Colombia, 23-24 September 2013
The importance of models and procedures
for planning, monitoring and control in the
provisi...
Colombia, 23-24 September 2013 2
Outline
Introduction
Communication Services –
Underlying System configurations
Planning: ...
ITU-T: QoS and QoE
Quality of Service (QoS):
Totality of characteristics of a
telecommunications service that bear on its
...
Speech Quality –
what we would like to have
Colombia, 23-24 September 2013 4
1m
“orthotelefonic reference position”
Speech Quality…
Colombia, 23-24 September 2013 5
speech
quality
talking
situation
listening
situation
conversational
situa...
End to End Conifguration
Colombia, 23-24 September 2013 6
ISCDSL ISC PBX GW
PSTN
1-15 ms240 ms
MSC BSS
90-120 ms
IP-
GW
Ne...
Contributions to Quality
The networks
Type of networks
Interconnection
QoS management
The endpoints
Types of terminals
Int...
Colombia, 23-24 September 2013 8
Outline
Introduction
Communication Services –
Underlying System configurations
Planning: ...
Reference Connection in the E-model
Colombia, 23-24 September 2013 9
Transmission Rating in the E-model
Rating factor R:
With:
R0 – Basic signal to noise ratio (takes into
account circuit noi...
Network planning & E-model (ITU-T
G.107 & G.108)
Basis of the E-model: Impairment
factors
Simultaneous impairment factor I...
How to derive Ie?
Ie is based on subjective tests and
can be derived as follows:
Equipment impairment factors for the
most...
Some Ie factors from G.113
Colombia, 23-24 September 2013 13
Codec type Reference
Operating
rate
[kbit/s]
Ie
value
PCM (se...
The E-model Prediction Range
R – value range: prediction on a
scale
Mapping to MOS:
For R < 0:
For 0 < R < 100:
For R > 10...
Guide for User Satisfaction
based on R-values
Colombia, 23-24 September 2013 15
Range of E-Model
Rating R
Speech
transmiss...
Guide on Transmission Planning:
ITU-T G.108
Demonstrates the application of the
E-model for end-to-end transmission
planni...
Colombia, 23-24 September 2013 17
Outline
Introduction
Communication Services –
Underlying System configurations
Planning:...
Networks & Network Monitoring
Main network related impairments:
Delay
Delay variation (jitter)
Listening speech impairment...
ITU-T Models for Perceptual based
Speech Quality Measurement
ITU-T P.862 (2001): PESQ
ITU-T P.863 (2011): POLQA
The basic ...
Principle
Intrusive test procedure
Objective prediction of MOS (mean
opinion score) as achieved in listening
test subjecti...
Application
Intrusive testing:
Insertion of a reference speech
sequence
Acquiring the transmitted, distorted
speech sequen...
Typical setups
Colombia, 23-24 September 2013 22
Central server
- automated call setup
- generation of test
sequences
- an...
Not Intrusive Testing - ITU-T P.563
Listening speech quality prediction based
on speech signal in a call
No reference file...
The wideband challenge
High quality expectation by the user
Wideband must be significantly
better in all quality aspects
S...
Wideband listening examples
Colombia, 23-24 September 2013 25
(.wav)
Fullband
Narrowband
Wideband
Mobile Phone
Mobile
sign...
Wideband Network Planning –
ITU-T G.107.1
The principle of the model is identical to
the narrowband version G.107
The mode...
Wideband Network Monitoring
Setup as in narrowband
Only intrusive testing available
Network monitoring is based on ITU-
T ...
Conclusions and Recommendations
ITU-T provides models for planning and
monitoring
Network planning is essential for achiev...
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La importancia de los modelos y procedimientos para la planificación, seguimiento y control en la prestación de servicios de comunicación

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La importancia de los modelos y procedimientos para la planificación, seguimiento y control en la prestación de servicios de comunicación

  1. 1. Colombia, 23-24 September 2013 The importance of models and procedures for planning, monitoring and control in the provision of communications services Dr.-Ing. H. W. Gierlich Head of Telecom Division CITEL (PCC.I)/ ITU Forum on Information and Communication Technology Service: Quality, Control and Surveillance (Cartagena de Indias, Colombia, 23-24 September 2013)
  2. 2. Colombia, 23-24 September 2013 2 Outline Introduction Communication Services – Underlying System configurations Planning: The ITU-T E-model (G.107 & G.108) Network Monitoring: P.862, P.863 & P.563 Wideband – The new Challenge Summary
  3. 3. ITU-T: QoS and QoE Quality of Service (QoS): Totality of characteristics of a telecommunications service that bear on its ability to satisfy stated and implied needs of the user of the service. Quality of Experience (QoE): The overall acceptability of an application or service, as perceived subjectively by the end- user. Quality of experience includes the complete end-to-end system effects (client, terminal, network, services infrastructure, etc.). Overall acceptability may be influenced by user expectations and context. Colombia, 23-24 September 2013 3
  4. 4. Speech Quality – what we would like to have Colombia, 23-24 September 2013 4 1m “orthotelefonic reference position”
  5. 5. Speech Quality… Colombia, 23-24 September 2013 5 speech quality talking situation listening situation conversational situation … from the user’s perspective
  6. 6. End to End Conifguration Colombia, 23-24 September 2013 6 ISCDSL ISC PBX GW PSTN 1-15 ms240 ms MSC BSS 90-120 ms IP- GW Netw. 1 IP- GW 10 - 400 ms10 - 400 ms add. 1 - 100 ms ! Netw. 2 Impact on speech quality: - delay now time variant - echo much more dominant - Coding distortion - background noise problems - insufficient quality of the analog network components (att., noise, distortion…) - insufficient quality of acoustical components A big problem of today‘s networks, interconnection & terminals : delay – unpredictable, load dependant, time variant
  7. 7. Contributions to Quality The networks Type of networks Interconnection QoS management The endpoints Types of terminals Interoperability Terminal – Network Terminal – Terminal The users‘ location Environmental conditions Colombia, 23-24 September 2013 7 • Network planning • Network monitoring • Laboratory terminal testing • Interoperability testing
  8. 8. Colombia, 23-24 September 2013 8 Outline Introduction Communication Services – Underlying System configurations Planning: The ITU-T E-model (G.107 & G.108) Network Monitoring: P.862, P.863 & P.563 Wideband – The new Challenge Summary
  9. 9. Reference Connection in the E-model Colombia, 23-24 September 2013 9
  10. 10. Transmission Rating in the E-model Rating factor R: With: R0 – Basic signal to noise ratio (takes into account circuit noise, room noises) Ix – Impairment factors (see next slide) A – Advantage factor (takes into account a potential advantage for a user for a specific transmission in a specific situation) Colombia, 23-24 September 2013 10 AIe-effIdIsRoR +−−−= Basic assumption: Psychological factors on the psychological scale are additive
  11. 11. Network planning & E-model (ITU-T G.107 & G.108) Basis of the E-model: Impairment factors Simultaneous impairment factor Is (non optimum loudness rating, non optimum sidetone, PCM coding distortion) Delayed impairment factor Id (impact of delay, talker- or listener echo) Equipment impairment factor Ie (all types of impairments in equipment such as coding distortion including the effect of packet loss) Colombia, 23-24 September 2013 11
  12. 12. How to derive Ie? Ie is based on subjective tests and can be derived as follows: Equipment impairment factors for the most popular codecs in ITU-T G.113 From subjective listening tests described in ITU-T P.833 From objective models (e.g. ITU-T P.863) following the procedure in ITU-T P. 834 Colombia, 23-24 September 2013 12
  13. 13. Some Ie factors from G.113 Colombia, 23-24 September 2013 13 Codec type Reference Operating rate [kbit/s] Ie value PCM (see Note) G.711 64 0 ADPCM G.726, G.727 40 2 G.721, G.726, G.727 32 7 G.726, G.727 24 25 G.726, G.727 16 50 LD-CELP G.728 16 7 12.8 20 CS-ACELP G.729 8 10 G.729-A + VAD 8 11 RPE-LTP GSM 06.10, full-rate 13 20 VSELP GSM 06.20, half-rate 5.6 23 ACELP GSM 06.60, enhanced full rate 12.2 5 ACELP G.723.1 5.3 19 MP-MLQ G.723.1 6.3 15
  14. 14. The E-model Prediction Range R – value range: prediction on a scale Mapping to MOS: For R < 0: For 0 < R < 100: For R > 100: Colombia, 23-24 September 2013 14 1000 <<R 1MOSCQE = 6 CQE 107)100)(60(035.01MOS −⋅−−++= RRRR 5.4MOSCQE =
  15. 15. Guide for User Satisfaction based on R-values Colombia, 23-24 September 2013 15 Range of E-Model Rating R Speech transmission quality category User satisfaction 90 ≤ R < 100 Best Very satisfied 80 ≤ R < 90 High Satisfied 70 ≤ R < 80 Medium Some users dissatisfied 60 ≤ R < 70 Low Many users dissatisfied 50 ≤ R < 60 Poor Nearly all users dissatisfied Connections with E-Model Ratings R below 50 are not recommended.
  16. 16. Guide on Transmission Planning: ITU-T G.108 Demonstrates the application of the E-model for end-to-end transmission planning in a wide range of networks Keep in mind: G.107 and G.108 are applicable for narrowband networks Colombia, 23-24 September 2013 16
  17. 17. Colombia, 23-24 September 2013 17 Outline Introduction Communication Services – Underlying System configurations Planning: The ITU-T E-model (G.107 & G.108) Network Monitoring: P.862, P.863 & P.563 Wideband – The new Challenge Summary
  18. 18. Networks & Network Monitoring Main network related impairments: Delay Delay variation (jitter) Listening speech impairment due to Coding Transcoding Interconnection Packet loss/jitter Colombia, 23-24 September 2013 18
  19. 19. ITU-T Models for Perceptual based Speech Quality Measurement ITU-T P.862 (2001): PESQ ITU-T P.863 (2011): POLQA The basic principle: Colombia, 23-24 September 2013 19 Typical Processing Steps (Schematic): Adaptation Hearing Model Comparison, Reference, Reduction, Signal Value Results of Listening Tests! S indexQ Speech Signal Test Object Hearing Model processed signal reference signal
  20. 20. Principle Intrusive test procedure Objective prediction of MOS (mean opinion score) as achieved in listening test subjectively Prediction on a MOS-scale: MOS 5 – excellent MOS 4 – good MOS 3 – fair MOS 2 – poor MOS 1 – bad Substitution of subjective tests for known codecs and impairments Colombia, 23-24 September 2013 20
  21. 21. Application Intrusive testing: Insertion of a reference speech sequence Acquiring the transmitted, distorted speech sequence Calculation of the speech quality by comparing to the reference Output: MOS LQOn – mean opinion score, objective, narrowband Colombia, 23-24 September 2013 21
  22. 22. Typical setups Colombia, 23-24 September 2013 22 Central server - automated call setup - generation of test sequences - analysis & statistics Fixed Network Probe @ NTP - automated call setup - generation of test sequences Probe @ NTP - automated call setup - generation of test sequences Mobile Network Mobile Probe - automated call setup - generation of test sequences Mobile Probe - automated call setup - generation of test sequences Fixed Network 2 Very difficult in monitoring: network one way transmission delay
  23. 23. Not Intrusive Testing - ITU-T P.563 Listening speech quality prediction based on speech signal in a call No reference file insertion required Average listening speech quality prediction on statistical evaluation of a high number of calls on the same connection Not recommended for test on a call by call basis Much less reliable than intrusive testing based on P.862 and P.863 Colombia, 23-24 September 2013 23
  24. 24. The wideband challenge High quality expectation by the user Wideband must be significantly better in all quality aspects Significant contribution to quality by the terminals First attemt to certify high quality wideband speech transmission: GSMA Colombia, 23-24 September 2013 24
  25. 25. Wideband listening examples Colombia, 23-24 September 2013 25 (.wav) Fullband Narrowband Wideband Mobile Phone Mobile signal processing RF-Interface air interface Speech Transcoder speech noise Wideband (.wav) Narrowband (.wav) …in noise
  26. 26. Wideband Network Planning – ITU-T G.107.1 The principle of the model is identical to the narrowband version G.107 The model reflects the improvements in quality in wideband: Maximum R = 129 (instead of 100 for narrowband) Model provides new wideband R calculation mapping R to the range of 0-100 All factors – R0 and Impairment factors are adapted accordingly Colombia, 23-24 September 2013 26
  27. 27. Wideband Network Monitoring Setup as in narrowband Only intrusive testing available Network monitoring is based on ITU- T P.863 POLQA ITU-T P.862 PESQ should not be used in wideband Colombia, 23-24 September 2013 27
  28. 28. Conclusions and Recommendations ITU-T provides models for planning and monitoring Network planning is essential for achieving high network QoS Network monitoring is essential to detect potential issues – e.g. changing radio conditions, changing network conditions (jitter, packet loss) Both is not sufficient to guarantee a good QoE – terminals play a major role for the overall speech quality Colombia, 23-24 September 2013 28

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