IMS White Paper

8/8/2019 IMS White Paper

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IP multimedia a new era in communications


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Contents

Executive summary 3

The renewal of person-to-person communications 4

IP multimedia and its benefits will generate new business 5

Examples of applications 6

IMS will build operators revenues and cut their costs 7

Open service creation 7

The essentials of IMS and SIP 8

IMS A major building block in convergent core networks 9

One network experience 9

IMS and voice 9

Conclusions 10

Glossary of terms and abbreviations 11


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Executive summary

Person-to-person mobile communication

is undergoing a transformation that

will see users sharing rich content like

never before.

Based on the technologies of IP

Multimedia Subsystem (IMS) and Session

Initiation Protocol (SIP), the mobile and

Internet domains will merge, allowing

users to access, create, consume and

share digital content using interoperable

devices.

With an IMS-based network, operators

will be able to set up and introducenew services much more quickly than

before, achieving a fast time to market

to meet changing customer demands.

New functionalities can be added easily,

lowering the cost of new services by

avoiding the need to build and run a

completely separate, parallel network to

support each feature.

Using IMS in their networks, operators

will be able to offer users a wide range

of applications that can reside in theterminal, in a server, or both. These

applications can interact with each

other to provide the user with rich

communications capabilities. Users will

be able to mix and match a variety of

IP-based services in any way they

choose during a single communications

session, integrating for example voice,

video, text, content sharing and presence

information.

Because IMS supports open service

creation and third party applications

and application servers, operators have

the chance to customize services and

applications for their own customers.

The importance of open service creation

is highlighted by a recent market study

on IP multimedia services, revealing

that different countries prefer different

service sets. Open service creation will

give operators the tools to optimize

IP multimedia services for local

requirements. It will also allow them

to develop their service concepts in

co-operation with external applicationdevelopers.

The use of IP in core networks makes

possible new service concepts and

convergence between fixed and mobile

networks. Being access agnostic and

supporting both fixed and mobile clients

and access, the IMS is a central building

block for convergent communications.

The coming world of converged

networks and services holds greatopportunities for operators and IMS will

be a major factor in making these

opportunities a success.


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The renewal of person-to-personcommunications

The phenomenal success of mobile

telephony has so far been built on a

modest set of services dominated by the

basic person-to-person voice call.

However, the building blocks of a

communications future that will offer

users far more options are now falling

into place.

Connectivity is more diverse than ever

with wireless and wire line access

technologies such as GPRS, EDGE,

WCDMA, DSL and WLAN becomingcommonplace and providing broadband

on the move.

Now it is the turn of the core network to

be developed by implementing the IMS.

Defined by the 3GPP, the IMS will form

the heart of a converged network and

will provide authentication, roaming

and network interconnectivity to allow

IP-enabled terminals to network fully.

With these elements in place,IP convergence, which will merge the

mobile and fixed network domains,

will become a reality. Packet-based

networks of all types will give users the

ability to access, create, consume and

share digital content using interoperable

devices that are connected with each

other anytime, anywhere.

Content-to-person services have

advanced in recent years with the

advent of applications such as browsing,

downloading and Internet access

coming to the fore. Mobile operators are

following this up now by placing an

increasingly high priority on renewing

person-to-person communications.

Richer person-to-person applications

demand a mechanism that can establish

a peer-to-peer connection between

IP-enabled devices. IMS is the network

technology to achieve this.

Research done by Nokia in cooperation

with the UK based research agency

Market and Opinion Research

International (MORI), indicates a clear

demand for IP multimedia services.

Between 33% and 43%, or 90 million

main mobile phone users in Great

Britain, Germany, Singapore and the USA

consider they would be likely to use

these services in the next two years.

The top three services in terms of likely

adoption are push to talk, video sharing

and instant messaging while content

sharing is also appealing to consumers

across countries.

Figure 1. Mixing and matching services in a single communication session

Push totalk

MessagingRich

messaging

Presence

VoiceInteractive

gaming

Videosharing

ChatContentsharing

Packet-switchednetwork

(GPRS or 3G)

IP Multimedia channelbetween terminals

The demand is there and users are

interested in the benefits that IP

multimedia services can bring. A clear

proof of this is already shown in the

market. The push to talk service has

been launched commercially by several

operators world wide. The importance

of presence has been recognized and

more and more operators are combining

presence with their other services.

The first operators are moving into the

phase of commercial deployment of IMS.


