1ma204_6e

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Voice over LTE (VoLTE) SpeechQuality Measurements

A lication NoteProducts:

ı R&S®CMW500

ı R&S®UPV

ı R&S®UPV66

ı R&S® AMU200

This application note and associated application

software may be used to conduct psychoacoustic

speech quality evaluation for Voice over LTE

(VoLTE) connections. The measurements are based

on recommendations ITU-T P.862 and ITU-T P.863.

The included software sequence performs

decoder/encoder calibration, connection setup for

the UE under test and subsequent speech quality

analysis under fading conditions.

O .

G e r l a c h

4

. 2 0 1 3 – 1

M A 2 0 4

_ 6 e

A p p l i c a t i o n N o t e

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Table of Contents

1MA204_ 6e Rohde & Schwarz Voice over LTE (VoLTE) Speech Quality Measurements 2

Table of Contents

1 Overview .............................................................................................. 3

2 Hardware Setup .................................................................................. 4

2.1 VoLTE Test Setup with MEDIA Server on CMW500 ................................................. 4

2.2 VoLTE Test Setup with Media Server on Media PC .................................................. 6

3 Software Requirements ...................................................................... 8

3.1 CMW500 ........................................................................................................................ 8

3.2 UPV ................................................................................................................................ 8

3.3 VoLTE Media Server .................................................................................................... 8 3.4 POLQA_CAL ................................................................................................................. 9

3.5 R&S Run ....................................................................................................................... 9

4 VoLTE POLQA / PESQ Measurements with RSrun ........................ 10

4.1 RSrun Configuration..................................................................................................10

4.2 Test Plan Description ................................................................................................11

4.2.1 Basic Initialization ........................................................................................................11

4.2.2 Fading Scenario ...........................................................................................................12

4.2.3 LTECallSetup ...............................................................................................................14

4.2.4 Speech_Quality_Measurement ...................................................................................16

4.2.5 LTECallDisconnect ......................................................................................................21

4.3 Program Flow .............................................................................................................22

4.4 Expected MOS/LQO Results .....................................................................................23

4.5 Running the Test........................................................................................................24

5 Literature ........................................................................................... 27

6 Additional Information ...................................................................... 28

7 Ordering Information ........................................................................ 29

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Overview

VoLTE Test Setup with MEDIA Server on CMW500


1 Overview

Cellular Radio Operators face an increasing pressure to free existing spectrum ascurrently used for voice-centric services in order to allow its re-use for a broad range of

integrated media applications. This means existing circuit-switched voice services have

to be offered as just one of many applications on a packet-switched network without

sacrificing the quality users have come to expect.

Stand-alone or integrated media voice is and will remain a key application for mobile

radio service subscribers. Operators of such services strive to ensure or even improve

voice quality despite the additional challenges that a packet-based transmission of

speech entails.

The VoLTE (Voice over LTE) packet service uses the IMS (IP Multimedia Subsystem)

as architecture. One of the key enablers for the architecture is the Session Initiation

Protocol (SIP) e.g. used for negotiating the codec type, AMR-NB (Adaptive Multirate-

narrow band) or AMR –WB (wideband) and coderate (e.g. 23.85 kbps).

VoLTE uses the AMR-WB codec and can transfer signals with twice the sample rate

(16000 Hz) as classic circuit switched systems, e.g. AMR-NB, GSM-HR (half-rate) or

GSM-FR (full rate). VoLTE on one hand has advantage of an enhanced frequency

spectrum and on the other hand variable latency and possible IP impairments.

The described solution in this application note explains the measuring of speech

quality with the PESQ (Perceptual Evaluation of Speech Quality) and POLQA

(Perceptual Objective Speech Quality Assessment) algorithm. As successor of PESQ,

the new POLQA method is designed for additional test applications such as SWB

(Super Wideband Mode), bandwidth extensions etc.. A further benefit of this algorithmis that the resulting MOS-LQO (Mean Objective Score – Listening Quality Objective)

results measured with other radio access technologies (e.g. GSM, CDMA2000) are

comparable to each other.

This application note describes how to perform VoLTE PESQ and POLQA

measurements with an R&S®CMW500 Wideband Communication Tester, an

R&S®UPV Audio Tester using the included test sequence for the R&S

®Run Sequencer

Software Tool. It contains an automated POLQA / PESQ measurement similar as

described in reference [7]. The test establishes a call to a LTE mobile or PC card,

configures fading & AWGN on the R&S® AMU, calibrates the audio interface for

R&S®UPV (decoder/encoder ) and performs either a POLQA measurement according

to recommendation ITU-T P.863 or PESQ measurement according to recommendationITU-T P.862 of the speech signal received (downlink) or transmitted (uplink) by the

user equipment (UE).

