key qos parameters for voice services workshop on “monitoring quality of service and quality of...
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Key QoS parameters for Voice Services
Workshop on “Monitoring Quality of Service and Quality of Experience of Multimedia
Services in Broadband/Internet Networks”
(Maputo, Mozambique, 14-16 April 2014)
Martin BrandVice Chair ITU-T Study Group 11
Joachim Pomy
[email protected], Germany
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Components and related QoS category with voice quality functions
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ITU-T G.114 ITU-T G.107
Highly interactive tasks (e.g., some speech, video conferencing and interactive data applications) may be affected by delays below 100 ms. For many intra-regional (e.g., within Africa, Europe, North America) routes in the range of 5000 km or less, users of VoIP connections are likely to experience mouth-to-ear delays < 150 ms.
Absolute delay does not impair the intelligibility of speech but if the total delay exceeds around 100 ms from mouth to ear, it begins to affect the interactivity of conversations. Therefore, if possible, large delays should be avoided.
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Contributing Factors
Delay - Codec
- Packet frame duration
- DSP/CPU processing time
- Play out buffer
- Link speed (serialization)
- Propagation delay
- De-jitter buffer delay
- PLC
- Codec
- Jitter - Use of VAD- Lost of packets- Transcoding- Sound level- Echo level
Distorsion
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E-Model Transmission Rating (R)ITU-T Rec. G.107
R summarizes the effects of network impairments including delay, distortions signal level & echo level
R= Ro- Is - Id- Ie + A
Simplified E-Model for codec and packet loss/burst impairments R = 93.4 – Ie
Ro= basic signal to noise ratio
Is= level impairments and distortion impairments
Id= delay impairments
Ie= codec and packet loss/burst impairments
A= advantage factor
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Provisional planning values for the equipment impairment factor (Ie)
Codec type Reference Operating rate kbit/s Ie value
ADPCM G.726, G.727 40 2
G.721(1988), 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
VSELP IS-54 8 20
ACELP IS-641 7.4 10
QCELP IS-96-A 8 19
RCELP IS-127 8 6
VSELP Japanese PDC 6.7 24
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
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E-Model Prediction of Echo and Delay Impairment
50
60
70
80
90
100
0 100 200 300 400 500
One-way Delay (ms)
R
TELR = 65 dBTELR = 60 dBTELR = 55 dBTELR = 50 dBTELR = 45 dB
Exceptional limiting case
Very satisfactory
Satisfactory
Some usersdissatisfied
Many usersdissatisfied
User Satisfaction
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Relation between R-value and user satisfactionR Value MOS CQEN
Value Categories of User Satisfaction
94 4,4293 4,4092 4,38 Very satisfied (Best)91 4,3690 4,3487 4,19585 4,1882 4,0981 4,06 Satisfied (High)80 4,0377 3,8573 3,7470 3,60 Some users dissatisfied (Medium)68 3,5060 3,10 Many users dissatisfied (Low)50 2,58 Nearly all users dissatisfied (Poor)
MOS = 1 + (0,035) × R + (000 007) × R (R - 60) (100 - R)NOTE 1: Connections with R-values below 50 are not recommended.NOTE 2: Although the trend in transmission planning is to use R-
values, equations to convert R‑values into other metrics e.g. MOS, % GoB, % PoW, can be found in ITU-T Recommendation G.107 [i.4], annex B.
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Provisional Planning Values for the Equipment Impairment Factor Ie under Conditions of Packet Loss
for Codecs G.711, G.729A + VAD and G.732.1 + VAD
0
10
20
30
40
50
60
0 5 10 15 20 25
Packet Loss %
Ie
G.711 without PLC G.711 with PLC Random Packet LossG.711 with PLC Bursty Packet Loss G.729A + VADG.723.1 + VAD GSM 06.60 EFR
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Subjective measurement Based on subjective experiments Mean opinion score Costly and time consuming
Objective measurement Good correlation with subjective
measurement Highly repeatable Real-time
5Excellent
4Good
3Fair
2Poor
1Bad
MOS
MOS - Speech Quality Measure
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Active voice quality measurement Active voice quality measurement techniques, also known as
intrusive models, require a test call to be made over the network. A comparison of reference and degraded signals produces a quality score based on MOS. This type of measurement is useful for the preinstallation testing of a system as well as network optimization.
Passive voice quality measurement Common to all communication technologies are Passive voice
quality measurement. Passive voice quality measurement is also known as a non-intrusive measurement.