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IP multimedia and its benefits willgenerate new business

User interfaces and services will be

independent of time and place, but at thesame time customized for the terminal

used. For example, a videoconference

could be held with different participants

using a fixed line connected to a PC,

a mobile phone connected via WCDMA

network, and a laptop connected via

WLAN. With IMS co-ordinating these

services, this is an example of true fixed

and mobile convergence.

Furthermore, users will gain easy access

to new applications because the same

SIP client in their terminal can be used

for all services. SIP capable phones are

becoming more widely available and

SIP clients are already available for

downloading into Nokia Series 60

Platform terminals.

Using IMS in their networks enables

operators to offer users a wide range of

applications that can reside in the

terminal, in a server, or both.

Additionally, these applications can

interact with each other to provide the

user with rich communications

capabilities.

There are two main benefits to users of

adopting IP-based peer-to-peer

communications.

First, users will be able to mix and

match a variety of IP-based services in

any way they choose during a single

communications session. Users can

integrate voice, video, text, content

sharing and presence as part of their

communication and can add or drop

services as and when they choose.

This is what is often referred to as a

rich call and is not possible without

peer-to-peer connection.

For example, two people can play an

interactive game directly between

terminals, make comments during the

game using voice and share files or

video with each other.

Second, these services and the way they

can be used will be available regardless

of the access network. Users will be

able to choose the access network that

gives them the best price, bandwidth or

availability at a particular time and

location.

Figure 2. SIP applications implemented in two domains.


SIP SIP

IP MultimediaSubsystem (IMS)

Application serversServices, applications

Presence

PoC

SIP/ISC


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Examples of applications

The key applications emerging for the

IP-converged world include:

Push to talkAlready implemented over GPRS

networks, push to talk provides direct

one-to-one or one-to-many voice

communication over the mobile

network, emulating the traditionalwalkie-talkie service. Calls are started

with the push of one key and connected

directly, thus enabling a conversational

voice service. Push to talk calls are half

duplex while one person speaks,

the others can only listen.

Video sharingVideo sharing enables mobile users to

share one-way video in real time while

they are already active in a voice session.

This is a great way to gain additional

revenue from voice calls and differentiate

within 3G services. Wideband operators

can offer one-way video sharing as an

enhancement to existing voice calls.

Content sharingA SIP-based peer-to-peer connection will

enable two or more users to share all

types of content. As an example, a user

could send the best photo as a MMS

(content push) and share the rest of

the photos with her friends (content

pull) by using content sharing. Direct

file sharing is possible not only

between mobile terminals but also

between mobiles and PCs or any other

IP connected device.

PresencePresence will add a new dimension to

personal communication. Widely used

in the Internet to support instant

messaging, presence enables mobileusers to allow their terminals to provide

dynamic status information about

subscribers, including their call/

connection status, identities, terminal

capabilities and availability. Presence is

an application in itself, but is also an

enabler and enhancement to other

applications such as rich call, push to

talk and messaging.

MessagingMessaging will evolve building on the

existing SMS, MMS and e-mail. From the

users perspective, messaging services

can converge into a single messaging

service using different messaging

technologies enabled by the network.

Messaging will be driven by user services

rather than enabling technologies as is

the case today. Key messaging services

are expected to include text messaging,

chat, multimedia messaging, voice and

video messaging, business messaging

and application messaging.

Figure 3. Video sharing between two devices.

Voice over IPThe importance of Voice over IP (VoIP)

is increasing all the time. It is already

widely used in fixed networks, using

VoIP capable fixed phones or PC VoIP

clients. The emergence of mobile

terminals capable of supporting both

cellular and WLAN access, allows mobile

terminals to use an IP-based connection

for voice within a WLAN access zone,

increasing the need for a VoIP solutionfor mobile operators. IMS is a central

element in an operators VoIP solution,

supporting both fixed and mobile SIP

clients, as well as working with PSTN.

VoIP to PSTN interworking is discussed

in more detail in the section on

convergence.

Rich callA rich call integrates voice, video and

text, supported with parallel sharing of

content (image, data, or other value-

added information) into a seamless and

coherent user experience. SIP provides

the essential elements for a rich call.

Third party SIP applicationsIMS and SIP enable open service creation,

bringing advantages to both application

developers and operators. Developers

can create applications that are used

directly by SIP-capable terminals, taking

advantage of the peer-to-peer capability

of IMS, although operators will remain in

control. More versatile services based onapplication servers are also possible.