The following abbreviations are used in the following text for R&S®

test equipment:

ı The R&S®CMW500 Wideband Communication Tester is referred to as CMW500.

ı The R&S®UPV Audio Analyzer is referred to as UPV.

ı The R&S® AMU200A Fading Simulator is referred to as AMU.

ı R&S®Run is referred to as RSrun.

ı R&S®

refers to Rohde & Schwarz GmbH und Co KG

POLQA®

and PESQ®

are a registered trademarks of OPTICOM Dipl.-Ing. M. Keyhl GmbH,Germany and of Psytechnics Ltd., UK

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Hardware Setup



2 Hardware Setup

The CMW will provide an internal audio board with various speech codecs in the near future but in the meantime, the audio connection can be established by an external

audio interface connected to the CMW or an additional PC. It is not recommended to

use the on-board audio interface of the external PC. The described setup is used for

measurements based on an electrical audio connection as shown in the following

figures.

External USB audio interfaces usually have balanced XLR inputs and balanced or

unbalanced ¼” output jacks. This requires following cables:

ı XLR female (UPV generator output) ↔ XLR female (audio interface input)standard microphone cable.

ı XLR male (UPV analyzer input 2) ↔ stereo jack ¼” (audio interface output) cable. ı 4-pin jack 1/8” (3.5 mm, mobile output) ↔ XLR male cable (UPV analyzer input 2

for downlink) and ↔ XLR female cable (UPV generator out 1 for uplink). The 4-pin jack can have two different pin outs depending on the mobile phone manufacturer.The UP-Z9 cable set contains these two different types.

The described setup is used for measurements based on an electrical audio

connection as shown in the following figures. It would also be possible to use an

acoustical audio interface (artificial head with artificial mouth and ear) instead of the

pure electrical connection. An additional calibration step is required in that case and

not described here. The following sections describe several different setup variations.

2.1 VoLTE Test Setup with MEDIA Server on CMW500

This setup consists of

1. CMW500 Communication Tester is connected to the LTE UE via RF. It provides

IMS infrastructure, establishes a VoLTE call and transmits RTP packets to and

from the UE. The remote client application VoLTE Media Server starts and stops

the FFMPEG, FFPLAY processes depending on TCP commands received from

the CMW500 DAU (port 1000) or the Remote PC (port 9900). Be sure to use the

LAN Switch 2 (rear) connector for remote control.

2. USB Audio Interface connected to the CMW500. Install the appropriate driver on

the CMW500 before connecting the audio interface. The Windows XP OS on the

CMW500 requires the UPV generator 2 output to be fed equally to the left and right

line or mic inputs of audio interface via XLR Y-cable (see Figure 2-1). If only one

input is used, the maximum detected level limited to –6 dBfs.

3. AMU200A Baseband Fading Simulator for simulating fading effects of the downlink

RF path.

4. UPV Audio Analyzer for performing POLQA and PESQ measurements of downlink

and uplink audio signals.

5. Remote PC equipped with a LAN interface with a fixed IP address (default

172.22.1.1) and the RSRUN test case SPEECH QUALITY MEASUREMENT.RSTP for

performing POLQA / PESQ measurements remotely.

6. LTE UE – with IMS / VoLTE capability.

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Hardware Setup



Ref InRef 1 Out

LAN172.22.1.6 255.255.255.0

AMU200A

I/Q Dig. Baseband OutI/Q Dig. Baseband In

LAN172.22.1.2255.255.255.0

LAN Switch 2 (Rear)172.22.1.3255.255.255.0

172.22.1.1255.255.255.0

tomicrophonein(UL)

UPV

CMW500 (VoLTE Media Server)

from

speakerout(DL)

LAN SwitchLAN1LAN2LAN3LAN4

Remote PC (CMWrun + VoLTE POLQA / PESQ add-on DLL) LAN

Line/Mic In L/R Line OutUSB

USB AudioInterface

RF

LTE UE172.22.1.100from CMW DHCP

Figure 2-1: VoLTE test setup with Media Server running on CMW500

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Hardware Setup

VoLTE Test Setup with Media Server on Media PC


CMW500 – LAN Switch 2 (Rear) UPV – LAN connector

Figure 2-2: CMW500 LAN remote config Figure 2-3: UPV LAN remote configuration

AMU – LAN Connector Remote PC – LAN connector

Figure 2-4: AMU LAN Configuration Figure 2-5: Remote PC LAN configuration

Note:

For demo purposes it may be convenient to use an LTE USB data device connected to

the Remote PC in conjunction with an IMS client also running there. In this case you

must use different subnets for remote control (e.g. CMW 172.22.2.3, UPV 172.22.2.2,

AMU 172.22.2.6 and Remote PC 172.22.2.1 ) and audio data stream traffic (e.g.

