(modified and merged Questions 6/9 and 9/9)
Rapid development of IP technologies enables cable television networks to be
a versatile infrastructure for various multimedia services. Based on
Recommendation J.112, "Transmission Systems for Interactive Cable Television
Services", Voice over IP/Video over IP services over IP-based cable television
networks are expected to be available to the market soon. New Recommendations
for these applications are strongly required to meet the demand of new services
in a timely manner.
IP-based cable television networks at a very high level have to connect with
three networks: HFC access network, IP network and PSTN. In consideration of
Voice over IP/Video over IP applications in IP-based cable television networks,
functional components noted below in clause 3 should be studied in relationship
with the three networks. System architecture should describe the specifications
of the functional components and define the interfaces between these networks
and IP based cable television networks.
Voice over IP application requires strict latency and packet-loss control in
IP-based cable television networks to compete with the same services over PSTN.
Video over IP application needs more bandwidth than voice applications. It is
not necessary to develop new codecs for the applications, however it is required
to specify which codecs should be mandatory to guarantee the basic voice/ video
services over IP-based cable television networks. The new Recommendations will
describe the mandatory and optional requirements for audio and video codecs in
the Voice over IP/Video over IP applications in accordance with the classified
In the application of Voice over IP/Video over IP, signalling interfaces are
important issues for session control for signalling, and for transcoding of
media streams between IP-based cable television networks and PSTN. For this
purpose some gateway functions, one for signalling and one for media, will be
required between the two networks. Signalling interfaces on media gateway and
signalling gateway should be studied for the connection between IP-based cable
television networks and PSTN. The media gateway should provide actual bearer
circuit interfaces and transcode the media stream, while the signalling gateway
should exchange the signalling information between the two networks. The
Recommendation should also include protocol descriptions on call signalling for
the three networks: IP-based network, PSTN and IP Network.
There should be an adapter between the telephone and IP-based cable
television network. The adapter device should provide a conversion function
between voice/video signals and IP packets, signalling functions, and a cable
modem function. Like ordinary telephone numbers associated with each telephone,
an IP address should be assigned to the adapter to identify source and
destination address. An adapter device that contains a subscriber-side interface
to the telephone and a network-side signalling interface to call control
elements in the network should be studied for the applications. The adapter
should provide codecs and all signalling and encapsulation functions required
for media transport and call signalling. MAC addresses and IP addresses should
be assigned to the adapter. The Recommendation for the adapter device that
contains such functions should be specified to support Voice over IP/Video over
IP applications over IP-based cable television networks.
Classified operation services under defined QoS should be available in
IP-based cable television networks. However QoS requirements and definitions
still remain unspecified. The transmission of streaming packets such as voice or
video signals requires very stringent specifications for real-time operation.
QoS requirements and classified QoS definitions should be studied and specified
for Voice over IP/Video over IP applications. In most cases packet loss and
latency in the packet streams are strictly related to the level of QoS. A
feedback control method of minimizing packet loss and latency from the receiver
device should be studied based on the analysis of received IP packets.
In addition to the distribution of television programmes, the cable
television infrastructure can provide a powerful tool for the capillary
distribution of various other services to the home, including services that are
based on interactivity and require a return channel.
The cable television infrastructure can thus also be used with advantage to
connect home users to such additional services as the Internet, as an extension
of the public switched network or of similar delivery systems. Connections via
the cable television network can provide high speed and good quality performance
for the delivery of such additional services, to the benefit of both the
providers of the services and of their users in the home.
Interconnection of cable television users to the public switched network or
to similar delivery systems requires the use of an appropriate modem at the user
premises, to be designed in such a way as to optimally meet the operating
requirements of those additional services.
System architecture for Voice over IP/Video over IP applications in IP-based
cable television networks
- What type of call signalling protocol should be used for these
- What class of Quality of Service (QoS) should be used for these
- What media stream transport and encoding methods should be included in
the new Recommendation?
- What mechanisms may need to be implemented in order to accommodate the
various technologies that could be used to extend the reach of the cable
- What device provisioning method should be appropriate for these
- What type of event messaging should be required for these applications?
- What class of security and privacy should be required for these
Audio and video codecs for Voice over IP/Video over IP applications in
IP-based cable television networks
- What type of audio and video codecs should be specified for these
- What parameters should be specified for latency and packet-loss control?
- What class of QoS should be specified for these applications in
relationship with each codec parameter?
Signalling interfaces used in IP-based cable television networks, PSTN and IP
networks for Voice over IP/Video over IP applications
- What PSTN gateway signalling protocols should be specified?
- What media gateway functions should be specified for the applications?
- What protocols should be specified for Internet signalling?
Adapters for Voice over IP/Video over IP applications in IP-based cable
- What type of codecs should be provided in the adapter to guarantee QoS
- What signalling protocol should be used?
- What audio indicators should be provided in the adapter to phones, such
as dial tone, ring-back tone, call waiting tone, etc.?
- How many and what type of analogue interfaces (plugs) should be provided
in the adapter?
- What event should be messaged to IP-based network?
- What provisioning method should be applied to the adapter?
- How many IP addresses and MAC addresses are required?
QoS requirements and definitions for Voice over IP/Video over IP applications
- What requirements and classifications should be studied for QoS?
- What method of controlling QoS should be specified for these
- What method of minimizing packet loss and latency should be specified in
Provision of additional services to the home user
- Which additional services (besides television and sound programming
delivery) could be carried with advantage to the user's premises by a cable
television network properly interconnected with the public switched network
or with similar delivery systems?
- Which operating requirements should be met for the delivery of those
additional services to the user's premises by cable television networks?
- Which functional characteristics should be recommended for the modems to
be placed at the user's premises in order that those operating requirements
may be optimally met?
- What enhancements to existing Recommendations are required to provide
energy savings directly or indirectly in Information and Communication
Technologies (ICTs) or in other industries? What enhancements to developing
or new Recommendations are required to provide such energy savings?
Tasks include, but are not limited to the preparation of a new set of
An up-to-date status of work under this Question is contained in the
SG 9 Work Programme.
- J.112, H.323, H.245, H.225, G.711, G.728, G.729/A
- Close collaboration will be required with Study Groups working on
architecture and IP networking studies (specifically Study Groups 11, 13 and
- To the extent that technologies for the extension of cable networks
within the home over metallic pairs are studied, collaboration with Study
Group 15 would be required, specifically with Q.2/15.
- IEEE 802.16 Working Group on Broadband Wireless Access
- IEEE 802.11 Working Group on Wireless Lans
NOTE - In performing the above studies, an effort should be made to adopt
network independent solutions. Special solutions for cable networks should be
avoided where possible.