CS-voice call

Invite

Video stream

Kate Lucy


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Open service creation

IMS supports open service creation and

third party applications and application

servers, enabling operators to tailor

services and applications for their

customers. Operators can develop the

new services themselves, outsource the

development work, or purchase the

applications from external sources.

IMS also allows operators to take

advantage of applications from third

party service providers and application

developers and hosted on external

servers.

More than thousand developer

companies worldwide are currentlyestimated to be working on SIP

applications bringing innovation far

beyond most previous expectations.

Some of these companies are already

developing and testing their applications

on Nokia terminals using SIP APIs and

SDKs.

The use of standard open specifications

based systems such as IMS is important

to application developers because it

enables them to create applications thatcan be used across networks and on

terminals of all types with minimal

customization.

The true potential of the IP converged

future will only be realized with the

involvement of this developer

community. Its creativity will be

harnessed by providing developers

with the open APIs and SDKs they need

to create SIP-based applications.

Applications can be quickly developed

due to the reuse of common IP protocols,

and quickly deployed by using the

common connectivity features of SIP to

establish connections.

This short time-to-market will make it

possible for services to be profitable in

a very short time. Services made

available only for the duration of a

football tournament or the Olympics,

for example, will be feasible.

In IP converged networks, the operator

has just one network to manage, while

SIP remains the enabling protocol. This

will lower the cost of new services by

avoiding the need to build and run a

completely separate, parallel network

to support each feature. Without IMS,

each time a new application needs to

be implemented, the operator must

re-engineer many of the same

functionalities that have been used

before in previous applications. Thisconstant replication of critical functions

is both costly and time consuming.

Additionally, because each service will be

built on separate servers as stand-alone

services they will inevitably work

slightly differently and the user will not

get a true seamless experience. In the

longer term, introducing more and more

services in this way will result in a core

network that is so complex it becomes

almost unmanageable and will

inevitably increase operationalexpenditure (OPEX).

Implementing new services on existing

infrastructure will also reduce the

equipment costs themselves. The cost

advantage will increase for every new

SIP service that is subsequently

implemented. OPEX will also be lower in

the longer run.

System capacity can also be improved,

because resources can be shared across

many services. Infrastructure

investments in firewalls, mobility

services and so on, which have been put

in place for SIP, can also be reused.

IMS will build operators

revenues and cut their

costs

It will be vital for operators to implement

IMS in their core network, not only to

maintain their competitiveness as other

operators move towards IP convergence,

but also to achieve cost savings and

allow smooth evolution of services.

New revenue streams will be created by

providing subscribers with multimedia

services that can be mixed and matched

in a controlled, secure and chargeable

way. Additionally, new services can be

implemented that were not previously

possible or were too complex or costly tobe practical, such as sharing video clips

between users.

Wider availability of an operators

services will also be achievable,

encouraging greater use. Services can be

created in one platform and made

available over multi-access networks,

broadening their reach and increasing

customer loyalty to reduce churn.

In addition, the same SIP based

architecture will support both person-to-person and content-to-person services.

Historically, service integration has been

time consuming in mobile networks,

because each service often required its

own protocols, standards and service

domains. With an IMS-based network,

operators will be able to set up and

introduce new services much more

quickly than before, achieving fast time

to market to meet changing customer

demand. With IP multimedia, service

integration is easy, since services are

created on top of a single IP-based

platform. Voice-based applications can

be integrated easily with content

sharing applications, mobile terminal

applications with PC applications,

and so on.


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essential for the success of any service

scenario.

All these mobile network specific

functionalities have been implemented

in the Nokia IMS. It provides a complete

service delivery for SIP services in both

mobile and fixed domains.

SIP has already been implemented in

2G GPRS networks. 3G networks are notessential for SIP-based sessions, although

the greater bandwidth of technologies

such as EDGE and 3G will greatly benefit

capacity-intensive applications such as

video sharing.

The essentialsof IMS and SIP

The major element needed for the

renewal of the core network to enable

IP-based peer-to-peer connectivity is the

IMS (IP Multimedia Subsystem), which

uses SIP (Session Initiation Protocol).

When a SIP client issues a find and

connect request, the IMS finds the relevant

terminals and connects them via IP.

SIP enables clients to invite other clients

into a session and negotiate control

information about the media channels

needed for the session. The IMS providesa full suite of network capabilities for

authentication of clients, network-to-

network interfaces and administrative

functions such as charging. The IMS

establishes packet data connections

between end points in a carrier-class,

chargeable way. Once established, the IP

connection can be used to exchange all

types of communication media,

including voice, video, content and more.

