(Continuation of Question 16/16) Motivation
This Question deals with network-based speech enhancement devices, including
electrical network echo control, acoustic network echo control, automatic level
control devices, and speech enhancement devices.
The application of echo cancellers continues to evolve in existing general
switched telephone networks (GSTN), cellular, ATM and emerging IP networks.
These applications bring new issues to echo canceller performance, and will
require study to ensure that network operators have adequate assurance of
transmission quality from echo cancellers complying with G.168. These issues may
result in adding and improving the tests within G.168, and studying the issues
arising from the deployment of echo cancellers to ATM and IP networks and new
services within the GSTN.
With the deployment of automatic level control (ALC) and voice enhancement
devices (VEDs), new issues are expected to arise as these devices are applied to
existing and emerging networks. As a result, Recommendation G.169 may need to be
revised and work on new Recommendation G.160 (VED) needs to continue to ensure
adequate transmission quality.
As echo cancellers are embedded into gateways it will become necessary to review
the applicability of G.168 to these devices and to develop either a separate
Recommendation or Annex to G.168 to ensure that any specific requirements for
these embedded echo cancellers are taken into account.
The Question will attempt to work electronically where possible and to make full
use of e-mail and conferencing facilities in an attempt to reduce its carbon
footprint.
Study items
Study items to be considered include, but are not limited to:
- Functional characteristics and requirements that are necessary for
network-based speech enhancement devices to provide good performance in existing GSTN and emerging ATM/IP and cellular networks
- Tests and requirements that are necessary to ensure good performance of speech
enhancement devices and how can they be enhanced to better correlate with
subjective test results
- Performance of speech enhancement devices in GSTN, ATM/IP, cellular and other
wireless environments with speech, facsimile and voiceband data signals, text
telephones, signalling tones, call-processing tones, etc
- Hardware and software tools that are necessary to support the testing of
speech enhancement devices
- Realistic echo paths and test signals that are required for testing speech
enhancement devices
- Design of in-path speech enhancement equipment so as not to interfere with
tandem codec avoidance mechanisms (e.g. codec bypass or tandem-free operation)
- Requirements of speech enhancement devices to minimise any degradations in
performance due to tandeming
- Requirements for speech enhancement devices to operate with wideband signals
- Impact of testing with voice-over-packet interfaces (e.g. IP) and overcoming
of any associated problems
- To consider any additions to Recommendations that may help to measure and
reduce the impact of climate change. Examples include reduced power consumption
of hardware and hardware tools, and reduced complexity of algorithms
Tasks
Tasks include, but are not limited to:
- Continue the development and enhancement of G.160-series Recommendations on VEDs
- Develop guidelines for the application of speech enhancement devices to be
included in the respective Recommendations above
- Develop new Recommendation or Annex to G.168 covering the requirements of
embedded echo cancellers
- Maintenance of ITU-T Recommendations G.164, G.165, G.168, G.169
An up-to-date status of work under this Question is found in the SG 16 work
programme (http://itu.int/ITU-T/workprog/wp_search.aspx?isn_sg=554).
Relationships
Recommendations:
- G.161, G.108.2, P.501, P.502, P.340, Q.115.1, Q.115.2, P.800-series
Questions:
- 14, 15 and 18/16 on network signal processing
- 7, 8 and 10/16 on sound activity detection, software tools and speech coding
aspects
Study Groups:
- ITU-T SG 2 on Telecommunications Management Network (TMN) aspects
- ITU-T SG 11 on signalling issues
- ITU-T SG 12 on application guidelines and subjective performance
- ITU-T SG 13 on ATM and IP issues
- ITU-R SGs 4 and 5 on voice on mixed terrestrial/satellite networks
Other Bodies:
- IP/MPLS Forum on ATM, MPLS and frame relay transport
- IETF working groups AVT and IPTEL on IP transport
- ETSI 3GPP, 3GPP2 and TIA on mobile networks and tandem-free operation
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