QoSQoS in IMSin IMS, , the emerging all IP the emerging all IP

cellular networkcellular network

September 2005

Ofer WeintraubStandard Insider Ltd.

2

The challengeThe challenge

3 Mo

tiva

tion

Comcast – Triple Play

Phase 1- Service Convergence

4

More motivation

$19/M /Subscriber$30/M/Subscriber

OIBDA

2.3%1.6%Monthlychurnrate

$56/M$69/M

AverageRevenuePer User(ARPU)

IndustryAverage

Nextel

Nextel2003

numbers

5

ITU NGNFG has a solution

MetroEthernet

3G RAN

ISC

OS

AS

SF

Pre

se

nc

eP

TT

Vo

ice

Mail

SM

S

MM

SS

trea

min

g

Co

nv

erg

ed

Se

rvic

es

an

d P

latfo

rms

MRFC

I-CSCF

LegacyGMSC

ConvergedServices

IMS

MGCF

Co

nve

rge

d S

erv

ice

In

terfa

ce

s

SGW

PSTN

PLMN

MRFP

S-CSCFP-CSCF

PDF

PS BackboneNetwork

RNC

SGSN

Service ProviderData Network

HA

BroadcastAccess Network

DVB / ISDB-T RAN

LegacyMSC/VLR

PDG/

WAG

BSC

2G RAN

PDG/WAG

HSS

AAA

Network DBs

Databases

GGSN

MGW

WiFi Hotspot

DNS

DHCP

INP

arla

yS

IP-A

S

WiMax RAN

TransportNetwork

AccessNetwork

LegacyHLR

CS BackboneNetwork

BGCF

PublicInternet

(CDMA systems are similar toGPRS and UMTS systems shown)

BMSC

MetroEthernetMetroEthernet

3G RAN

ISC

OS

AS

SF

ISC

OS

AS

SF

Pre

se

nc

eP

TT

Vo

ice

Mail

SM

S

MM

SS

trea

min

g

Co

nv

erg

ed

Se

rvic

es

an

d P

latfo

rms

MRFC

I-CSCF

LegacyGMSC

ConvergedServices

IMS

MGCF

Co

nve

rge

d S

erv

ice

In

terfa

ce

s

SGW

PSTN

PLMN

PSTN

PLMN

MRFP

S-CSCFP-CSCF

PDF

PS BackboneNetwork

RNC

SGSN

Service ProviderData Network

HA

BroadcastAccess NetworkBroadcastAccess Network

DVB / ISDB-T RAN

LegacyMSC/VLR

PDG/

WAG

BSC

2G RAN

BSCBSC

2G RAN

PDG/WAG

HSS

AAA

Network DBs

DatabasesDatabases

GGSN

MGW

WiFi Hotspot

DNS

DHCP

INP

arla

yS

IP-A

S

WiMax RAN

TransportNetwork

AccessNetwork

LegacyHLR

CS BackboneNetwork

BGCF

PublicInternetPublicInternet

(CDMA systems are similar toGPRS and UMTS systems shown)

BMSC

6

PoC

Server

You RTP IP

IMS

Are RTP IP Fired RTP IP

FiredRTP

IPFired

RTP

IP

1-to-Many call

Push to Talk in IMS environment

7

Overall architecture

IMS Service Delivery Plane

User Equipment

Application Plane

IMS Session Control Plane

IP backbone

Legacy PSTN/PLMN

MGW

GGSN

SGSN

Service Platforms

Service Enablers

P/I CSCF S CSCF

Legacy Services

Native IMS

Services

Source: HP

December 2004

Media Plane

Control Plane

Service Plane

Application Layer

8

IMS IMS QoSQoS conceptsconcepts

9

IMS Architecture

UTRAN

SGSN GGSN

Media Plane

Control Plane

I-CSCF

S-CSCF

HSS

Other IP

Networks

Other IP

Networks

MRF

External SIP

Applications

Servers

External SIP

Applications

Servers

IMS

ALG

PDF

P-CSCF BGCF

MGCF

T-SGWMGW

PSTN

ISDN

PSTN

ISDN

10

IMS QoS Architecture

UTRAN

SGSN GGSN

Media Plane

Control PlaneOther

IPNetworks

Other IP

Networks

PSTN

ISDN

PSTN

ISDN

PDF

P-CSCF

SIP

CO

PS

Dia

met

er

DiffServDiffServ

11

Packet Data Protocol (PDP) Context

Primary PDP contextPrimary PDP context

Secondary PDP contextSecondary PDP context

AAC Music

H.263 Video

GGSN

PDP Context = IP address + Bearer QoS attributes ☺

12

Gq

Policy set-up

infoQoS-related application-level

parameters (e.g., SDP)

P-CSCFApplication

Function (AF)

UE GGSN

UTRAN & CN

PDF

QoS Management Functions & Flow

Translation Translation

BS = Bearer Service

IP BSManager

IP BSManager

UMTS BSManager

UMTS BSManager

UMTS QoSparameters

☺

Go

Policy Enforcement

Diffserv edge, RSVP, etc.

IP QoSparameters

Policy Decision

Decisions concerning

Service Based Local PolicyCommon Open Policy Service

(COPS) protocolQoS authorization token

13

Policy Enforcement by a “Gate”

UEUE GGSNGGSN

PDF

Go

Upstream gate

Downstream gate

IP IP ConncetivityConncetivity

Access Network (IPAccess Network (IP--CAN)CAN)

☺

• A Gate may be opened or closed• on the basis of IP destination address and port

• Closed � no packets are allowed to pass through

• Opened � packets subject to DiffServ edge treatment

14

IP BS Manager Capability

RequiredOptionalIP Policy Enforcement Point

OptionalOptionalRSVP / IntServ

RequiredOptionalDiffServ Edge Function

GGSNUECapability

MPLS Diff-Serv +

MPLS DS-TE

No state Aggregated state Per-flow state

Best effort DiffServ RSVP / IntServ

☺

15

DiffServ – Differentiated Services (cont.)

� PHB Groups:� AF (Assured Forwarding, RFC 2597) – “drop

preferences” define chance of packet getting dropped during congestion – several classes (e.g., bronze, silver, gold)

� EF (Expedited Forwarding, RFC 2598) – requires that (at each node) the egress (outbound) rate exceed the ingress (inbound) rate for a conforming aggregate – highest class

� BE (Best Effort) – whatever bandwidth left

� Others …

☺

16

Setting up end-to-end QoSMO network flow

UE SGSN GGSN P-CSCF (PDF)

Activate PDP contextCreate PDP context

COPS REQActivate PDP context

COPS DECPolicy Information

COPS RPT

Activate PDP context

Create PDP context response

Activate PDP context Accept

Setting end-to-end PDP with well defined QoS

17

Short Summary

� Proper QoS is vital for the success of IP services

� Let’s face it. It still crappy

� Stringent schemes for QoS (e.g. RSVP) also exist but they are

optional

� It will take time until PS completely replaces CS voice

( 7+ years )

� Enough time to set up QoS correctly

� IMS is in very early trialing stage worldwide

� 30 something trials worldwide

� Huge momentum behind it, so it probably will happen

QoSQoS in IMSin IMS, , the emerging all IP the emerging all IP

cellular networkcellular network

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