the communications with the SMS-GMSC and the SMS-IWMSC.

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GGSN (GGSN (Gateway GPRS Support NodeGateway GPRS Support Node)) functionsfunctions

Routing: IP router which supports dynamic or static routing, Security: Includes firewalls for filtering the packets coming

from external IP networks. Gateway: Allows the connection to other IP or GPRS

networks. Mobility management: Allows the routing of the packets

towards the users SGSNs, according to their mobility. Sessions management: At each session, the GGSN allocates

an IP address to the mobile. Billing: Production of the CDRs according to the quantity

of information and the session duration (attachment, duration of active PDP context).

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GPRS introduction GPRS introduction iin a GSM networkn a GSM network

.. < > ^ ... . . .

BTS

BTS

BSC

PCU

Gb Gs

SGSN Gr, Gd, Gf

Gn

Border Gateway

GGSN

Inter-operator

GPRS backbone

GPRS backbone

Internet PDN

Router LAN

Service plate-form

WAP, WWW, ...

SS7 Network

Gc

Gf EIR

Gr

TRAU

MSC/VLR

PSTN

HLR A

Abis

IN Plate-form

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GSM to GPRS EvolutionGSM to GPRS Evolution

BSS Evolution: -  Replace/Upgrade existing elements: BTS, BSC, O&M, Network planning, Links (Abis, Ater, …). -  New element: PCU (Packet Controller Unit). NSS Evolution: - A new core network (GSS) dedicated to GPRS: IP/ATM based, network packet nodes (SGSN, GGSN), Internet equipment (DNS servers, Firewalls, …). -  Evolution of the network elements: HLR, MSC/VLR, SS7.

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Main Main characteristicscharacteristics

Same physical layer as GSM. Service separated from GSM:

Different fixed networks (new network entities and new protocols).

New mobiles, 3 types: - A: GSM and GPRS at the same

time, - B: GSM or GPRS (« dual mode » in

idle mode), - C: GSM or GPRS a priori.

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Services Services classificationclassification

Services

Service type Sub-types Characteristics

Point-to-Point (PtP)

PtP – Connectionless Network Service (CNLS)

Data packet transfer between two points via a connection-less service (e.g. Internet) or via connection oriented service (e.g. X25)

PtP – Connection Oriented Network Service (CONS)

Data packet transfer from a point towards a geographical area (group of cells)

Point-to-Multipoint (PtM)

PtM – Multicast (PtM-M)

Multicast service (cf. IP)

PtM – IP Multicast (IP – M)

Data packet transfer towards a predefined group of users in a geographical area

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Enhanced Data rates for Enhanced Data rates for the GSM Evolution: 3Gthe GSM Evolution: 3G

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Enhanced Data rates for GSM Evolution Enhanced Data rates for GSM Evolution (EDGE)(EDGE)

Objective:Increase the data bitrates (GPRS EGPRS). Bitrates:

- 473 kb/s for the terminals of 100 km/h maximum. - 80-130 kb/s on average.

- 144 kb/s for the terminals of 250 km/h maximum. Means:-1- New modulation (8-PSK).-2- Link adaptation. New mobiles, upgrade/replacement of TRXs

and capacity enhancement (Abis, …).

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EDGE introductionEDGE introduction

.. < > ^ ... . . .

BTS

BTS

BSC

PCU

Gb Gs

SGSN Gr, Gd, Gf

Gn

Border Gateway

GGSN

Inter-operator

GPRS backbone

GPRS backbone

Internet PDN

Router LAN

Service plate-form

WAP, WWW, ...

SS7 Network

Gc

Gf EIR

Gr

TRAU

MSC/VLR

PSTN

HLR A

Abis

IN Plate-form

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III. 3G services and III. 3G services and evolutionevolution

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Internet and GSMInternet and GSM

0

200

400

600

800

1000

1200

1996 1997 1998 1999 2000 2001 2003

Mill

ion

s o

f u

se

rs

GSMInternet

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Motivations for a new Motivations for a new systemsystem

Convergence: computer, telecommunications and audio applications.

Present services: Mainly voice (> 70 % of cellular operators revenues).

Extend to data and combination of voice/data. New frequency bands (WARC 92). Migration (operators and providers) towards

more diverse and developed applications and services.

Technological progress (networks, systems, DSP, …)

Definition and development of new systems.

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Development initial planningDevelopment initial planning 1998-1999 Radio interface definition

2000 First demonstrations of 3G systems

May 2000 IMT-2000 specifications validation by ITU-R

2000-2001 3G licenses allocation in Europe

Mid-2001 First 3G networks opened in countries such as Japan, based on first 3G specifications

Mid-2002 3G terminals available (first specifications)

2002 3G pilot networks in Western Europe.