CMW500 P-CSCF Address 172.22.1.201 UE 172.22.1.100 (received from

CMW500 DAU DHCP).

Figure 2-6: UE IP configuration Figure 2-7: CMW500 P-CSCF config

If the subnets are not separated it can happen that the audio data stream takes the

direct IP path without being degraded by the encoder (FFMPEG) and decoder

(FFPLAY) resulting in perfect (POLQA 4.5000, PESQ 4.0000), but false MOS-LQO

values.

2.2 VoLTE Test Setup with Media Server on Media PC

This setup is similar to 2.1 with the difference that the VoLTE Media Server runs on a

separate Media PC. It uses no CMW or UPV CPU resources and is ideal for

performing demos at various locations without the need of installing additional software

on the CMW500 or UPV. It consists of

1. CMW500 Communication Tester which is connected to the LTE UE via RF,

provides IMS infrastructure, establish a VoLTE call and transmits VoLTE data

packets to and from the UE. Be sure to use the LAN Switch 2 (rear) connector for

remote control.

2. UPV Audio Analyzer which uses one analyzer input / generator output pair for

measuring the downlink and the other one for the uplink data stream.

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Hardware Setup

VoLTE Test Setup with Media Server on Media PC


3. AMU200A Baseband Fading Simulator for simulating fading effects of the downlink

RF path.

4. Media PC with Windows 7 OS, LAN interface and an internal or external USB

audio interface. Both interface types require the appropriate driver to be installed

first.

5. LTE UE – with IMS / VoLTE capability.

6. Remote PC controlling the test setup via RSrun for performing POLQA / PESQ

measurements

Ref InRef 1 Out

LAN172.22.1.6255.255.255.0

AMU200A I/Q Dig. BB OutI/Q Dig. Baseband In

172.22.1.1255.255.255.0

172.22.1.5255.255.255.0

LAN Switch 2 (Rear)

172.22.1.3255.255.255.0

LAN172.22.1.2255.255.255.0

tom

icrophonein

(UL)

UPV

CMW500

from

speakerout(DL)

LAN Switch

LAN1LAN2LAN3LAN4LAN5

Remote PC (RSrun + VoLTE POLQA / PESQ add-on DLL) LAN

RF

LTE UE172.22.1.100

Media PC with Windows 7 OS Line-In Line-Out

(VoLTE Media Server + internal or external USB audio interface) LAN

Figure 2-8: VoLTE test Setup with Audio Interface in external PC

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Software Requirements

CMW500


3 Software Requirements

For running the VoLTE POLQA / PESQ test plan with RSrun you need followingsoftware environment to be installed on the CMW500, UPV and PC units:

3.1 CMW500

On the CMW500 following software options are mandatory (the version numbers

should be equal are higher):

ı CMW BASE v3.0.11

ı CMW Data Application Support v3.0.20

ı CMW LTE Sig v3.0.20

3.2 UPV

Please use UPV firmware version 3.3.1 or higher.

3.3 VoLTE Media Server

The VOLTE MEDIA SERVER program installer (CMW-MEDIA-SERVERv1.2.2.3.exe or

higher) can be downloaded from the GLORIS CMW Customer Web. It contains

ı MEDIASERVERGUI.EXE – Receives command strings via TCP from CMW500 DAU

(default 172.22.1.3, port 1000) and Remote PC (default 172.22.1.1, port 9900).

ı FFMPEG.EXE – VoIMS (Voice over IMS) customized downlink encoder.

ı FFPLAY.EXE – VoIMS customized uplink decoder.

and must be installed where the audio interface is located, either on the CMW500 (see

2.1) or an external Media PC (see 2.2) to the selected directory (default C:\Program

Files\Rohde-Schwarz\MediaServer\).

Note:

The M EDIAS ERVER icon should be placed into the S TART P ROGRAMS S TARTUP

menu so it will automatically start when the CMW500 or Media PC is booted.

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Software Requirements

POLQA_CAL


3.4 POLQA_CAL

Install POLQA_CAL_102.msi on the UPV to the default directory as shown below.

Figure 3-1: POLQA_CAL installation on UPV

The UPV settings files and reference wave files are located in the C:\Program

Files\Rohde&Schwarz\POLQA_CAL\Files\ subdirectory. The files in that directory can

be copied to e.g. D:\UPV\POLQA_CAL\. This directory name must be used in the

Speech_Quality_Measurement GUI (see Figure 4-10).