SIP is defined by the IETF and has beenwidely used throughout the Internet.

It shares much with Internet protocols

such as HTTP and SMTP (protocol header

formats). Like HTTP, SIP is a text-based

client-to-server protocol. SIP has been

adopted by the 3GPP as the session

management protocol and is the basis

for IMS.

First defined in the 3GPP Release 5

standard (and being further developed

in subsequent releases), IMS provides

mobile operators with a common and

tightly standardized platform for

deploying SIP applications. These can

reside directly in SIP-capable terminals,

in an application server, or both.

The IMS supports a standardized IMS

Service Control (ISC) interface, which

allows open connectivity towards SIP

application servers.

Like SIP, IMS is access independent,

working with existing voice and datanetworks in both the fixed domain (for

example PSTN, ISDN, WLAN and Internet)

and the mobile domain (for example

GSM, CDMA and WCDMA). However,

implementing SIP applications in mobile

networks have some key differences

compared to the fixed domain. The most

essential ones are related to mobility

management, security architecture and

customer care and billing.

A major area of mobility management

is optimizing the resources of radio air

interface based on Quality of Service

(QoS) parameters for different services.For example, video sharing service can

be deployed using streaming traffic class,

guaranteeing the right user experience.

Another important area of mobility

management is handling the abnormal

traffic cases typical for radio networks,

such as handset battery running out or

terminal moving out of network

coverage during an active session.

IMS security architecture consists of

access security and network domain

security. For access security, IMS supports

IETF authentication typical for fixed

SIP clients, as well as SIM-based

authentication, which is the most

favoured one for mobile terminals.

Network domain security provides

security between network domains

and nodes within one domain. In a

typical case, this means a well-defined

security architecture between

operators core networks.

Regarding customer care and billing,the most important features are support

for both prepaid and postpaid mobile

subscriptions. Also easy-to-use auto-

provisioning for the new services is

Figure 4. Session establishment with IMS


Any IP connection(e.g. GPRS, EDGE,

WCDMA, WLAN, ADSL)

IP-based servicespossible between

terminals

SIP capableterminal

SIP

Find andconnect

IP Multimedia Subsystemfinds the other terminal and

connects the terminals with IP

SIP

IMS

The main functions of the IMS for

providing complete service delivery

include:

Authentication and authorization of

both mobile and fixed SIP clients

Control over sessions for person-to-

person, person-to-group and

content-to-person multimedia

communication

Charging functionality that allows

the operator to apply time-based,

event-based or volume-based

charging to subscribers

Implementation of the relevant QoS

mechanism for the IP services being

used in the communications session

Functionality to connect roaming

users to the home domain for IPmultimedia services

Access and network domain

security functions


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WLAN devices. IMS also provides the

necessary interworking with other

SIP-based networks such as enterprise

intranets.

IMS and voice

Voice over IP is having a significant

impact on traditional telephony, with the

growing adoption of VoIP using the

Internet, and the introduction of VoIP

services by fixed operators using their

own IP networks. VoIP over WLAN is

becoming common within enterprises

and at homes as a natural extension of

WLAN data access. The introduction of

WLAN capable multiradio terminals

allows the mobile to be used as an IP

phone when in the WLAN coverage area.

Crucially for the evolution of VoIP

services, the IMS works with PSTN and

mobile networks via signalling and

media gateways. The samesupplementary services are provided

for VoIP calls as we have today for

circuit switched calls.

IMS A major building blockin convergent core networks

interworking to existing voice networks.

Both fixed and mobile networks are

enhanced to enable IP multimedia

person-to-person services and bring

mobility to media consumption and

business services. This means that

service delivery will be access network

agnostic. The ability to employ all

services all the time is the automatic

result of ubiquitous access and Internet

technologies, such as SIP and HTTP.

Overall, the user experience will be

seamless: the same voice and

multimedia services are used in the

same way, independent of the access

network and the terminal, providing

people with both mobility and

personalization. Nokia can help to make

this simple both for the consumer and

network operator.

IMS is the technology that will link all

the many aspects of communications

into a converged whole. IMS supportsboth 3GPP and IETF SIP clients and can

be connected to several types of devices,

whether mobile terminals, fixed PCs or

Convergence of fixed and mobile

communications is happening today.

