Transcript 3G IP MULTIMEDIA SUBSYSTEMS BY:

3G IP MULTIMEDIA SUBSYSTEMS
BY:RAJESH NAYAKANTI
VARUN DRAVIDAM
INTRODUCTION TO 3G
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3G is the third generation of tele standards and
technology for mobile networking, superseding
2.5G. It is based on the International
Telecommunication Union (ITU) family of
standards under the IMT-2000.
3G networks enable network operators to offer
users a wider range of more advanced services
while achieving greater network capacity through
improved spectral efficiency.
3G networks are wide-area cellular telephone
networks that evolved to incorporate high-speed
Internet access and video telephony. IEEE 802.11
networks are short range, high-bandwidth
networks primarily developed for data.
3G ARCHITECTURE
CS Domain
PSTN
IMS
Internet
Access Network
PS Domain
MODEL OVERVIEW
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Access network provides radio connectivity and most of
the mobility handling
CS domain provides traditional mobile voice service plus
some new 3G services like video call
PS domain provides packet based connectivity to existing
packet based networks, that is the Internet
IMS provides introduces the IP multimedia services, like
VoIP. It provides SIP based signalling.
The public switched telephone network (PSTN) is the
worldwide collection of interconnected public telephone
networks that was designed primarily for voice traffic.
IP MULTIMEDIA SUBSYSTEM (IMS)
The IP Multimedia Subsystem (IMS) is the
technology that will merge the Internet (packet
switching) with the cellular world (circuit
switching).
 It will make Internet technologies, such as the
web, email, instant messaging, presence, and
videoconferencing available nearly everywhere.
 It is a core network technology, that can serve as
a low-level foundation for technologies like Voice
over IP (VoIP), Push-To-Talk (PTT), Push-To-View,
Video Calling, and Video Sharing. IMS is based
primarily on SIP (session initiation protocol).
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IMS ARCHITECTURE
IMS ARCHITECTURE OVERVIEW
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CSCF (Call/Session Control Function) is a SIP (Session
Initiation Protocol) server which processes SIP signalling
in the IMS. There are 3 types of CSCFs depending on the
functionality they provide.
P-CSCF is the first point of contact between the IMS
terminal and the IMS network. All the requests initiated
by the IMS terminal or destined to the IMS terminal
traverse the P-CSCF. This node provides several functions
related to security.
I-CSCF (Interrogating-CSCF) provides the functionality of
a SIP proxy server. It also has an interface to the SLF
(Subscriber Location Function) and HSS (Home
Subscriber Server).
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S-CSCF (Serving-CSCF) is a SIP server that performs session
control. It maintains a binding between the user location and
the user’s SIP address of record Like the I-CSCF, the S-CSCF
also implements a Diameter interface to the HSS.
SIP AS (Application Server): The AS is a SIP entity that hosts
and executes IP Multimedia Services based on SIP.
IM-SSF (IP Multimedia Services Switching Function acts as an
Application Server on one side and on the other side, it acts
as an SCF (Service Switching Function) interfacing the
gsmSCF (GSM Service Control Function) with a protocol based
on CAP (CAMEL Application Part).
MRF (Media Resource Function) provides a source of media
in the home network. It is further divided into a signalling
plane node called the MRFC (Media Resource Function
Controller) and a media plane node called the MRFP (Media
Resource Function Processor)
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BGCF (Breakout Gateway Control Functions): BGCF a SIP
server that includes routing functionality based on
telephone numbers.
SGW (Signalling Gateway): SGW performs lower layer
protocol conversion.
MGCF (Media Gateway Control Function) implements a
state machine that does protocol conversion and maps
SIP to either ISUP (ISDN User part) over IP or BICC
(Bearer Independent Call Control) over IP.
The Home Subscriber Server (HSS) contains all the user
related subscription data required to handle multimedia
sessions. These data include, among other items,
location information, security information
SESSION CONTROL ON THE INTERNET
Regular transaction
Invite ack transaction
SESSION CONTROL PROCESS
UAC which is the user agent client where as uas is
the user agent server.
 In the session control UAC sends a bye request to
the UAS and if the UAS accepts it then the regular
transaction takes place in the session control.
 In the INVITE ACK transaction UAC sends a request
to the UAS and in this process the ringing takes
place and if it is accepted by the UAS the ACK is
taken place between UAC and UAS.
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SESSION PROCESSING
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Regular transactions are initiated by any request but
INVITE, ACK, or CANCEL shows a regular BYE transaction.
In a regular transaction, the user agent server receives a
request and generates a final response that terminates
the transaction.
An INVITE–ACK transaction involves two transactions; an
INVITE transaction and an ACK transaction
The user agent server receives an INVITE request and
generates zero or more provisional responses and a final
response.
MESSAGE FLOW FOR SESSION ESTABLISHMENT
Cancel transaction
MESSAGE FLOW PROCESS
In the message flow UAC sends a request to the
proxy and then it sends the message to UAS and
then the ringing takes places in this process.
 In this if the UAS can cancel the request or just can
ok the request .
 If the UAS cancel the request then the request gets
terminated and in this way the cancel transaction
takes place in the message flow process in IMS.
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CANCEL transactions are initiated by a CANCEL
request and are always connected to a previous
transaction (i.e., the transaction to be cancelled).
 CANCEL transactions are similar to regular
transactions, with the difference that the final
response is generated by the next SIP hop
(typically a proxy) instead of by the user agent
server.
 Canceltransaction cancelling an INVITE
transaction. Note that the INVITE transaction,
once it is cancelled, terminates as usual (i.e., final
response plus ACK).
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APPLICATIONS OF IMS
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Interactive Gaming
Shared folders
Instant Messaging services
Voice Messaging
Voice and Video Telephony
Video-conferencing
BENEFITS OF IMS
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IP Multimedia Subsystem Benefits
Lower Costs
Best of Breed
Value Chain Control
Integrated, Interoperable Services
End-user benefits
FUTURE WORKS
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Cisco Systems has developed an architecture
called the Cisco IP Next-Generation Network for
IMS. Cisco IP NGN helps service providers develop
and plan their organizations, their specific
network architectures, and business models for
the future
HP Service Delivery Platform for IP Multimedia
Subsystem The future of telecommunications resides in a
new network architecture, the IP Multimedia Subsystem
IMS. This new advanced architecture facilitates the
creation and delivery of new real-time, person-to-person,
multimedia services
CONCLUSIONS
IMS is the Universal base for other services
 It has many Advantages for users and operators.
 In this way IMS plays a key role in the mobile
communication and it also used for Instant
Messaging services.
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