3.5 R&S Run

Install R&S RUN 1.0.12 or higher on the REMOTE PC. Download it from

http://www.rohde-schwarz.com/appnote/1MA204.html. It contains the

SPEECH _QUALITY _MEASURMENT (requires existing LTE connection) and

VOLTE_SPEECH _QUALITY _MEASUREMENT (automatic LTE connection) test case and

test plan. The VoLTE_Speech_Quality_Measurement test plan is dimmed in case the

option CMW-KT055 CMWrun/RSrun Sequencer LTE is not installed on the CMW500.

http://www.rohde-schwarz.com/appnote/1MA204.html



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VoLTE POLQA / PESQ Measurements with RSrun

RSrun Configuration


4 VoLTE POLQA / PESQ Measurements with

RSrun

4.1 RSrun Configuration

Start RSrun first. In this example the hardware setup described in section 2.1 is used.

Before loading the test plan it is necessary to define the devices’ resource strings in

the Resources SCPI Connections… menu. In this example a CMU500

Communication Tester, a UPV Audio Analyzer and an AMU200 Fading Simulator are

used.

Figure 4-1: RSrun SCPI Connections menu

Make sure to set the UPV Timeout to 60 seconds by pressing CONFIGURE… to avoid

timeout errors. Do the same for the CMW500 and AMU.

Figure 4-2: Set UPV Resource Name and Timeout

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Test Plan Description


4.2 Test Plan Description

The test plan VOLTE SPEECH QUALITY MEASUREMENT.RSTP needs the CMW-KT055

Sequencer LTE option to be installed. The example test plan in chapter 4.4 (SPEECHQUALITY MEASUREMENT.RSTP) is platform independent and does not need this option.

Figure 4-3: RSrun test plan VoLTE Speech Quality Measurement

The test plan consists of several test items and custom SCPI sequences.

4.2.1 Basic Initialization

This component handles the basic configuration and e.g. resets the CMW500 to

default settings. By double clicking BASICINITIALIZING a configuration window opens.

Check RESET INSTRUMENT(S). This should always be performed to ensure identical

starting conditions on different systems.

Figure 4-4: Basic Initialization

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Recall CMW Configuration (SCPIPollState)

This function recalls the test setup for a certain UE.

Figure 4-5: LTE Call Setup Parameters

4.2.2 Fading Scenario

Figure 4-6: Fading & AWGN Settings

ı FADER – Selects external AMU fader (connected via digital I/O) or CMW internal

fader (default External).

ı FADING SCENARIO – Choose type of signal path in the CMW and AMU. Either

SISO (Single In – Single Out) Path A or B or MIMO (Multiple In – Multiple Out).

The Scenario must be set in the CMW before the mobile is attached.

ı S YSTEM BANDWIDTH – Defines the expected bandwidth (10 or 20 MHz) of the LTE

signal (default 10 MHz).

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ı MIN.NOISE TO SBW RATIO – Defines the ratio of the noise bandwidth to the system

bandwidth. High precision power measurements (tolerance 0.01 dB) require the

noise signal have at least the same bandwidth as the signal. This can be ensured

by increasing the noise bandwidth (e.g. Ratio = 1.2).ı BIT RATE – Only important in case En/N0 of the corresponding SNR (Signal to

Noise Ratio) should be display correctly.

IMS Configuration (SCPICommandList)

This command sequence allows to change the IMS settings independently from the

recalled CMW configuration, e.g.

CONF:DATA:CONT:IMS:UAUT OFF; // User Authentification OFF

CONF:DATA:CONT:IMS:VOIC:PREC WNPR; // No Preconditions

CONF:DATA:CONT:IMS:VOIC:LOOP OFF; // Loopback OFFCONF:DATA:CONT:IMS:VOIC:MEND:IPAD '172.22.1.3'; // Media Endpoint 172.22.1.3

SOUR:DATA:CONT:IMS:STAT ON; // Turn IMS ON

IMS ON? (SCPIPollState)

Waits until IMS is turned ON or timeout occurred.


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4.2.3 LTECallSetup

As soon as IMS is turned ON, an LTE cell is established were the UE can attached to.

The following screen shot shows the configuration window which opens when double

clicking LTECALLSETUP in the list:


Please make sure that the UE parameters are entered correctly or else the UE will not

be attached and the test terminated.

LTE Call Setup parameters in our example that differ from default:

SCENARIO = OL Spatial MUX

BAND = Band7

RF DOWNLINK CONNECTOR 1 = RF 1 COM

RF DOWNLINK CONNECTOR 2 = RF 3 OUT

RF UPLINK CONNECTOR = RF 1 COM

SCHEDULING T YPE = User def. Channels

#RB = 45 (DL), 50 (UL)

MODULATION = 64-QAM (DL 1&2), QPSK (UL)

TBS IDX. = 15 (DL 1&2), 10 (UL)

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Connection Type Advanced… parameters:

Figure 4-9: Connection Parameters

CONNECTION T YPE = Data Application

This is required to establish a VoLTE call over the IP Layer. The IP handling in thedirection to the UE is handled by the DAU (IPv4 or IPv6).

