ON APPLICATION-PERCEIVED QUALITY OF SERVICE IN WIRELESS NETWORKS
Wireless and Mobile Internet have changed the way people and businesses
operate. Communication from any Internet access point, including wireless
networks such as UMTS, GPRS or WLAN has enabled organizations to have
a mobile workforce. However, networked applications such as web, email,
streaming multimedia etc. rely upon the ability of timely data delivery. The
achievable throughput is a quality measure for the very task of a communication
system, which is to transport data in time. Throughput is thus one
of the most essential enablers for networked applications. While in general,
throughput is defined on network or transport level, the application-perceived
throughput reflects the Quality of Service from the viewpoints......
ON APPLICATION-PERCEIVED
QUALITY OF SERVICE
IN WIRELESS NETWORKS
Stefan Chevul
Blekinge Institute of Technology
Licentiate Dissertation Series No. 2006:11
School of Engineering
On Application-Perceived
Quality of Service
in Wireless Networks
Stefan Chevul
Blekinge Institute of Technology Licentiate Dissertation Series
No 2006:11
ISSN 1650-2140
ISBN 91-7295-096-X
On Application-Perceived
Quality of Service
in Wireless Networks
Stefan Chevul
Department of Telecommunication Systems
School of Engineering
Blekinge Institute of Technology
SWEDEN
c
� 2006 Stefan Chevul
Dissertation Series No. 2006:11
ISSN 1650-2140
ISBN 91-7295-096-X
© 2006 Stefan Chevul
Department of Telecommunication Systems
Department of Telecommunication Systems
School of Engineering
School of Engineering
Publisher: Blekinge Institute of Technology
Blekinge Institute of Technology
Printed by Kaserntryckeriet, Karlskrona, Sweden 2006
ISBN 91-7295-096-X
Printed by Kaserntryckeriet AB, Karlskrona, Sweden
This publication was typeset using L TEX.
A
To my family.
Abstract
Wireless and Mobile Internet have changed the way people and businesses
operate. Communication from any Internet access point, including wireless
networks such as UMTS, GPRS or WLAN has enabled organizations to have
a mobile workforce. However, networked applications such as web, email,
streaming multimedia etc. rely upon the ability of timely data delivery. The
achievable throughput is a quality measure for the very task of a communi-
cation system, which is to transport data in time. Throughput is thus one
of the most essential enablers for networked applications. While in general,
throughput is defined on network or transport level, the application-perceived
throughput reflects the Quality of Service from the viewpoints of the applica-
tion and user.
The focus of the thesis is on the influence of the network on the application-
perceived Quality of Service and thus the user perceived experience. An
analysis of application based active measurements mimicking the needs of
streaming applications is presented. The results reveal clear influence of the
network on the application-perceived Quality of Service seen from variations
of application-perceived throughput on small time scales. Results also indi-
cate that applications have to cope with considerably large jitter when trying
to use the nominal throughputs. It was observed that the GPRS network had
considerable problems in delivering packets in the downstream direction even
when the nominal capacity of the link was not reached.
Finally, the thesis discusses the suitability of wireless networks for different
mobile services, since the influence of the network on the application-perceived
Quality of Service is of great significance when it comes to customer satisfac-
tion. Therefore, application-perceived Quality of Service in wireless networks
must also be considered by the mobile application programmer during the
application development.
vii
Preface
This thesis reports on my research in the field application-perceived Qual-
ity of Service. The work was done at the School of Engineering at Blekinge
Institute of Technology (BTH) in the context of the Personal Information
for Intelligent Transport Systems through Seamless communications and Au-
tonomous decisions (PIITSA) project funded by the Swedish Agency for In-
novation Systems VINNOVA (project number 2003-02873), www.vinnova.se.
Other partners are: Saab Communication in V¨xj¨; the Swedish National
a o
Testing and Research Institute (SP), and the Swedish National Road Admin-
istration (V¨gverket). Parts of my research material have been published in
a
the following publications:
1. Stefan Chevul, Johan Karlsson, Lennart Isaksson, Markus Fiedler, Pe-
ter Lindberg and Lars Strand´n. Measurement of Application-Perceived
e
Throughput in DAB, GPRS, UMTS and WLAN Environments. In Pro-
ceedings of RVK’05, June 2005, Link¨ping, Sweden.
o
2. Markus Fiedler, Stefan Chevul, Lennart Isaksson, Peter Lindberg and
Johan Karlsson. Generic Communication Requirements of ITS-Related
Mobile Services as Basis for Automatic Network Selection. In Proceed-
ings of NGI’05, April 2005, Rome, Italy.
