Transcript codecs, over QoS-engineered IP networks

Characterising End to End
Quality of Service in TIPHON
Systems
Helmut Schink
Siemens AG
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Approach to Characterizing
Multimedia QoS

QoS is defined subjectively as perceived by the user,

It is end to end (e.g. mouth to ear for speech),

A number of QoS Service Classes are defined,

Classes include guaranteed quality (statistically) and
unguaranteed (best effort).
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
ITU-T G.109 Voice Quality Categories
ITU-T G.109 defines categories of voice quality
for conventional 3.1 KHz telephony in terms of R
R-value range
Speech transmission
quality category
User satisfaction
Example of typical scenarios
90  R < 100
Best
Very satisfied
PSTN to PSTN, Local
80  R < 90
High
Satisfied
PSTN to PSTN, Natl/Intl. (64 kb/s)
70  R < 80
Medium
Some users dissatisfied
PSTN to PSTN, Intl (with compression); PSTN to
Mobile, Natl
60  R < 70
Low
Many users dissatisfied
PSTN to Mobile, Intl; Mobile to mobile, Natl; Satellite
(64 kb/s)
50  R < 60
Poor
Nearly all users dissatisfied
Mobile to Mobile Intl; Satellite (with compression)
NOTE 1 – Connections with R-values below 50 are not recommended.
NOTE 2 – R-values can be translated into other metrics e.g. MOS, %GoB, %PoW
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Definition of TIPHON Speech
QoS Classes

BEST: providies voice quality better than PSTN, using
wideband audio (eg 7 kHz) codecs, over QoS-engineered IP
networks

HIGH: provides voice quality comparable to PSTN, over
QoS-engineered IP networks

MEDIUM: provides voice quality comparable to mobile
telephony, over QoS-engineered IP networks

BEST EFFORT: provides usable voice quality, but not
guaranteed, over non QoS-engineered IP networks
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
TIPHON QoS Class Performance Metrics
Each TIPHON class is defined by three performance metrics

Listening Speech Quality (one-way, non
conversational),

End-to-end delay,

Overall Transmission Quality Rating (R)
(combines codec performance and effects of
network impairments into one subjective
metric via G.107 Emodel )
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
The TIPHON Speech QoS Classes
Class
Listener Speech
Quality
(One-way Nonconversational)
End-to-end
Delay (G.114)
Overall
Transmission
Quality Rating (R)
Guaranteed
(Best)
Better than
G.711
< 100ms
N.A.
Guaranteed
(High)
Guaranteed Unguaranteed
(Medium)
(Best Effort)
Equivalent or
better than
G.726 at 32
kbit/s
Equivalent or
better than
GSM-FR
Undefined
< 100ms
< 150ms
< 400ms*
> 80
> 70
> 50*
* Target
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Relationship between TIPHON
Service Classes & R Value
BEST
HIGH
MEDIUM
BEST EFFORT
R-value
100
90
BEST
G.109
Performance Categories
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
80
HIGH
70
MEDIUM
60
LOW
50
POOR
Parameters Determining
QoS in IP Networks
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Factors Influencing QoS
Usual factors:
 Levels, echoes, delay, noise,
terminal acoustics.
Specific Packet Related Factors:
 Delay Jitter
 Packet Loss,
 Codec performance.
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Inter-relationship of QoS Factors
Network
Packet Loss
Overall
Packet
Loss
Codec
Performance
Network Jitter
Network Delay
Network Factors
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Perceived
Quality
Jitter
Buffers
Overall
Delay
Application Factors
QoS Service Level
Derivation of Transport QoS Parameters
QoS Service Class
SERVICE
Codec, Frames per Packet, Frame Size, Jitter Buffer Size,
Overall Delay, Overall Packet Loss, FEC (Redundancy)
APPLICATION
Network Packet Loss, Mean Delay, Delay Variation
TRANSPORT
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
Extension to Multimedia QoS Classes
Interactive
Responsive
Timely
Non-critical
Packet Loss
5%
Voice/video
messaging
Conversational
voice and video
0%
Zero
loss
100 msec
Command/
control
(eg Telnet,
Interactive
games)
1 sec
Transactions
(eg E-commerce,
Web-browsing, E-mail
access)
Streaming
audio/video
10 sec
Paging,
Downloads
(eg FTP,
still image)
Delay
Fax
Background
(eg Usenet)
TIPHON VoIP requirements address this quadrant
from a user perspective, packet loss and delay are the fundamental performance
metrics for all multimedia services
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva
100 sec
Further Information
TR 101 329 - Part 2
TIPHON; Quality of Service (QoS) Classes
TIPHON Web site
http://www.etsi.fr/tiphon/
Access to Documentation
http://docbox.etsi.org/tech-org/
tiphon/Document/tiphon/07-drafts/wg5/
IP Networking & MEDIACOM 2004 Workshop
24 - 27 April 2001 Geneva