International Telecommunication Union
Quality of service for the
user (parameters, models,
measurement) and
interoperability issues
Jean-Yves Monfort
ITU-T SG 12 Chairman
France Telecom, R&D Division
ITU-T Workshop on Home Networking and Home Services
Tokyo, Japan, 17-18 June 2004
General messages on QoS and Interoperability from
the CTO's meeting organized by TSB Director (Dec 2003) ,
applicable to Home networking and Home services
ITU-T
http://www.itu.int/ITU-T/tsb-director/cto/index.html
- ITU-T should ensure global interoperability
(Interoperability for all major services required on a
global scale and interoperability for the required core
middleware functionalities).
- Mechanisms to provide end-to-end QoS are
required (including session based QoS, QoS Classes or
High quality classes,…)
- Simplicity and ease of use for the end users ,
QoS determined by user choice of service, and high quality
for voice (e.g. wideband)
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Some Preliminary results for the workshop on
Wideband speech Quality : Prediction and
Assessment. Mainz, 8-9 June 2004
ITU-T
-Even all the elements (coders, protocols,
terminals,…) were developped, Wideband speech was not
a success for ISDN; VoIP will certainly give the success.
-Wideband speech increases the perceived quality
and mainly the intelligibility, specially in noisy environment.
- E-Model (G.107) and P.862 are now well known
and used for narrow-band speech; some substancial
progress are expected in the near future to predict and to
assess wideband speech quality, and to assess the speech
quality whatever the bandwidth.
- The possibility to define "category" classes, based
on acoustics and signal processing performance.
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Challenges for QoS Statements/Conclusions of
ITU-T Workshop on QoS . Valid for HN/HS
ITU-T
http://www.itu.int/ITU-T/worksem/qos/index.html
• "Need for interworking standards to achieve end to end QoS"
• "Need for a common understanding and implementation of QoS
classes" whatever the network (cellular, wireless, wireline
access)
•"Generic requirements for IP QoS and traffic signalling" being
developed in ITU-T SG 11(and on-going activities in Q.EE/11)
TRQ.IPQOS.SIG.CS1(Y.1541/Y.1221 specifications are being applied, but
work is still
needed to enable implementation of QoS control-based networks."
• "Need to define the specific signalling system(s) to be used to
implement assured QoS in IP-based networks.
The alternatives are
- a broad consensus, or
- many gateways to be needed.
Need for collaborations/cooperations."
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Challenges for QoS Statements/Conclusions of
ITU-T Workshop on QoS – Oct 2003Valid for HN/HS
ITU-T
•"More work needed to understand the relationship between
Service Level Specification, monitoring and application
monitoring"
•"Ultimately the issue for accelerating deployment of QoS that fully
supports the user experience is capital, which these days is only made
available when persuasive business cases have been made "
A general remark, but well adapted to QoS
To ensure IP QoS interoperability it is needed to :
- ensure a high level leading role
- have experts from each relevant (standardisation) bodies working
together, to understand each other aims, working methods, process
and to work with coherent schedules
- ensure that the areas of work in progress are in line with the
guidelines in the relevant bodies
- have the relevant support of the experts of a company, working in
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ITU-T
Rec. G.1000
"Communications quality of service:
A framework and definitions"
o Provides a
framework and
definitions for
communications
quality of service
o Establishes a uniform
approach to quality
of service across the
ITU-T
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CUSTOMER
Customer’s
QoS
Requirements
QoS
Perceived
By Customer
SERVICE
PROVIDER
QoS Offered
By
Provider
QoS
Achieved by
Provider
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SG 12 Questions to be involved in cooperation
on Home networking/Home services
ITU-T QUESTION O/12 – QoS and performance
coordination
The main focus are :
- Coordination of QoS-related activities in the ITU-T
(ongoing), with the focus on identifying gaps in QoS
standardization that present interoperability obstacles
to achieving e2e QoS.
- Coordination among various standards activities on
QoS and collaboration with other standards bodies
(ongoing), with an emphasis on interoperability.
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ITU-T
Mapping of user-centric QoS
requirements (G1010)
o 8 distinct groupings, covering the
Packet Loss
5%
range of applications
o Distinction between applications
which can tolerate some
information loss and those that
cannot
o Main distinction in terms of delay
Conversational
voice and video
0%
Zero
loss
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100 msec
Command
/ control
(eg Telnet,
Interactive
games)
Voice/video
messaging
1 sec
Transactions
(eg E-commerce,
Web-browsing, Email access)
Streaming
audio/video
10 sec
Messaging,
Downloads
(eg FTP,
still image)
Delay
Fax
100 sec
Background
(eg Usenet)
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Benefit of end-user QoS
category model
ITU-T
o QoS Category Model is based on end to end user
perception of impairments, therefore not
dependent on any specific technology for its
validity
o Provides an indication of the upper and lower
boundaries for applications to be perceived as
essentially acceptable to the user
o Shows how the underlying impairments of
information loss and delay can be grouped
appropriately, without implying that one class is
“better” than another
o Provides basis for realistic network QoS classes (in
complementarity with ITU-T Rec. Y.1541)
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SG 12 Questions to be involved in cooperation
on Home networking/Home services
ITU-T
QUESTION M/12 – Multimedia QoE/QoS performance
requirements and assessment methods
Main focus related to HN/HS :
-Identify examples of multimedia applications and services
(interactive, streaming, browsing, e-commerce, file transfer etc)
and the underlying media involved (voice, video, still image, text,
data etc).