UE registered? (SCPIPollState)

Checks if the UE has been registered on IMS level.

VoIMS Configuration (SCPICommandList)

If the UE has been correctly registered the following VoIMS parameters are set in this

test item.

CONF:DATA:CONT:IMS:VOIC:TYPE AUD; // Call Type: Audio

CONF:DATA:CONT:IMS:VOIC:AMRT WID; // AMR Wideband Codec

CONF:DATA:CONT:IMS:VOIC:COD 9:ENAB ON; // 23.85 kb/s

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This corresponds to following manual settings:

Figure 4-10: Voice over IMS Configuration

4.2.4 Speech_Quality_Measurement

If UE has been successfully registered in the preceding step this test makes a VoIMS

call if not already established manually, calibrates the sound interface and performs a

POLQA or PESQ measurement. By double clicking the

SPEECH _QUALITY _MEASUREMENT test item the following configuration window opens.

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Figure 4-11: Speech Quality Measurement Parameters

Codec Calibration

ı LINE IN – The UPV generator output fed to the audio interface input (always

Generator 2).

ı LINE OUT – The UPV analyzer input where the audio interface output is fed to

(always Analyzer 2).

ı UE IN – The UPV generator output fed to the UE input (always Generator 1).

ı UE OUT – The UPV analyzer input where the UE output is fed to (always Analyzer

1).

ı CAL TONE FREQ – Frequency used for UPV decoder/encoder calibration (always

1000 Hz).

ı UPV DIRECTORY – The directory on the UPV where the files from section 4.2 are

installed (default D:\UPV\POLQA_CAL\).

ı UPV CAL SETTINGS – UPV settings for decoder/encoder calibration (always

“UpvCal.set”).

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ı DECODER CAL – File for decoder calibration result (always

“DecoderCalibration.txt”).

ı ENCODER CAL – File for encoder calibration result (always

“EncoderCalibration.txt”).

ı MOBILE CAL – File for UE output calibration (always “MobileDLCalibration.txt”).

Remote PC --> VoLTE Media Server

ı TARGET IP – IP address or computer name of the instrument or PC where the

Media Server is running (default 172.22.1.3, Media Server installed on CMW500).

ı DIRECTORY – Installation directory of Media Server (default C:\Program

Files\Rohde-Schwarz\Media Server\1.2\) depends on VoLTE Media Server

version number (e.g. v1.2.0.2)

ı TARGET PORT – Port number for command transmission between Remote PC andinstrument or PC where VOLTE MEDIA SERVER is running on (default 9900).

CMW DAU --> VoLTE Media Server

ı DIRECTION – Choose between DOWNLINK (default) and UPLINK.

ı MEDIA ENDPOINT – Indicates IP address of instrument or PC where VOLTE MEDIA

SERVER is running on (same as TARGET IP, default 172.22.1.3).

Fading Simulator

ı STANDARD – Select from all available LTE fading standards for SISO and MIMO(default LTE EPA 5Hz (SISO Path A)).

Figure 4-12: LTE Fading Standards

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ı AWGN – Turns AWGN ON/OFF (default ON).

ı SNR – Signal to Noise Ratio of AWGN signal (default 10.0 dB).

ı

CALIBRATE EXT. FADER INSERTION LOSS – Determines insertion loss of the currentfading standard which is added to the cable loss and fed to CMW EXTERNAL

ATTENUATION of the RF OUTPUT (TX).

Figure 4-13: RF External Attenuation

Ext.Attenuation (TX) = Insertion Loss + Cable Loss = 10.5 dB + 2.0 dB = 12.5 dB

Ext.Attenuation (RX) = Cable Loss = 2.0 dB

ı CAB. LOSS – The cable loss is fed to the CMW EXTERNAL ATTENUATION of the RF

INPUT (RX).

POLQA / PESQ Measurement

ı UPV MEAS SETTINGS – UPV settings file for performing POLQA or PESQ

measurements (default “POLQA_Wide_Downlink_Autogain.set”). The

measurement type is defined by the name POLQA Measurement of super-

wideband downlink audio signal with UPV autogain turned ON. The Autogain

feature adjusts the analyzer input level (degraded signal) to the generator level

(reference signal). The POLQA algorithm requires the reference and degraded

signal to have the same level (difference < 0.5 dB).

ı MOS SAMPLE SIZE – Number of measurements used for obtaining an average

MOS value (default 3).

