IP multimedia subsystem (IMS) is a generic architecture for offering multimedia
and voice over IP (VoIP) services, defined by 3rd generation partnership project
(3GPP). IMS is access independent as it supports multiple access types including
GSM, WCDMA, CDMA2000, WLAN, wireline broadband, and other packet data
applications. IMS is standardized reference architecture and consists of session
control, connection control and an applications services framework along with
subscriber and services data, and it supports a wide range of services that are
enabled based on SIP protocols. IMS architecture delivers multimedia services
that can be accessed by a user from various devices via an IP network or
traditional telephony system. The underlying network architecture is divided
into four layers: device, transport, control, and service layer. It enables new
converged voice and data services, while allowing for the interoperability of
these converged services between Internet and cellular subscribers. IMS uses
open standard IP protocols, defined by the IETF.
|
Global IMS Deployments |
|
Wireless Operator
|
Infrastructure Vendor
|
Service Planned
|
|
BT (UK)
|
Undisclosed
|
BT Fusion (Formerly Project Bluephone) fixed/mobile
converged phone service |
|
eAaccess (Japan)
|
Lucent
|
Multimedia, HSDPA
|
|
France Telecom
|
Siemens
|
Fixedmobile convergence |
|
MM02 (UK)
|
Siemens
|
Push-to-talk over cellular (POC), multimedia conferencing
|
|
Saunalahti (Finland)
|
Nokia
|
VoIP and rich multimedia to both mobile and fixed telephony
customers |
|
Sprint (US)
|
Lucent
|
EV-DO
|
|
Telecom Italia Mobile
|
Ericsson and Nokia |
Video sharing |
|
Telefonica (Spain)
|
Ericsson
|
Converged wireless/wireline IMS deployment
|
|
Telia Sonera
(Nordic region)
|
Ericsson, Nokia, and Siemens
|
Instant messaging, video sharing, gaming among different
mobile operators |
|
Telkomsel
(Indonesia)
|
Nokia
|
3G services, such as video sharing. Based on standardized
3GPP and Internet Engineering Task Force technologies. Enabled by IMS core
network
|
|
TMN (Portugal)
|
Nokia
|
Video sharing |
|
Source: inCode Wireless
|
Why IMS?
There are many good answers, but perhaps the key one is that IMS
delivers innovative multimedia services over fixed and mobile networks using
open standards. IMS addresses key issues such as convergence, service creation
and delivery, service interconnection and open standards. One key benefit of IMS
is that it enables true convergence, and interworks in several dimensions-across
fixed and mobile access-in the service layer, control layer and connectivity
layer. The IMS architecture provides for a number of common functions that are
generic in their structure and implementation, and can be reused by virtually
all services in the network. Securing these common functions provides many
benefits: less parallel development, more reliable systems, and higher-level
abstractions for service developers, enabling them to focus on the actual
application.
In IMS, the sign-on and authentication process becomes
simpler, both for operators and subscribers. IMS services are primarily intended
to address a mass market, with telecom-grade quality of service.
In addition, IMS also needs to provide support for a complex
service mix. These service bundles will most likely have different numbers of
users with different user behavior, which will affect dimensioning of the
network. In this situation, IMS network architecture offers a big advantage,
since it is designed to scale independently of the traffic mix.
Today's consumers are already demanding a new level of
mobility. The most promising source is multimedia services. These services can
not only be rapidly deployed in undeveloped markets, but can also be readily
overlaid on existing network infrastructures, reducing associated costs. More
importantly, IP-based multimedia services are expected to deliver the rapid
growth that network operator's need and seek.
Nilabh Jha
nilabhj@cybermedia.co.in
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