- Development of new Rec. G.MMPERF, providing
guidance on end-user performance expectations for multimedia
applications
- Identify simple analysis techniques for estimating end to end
performance for multimedia applications (“non-voice E-model”),
including web-based applications, video conferencing and
computer-supported cooperative work (CSCW).
- Development of simplified planning models for estimating end
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As an exemple for on-going G.MMPERF :
On-line games
ITU-T
Based on subjective tests with real users it appears that
a target value of 70 ms as the maximum delay should be more
appropriate than the preliminary value (200ms)
the maximum delay variation around the mean value should be
+/- 20ms, because the player adapts his playing to the latency, and a
greater variation is annoying. (These limits are based on "acceptability
testing").
Note : Some games (as FPS -First Person Shooting-)
are very sensitive to this delay variation. For other games the maximum
value could be limited to 150ms
(These values are based on Games-on-line implemented on
PC).
The minimum data rate should be 40 kbit/s (for the client).
This value shall be greater for the server. This is applicable to PC and
consoles.
It appears that the more popular "games on line" on PCs are IP
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Other important topics related to QoS (on –
going activities)
ITU-T
-Quality assessment for Voice and multimedia Services
-Subjective quality assesment (recently approved P.880
Continuous Evaluation of Time Varying Speech Quality and P.851 Subjective quality
evaluation of telephone services based on spoken dialogue systems )
- Objective Quality assesment : 3 types of models are
developped ( Opinion models –E-Model, G.107-,
Psychoacoustic models –P.862 and P.563 and models
associated to INMD –P.562-).
- Quality assesment methodologies for multimedia
services (SG9/SG12)
On-going work under a JRG Multimedia Quality
Assessment
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SG 12 Questions to be involved in cooperation
on Home networking/Home services
ITU-T
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QUESTION K/12 - IP based multimedia services (e.g. voice,
video, data) end to end transmission planning for multiple
interconnected networks (e.g. cellular, wireless, wireline networks)
- QoS Interoperability Issues :
- Definition of interworking functions required to support
interfacing between cellular/wireless/wireline networks sufficient to
enable service providers to comply with end to end performance
objectives for the QoS classes and to take into consideration the
network performance parameters across network sections
- Analysis of the impacts of interworking functions between
different network sections on end to end QoS.
- Apportionment functions and mechanisms
Static and dynamic allocation of performance parameter
values across networks (cellular, wireless, wireline access and
backbone networks)
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SG 12 Questions to be involved in cooperation
on Home networking/Home services
ITU-T
QUESTION B/12 - Speech transmission characteristics and
measurement methods for terminals and gateways interfacing
packet-switched (IP) networks
- Enhancement of Recommendation P.1010 on Fundamental
Voice Transmission Objectives for IP Terminals and Gateways
regarding wideband telephony
- Production of a new Recommendation P.VOIP-MM on
Measurement Methodologies for IP Terminals and Gateways
QUESTION C/12 – Speech transmission characteristics of speech
terminals for fixed circuit-switched, mobile and packet-switched
(IP) networks
Speech transmission characteristics and measurement
methods are needed for voice terminals using new access techniques
(e.g., power line access, WLAN, etc.)
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Other important topics related to QoS (on –going
activities)
ITU-T
- Handbook on QoS will be available soon
(prepared by WP2/2)
- On-going work on network performance :
- Ethernet (Y.ethperf)
- Hybrid networks (Y.hybperf)
Note that other relevant
recommendations have been approved recently :
- Y.1561: Performance and availability
parameters for MPLS networks (may 2004)
- Y.1560: TCP performance parameters and
objectives (september 2003)
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Important topics on QoS in ITU-T (other than
those presented by SG 9 and 12)
ITU-T
SG 13 has initiated works under JRG-NGN
Recommendation Y.1291 (ex-Y.qosar) "An architectural
framework for support of Quality of Service (QoS) in
Packet networks has been approved in early may.
Still under development (meeting this week inGeneva)
Draft Recommendation Y. 123.qos "A QoS Architecture
for Ethernet-Based IP Access Network"
It is a basis to specifiy a layered reference model and
methods for support of QoS in Ethernet-based IP access
network and associated protocol requirements.
SG 11, on-going work on QoS signalling.
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Progress also expected in the new NGN Focus Group
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ITU-T
Thanks
Questions?
Jeanyves.monfort@francetelecom.com
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