2002-2003 3G applications development

Mid-2004 3G commercially available

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UMTS main UMTS main features (1)features (1)

Integration of existing mobile services (cellular, cordless, paging, PMR, …) and introduction of service portability (Virtual Home Environment, …).

Choice among various terminals and service providers.

Flexible terminals supporting several radio interfaces (software radio).

Global roaming for terminals and services.

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UMTS main UMTS main features (2)features (2)

Voice quality similar to that of fixed networks.

Satellites services for areas non covered by terrestrial BTS.

UMTS frequency spectrum: 1885-2025 MHz and 2110-2200 MHz.

Security and anti-fraud techniques against access to data by non-authorized persons or entities.

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1997 2000 2005

Uplink

Downlink

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UMTS main UMTS main features features (3)(3)

Wideband multimedia mobile services: 2 Mb/s for indoor, reduced mobility (10 km/h), 384 kb/s for urban outdoor (120 km/h), 144 kb/s for rural outdoor, important mobility (500 km/h). Variable quality of service (BER between 10-3 and 10-

6, delays between 30 and 300 ms). Asymetric and variable bitrate transmission. Multiples services per user: Speech : 8 kb/s, Data : 2,4 at 6x64 = 384 kb/s, Video : 384 kb/s, Multimedia.

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Objectives and Objectives and Features (1)Features (1)

Wideband. Service integration. Packet access. Techniques for capacity

enhancement: multi-user detection, interference cancellation, adaptive antennas, MIMO, … Inter-system (GSM – 3G) and

inter-frequencies (hierarchical networks) handover.

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Objectives and Objectives and Features Features (2)(2)

Main challenge: Merge mobile phone radio coverage to Internet and other multimedia applications. 3G systems must provide: Flexible multimedia services management,  Internet access, Flexible services support, Packet access at an interesting cost for « Best Effort » services. Most of multimedia applications accessible through Internet:

3G access = Mobile Internet.

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Introduction of Introduction of UMTSUMTS

RNC

Node B

Iub

Iub

Iu

UMTS Core Network

UE

Node B

UMTS Radio Access Network

GPRS/EDGE Radio Access Network

GPRS core network

Internet

NSS

40

Zone 4Global

Zone 1in building

Zone 2Urban

Zone 3Suburban

UTRA/TDD

UTRA/FDD

GSM

MSS

3G environment and multi-mode terminals 3G environment and multi-mode terminals (UMTS Forum)(UMTS Forum)

Basic terminalPDA

Audio/video terminal

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Evolution from 2,5G to Evolution from 2,5G to 3G networks3G networks

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UMTS R99 main featuresUMTS R99 main features

UMTS Core Network

UE

UTRAN

Services

New radio access system (WCDMA-based): higher bitrates, HO with GSM

Camel, GPRS-based core network with improvements (security, GTP, …)

OSA (Open Systems Architecture), USSD (Unstructured Supplementary Service Data), MMS, LCS (cell level), streaming, GSM services (SMS-PtP/CB), SMS, VHE

EMS, MMS, MExE (Mobile Execution Environment, terminals classified by classmark), SAT (SIM Application Toolkit, interoperability

between all USIM and UE), VHE

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UMTS R4 FeaturesUMTS R4 Features

UMTS Core Network

UE

UTRAN

Services

New TDD access mode, evolution of UTRAN transport (IP introduction), radio interface improvement (e.g. UTRA repeaters ), RAN improvements (e.g. overhead compression)

Packet transport improvement in the core network, TrFO (Transcoder Free Operation), Tandem Free

between 2G and 3G

Authentication algorithm, VHE and OSA evolutions, LCS support in circuit and packet domains (OTDOA and A-GPS)

MExE release 4, MMS r4, SMS/EMS improvements, Terminal Local Model-USAT Local (allows USIM applications to access other devices

with Bluetooth),

44

UMTS R99/R4 and UMTS R99/R4 and GSM/GPRSGSM/GPRS

UMTSRadio

GSMRadio

PSTN/ISDN

PublicIPGGSN

VMSC

VLR

SGSN

GPRSVLR

HLRCAMEL

PS

CS

GMSC

Core Network

IP/ATM Core

Network(s)

45

UMTS R5 FeaturesUMTS R5 Features

UMTS Core Network

UE

UTRAN

Services

HSDPA (bitrates between 1 and 5 Mb/s), Smart antennas, IP transport in UTRAN (IP-

RAN) with DiffServ introduction, SIP (call control), End-to-end QoS improvements, IuFlex (traffic load

sharing between core nodes

IMS (VoIP, chatt, jeux, white shared board, flexible billing, …), OSA improvements (VAS offered by third parties, VHE easier),

Extended streaming (optimisation, 2 and 3D graphics, MIDI audio, …)