There are five significant enablers of

this trend:

Wide spread use of IP and SIP

Range of complementary radio access

Development of devices with a

number of functions

Digitization of content

Multi-radio handsets

Operators are considering how to launch

innovative service bundles over manyaccess types, whilst looking to reduce

costs by consolidating their core

network. Consumers and business users

want to access a wider variety of

networks and services with a smaller

number of devices.

Three prime trends clearly demonstrate

this:

Voice is going mobile: an increasing

proportion of all voice calls are being

made over mobile networks. The rapid development of new IP

multimedia services in both the fixed

and mobile domains. SIP will help

converge the two.

The growing popularity of VoIP

telephony over fixed networks, with

SIP as a major enabler.

These trends show that communication

is moving from the circuit-switched

domain towards open IP-based

networks. In this evolution IMS plays a

crucial role. The use of IP in the core

networks makes possible new service

concepts and convergence between

fixed and mobile networks.

One network experience

The individual perception of fixed-

mobile convergence will be that of a

common service experience, regardless

of network type. Mobile phones will

increasingly be able to use IP-basedcommunication services. The PSTN is

migrating to IP, which brings VoIP

telephony services and smooth

Figure 5. People want mobility and personalization

My phonebook

My agendaMy messages

My presence info

My applications

My ringing tones

On the move Home

Office


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Conclusions

Person-to-person (both one-to-one and

one-to-many) IP-based multimedia

services are universally recognized as

being the future direction for the mobile

communications industry. Operators

around the world will undoubtedly

move towards IP convergence over the

next few years, with IMS being one of

the major enablers.

An IP-based service architecture, capable

of supporting multimedia and service

integration, will be a key element of

future cellular networks. SIP will be the

standard signaling protocol/mechanismto support multimedia sessions in 3GPP

Release 5 networks and beyond. This

choice ensures that future multimedia

services will be truly IP based.

By implementing SIP, the operator gets

the whole array of IP based services in

the same network that is easy to

implement, manage and control.

Developing and introducing new

services are simplified compared to the

conventional networks.

All the key components for IP convergence

are available today. IMS infrastructure

equipment is commercially available,

service development tools are widely

available from sources such as Forum

Nokia, and IP-capable terminals are

becoming available. SIP applications,such as push to talk, are already being

deployed.

Operators benefit from taking

advantage of the opportunity today and

implementing the necessary IMS

machinery in their core network.

The winners in IP multimedia will be

those that are proactive and take the

early initiative.


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The contents of this document are copyright 2004 Nokia. All rights reserved. A license is hereby granted to download and print a copy of this document for personal use only.

No other license to any other intellectual property rights is granted herein. Unless expressly permitted herein, reproduction, transfer, distribution or storage of part or all of

the contents in any form without the prior written permission of Nokia is prohibited.

The content of this document is provided as is, without warranties of any kind with regards its accuracy or reliability, and specifically excluding all implied warranties,

for example of merchantability, fitness for purpose, title and non-infringement. In no event shall Nokia be liable for any special, indirect or consequential damages, or any

damages whatsoever resulting form loss of use, data or profits, arising out of or in connection with the use of the document. Nokia reserves the right to revise the document

or withdraw it at any time without prior notice.

Nokia and Nokia Connecting People are registered trademarks of Nokia Corporation. Nokia product names are either trademarks or registered trademarks of Nokia.

Other product and company names mentioned herein may be trademarks or trade names of their respective owners.

Glossary of terms and abbreviations

3GPP

3rd Generation Partnership Project

API

Application Program Interface

CDMA

Code Division Multiple Access

DSL

Digital Subscriber Line

EDGE

Enhanced Data Rates for GSM Evolution

GPRS

General Packet Radio Services

GSM

Global System for Mobile communications

HTTP

Hyper Text Transfer Protocol

IETF

Internet Engineering Task Force

IMS

IP Multimedia Subsystem

IP

Internet Protocol

ISC

IMS Service Control

ISDN

Integrated Services Digital Network

MMS

Multimedia Messaging Service

PoC

Push to Talk over Cellular

PSTN

Public Switched Telephone Network

QoS

Quality of Service

SDK

Software Development Kit

SIP

Session Initiation Protocol

SMS

Short Message Service

SMTP

Simple Mail Transfer Protocol

UMTS

Universal Mobile Telecommunications

System

VoIP

Voice over Internet Protocol

WCDMA

Wideband Code Division Multiple Access

WLAN

Wireless Local Area Network


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Phone: +358 (0) 7180 08000

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