These models monitor live network traffic and again measure the voice quality on the MOS scale. Passive measurement is ideal for the testing of systems already in use
QoS Voice Testing (1)
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PSQM ITU-T Rec. P.861 - designed for codec evaluation. Assesses error loudness, noise disturbance and asymmetry to predict a PSQM value Withdrawn February 2001
PAMS - developed for real world networksAssesses time aligned, level aligned, spectrally weighted error surface
PESQ© - ITU-T Rec. P.862 Perceptual Evaluation of Speech Quality
Designed for network avaluation, using specific scale
PESQ© - ITU-T Rec. P862.1 (PESQ extension from Nov.2003)
Linear mapping to P.800 MOS scale
QoS Voice Testing (2)
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PESQ© - ITU-T Rec. P862.3 [2007] (Implementation guide, Methods for objective and subjective assessment of quality)
POLQA – ITU-T Rec. P.863 [2011] 3SQM, perceptual single-sided speech quality measure
(non-intrusive) according to ITU-T rec. P.563 [2004]
QoS Voice Testing (3)
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The instance of media-information quality assessment methods comparison
Accuracy
Cost High Good Average Method type
High PESQ, POLQA Active
Average P.563 Passive
Low E-modelPassive/
Modelling
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GUIDANCE ON OBJECTIVES FOR QUALITY RELATED PARAMETERS AT VOIP SEGMENT-CONNECTION POINTS
RESULTS PUBLISHED IN ETSI TR 102 775 V.1.6.1
17
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Scope of the development
To provide guidance on the quality parameters that need to be considered at the Segment-connection of Voice over IP (VoIP) services and provides guidance on objectives for these parameters.
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Reference Configuration
UNI
CPN CPN
NNI NNI
Total transit segment
UserSegment A
AccessSegment A
UserSegment C
AccessSegment C
NGNProvider A
NGNProvider C
NGN Provider B
TransitSegment
A1
TransitSegment
C1
TransitSegment
B1
UNI
Regional Metro
Regional
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Generic Segment-connection Points
Service Layer
Transport Layer
UNI UNISBC SBC SBC SBC
IP Transit
Interconnection Serveror
Transit Network
Access Network Access NetworkNGN NGN
UNI-UNI
CPN CPN
QoS View
NGN Functional Archutecture View
RACS
I-BGF
Service ControlSubsystem
Non-compatibleControl domain
CompatibleControl domain
IWF
SoIx interconnection reference model
Iz/Ic Iz/Ic
Iz
Ic
Iz
Iw
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End-to-End delay values between originating and terminating Service Provider premises
West Europe Vienna
North Europe RU – VladimirRU – MoskwaSE - Östersund
East Europe RO – BucharestHU – Budapest
South Europe GR–AthensIT - Roma
East Asia (CN-Dongguan)
South Asia Malaysia - MY
Oceania Australia -AUSydney
N. America East Cost USWashington DC
N. America West Cost USVancouver
Central America Panama - PAMexiko- MEX
South America Brasilia - BR
Africa ZA - Cap town Burkina Fasso
West Europe BernParisFrankfurt
DE - AT (Frankfurt –
Vienna)7 ms
CH – DE (Bern –
Frankfurt)8 ms
CH - AT(Bern – Vienna)10 msFR- AT(Paris -. Vienna)15 ms
CH - RU (Bern – Vladimir)23 msCH - RU(Bern – Moskwa)22 ms DE- RU (Frankfurt- Moskwa)21 ms DE-SE(Frankfurt – Östersund)12 ms
CH-RO(Bern – Bucharest)25 ms DE-RO(Frankfurt – Bucharest)18 ms DE-HU (Frankfurt – Budapest)12 ms
CH-GR(Bern – Athens)30 ms DE-GR (Frankfurt – Athens)24 ms IT-CH(Roma – Cern)
22 ms
Frankfurt – Roma13 ms
CH – CN (Bern- (Dongguan)150 ms DE-CN (Frakfurt – Dongguan)160 ms
CH- MY110 ms DE – MY115- 164 ms
CH-AU(Bern – Sydney)170 ms DE-AU(Frankfurt – Melburne)165 ms DE-AU (Frankfurt – Sydney)146 ms
CH- US(Bern –Washington)46 ms DE-US (Frankfurt –Washington)55 ms
