The Transition Agents
Monday, October 14, 2002
Media gateway controllers at TDM switches can make migration to next-gen
networks smooth.
As technologies for carrying voice and data mature
and converge, service providers and enterprises are increasingly viewing voice
over packet (VoP) based network as a way to reduce communications costs, boost
end-user productivity and enable new applications. Such network architectures
not only handle multiple kinds of traffic in a cost-effective way but also
competitive services, which integrate voice, data and multimedia, which are
going to be the key differentiators.
Operators’ Strategy
When considering the deployment of NGNs, strategy
of a telecom operator is going to depend upon its history (incumbent vs green
field), market situation (deregulated vs monopolistic, strength of
competitors), status of its networks (single equipment provider vs several,
recent or less recent products), and the evolution of its customers’ needs
(traffic, services, etc).
For the operator, some of the key reasons in favor
of NGNs are to:
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l reduce time to market for new technologies and services
l facilitate vendor, carrier, or third-party development of
software
l reduce operational complexity by standardized modular
systems
l separate call processing from switching/transport function
through open interfaces
The associated objectives underlying this approach
would include:
l support ATM and IP connections in addition to legacy TDM
connections
l keep the present level of voice features when evolving
from TDM-based networks to VoP solution
l support voice, video and data services
To address these needs, the vendors are developing
NGN solutions (including call servers/softswitches, trunking and access
gateways, IP/ATM networks nodes, etc) to cope with the actual requirements of
different operators, and are offering traditional voice services as well as advanced
new multimedia services.
The new operators may directly install
softswitches and gateways (trunking or access gateways) to handle the Class 4
or Class 5 applications. However, Class 5 application on softswitches will take
some time to develop. So they look for platforms, which can provide Class 5
applications on TDM at present, but which can migrate to NGN smoothly.
Large installed base of TDM-based traditional
networks, make the incumbent operators look for a smooth transition to the full
NGN architecture, to protect the large investments already made in the access
nodes. Hence, they look for hybrid-platforms, which can give all the features
of TDM and evolve to a softswitch—integrated inside the TDM switch
itself—ensuring migration of subscribers from the TDM environment to the NGN
environment, without any discontinuity.
Platforms being designed for these large incumbent
operators address the following requirements:
n investment protection by reuse of the installed switches
as well as external devices, such as IN service control points, network
management centers or customer-care and billing systems
n networks’ smooth evolution without service disruption
n functional continuity of features and services
NGN Network Strategy
Existing networks, catering to separate
voice and data transports, can be optimized by the introduction of new
high-capacity switches to drastically reduce the number of switches and thus,
the OPEX costs.
At access level, voice and data convergence is
already happening through mass deployment of ADSL on copper lines. At the
transit level, NGN is implemented initially via VoP transport with stand-alone
call servers (Class 4 or transit call servers), controlling trunking gateways
in charge of the PSTN-to-packet adaptation.
Introduction of the media gateway controller (MGC)
feature in TDM switch, enables the operators to move smoothly to NGN with full
continuity of services at the desired deployment pace. MGC allows control of
additional gateways, which interconnect existing access unit/trunk to packet
network.
This solution allows a progressive
hand-over of voice traffic from the TDM world to the data world, while
retaining the existing end-user services as well as the control and management interfaces.
This would ensure networks’ smooth evolution without service disruption,
besides investment protection.
By Niraj K. Gupta, "from my cell",
Voice & Data, October 2002