3. Stefan Chevul, Lennart Isaksson, Markus Fiedler and Peter Lindberg,
Measurement of Application-Perceived Throughput of an E2E VPN Con-
nection Using a GPRS Network, In Second International Workshop of
the EURO-NGI Network of Excellence, LNCS Volume 3883 / 2006, pp.
255 – 268, July 13-15, 2005, Villa Vigoni, Italy.
ix
4. Lennart Isaksson, Stefan Chevul, Markus Fiedler, Johan Karlsson and
Peter Lindberg. Application-Perceived Throughput Process in Wireless
Systems. In Proceedings of ICMCS’05, August 2005, Montreal, Canada.
5. Markus Fiedler, Lennart Isaksson, Stefan Chevul, Peter Lindberg and
Johan Karlsson, Measurements and Analysis of Application-Perceived
Throughput via Mobile Links, In Proceedings of the 2005 3ed Perfor-
mance Modeling and Evaluation of Heterogeneous Networks (HET-
NETs) T06, July 18-2, 2005, Ilkley, West Yorkshire, U.K.
6. Peter Lindberg, Stefan Chevul, Roland Waltersson, Markus Fiedler and
Lennart Isaksson. Seamless Communication for ITS Applications. In
Proceedings of 13th World Congress of ITS, October 2006, London,
England.
7. Stefan Chevul, Lennart Isaksson, Markus Fiedler, Peter Lindberg and
Roland Waltersson. Network Selection Box: An Implementation of
Seamless Communication, Accepted for publication in Third EURO-
NGI Workshop on Wireless and Mobility, LNCS, November 2006.
8. Markus Fiedler, Kurt Tutschku, Stefan Chevul, Lennart Isaksson and
Andreas Binzenh¨fer, The Throughput Utility Function: Assessing Net-
o
work Impact on Mobile Services, In Second International Workshop of
the EURO-NGI Network of Excellence, LNCS Volume 3883 / 2006, pp.
242 – 254, 13-15 July 2005, Villa Vigoni, Italy.
9. Bj¨rn M˚
o artensson, Stefan Chevul, H˚akan J¨rnliden, Henric Johnson,
a
and Arne Nilsson, SuxNet - Implementation of Secure Authentication
for WLAN, Research Report 2003:3, ISSN: 1103-1581, 2003.
10. Patrik Carlsson, Markus Fiedler, Kurt Tutschku, Stefan Chevul, and
Arne Nilsson, Obtaining Reliable Bit Rate Measurements in SNMP-
Managed Networks, ITC Specialist Seminar, pp. 114 – 123, W¨ rzburg,
u
2002.
11. Katarzyna Wac, Patrik Arlos, Markus Fiedler, Stefan Chevul, Lennart
Isaksson, and Richard Bults. Accuracy evaluation of application-level
performance measurements. Submitted.
x
Acknowledgement
I owe a sincere gratitude to Dr.-Ing. Markus Fiedler for the inspiration, invalu-
able support and advice. I am also grateful to Professor Arne A. Nilsson, for
accepting me as a PhD student. I also wish to thank Docent Adrian Popescu
for his valuable discussions and suggestions.
Special thanks go to my fellow researchers in the group of telecommunica-
tion systems for encouragement and many interesting discussions.
I would like to express my deepest gratitude to my parents, Gy¨ngyi and
o
Istv´n, for their endless support and encouragement during both bad times
a
and good times.
Finally, I would like to express my infinite gratitude to my beloved wife
Orsolya for her understanding and comfort.