ı SHOW DETAILS – Shows all POLQA results if checked, and only the average,

minimum, maximum and standard deviation if unchecked (default ON).

ı MOS LIMIT – The lower MOS limit for passing a test (default 3.00).

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Speech Quality Measurement Subroutines

The DLL contains the following subroutines which can be switched ON or OFF.

Figure 4-14: Speech Quality Measurement Subroutines

ı UPVINIT – Resets the UPV audio analyzer.

ı AMUINIT – Resets the AMU fader.

ı LTEFADINGAWGN – Set fading standard and SNR. Turns fading and AWGN ON.

ı DECODERCAL – A full scale sine wave is generated on the USB audio interface of

the UPV / Media PC and the actual voltage level measured by the defined UPV

analyzer input. This voltage level serves as reference value for the UPV generator

output. It is measurement system dependent and only needs to be performed from

time to time.

ı ENCODERCAL – Measures the Media PC audio interface input voltage after A/D

conversion by looping its input and output on the digital side and measuring its

output with the corresponding UPV analyzer. The calibration value is system

dependent and only needs to be performed from time to time.

ı VOIMSCALLESTABLISH – Checks if the VoIMS call state is ON and establishes a

call if necessary. As soon as the call has been automatically or manually

answered the VoLTE Media Server starts the FFMPEG encoder for DL and

FFPLAY for UL instances on the CMW or Media PC. Now the system is ready to

transfer an audio data stream in either direction.

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FFMPEG and FFPLAY are customized versions of the FFMPEG open source

software package.

Figure 4-15: FFMPEG encoder and FFPLAY decoder

ı MOBILEOUTCAL – Measures the line output voltage of the UE. The Mobile output

calibration must be performed after changing the UE.

ı POLQAPESQMEASUREMENT – Measures the POLQA or PESQ MOS-LFO value by

starting the MOS Reference file on the UPV and comparing the original with the

received signal.

ı VOIMSCALLRELEASE – Drops the VoIMS call.

4.2.5 LTECallDisconnect

Drops the LTE connection.

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Program Flow


4.3 Program Flow

The VoLTE Media Server must be running either on the CMW or Remote PC before

performing the RSrun sequence. It is convenient to put the Media Server program iconinto the Start Programs Startup menu so it will automatically start when the CMW

or Remote PC is booted. The following sequence shows the simplified program flow for

a downlink POLQA measurement. The Remote PC sends and reads SCPI messages

via VISA protocol to and from the UPV, AMU and CMW500, and TCP messages to

and from the VoLTE Media Server program running on the CMW or Remote PC.

Start RSrun on Remote PC

CMW (VISA):Init CMW // Reset CMW

AMU (VISA): Fading Scenario // SISO A/B or MIMO

CMW (VISA):Attach LTE UE // CMW turns LTE signalling ON and attaches

to the UE CMW (VISA):Register VoIMS // CMW turns IMS ON and registers UE on

IMS level

The SPEECH QUALITY MEASUREMENT test case (marked red) begins here:

UPV (VISA): Init UPV // Reset UPV

AMU (VISA): Fading + AWGN // Set LTE fading standard and AWGN

UPV (VISA): Load “UpvCal.set” // Load UPV setting for decoder / encoder cal

MPC: RUN “CsSinWav.exe” // Play sine wave on USB audio interface

UPV (VISA): Calibrate Decoder // Measure signal level of USB audio interface

and set UPV generator referenceaccordingly

MPC: STOP “CsSinWav.exe”

MPC: RUN “CsWavRec.exe” // UPV generator 2 sends sine wave to USB

UPV (VISA): Calibrate Encoder audio interface. The digital signal at the

ADC is looped to the DAC and the level

measured with UPV analyzer 2

MPC: STOP “CsWavRec.exe”

CMW (VISA):Perform VoIMS call // After answering the phone, FFMPEG coder

and FFPLAY decoder are started by the

Media Server.

UPV (VISA): Calibrate Mobile Out // Measure UE output voltage

UPV (VISA): Load “POLQA_Wide_Downlink_Autogain.set”

// Load UPV setting for POLQA measurement

UPV (VISA): Measure MOS-LQO // Starts a reference wave file on the UPV

and measures the MOS-LQO for a

defined number of times

CMW (VISA): Release VoIMS call

CMW (VISA): Disconnect UE // CMW turns LTE signalling OFF

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Expected MOS/LQO Results


4.4 Expected MOS/LQO Results

The following table shows ideal PESQ / POLQA MOS/LQO results for different

narrowband codec types.