CH-US(Bern – Vancouver)75 ms DE-US (Frankfurt –Vancouver)75 ms
CH-PA(Bern – Panama)103 ms DE-MEX(Frankfurt – Mexiko City) 75 ms
CH-BR (Bern – Sao Paulo)136 ms DE-BR (Frankfurt –Sao Paulo)125 ms
CH-ZA (Bern - Cape Town)108 ms DE-ZA (Frankfurt – Cape Town)90 ms BE-BF 90 – 130 ms
North Europe(SE-
Östersund)
SE - RU(Östersund – Moskwa)10 ms
SE-RO(Östersund – Bucharest)30 ms
SE-GR(Östersund- Athens)42 ms
SE-CN 150 ms
SE-MY124 ms
SE-AU171 ms
SE-US62 ms
SE-US83 ms
SE- PA84 ms SE-MEX78 ms
SE-BR155 ms
SE-ZA 87 ms
East Europe(HU- Budapest)
HU- RU(Budapest – Moskwa)33 ms
HU – RO (Budapest- Bucharest)14 ms
HU – GR (Budapest – Athens)20 ms
HU-CN 166 ms
HU-MY125 ms
HU-AU170 ms
HU-US60 ms
HU-US100 ms
HU-PA 95 ms HU- MEX96 ms
HU-BR152 ms
HU-ZA100 ms
South Europe(IT- Roma)
IT- RU (Roma – Moskwa)38 ms
IT-RO (Roma – Bucharest)32 ms
(IT-GR)Roma – Athens23 ms
IT-CN 160 ms
IT-MY150 ms
IT-AU160 ms
IT-US 55 ms
IT-US95 ms
IT – PA104 ms IT- MEX113 ms
IR-BR108 ms
IT-ZA 95 ms
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Reference Configurations (1)
IP TransitSBC ADM DL CL SBC SBC SBCADMDLCL
Backbone
SBCTETE MGW EC
PSTNVoNGN
Local exchange
Transit exchange
SBCTETE Subscriber linedigital junction
MSAN (MGW)EC
PSTN
VoNGN
NGN PSTN/ISDN access Configuration
PSTN/ISDN classic access Configuration
ADM Add-Drop-MultiplexerDL router Distribution LayerCL router Core LayerTRAU Transcoder and Rate Adaption ETH Ethernet Unit
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Reference Configurations (2)
IAD SBCTETE
PSTN
DSLAMETH2X
ADM 4x
BRAS /BNG VoNGN
Access DSL Configuration
NodeB
RNCATM ATM MGW SBCTRAUVoNGN
Access configuration from UMTS Release 4
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Delay with regional propagation delay (1 400 km / 7 ms)
Uplink / Downlink
256 kbit/s
384 kbit/s
512 kbit/s
768 kbit/s
1024 kbit/s
1152 kbit/s
1536 kbit/s
2048 kbit/s
2304 kbit/s
3072 kbit/s
6144 kbit/s
POTS
POTS - - - - - - - - - - - 55 ms
R=91256 kbit/s 128 ms
R=90
118 ms
R=90
113 ms
R=90
108 ms
R=90
104 ms
R=90
103 ms
R=91
102 ms
R=911
101 ms
R=91
101 ms
R=91
100 ms
R=91
97 ms
R=91
82 ms
R=91
384 kbit/s - 108 ms
R=90
102 ms
R=91
97 ms
R=91
95 ms
R=91
93 ms
R=91
94 ms
R=91
92 ms
R=80
92 ms
R=91
91 ms
R=91
91 ms
R=91
75 ms
R=91
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Delay with regional propagation delay (1 400 km / 7 ms)
Uplink / Downlink
256 kbit/s
384 kbit/s
512 kbit/s
768 kbit/s
1024 kbit/s
1152 kbit/s
1536 kbit/s
2048 kbit/s
2304 kbit/s
3072 kbit/s
6144 kbit/s
POTS
POTS - - - - - - - - - - - 55 ms
R=91256 kbit/s 128 ms
R=90
118 ms
R=90
113 ms
R=90
108 ms
R=90
104 ms
R=90
103 ms
R=91
102 ms
R=911
101 ms
R=91
101 ms
R=91
100 ms
R=91
97 ms
R=91
82 ms
R=91
384 kbit/s - 108 ms
R=90
102 ms
R=91
97 ms
R=91
95 ms
R=91
93 ms
R=91
94 ms
R=91
92 ms
R=80
92 ms
R=91
91 ms
R=91
91 ms
R=91
75 ms
R=91
G.711/20
Uplink / Downlink
256 kbit/s
384 kbit/s
512 kbit/s
768 kbit/s
1024 kbit/s
1152 kbit/s
1536 kbit/s
2048 kbit/s
2304 kbit/s
3072 kbit/s
6144 kbit/s
POTS
512 kbit/s
- - 97 ms
R=91
92 ms
R=91
91 ms
R=91
91 ms
R=91
91 ms
R=91
91 ms
R=91
90 ms
R=91
90 ms
R=91
90 ms
R=91
74 ms
R=91
768 kbit/s
- - - 91 ms
R=91
90 ms
R=91
90 ms
R=91
90 ms
R=91
89 ms
R=91
89 ms
R=91
89 ms
R=91
89 ms
R=91
73 ms
R=911024 kbit/s
- - - - 90 ms
R=91
89 ms
R=91
89 ms
R=91
89 ms
R=91
89 ms
R=91
88 ms
R=91
88 ms
R=91
73 ms
R=91
2048 kbit/s
- - - - - - - 88 ms
R=91
88 ms
R=91
88 ms
R=91
88 ms
R=91
88 ms
R=91
GSM 202 ms
R=81
196 ms
R=81
194ms
R=82
193 ms
R=82
193 ms
R=82
192 ms
R=82
192 ms
R=82
192 ms
R=82
192 ms
R=82
191 ms
R=82
191 ms
R=82
175 ms
R=83UMTS Rel.4 207 ms
R=80
201 ms
R=81
199 ms
R=81
198 ms
R=81
198 ms
R=81
197 ms
R=81
197 ms
R=81
197 ms
R=81
197 ms
R=81
196 ms
R=81
196 ms
R=81
180 ms
R=82LTE 163ms 157
ms155 ms