Stefan Chevul
Karlskrona, December 2006.
xi
Contents
1 Introduction 1
1.1 Evolution of Wireless Networks . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Main contribution . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Thesis outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Short Technical Overview of Wireless Networks 7
2.1 Global System for Mobile Communications (GSM) . . . . . . . 8
2.2 General Packet Radio Service (GPRS) . . . . . . . . . . . . . . 10
2.3 Universal Mobile Telecommunications System (UMTS) . . . . . 16
2.4 Wireless Local Area Network (WLAN) . . . . . . . . . . . . . . 21
2.5 4G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3 Application-Perceived Throughput 25
3.1 Foundations of Application-Perceived
Speed and Throughput . . . . . . . . . . . . . . . . . . . . . . . 25
3.2 Averaging Interval versus Observation Interval . . . . . . . . . 29
3.3 Application-Perceived Throughput Statistics . . . . . . . . . . 30
4 Traffic Measurements Methodology 35
4.1 Active Measurements . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2 Passive Measurements . . . . . . . . . . . . . . . . . . . . . . . 36
4.3 Measurements of Application-Perceived Throughput . . . . . . 38
4.3.1 Layer of interest . . . . . . . . . . . . . . . . . . . . . . 38
4.3.2 Initial delay . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.3.3 Warm-up phase . . . . . . . . . . . . . . . . . . . . . . . 41
xiii
CONTENTS
4.3.4 User Datagram Protocol Traffic Generator . . . . . . . . 41
4.3.5 Measurement Setup . . . . . . . . . . . . . . . . . . . . 44
4.3.6 Parameter Settings . . . . . . . . . . . . . . . . . . . . . 46
5 Measurements of Application-Perceived Throughput 47
5.1 GPRS Measurements . . . . . . . . . . . . . . . . . . . . . . . . 48
5.1.1 Internet Service Provider (ISP) A: GPRS downlink . . . 49
5.1.2 ISP A: GPRS Uplink . . . . . . . . . . . . . . . . . . . 49
5.1.3 ISP B: GPRS downlink . . . . . . . . . . . . . . . . . . 54
5.1.4 ISP B: GPRS Uplink . . . . . . . . . . . . . . . . . . . . 56
5.1.5 E2E VPN connection over ISP A’s GPRS network . . . 62
5.2 UMTS Measurements . . . . . . . . . . . . . . . . . . . . . . . 67
5.2.1 ISP A: UMTS Downlink . . . . . . . . . . . . . . . . . . 67
5.2.2 ISP A: UMTS Uplink . . . . . . . . . . . . . . . . . . . 71
5.2.3 ISP B: UMTS Downlink . . . . . . . . . . . . . . . . . . 78
5.2.4 ISP B: UMTS Uplink . . . . . . . . . . . . . . . . . . . 78
5.3 WLAN Measurements . . . . . . . . . . . . . . . . . . . . . . . 81
5.3.1 Institute of Electrical and Electronics Engineering
(IEEE) 802.11b . . . . . . . . . . . . . . . . . . . . . . . 83
5.3.2 IEEE 802.11g . . . . . . . . . . . . . . . . . . . . . . . . 86
5.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6 Wireless network suitability for different mobile services 91
6.1 Wireless a-priory network . . . . . . . . . . . . . . . . . . . . . 92
6.2 Passive E2E application-perceived quality monitoring . . . . . 93
6.3 Seamless Communications . . . . . . . . . . . . . . . . . . . . . 95
7 Conclusions and future work 99
Appendix A Acronyms 101
Appendix B Excerpt from server trace file. 107
Appendix C Excerpt from client trace file. 109
Bibliography 111
xiv
List of Figures
2.1 GSM Network Architecture. . . . . . . . . . . . . . . . . . . . . 9
2.2 GPRS Network Architecture. . . . . . . . . . . . . . . . . . . . 13
2.3 GPRS attach procedure [1]. . . . . . . . . . . . . . . . . . . . . 14
2.4 GPRS transmission plane [1]. . . . . . . . . . . . . . . . . . . . 15
2.5 Channel coding (384 kbps). . . . . . . . . . . . . . . . . . . . . 19