PESQ (P.862.1) POLQA (P.863)

AMR 12.2 kbps 4.15 4.20

AMR 7.95 kbps 3.90 3.95

AMR 6.70 kbps 3.75 3.85

AMR 4.75 kbps 3.40 3.65Table 4-1: Expected MOS/LQO Results with various code rates

The following table shows POLQA (P.863) MOS/LQO results for AMR narrowband

(NB) 12.2 kbps code rate under fading condition and various AWGN levels. The MOS

SAMPLE SIZE was set to 20 resulting in a measurement duration of 5 minutes (= 15seconds per sample). For a MOS precision < 0.1 the MOS Sample Size needs to be

increased to > 50.

Fading Standard AWGN MOS/LQO Std.Dev

None (baseband routed through CMW) OFF 3.9503 0.1172

None (baseband routed in AMU) OFF 3.9795 0.1097

6.0 dB 3.9331 0.1816

2.0 dB 3.9071 0.2313

0.0 dB 3.8518 0.3080

LTE EPA 5Hz (SISO Path A) OFF 3.9885 0.0970

6.0 dB 3.5246 0.4299

2.0 dB 2.9119 0.4935LTE ETU 300Hz (SISO Path A) OFF 3.9842 0.0859

6.0 dB 3.9577 0.0940

2.0 dB 3.6429 0.4332

0.0 dB 3.3992 0.4685

-1.0 dB 3.1589 0.3979Table 4-2: MOS/LQO results for AMR Narrow Band 12.2 kbps code rate

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The following table shows POLQA MOS/LQO results for AMR Super-Wideband (WB)

12.65 kbps code rate under fading condition and various AWGN levels.

Fading Standard AWGN MOS/LQO Std.Dev

None (baseband routed through CMW) OFF 3.9007 0.1156None (baseband routed through AMU) OFF 3.8703 0.0869

6.0 dB 3.8737 0.1118

2.0 dB 3.8945 0.0487

0.0 dB 3.8576 0.1683

-1.0 dB 3.8859 0.0522

LTE EPA 5Hz (SISO Path A) OFF 3.9053 0.0565

6.0 dB 3.3464 0.4645

2.0 dB 2.6242 0.4502

LTE ETU 300Hz (SISO Path A) OFF 3.8888 0.0655

6.0 dB 3.8513 0.1199

2.0 dB 3.6203 0.3462

0.0 dB 3.2800 0.3204

-1.0 dB 2.5673 0.3905Table 4-3: MOS/LQO results for AMR Super-Wideband 12.65 kbps

The conclusion of both NB and WB tables is that the speech quality is hardly affected

by fading or AWGN on their own, but decreases significantly when fading and AWGN

are engaged. The LTE EPA 5Hz fading standard in conjunction with AWGN degrades

the speech quality more than the LTE ETU 300 Hz one. The standard deviation is also

higher since a single measurement only covers a certain portion of all possible states

due to the slow speed (5 Hz).

4.5 Running the Test

The example below shows how to run the SPEECH QUALITY MEASUREMENT.RSTP test

plan. The VoLTE device (mobile or USB stick with additional IMS server software)

must be attached and registered before the test is run.

To start the test press the RUN arrow in RSrun.

Figure 4-16: Start a Test Plan

RSrun switches to the Measurement Report view and shows the status and results of

the VoLTE POLQA / PESQ Measurement. The results for the decoder / encoder

calibration are shown as well as the POLQAPESQMEASUREMENT results. The 1st

line

shows the average value, the following numbered lines with the POLQA / PESQ MOS

values of the single measurements are shown in case the DETAILS checkbox is ON.

The ANALYZER ATTENUATION shows the level difference between reference and

degraded signal and should range inside the limits -1.0 dB to +1.0 dB. AVG.DELAY

displays the delay of the degraded signal to the reference signal. The last line shows

statistic information such as the minimum, maximum and standard deviation of the

MOS-LQO values.

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Figure 4-17: Measurement Report

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Literature

Running the Test


5 Literature

[1] R&S®UPV Operating Manual

[2] Application Note 1GA49, “Psychoacoustic Audio Quality Measurements Using

R&S®UPV Audio Analyzer ”

[3] Application Note 1GA50, “ Calibration Tool for PESQ®

Speech Quality Tests”

[4] Application Note 1MA119 "PESQ®

Measurement for GSM with R&S®CMUgo"

[5] Application Note 1MA136 "PESQ®

Measurement for CDMA2000 with R&S®CMUgo"

[6] Application Note 1MA137 "PESQ

®

Measurement for WCDMA with R&S

®

CMUgo"

[7] Application Note 1MA149 “VoIP Measurements for WiMAX"

