hearing isa fascinatingsensation - itu · hearing isa fascinatingsensation dr.-ing. h. w. gierlich...

VoLTE Terminal Testing and Interworking©HEAD acoustics GmbH 1

HEARING IS A FASCINATING SENSATION

Dr.-Ing. H. W. GierlichManaging Director Telecom Division

© HEAD acoustics GmbH

Challenges in VoLTETerminal Testing and

Interworking

ITU Workshop on “Voice and Video over LTE”Geneva, Switzerland, 1 December 2015

Advanced speech quality testing © HEAD acoustics GmbHH. W. Gierlich 2

Outline

A variety of challenges exist in VoLTE testing andinterworking - The following selected topics are addressedin this presentation:

� LTE Setup for Voice Communication - Obstacles� Delay and Delay Testing� Network Impairments, Delay & Jitter Profile Testing� Challenges in Superwideband & Fullband� Positional Dependant Testing of Mobile Terminals� Summary



Outline

� Introduction� LTE Setup for Voice Communication - Obstacles� Delay and Delay Testing� Network Impairments, Delay & Jitter Profile Testing� Challenges in Superwideband & Fullband� Positional Dependant Testing of Mobile Terminals� Summary


Call Handling 4G in a Test Setup

Test EquipmentWith Reference

Access

VoLTENetwork Simulator

DUT

Co-dec

IMS

Signal Generation

&Analysis

Co-dec

IMS registration

VoLTE call

IMS registration

• Both DUT and reference gateway for testing are registerd in the test IMS server

• VoLTE call takes place between DUT and reference gateway• Reference gateway takes care of encoding/decoding



Difficulties in VoLTE Call Setup

� Network provider flash their own firmware (Branding) with their special VoLTE support => special procedures for IMS Signaling/Registration are needed.

� Network providers use different LTE Cell/Signaling settings/parameters (e.g. LTE Band, MNC/MCC, Security Settings, Shared-Key, etc…). These parameters often are confidential and unknown if not provided.

� SIM-Lock, the device under test needs a special - provider specific -UICC (SIM card) for testing.

� DUTs normally are locked to their home network. In order to connect to the radio tester the correct MNC/MCC settings must be known, otherwise the roaming procedure does not allow VoLTE connections.

� The SIP/IMS registration is very sensitive to errors or unknown SIP messages depending on the implementation of the IMS in the VoLTEnetwork simulators.

� VoLTE settings in DUTs may be fixed (e.g. P-CSCF Address set to a fixed address) -> the address used in the radio tester cannot be configured.


Difficulties VoLTE Call Setup

� Buggy VoLTE implementation in devices under test (e. g. SIP call negotiation with octet-aligned mode but DUT is sending the speech packets in bandwidth efficient mode).

� If no IMS APN (access point name) or matching PDP (packet data protocol) contexts is available in the DUT => no IMS registration => no VoLTE call.

� IPsec parameters are needed if device under test only work with a secure connection (IMS-AKA).

� No access to VoLTE settings in DUT for changing required parameters for audio tests.

� How to handle eSIM?



Difficulties in VoLTE Call Setup

=>Most of these issues not only lead to difficulties in testing –the differences in IMS settings prevent interworkin g between

network operators in general!

Solution for testing:Define a generic test mode and IMS setting implemen ted in all

terminals.

Potential solution for interworking:Define a minimum set of IMS settings used in interw orking.


Outline




3GPP & GSMA: Delay Testing

Delay measurement direction by cross correlation

Cross correlation avg. FFT Size:65536 Overlap:0,0% Envelope Normalized %

0

20

40

60

80

100

t/s0 25m 50m 75m 0.125 0.15 0.175 0.2

33 ms

Requirement 4G: Roud trip delay MTSI < 190 ms (min. Reqi rement) Performance goal < 150 ms


Drift: 815 µs/min � 13,6 ppm

Delay in VoLTE - Not Stable, Delay Drift due to Clock Drift

t/s

0.115

0.116

0.117

0.118

0.119

0.12

0.121

0.122

0.123

0.124

0.125

t/s0 20 40 80 100 120%26 27 28 29 30 31

RCV(2)*Source

Receiving Direction



t/s

0.115

0.116

0.117

0.118

0.119

0.12

0.121

0.122

0.123

0.124

0.125

t/s0 20 40 80 100 120%26 27 28 29 30 31

RCV(2)*Source

Delay Results VoLTE – Clock Drift Compensation

Receiving Direction

t/s

0.136

0.138

0.14

0.142

0.144

t/s0 20 40 80 100 120%29 30 31 32 34 35 36 37 38

RCV(2)*Source

� Clock Drift- Not compensated:

815 µs/min48000 Hz

- Compensated:0 µs/min48000,67 Hz

� Synchronized testing possible


Call by call delay variation and theoretical background:• Clock syncronization absolutely required to avoid delay drift during

testing• Clock sychronization does NOT allow packet stream synchronization

VoLTE Terminal Delay: Call by Call Variation

Phase shiftbetween packet

streams from callto call



Call by call delay variation: measurement examples in sending• Delay variation measured over 30 calls• Delay variation within the expected range of 20 ms (packet size)

Delay Testing: Results in Sending

=> In 3GPP:5 Tests, take maximum to

address call to callvariation


Jitter & Packet Loss – Simulation in Testing

USB

AES/EBUAcoustic

Analog

RF(LTE / 4G)

DUT

HMS II.3HHP III.1

Ethernet

USB

= Speech= Control

EthernetJitter & Packet

Loss byTCN - Profiles

USB

Delay & lossprofiles from

TS 26.131, Rel. 12,synchronized to

audio data

VoLTE NetworkSimulator

Network ImpairmentSimulator (MFE IX)

IP Reference Gateway (MFE VIII.1)

Analog/Digital Interfavce (MFE VI)

Testsystem



Simulated Jitter & Packet Loss: Typical Test Results

0 20 40 60 80 100 120 140 1600

20

40

60

80

Time [s]

Del

ay [m

s]

delay_profile_20msDRX_10pctBLER_e2e

DelayDrops

0 20 40 60 80 100 120 140 160

0.05

0.1

0.15

0.2

Time [s]

De

lay

[s]

DUT #3 - Delay vs. Time (delay_profile_20msDRX_10pctBLER_e2e)

Delay vs. Time: Profile 1Delay vs. Time: Clean Channel

0 20 40 60 80 100 120 140 1601

2

3

4

5DUT #3 - POLQA vs. Time (delay_profile_20msDRX_10pctBLER_e2e)

Time [s]

PO

LQA

[MO

S]

Profile 1Clean Channel

Increased meandelay due to jitterbuffer increase

POLQA scoresalmost

unchanged

Example for one terminal: 20 ms DRX cycle, 10% BLER


Outline




How does it sound?Frequency response tolerance schemes under discussion;

Superwideband & Fullband with EVS

EVS FB @ 16,4 kbit/s


How does it sound?….when combining 2 terminals performing within the limits

Interoperability - Superwideband & Fullband with EVS

Fullband:OptimumWorst highpassWorst lowpass

For comparison narrowband:OptimumWorst highpassWorst lowpass



Outline



Artificial Head & Artificial Ear

• HATS acc. to ITU-T P.58

• Artificial ear acc. to ITU-T P.57

• Positioning acc. to ITU-T P.64



HHP IV Video


Positional Robustness 1 / 2 Without Background Noise

3rd octave FFT Size:4096 Overlap:0,0% Hanning Ch.1 - Ch.2 L/dB

-35

-30

-25

-20

-15

-10

-5

0

5

10

f/Hz100 200 500 2000 5000

normal Positiondow nw ards


-35

-30

-25

-20

-15

-10

-5

0

5

10

f/Hz100 200 500 2000 5000




Positional Robustness 2 / 2 With Background Noise


-35

-30

-25

-20

-15

-10

-5

0

5

10

f/Hz100 200 500 2000 5000



-35

-30

-25

-20

-15

-10

-5

0

5

10

f/Hz100 200 500 2000 5000



Summary

� Advanced mobile terminals require more advanced and morerealistic testing procedures

� Still many unresolved issues in VoLTE call setup and IMS-b asedinterworking

� VoLTE introduces more variability in communicational qua lity –e.g. for delay and delay variation

� Terminal interworking concerning sound quality in super -wideband and fullband from mouth to ear is critical and still an unresolved topic

� Testing taking into account time variant user behavior an d signalprocessing gets more important – e.g. positional robustne sstesting

hearing isa fascinatingsensation - itu · hearing isa fascinatingsensation dr.-ing. h. w. gierlich...

Documents