Wideband AMR (wider bandwidth for voice), GTT (Global Text Telephony, real time text

communication), LCS improvements with A-GPS, MMS/EMS improvements

46

UMTS Core Network

UMTS Radio Access Network

GPRS/EDGE Radio Access Network

GPRS core network

Internet

NSS

IP Multimedia System

Introduction of Introduction of IMSIMS

47

UMTS R6 FeaturesUMTS R6 Features

UMTS Core Network

UE

UTRAN

Services

Infrastructure sharing, QoS/IP, ... WLAN (loose coupling) with AAA function reuse, access with USIM

MBMS (multimedia broadcast service), IMS phase 2 (independant access from the radio access UMTS, GERAN,

WLAN), Presence and Instant Messaging, Push-To-Talk

SES (Speech Enhanced Services): distributed voice recognition, MIMO (multiple antennas in the

terminals), Terminal management (configuration, performances, downloading)

48

E-GGSN

E-SGSN

RNC

RNC

E-GGSN

Roadmap to All-IP Networks - 3GPP R6+Roadmap to All-IP Networks - 3GPP R6+

PS + IM DomainAll-IP

IPv4 & IPv6 Networks

IP inUTRAN

49

UMTS features and sub-systems for service provisionUMTS features and sub-systems for service provision

Introduction of IPDevelopment of multimedia IP services with hardware and software componants integration

Customization User framework portability

Provision by third parties

Services development by external applications and contents providers

Terminal related

Adaptation of the service to the user terminal according to its characteristics, task sharing with the network

MeXE Mobile eXecution

Environment

VHE Virtual Home Environment

OSA Open Service

Access

IMS IP Multimedia

Service

50

IMS - IP Multimedia ServiceIMS - IP Multimedia Service

Principles

Drawbacks

QoS characteristics differentiation for voice or video associated with a multimedia session (streaming, IM, etc.)

Separation of the planes IP data and session control (SIP)

Independant from the access network

Introduction of multimedia services with QoS managementIntegration with other networks (WLANs, fixed, CDMA2000, …)Flexible billing: billing / service, connectivity, QoS, time, destination

Advantages

IMS for mobile networks GPRS, EDGE, UMTS & CDMA2000

Non real time services IP multimedia applications plate-

form IETF specifications based

IMS extended to wideband fixed networks (xDSL, WLAN, cable, …)

Supports services convergence on fixed and mobile networks (conversion

CS voice traffic in IP)

R6R5

Implementation of many equipments, softwares, interfaces, protocols, which may cause integration, interworking and optimisation problems

Ex.: S-CSCF (Call Status Control Function); SIP AS (SIP Application Server); OSA SCS (Service Capability Server); IM-SSF (Inter-working Module); CSE (Camel Service Environment); HSS (Home Subscriber Server)

Security and QoS with Internet interconnection

51

CompoComponnants ants andand interactions interactions betweenbetween IMS IMS andand otherother networksnetworks

ApplicationServers

(SIP, OSA, CAMEL)

SessionControl

MediaControl

IMS

User Data

MediaGateway

PSTN

Packetnetwork

ISUP

Packet SupportNode

Backbone IP PacketGateway

RNC

RAN

Core packet

SIP

SIP

MediaGateway

PCM

AMR

52

VHE VHE - - Virtual Home EnvironmentVirtual Home Environment

Principles

•PSE (Personal Service Environment) portability between networks and terminals: user – services interaction modes, multiple subscriptions management (pro/perso), multiple terminals and preferences according to the location.

•Same features always available to the user: interface and services customization, whatever the network and the terminal.

• Independancy relatively to the network (roaming) and the terminal

Applications

VAB Virtual Address

Book

Use of many types of terminals to

access and update user data

Customer Care service

Support to the users: interactive

tutorials, problems detection and

solutions proposal, on-line assistance,

…

Calender multiparty application

Coordinated calendar

management among remote users: answers

collection, meeting dates

determination, …

Multimedia Delivery service

Adaptation of the video to the user

terminal

53

OSA OSA - - Open Service AccessOpen Service Access

Supervision of the services and contents by the operator QoS management by external providers for offered services

Principles

Drawbacks

Introduction of SCF (Service Capability Features) to provide applications with service features: call control, user location,…

Access to network features which application developpers will use to develop or improve services

Introduction of services by third parties through standardized interfaces and applications

Easier introduction of application and service providers

Advantages

VPN, teleconferencing, LBS Applications implemented in one

or many application serversApplications

54

MExE - Mobile Execution EnvironmentMExE - Mobile Execution Environment

Définition, standardisation and implementation of these terminal classes

Principles

Drawbacks

Standardised execution environment for the mobiles

Negociation of the features between UE and MExE server during service initiation or dynamically