[8] Application Note 1MA202 “Next-Generation (3G/4G) Voice Quality Testing with

POLQA®"

http://www2.rohde-schwarz.com/en/products/test_and_measurement/audio/UPV-%7C-Manuals-%7C-22-%7C-2224-%7C-2234.html



http://www2.rohde-schwarz.com/en/service_and_support/Downloads/Application_Notes/?query=1ga49&type=20&downid=5219






http://www2.rohde-schwarz.com/en/service_and_support/Downloads/Application_Notes?type=20&downid=5474





http://www2.rohde-schwarz.com/en/service_and_support/Downloads/Application_Notes/?query=1ma119&queryButton=Go&type=20&downid=2788







http://www2.rohde-schwarz.com/en/service_and_support/Downloads/Application_Notes/?query=1ma136&type=20&downid=4976
































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Additional Information

Running the Test


6 Additional Information

Please send your comments and suggestions regarding this application note to

[email protected]

mailto:[email protected]



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Ordering Information

Running the Test


7 Ordering Information


Wideband Radio Communication Tester

CMW500 Wideband Radio Comm. Tester 1201.0002K50

CMW-PS502 Basic Assembly 1202.5408.02

CMW-S550B Basic Interconnection, flex. Link, for non-signaling, signaling

and IQ access

1202.4801.03

CMW-S590D RF front end, advanced funct. 1202.5108.03

CMW-S600B CMW500 front panel 1202.0102.03

CMW-B300A Signaling Unit Wideband (SUW), for WCDMA / LTE 1202.6304.02

CMW-B570B Extra RF Converter (TRX) 1202.8659.03

CMW-B660AOption Carrier 1202.7000.02

CMW-B661A Ethernet Switch 1202.7100.02

CMW-B690B OCXO, high stability 1202.6004.02

CMW-KAA20 IMS basic service 1207.8657.02

CMW-B450A Data Application Unit (hw opt.) 1202.8759.02

CMW-KA100 Enabling of IP-Data interface for IPV4 1207.2607.02

CMW-KS500 LTE FDD Release 8, SISO, signaling/network emulation 1203.6108.02

CMW-KS510 LTE Release 8, SISO, signaling / network emulation,

advanced functionality

1203.9859.02

CMW-KS520 LTE MIMO2x2, signaling / network emulation, generic

feature

1207.3555.02

CMW-KT055

CMWrun/RSrun Sequencer LTE 1207.2107.xx

CMWPC Smartcard for CMWPC 1201.0002K90

CMW-S089A USB Smartcard for CMWPC 1202.7900.02

CMW-KM050 IP Based Measurements 1203.9359.02

Audio Analyzer

UPV Audio Analyzer 1146.2003.02

Or

UPV66 Audio Analyzer without Display 1146.2003.66

UPV-K61 PESQ Software Option 1401.7309.02

UPV-K63 POLQA Software Option 1402.1156.02

UPV-K1 Universal Sequence Controller 1401.7009.02

UPV-K4 RC for IEC625 / IEEE488, RS232, USB and LAN 1401.9001.02

UP-Z9 Headset Cable Set for UPV 1411.3106.02

Fading Simulator

AMU 200 Baseband Signal Generator 1402.4090.02

AMU-B13 Baseband Main Module 1402.5500.02

AMU-B14 Fading Simulator 1402.5600.02

AMU-B15 Fading Simulator Extension 1402.5700.02

AMU-B17 Analog/Digital Baseband Inputs 1402.5900.02

AMU-B18 Digital I/Q Output 1402.6006.02

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About Rohde & Schwarz

Rohde & Schwarz is an independent group of

companies specializing in electronics. It is a leading

supplier of solutions in the fields of test and

measurement, broadcasting, radiomonitoring and

radiolocation, as well as secure communications.

Established more than 75 years ago, Rohde &

Schwarz has a global presence and a dedicated

service network in over 70 countries. Company

headquarters are in Munich, Germany.

Regional contact

Europe, Africa, Middle East+49 89 4129 [email protected]

North America1-888-TEST-RSA (1-888-837-8772)[email protected]

Latin America

[email protected]

Asia/Pacific+65 65 13 04 [email protected]

China+86-800-810-8228 /[email protected]

Environmental commitment

ı Energy-efficient products

ı Continuous improvement in environmental

sustainability

ı ISO 14001-certified environmental

management system

This application note and the supplied programs

may only be used subject to the conditions of use

set forth in the download area of the Rohde &

Schwarz website.

R&S®

is a registered trademark of Rohde & Schwarz GmbH & Co.

KG; Trade names are trademarks of the owners.

Rohde & Schwarz GmbH & Co. KG 2 / 0 2 . 0 0

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1ma204_6e

Documents

volte test setup

volte media server

lte volte connections

volte polqa pesq measurements

connection setup

media pc

hardware setup

test plan description