QoS /QoE in the context of videoconferencing services over LTE/4G networks.
NDIAYE Maty– PhD student within France Telecom / Orange Labs
ETSI workshop on telecommunications quality matters
28/11/2012, Vienna (Austria)
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Agenda
part 1 Scope of the current study
part 2 Videoconferencing services and associated codecs
part 3 LTE/4G in a nutshell
part 4 Goal of the experiment
part 5 Description of the experimentation
part 6 IP results
part 7 Summary and next step
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Scope of the current study
With the important technology advances in the area of mobile devices, the
development of data traffic on current 3G mobile networks is rocketing :
Emergence of voice and video services, in particular video conferencing for
personal and professional use over mobile devices
The growth of consumer demands for multimedia services generates huge
amount of video traffic on mobile networks
This increase of mobile data consumption pushes operators to invest in new
mobile broadband networks relying on advanced radio and IP network
technologies
3GPP has then defined a new standard LTE/4G [Release 8]
integrating several quality levels to cope with these new applications and services
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Videocalling services and associated codecs
With LTE,
– more bandwidth and less latency for streaming multimedia contents
– some applications are very sensitive to network/radio conditions.
– there is a need to check that conversational services will perform efficiently with
this new mobile network.
To ensure the best Quality of Experience (QoE) when dealing with mobile
video calls
- Selection of video and audio codecs in line with the capabilities of bearers
- The user expectations (low-cost, regular, premium services)
- Tradeoff between the right bitrate and the highest video and audio quality.
No specific media codecs are defined for these types of services over LTE :
Some recommendations propose to use the existing codecs (AMR, AMR-WB
(voice) and H.263, H.264 (video)
However, active works are ongoing to develop High-Efficiency Video Coding (HEVC)
(video) and Enhanced Voice Service (EVS)(voice and audio). QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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LTE/4G in a nutshell
Two main components: Evolved Packet Core
(EPC) and e-UTRAN .
Throughput expected around 100 Mbps in DL
and 50 Mbps in UL
Reduced latency complying with the expectations
of real-time applications
QoS management through bearers set-up.
New radio technologies : OFDMA, SC-FDMA and
MIMO.
All IP architecture, relying on IMS system
handling SIP protocol. Figure 1 : LTE Architecture (cisco.com)
Figure 2 : Qos managment
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Goal of the experimentation
What ? : The main target is to study the usability of existing standardized codecs
when dealing with videoconferencing services over currently deployed LTE/4G
networks.
Where ? : Experiments were launched with the use of available LTE dongles and
on the ImaginLab 4G/LTE experimental platform deployed in Brest (France) by
Images and Networks French Cluster. (http://www.images-et-reseaux.com/en)
How ? : Connections were set-up using “best effort” mode (non-guaranteed QoS),
without mobility in the present case, close to the antenna (approximately between
150-200m), within a building, using 2,6 GHz radio frequency.
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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LTE cartography (source : Images and Networks French Cluster)
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Technical description of the experimentation
Experimentation tools used :
Orange Labs internally developed probe called “SondeQoS” :
- The tool is able to set-up and tear-down videocall using the SIP protocol.
- Several codecs are implemented when setting-up end-to-end calls over the LTE
network with several configurations (e.g. H264 / G722.2 or H263 / G711)
- Different reference audio and video files can be injected within the tool so as to stream
different contents (image resolution, frame per second, bitrate, etc…)
- Several key performance metrics can be gathered at the end of each call and the
outcoming audio and video files can be stored for quality inspection
CIF( 320x288)
resoulution 4CIF( 704x576)
resoulution
720p( 1080x720)
resoulution
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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QoS & QoE over LTE/4G
Description of the experimentation: simulation of end-
to-end calls over the LTE/4G via SondeQoS probe
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Interpretation of IP results
MOS=[4.18 4.42] Call registration =[04.41ms 05.87ms]
Call establishment=[02.189ms 04.278ms]
Percentage of audio lost packets= [0% 0.07%]
Percentage of video lost packets= [0% 0.15%]
Jitter=[0ms 1.27ms]
Codec flow: G.711 = 64 kbps
AMR-NB = variable rate & Voice activity detection(VAD)= on (1)
G.722 = 64 kbps G722.1 = 2*32 kbps stereo
AMR-WB = 12.65 kbps & VAD =1
H.263 profile= Baseline profile Max picture rate= 625 picture s /sec
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
Configuration
Parameters
H.263/G.711
H.263/AMR-NB
H.263/G.722
H.263/G.722.1
H.263/AMR-WB
Call registration
04.79ms
05.44ms
04.41ms
05.30ms
05.87ms
Call establishment 02.189 ms 02.756 ms
04.278 ms 03.361 ms 02.741 ms
Throughput
(average)
Audio
UL = 87.31 kbps
DL =85.60 kbps
Video
UL = 861.80 kbps
DL = 1300.92 kbps
Audio
UL = 8.98 kbps
DL = 7.80 kbps
Video
UL= 784.19 kbps
DL = 1417.47 kbps
Audio
UL = 85.60 kbps
DL = 85.60 kbps
Video
UL= 1608.20 kbps
DL = 1380.62 kbps
Audio
UL = 85.60 kbps
DL = 85.60 kbps
Video
UL= 1112.68 kbps
DL = 1049.85 kbps
Audio
UL = 9.91 kbps
DL = 9.42 kbps
Video
UL = 1010.56 kbps
DL = 1304.97 kbps
MOS
Audio
UL & DL = 4.36
Audio
UL & DL ≈4.41
Audio
UL = 4.18
DL = 4.23
Audio
UL = 4.40
DL = 4.35
Audio
UL = 4.37
DL = 4.42
Jitter
(average)
Audio
UL = 0.01 ms
DL = 0.44 ms
Video
UL =0.16 ms
DL= 0.05 ms
Audio
UL = 0.21 ms
DL = 0.95 ms
Video
UL =0.17 ms
DL= 0.26 ms
Audio
UL = 0.01 ms
DL = 0 ms
Video
UL =0.15 ms
DL= 0.11 ms
Audio
UL = 1.20 ms
DL = 1.14 ms
Video
UL =0.16 ms
DL= 0.03 ms
Audio
UL = 1.27 ms
DL = 0.75 ms
Video
UL =0.17 ms
DL= 0.05 ms
Percentage of lost
packets
Audio
UL = 0.03%
DL = 0.02%
Video
UL = 0.02%
DL = 0.01%
Audio
UL = 0.03%
DL = 0%
Video
UL = 0.15%
DL =0%
Audio
UL = 0.06%
DL = 0%
Video
UL = 0.07%
DL =0%
Audio
UL = 0%
DL = 0.03%
Video
UL = 0%
DL =0.04%
Audio
UL = 0.07%
DL = 0%
Video
UL = 0.02%
DL =0%
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Interpretation of IP results
MOS=[4.22 4.42] Call registration =[04.16ms 06.16ms]
Call establishment=[02.171ms 03.361ms]
Percentage of audio lost packets= [0% 0.03%]
Percentage of video lost packets= [0% 0.08%]
Jitter=[0ms 1.35ms]
Codec flow: G.711 = 64 kbps
AMR-NB = variable rate & Voice activity detection(VAD)= on (1)
G.722 = 64 kbps G722.1 = 2.32 kbps stereo
AMR-WB = 12.65 kbps & VAD =1
H.264 profile= Baseline profile Level= level 2
Max picture rate= 625 pictures /sec
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
Configuration
Parameters
H.264/G.711
H.264/AMR-NB
H.264/G.722
H.264/G.722.1
H.264/AMR-WB
Call registration 05.06ms 05.04ms 04.16ms 06.16ms 04.91ms
Call establishment 02.171ms 02.186ms
02.309ms 03.361ms 02.457ms
Throughput
(average)
Audio
UL = 83.88kbps
DL =85.60Kbps
Video
UL = 1353.31kbps
DL = 1399.15kbps
Audio
UL = 8.28kbps
DL =7.80 kbps
Video
UL= 1220.56kbps
DL = 1655.55Kbps
Audio
UL = 82.17kbps
DL = 85.60Kbps
Video
UL= 1311.35kbps
DL = 1912.02Kbps
Audio
UL = 85.60kbps
DL = 85.60kbps
Video
UL= 1112.68kbps
DL = 1049.85kbps
Audio
UL = 33.01kbps
DL = 9.42kbps
Video
UL = 1129.49kbps
DL =1136.97 kbps
MOS
Audio
UL = 4.36
DL = 4.33
Audio
UL = 4.42
DL = 4.42
Audio
UL =4.24
DL = 4.22
Audio
UL = 4.40
DL = 4.35
Audio
UL =4.42
DL = 4.42
Jitter
(average)
Audio
UL = 0.01ms
DL = 0.94ms
Video
UL =0.02ms
DL= 0.04ms
Audio
UL = 0.09ms
DL = 0ms
Video
UL =0.03ms
DL= 0.01ms
Audio
UL = 0.02ms
DL = 0 ms
Video
UL =0.02ms
DL= 0.03ms
Audio
UL = 1.20ms
DL = 1.14ms
Video
UL =0.16ms
DL= 0.03ms
Audio
UL =1.35 ms
DL = 0.63ms
Video
UL =0.07ms
DL=0.01ms
Percentage of lost
packets
Audio
UL =0.03 %
DL = 0 %
Video
UL = 0.07%
DL = 0%
Audio
UL =0 %
DL = 0%
Video
UL = 0.07%
DL =0.04%
Audio
UL = 0.02%
DL = 0%
Video
UL =0.08 %
DL =0%
Audio
UL = 0%
DL = 0 %
Video
UL =0 %
DL =0.04%
Audio
UL = 0%
DL = 0%
Video
UL = 0%
DL =0.04%
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Encountered difficulties
Difficulty when connecting the LTE/4G dongle to a Linux environment:
The Operating System Ubuntu seems the most flexible when dealing with these
devices
Resolved thanks to AT commands (3GPP TS 27.007 V11.3.0 (2012-06)).
Non-conformity of the specification implementation.
SIP Register messages have to be customized so as to register with the IMS call
manager
Interoperability issues of the firmware version with the LTE/4G architecture
In some cases, the dongle firmware has to be upgraded or downgraded to
work correctly with the underlying LTE platform
The current underlying system was not able to manage differenciated QoS
The tests were run so far within a building, which show that 2,6 GHz Frequencies are
not well-suited for in-door tries
The LTE connection is asymmetrical so that the QoS on the UL and DL may be very
different
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Summary
A first experiment of videocalling on experimental LTE network
These trials were performed using a true IMS infrastructure (Session Border
Controller, IMS Call Server, end-to-end delays, real-life variable radio conditions)
Several LTE dongles from different vendors were tested over Linux and
Windows
An internally developped tool was made ready for operational
measurements
This set of tests give a better knowledge about metrics to calculate (call
establishment time, registration time, bandwidth, loss, jitter)
Different resolutions of images and audio and video coding schemes were
used
The asymmetrical behaviour of the LTE connection is an issue that may
have impact of the choice of codec.
The 2,6GHz Frequencies are not well-suited for in-door tries
QoS /QoE in the context of videoconferencing services over LTE/4G networks.
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Next steps
Integrate outdoor mobility, distance to cell in real-live network
QoS management ( PCRF to be included) with the addition of different
configuration parameters (such as QCI, ARP or DSCP)
Tests under variable radio conditions (network disturbance tools)
Integration of new codecs (such as OPUS or HEVC (2013))
Subjective testing
QoS /QoE in the context of videoconferencing services over LTE/4G networks.