Key QoS parameters for Voice Services Workshop on “Monitoring Quality of Service and Quality of...

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

Maputo - Mozambique - 14 - 16 April 2013 2

Components and related QoS category with voice quality functions


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.


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


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


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


Codec combination


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


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.


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


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


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)


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



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]



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


GUIDANCE ON OBJECTIVES FOR QUALITY RELATED PARAMETERS AT VOIP SEGMENT-CONNECTION POINTS

RESULTS PUBLISHED IN ETSI TR 102 775 V.1.6.1

17


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.


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


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


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


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


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


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


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


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.


Guidance on Access Segment Objectives


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.


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].


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


Delay Objectives for BEST (G.109) voice communication quality (R > 90) and Access Network Jitter < 35 ms


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.


RTP is transferred preferentially


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


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:


Any questions ?

Contact:[email protected]

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