154 ms
154 ms 154 ms 153 ms
153 ms 153 ms 152 ms 152 ms 136 ms
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Relation between R-value and user satisfactionR Value MOS CQEN
Value Categories of User Satisfaction
94 4,4293 4,4092 4,38 Very satisfied (Best)91 4,3690 4,3487 4,19585 4,1882 4,0981 4,06 Satisfied (High)80 4,0377 3,8573 3,7470 3,60 Some users dissatisfied (Medium)68 3,5060 3,10 Many users dissatisfied (Low)50 2,58 Nearly all users dissatisfied (Poor)
MOS = 1 + (0,035) × R + (000 007) × R (R - 60) (100 - R)NOTE 1: Connections with R-values below 50 are not recommended.NOTE 2: Although the trend in transmission planning is to use R-
values, equations to convert R‑values into other metrics e.g. MOS, % GoB, % PoW, can be found in ITU-T Recommendation G.107 [i.4], annex B.
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Maximal IPDV values for xDSL and ETH Access Segment
Parameter Value
Access Network (sending side) < 35 ms
Access Network (receiving side);
< 10 ms (note)
NOTE: 10 ms are recommended, the maximum IPDV value is 40 ms.
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Guidance on Objectives for Total Transit Segments
Parameter Value IPDV
Intra-continent Jitter Value -5 ms per Provider (maximum of 2 involved in the service delivery chain) (see note)
10 ms
IPDVInter-continent Jitter Value -10 ms per Provider (maximum of 2 involved in the service delivery chain) (see note)
20 ms
IPLR 3,0 × 10-4
IPER 3 × 10-5
Ie 0NOTE: The Jitter Values are based on values contained
in the GSMA document IR.3445 [i.15].
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Dependence of DSP/CPU processing time TriplePlay-Results IAD_2_IAD
Test requerments : routed IAD-Konfiguration,worst case two TV Streams, Testlabor HSI- Connection and activated WLAN, VP-voice upstream Bandwith 384 kBit/s.
Supplier: 1 2 3 4IAD_2_IAD MOS ValueQoS two wire (PSTN)10 ms packetization 20 ms packetization
4,24,2
4,24,2
4,04,0
4,24,1
Delay / Delay Range/ Std-Dev (each direction max values)
10 ms packetization
20 ms packetization 58/29/10
66/35/11 86/10/495/0/0
111/10/4 114/13/6
63/17/666/10/4
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Delay Objectives for BEST (G.109) voice communication quality (R > 90) and Access Network Jitter < 35 ms
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Bandwidth calculations and prioritization in VoIP systems
The IP delay of VoIP packets over a link transporting Voice and Data depends on following factors:
• the instantaneous system load (not the average system load),• the size of the packets (both the size of the RTP packets and IP
data packets on the same links),• the manner in which QoS is implemented in the system (a system
with priority, such as Diff-Serv, behaves differently than a system with best effort).
The delay and jitter increase linearly up to a limit of parallel VoIP channels. Above this limit, the bandwidth utilization and the delay increase exponentially and the VoIP transmissions become unstable.
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The maximum link capacity
The maximum capacity with Diff-Serv is bandwidth dependent. For example, the utilization for a 386 kbit / s link should not be higher than 85%, a 4 Mbit/s link can be utilized with 96 %.
Utilization (ρ1+ ρ2) Link capacity RHO < 0.96 > 4 Mbit/sRHO < 0,95 3 Mbit/sRHO < 0,89 2 - 3 Mbit/sRHO < 0,89 1 - 2 Mbit/sRHO < 0,85 0,386 - 1 Mbit/s Tests conditions:
Data utilization ρ2= 62 %;
Data Packet size = 1500 bytes;
Codec: G.711
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QoS is implemented by over-dimensioning of the system
Without prioritization only 40 % to 80% of the bandwidth can be used depending on the flow characteristics, as can be seen in the following figure: