a methodology for deriving voip equipment impairment factors for a mixed nb/wb context
DESCRIPTION
A presentation made in UL about our work on extending E-Model to wideband telephony applications.TRANSCRIPT
![Page 1: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/1.jpg)
Wireless Access Research
Adil Raja August 2007
A Methodology for Deriving VoIP Equipment Impairment Factors for a
Mixed NB/WB Context
Adil Raja
13th August, 2007
![Page 2: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/2.jpg)
Wireless Access Research
Adil Raja August 2007
VoIP- The Shift to WB Paradigm
• The NB and WB would have to coexist for some time. i.e. operate either in cascade or in parallel.
• This work proposes an extension to E-Model for the parallel case.
![Page 3: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/3.jpg)
Wireless Access Research
Adil Raja August 2007
The E-Model
• An Instrumental Model initially designed for NB handset telephony.
• R= R0-Is-Id-Ie,eff+A• R0=93.2 – the basic SNR.• Is - simultaneous impairments e.g. OLR, non-
optimum sidetone.• Id - e.g e2e delay and echo.• Ie,eff Impairments due to low-bitrate codecs and
packet loss.• A – Advantage factor.
![Page 4: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/4.jpg)
Wireless Access Research
Adil Raja August 2007
The E-Model…
• R <-> MOS
![Page 5: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/5.jpg)
Wireless Access Research
Adil Raja August 2007
Moller’s WB extension to E-Model
• Consider Two experiments• Each experiment is composed of two sets of speech
samples.• MOS evaluation is done based on ACR paradigm.• One set is evaluated in the NB/WB context.• The other set is evaluated in the NB context, by
downsampling the WB coded speech samples.
![Page 6: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/6.jpg)
Wireless Access Research
Adil Raja August 2007
ExampleSpeech quality evaluation on narrowband
conditions only
1
2
3
4
5
1
Su
bje
ctiv
e M
OS
C1 C2
C3 C4
C5 C6
C7 C8
C9 C10
C11 C12
C13 C14
C15 C16
C17 C18
C19 C20
C21 Reference
Speech quality evaluation for narrowband and wideband conditions
1
2
3
4
5
1 2
Su
bje
cti
ve
MO
S
C1 C2
C3 C4
C5 C6
C7 C8
C9 C10
C11 C12
C13 C14
C15 C16
C17 C18
C19 C20
C21 Reference
![Page 7: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/7.jpg)
Wireless Access Research
Adil Raja August 2007
ExampleRelationship between MOS for narrowband conditions
and MOS for wideband conditions
1
2
3
4
5
1 2 3 4 5
Subjective NMOS
Su
bje
cti
ve
MM
OS
STUDY GROUP 12 – DELAYED CONTRIBUTION 46
Discussion on unified objective methodologies for the comparison of voice quality of narrowband and wideband scenarios
![Page 8: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/8.jpg)
Wireless Access Research
Adil Raja August 2007
The Extension
• Rnb=a+(eRnb/wb/b-1)
• a=169.38
• b=176.32
• The R-scale is stretched by 29%
• A linear extension with somewhat similar results exists.
![Page 9: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/9.jpg)
Wireless Access Research
Adil Raja August 2007
R-scale extension with PESQ
• Two sets of speech samples are created.
• Both contain stimuli coded by NB and WB codecs. (124 samples each).
• The first (NB/WB) set is evaluated using PESQ-WB.
• The NB coded stimuli were upsampled to 16 kHz.
![Page 10: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/10.jpg)
Wireless Access Research
Adil Raja August 2007
R-scale extension with PESQ
• How to evaluate the 2nd part of the test?
• For the 2nd (NB) part of test three options were considered for evaluating the samples.
• In Option 1 All the files (ref|deg of NB|WB) were downsampled to 8 kHz.
• This qualifies as a NB test.
![Page 11: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/11.jpg)
Wireless Access Research
Adil Raja August 2007
R-scale extension … Option 1
RNB=a+b*RNB/WB
Max RNB=100.48
Suggests no extension.
![Page 12: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/12.jpg)
Wireless Access Research
Adil Raja August 2007
The outcome
![Page 13: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/13.jpg)
Wireless Access Research
Adil Raja August 2007
R-scale extension … Option 2
All Evaluation is done by PESQ-WB.
Contracts the scale instead.
![Page 14: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/14.jpg)
Wireless Access Research
Adil Raja August 2007
R-scale extension … Option 3
• Same as Option 2 but the Ref samples for NB stimuli are downsampled/upsampled.
• This would clearly tantamount to repeating option 1 but with PESQ-WB
![Page 15: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/15.jpg)
Wireless Access Research
Adil Raja August 2007
An Alternative
Using Supp 23 Exp 1&3.
Mapping between PESQ-WB & -NB evaluted NB coded samples.
Max RNB=107.1786
![Page 16: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/16.jpg)
Wireless Access Research
Adil Raja August 2007
The Codecs
• G.729
• AMR-NB – 7.4 & 12.2 kbps
• G.723.1 – 6.3 kbps
• G.722.1 24/32 kbps
• G.722.2 – all 9 modes
![Page 17: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/17.jpg)
Wireless Access Research
Adil Raja August 2007
Other metrics
• MLR - [0,2.5,. . . , 15, 20, . . . , 40]%• CLP - 10, 50, 60, 70 and 80%. • PI – 10-60 ms.• A total of 2,820 conditions were simulated• A given condition was applied to a file for 30 times; to
negate the effect of loss location.• Thus a total of 3,38,400 speech files were created.• Evaluation was done on beowulf using PESQ-WB
![Page 18: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/18.jpg)
Wireless Access Research
Adil Raja August 2007
Ie,wb,eff vs various codecs
![Page 19: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/19.jpg)
Wireless Access Research
Adil Raja August 2007
Scatter plot –training data
![Page 20: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/20.jpg)
Wireless Access Research
Adil Raja August 2007
Scatter plot-Testing data
![Page 21: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/21.jpg)
Wireless Access Research
Adil Raja August 2007
Surface plots of the derived functions
![Page 22: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/22.jpg)
Wireless Access Research
Adil Raja August 2007
Parameter Significance
![Page 23: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/23.jpg)
Wireless Access Research
Adil Raja August 2007
Ie,wb,eff vs mlr and mbl
![Page 24: A Methodology for Deriving VoIP Equipment Impairment Factors for a Mixed NB/WB Context](https://reader035.vdocument.in/reader035/viewer/2022062513/5576b92dd8b42ad0448b50bb/html5/thumbnails/24.jpg)
Wireless Access Research
Adil Raja August 2007
Ie,wb,eff vs mlr and PI