Transcript IMS-based
INTRODUCTION
1.1 Why the Internet Protocol Multimedia
Subsystem
1.2 Where did it come from?
1.1 WHY THE INTERNET
PROTOCOL MULTIMEDIA
SUBSYSTEM
New communication paradigm
networking Internet Protocol (IP)-based mobile
devices
terminals
large, high-precision displays
built in cameras and a lot of resources for
applications
always-on-always-connected application devices
applications
no longer isolated entities exchanging information
more exciting applications are peer-to-peer entities,
which facilitate sharing
browsing
whiteboard
game experience
two-way radio session (i.e., push to talk)
Figure 1.1 shows the key ingredient to a peer-topeer connection between the new IP-enabled
mobile devices
IMS
a global system used to enable applications in mobile
devices to establish peer-to-peer connections
True integration of voice and data services
increases productivity and overall effectiveness
The development of innovative applications
integrating voice, data and multimedia will
create demands for new services
presence
multimedia chat
conferencing
push to talk
Figure 1.2 shows
a consolidated network where the IMS introduces
multimedia session control in the packet-switched
domain
at the same time brings circuit-switched functionality
in the packet-switched domain
Traditional mobile communication system has
been divided in three parts
terminals
radio access network (RAN)
core network
With IMS-based system
"radio access network" should be replaced by "access
network"
an IMS system can be deployed over non-RANs as
well
1.2 WHERE DID IT COME FROM?
1.2.4 3GPP Release 5 and Release 6
1.2.4 3GPP RELEASE 5 AND RELEASE
6
Release 5 introduced IMS as part of 3GPP
standards
IMS is a standardized access-independent IPbased architecture
interworks with existing voice and data networks for
both
fixed network users (e.g., PSTN, ISDN, Internet)
mobile users (e.g., GSM, CDMA)
is able to establish peer-to-peer IP communications
with all types of clients with the requisite quality of
services
functionalities
session management
complete service delivery
e.g., registration, security, charging, bearer
control, roaming
The functional content of 3GPP Release 5 was
frozen in March 2002
Release 6 is completed in 2004
Table 1.1 shows the most important features of
Release 5 and the items postponed to Release 6
AKA:Authentication and Key Agreement
3GPP has defined a finite architecture for SIP-based
IP multimedia service
a functionality of logical elements
a description of how elements are connected
selected protocols and procedures
Optimization for the mobile communication
environment has been designed in the form of
user authentication and authorization based on
mobile identities
definite rules at the user network interface for
compressing SIP messages
security and policy control mechanisms that allow
radio loss and recovery detection
IMS development is distributed to multiple
working groups in 3GPP
The working method has three different stages
stage 1
a service description from a service user and
operator point of view are evaluated
stage 2
problems are broken down into functional elements
and the interactions between the elements are
identified
stage 3
all the protocols and procedures are defined in
detail
Figure 1.3 shows
the most important working groups and
responsibility areas that are involved in the
development of IMS