Execution of service applications inside the UE or in the MExE server

MExE defines the classmarks to support various terminals (Classmark 1: WAP environment, Classmark 2: PersonalJava, Classmark 3: J2ME CLDC MIDP environment )

Adaptation of the services to user terminalsAdvantages

55

UUSIMSIM characteristics characteristics

64K, 128K, eventually 1MoCapacities

Operator and user profiles management through radio interface (OTA, Over The Air): VAS real-time implementation, with updates and applets downloading, file management, …

Profile management

Point-to-point messages exchange security provision in OTA

Security

Pro-active SIM card for execution of features; management of UE by USIM and thus by the operatorSIM Application

Toolkit (STK)

OTA based on SMS transport, then via other bearers (CSD, GPRS, UMTS)

Operations

56

Interactions Interactions forfor service service provision in UMTSprovision in UMTS

IMSMultimedia IP

servers

Application and

Content providers

Application servers BDD & user profiles

(PSE, VHE, …) OSA

RAN

(CAC, LC)

QoS management

USAT, MeXE, OTA, CAMEL, LCS, …

57

Services evolution in UMTS R99/R4/R5/R6 Services evolution in UMTS R99/R4/R5/R6 networksnetworks

Release Services

R99 MMS, streaming, LCS (cell), MExE, SAT, VHE,

R4 TrFO, VHE, OSA, LCS in PS and CS,

R5 VoD, IMS, HSDPA, Wideband AMR, GTT

R6 MBMS, IMS phase 2

Evolution of the services (voice and interpersonal services)

Voice

SMS/MMS

Voice

Messaging

Videotelephony

Voice/Videotelephony

Instant Messaging/Presence

Rich Call Services

Messaging

Voice/Videotelephony

IM/Presence

Messaging

RCS

LCS

GTT

58

QoS and planning QoS and planning problems in UMTSproblems in UMTS

59

QoS QoS problems iproblems in UMTSn UMTS

Necessary definition of end-to-end QoS management functions No 3GPP specifications for QoS in PS and in IMS Implementation choice depends on the operator preferences,

the network, the service model, equipment providers, … Resources negociated between operators through DiffServ,

DSCP at network borders

QoS guaranteed in CS but not in IP: QoS problems similar in UMTS as in any IP network

QoS provision in IP ?

60

QoS QoS provision iprovision in UMTSn UMTS

Radio access

RSVP, overprovisionning, DiffServ/ IntServ, MPLS In R5, definition of 5 signalling scenarios for end-to-end QoS:

-3 with PDP/DiffServ interworking,

-2 with RSVP signalling

Core network

CAC - Call Admission Control

•RNC: admits or rejects new users or new RAB (Radio Access Bearers) according to network load, users priorities and resource availability

•Used at network UE access: RAB reconfiguration or allocation and HO according to the events

•UL channel interference and DL power related

Load/Congestion Control

• RNC: supervises, detects and manages congestion situations during users connection

• Load reduction via queueing mechanisms,, by delaying the packets of the best effort traffic

• Mechanisms not standardised, designed by the equipment vendors and optimised by the operators

• Principles: CAC based on the interference level, on the admission politics/load factor, etc.

61

Cell breathing phenomena

Cas 1 : 10 utilisateurs Cas 2 : 20 utilisateurs

-10 < C/I < -5 dB -15 < C/I < -10 dB

-15 < C/I < -50 dB cellu les

Case 1: 20 users Case 2: 10 users

Radio phenomenaRadio phenomena

cells

62

Capacity, cell radius and Capacity, cell radius and noise risenoise rise

R

Charge de la cellule = 20 % de la capacité maximum

Niveau d’interférence = y dB

R

R’

Charge de la cellule = 50 % de la capacité maximum

Noise Rise = 2 dB

Niveau d’interférence = y + 2 dB R

R et R’ sont les rayons des cellu les dans les deux situations de charge

Cell load = 20% of the maximum capacity

Interference level= y dB

R and R’ are the cell radius in the 2 load

situations

Cell load = 50% of the maximum capacity

Interference level= y + 2 dB

63

WCDMA systems and planningWCDMA systems and planning

• Interaction between coverage and capacity (estimation of interference level, relation between user number and cells bitrates),

• Multi-services aspect (differents services with different Eb/N0),

• Power control (minimum transmission power of the MSs and BTSs, difference between UL and DL),

• Rake receiver and Soft HO.

64

ConclusionsConclusions

UMTS introduces:

an environment to develop and provide services: wideband, flexible, customized, accessible from outside, open on Internet, … with Internet and computer-related technologies.

Richer and wideband servicesRicher and wideband services

But:

More complexity (design, planning, integration, deployment, security, optimisation, operation).