2.6 UTRAN architecture. . . . . . . . . . . . . . . . . . . . . . . . 19
2.7 Packet service in UMTS. . . . . . . . . . . . . . . . . . . . . . . 20
2.8 User plane protocol stack for packet switched UMTS. . . . . . 21
2.9 IEEE 802.11 protcol architecture. . . . . . . . . . . . . . . . . . 22
2.10 WLAN network using Infrastructure Base Station Subsystem
(BSS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.1 Concept of application-perceived speed. . . . . . . . . . . . . . 27
3.2 Anticipated time plot, throughput histograms at input and
output and throughput histogram difference plot (from left to
right) in case of a shared bottleneck [2]. . . . . . . . . . . . . . 33
3.3 Anticipated time plot, throughput histograms at input and
output and throughput histogram difference plot (from left to
right) in case of a shaping bottleneck [2]. . . . . . . . . . . . . . 33
4.1 UDP generator with time stamps. . . . . . . . . . . . . . . . . 43
4.2 Measurement scenarios. . . . . . . . . . . . . . . . . . . . . . . 45
5.1 ISP A: GPRS downlink scenario, 130 ms inter-packet delay. . . 50
5.2 ISP A: GPRS downlink scenario, 70 ms inter-packet delay. . . . 51
5.3 ISP A: GPRS uplink scenario, 130 ms inter-packet delay. . . . . 53
xv
LIST OF FIGURES
5.4 GPRS uplink scenario, 80 ms inter-packet delay. . . . . . . . . 55
5.5 ISP B: GPRS downlink scenario, 130 ms inter-packet delay. . . 57
5.6 ISP B: GPRS downlink scenario, 70 ms inter-packet delay. . . . 58
5.7 ISP B: GPRS uplink scenario, 130 ms inter-packet delay. . . . . 60
5.8 ISP B: GPRS uplink scenario, 70 ms inter-packet delay. . . . . 61
5.9 ISP A: VPN 3DES-SHA-1 GPRS uplink scenario, with 80 ms
inter-packet delay. . . . . . . . . . . . . . . . . . . . . . . . . . 63
5.10 ISP A: VPN 3DES-MD5 GPRS uplink scenario, with 90 ms
inter-packet delay. . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.11 ISP A: VPN SHA1 GPRS uplink scenario, with 90 ms inter-
packet delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.12 ISP A: VPN 3DES-SHA-1 GPRS downlink scenario, with 120
ms inter-packet delay. . . . . . . . . . . . . . . . . . . . . . . . 65
5.13 ISP A: Loss ratios on uplink. . . . . . . . . . . . . . . . . . . . 67
5.14 ISP A: Loss ratios on downlink. . . . . . . . . . . . . . . . . . . 68
5.15 ISP A: UMTS downlink scenario, 90 ms inter-packet delay. . . 69
5.16 ISP A: UMTS downlink scenario, 30 ms inter-packet delay. . . 70
5.17 ISP A: UMTS downlink scenario, 10 ms inter-packet delay. . . 72
5.18 ISP A: UMTS uplink scenario, 90 ms inter-packet delay. . . . . 74
5.19 ISP A: UMTS uplink scenario, 60 ms inter-packet delay. . . . . 76
5.20 ISP B: UMTS downlink scenario, 30 ms inter-packet delay. . . 77
5.21 ISP B: UMTS downlink scenario, 10 ms inter-packet delay. . . 79
5.22 ISP B: UMTS uplink scenario, 50 ms inter-packet delay. . . . . 82
5.23 IEEE 802.11b, 2 ms inter-packet delay, no security. . . . . . . . 84
5.24 IEEE 802.11b, 2 ms inter-packet delay, with security. . . . . . . 85
5.25 IEEE 802.11g, 1 ms inter-packet delay, with security. . . . . . . 87
6.1 Virtual Network Interface in the NSB. . . . . . . . . . . . . . . 96
6.2 Encapsulated packet for tunnelling purpose. . . . . . . . . . . . 97
6.3 Building blocks of the NSB. . . . . . . . . . . . . . . . . . . . . 97
6.4 Relative overhead vs. frame size ratio. . . . . . . . . . . . . . . 98
xvi
List of Tables
2.1 Nominal throughput for GPRS at link level. . . . . . . . . . . . 11
2.2 GPRS handset classes. . . . . . . . . . . . . . . . . . . . . . . . 12
2.3 Delay classes in GPRS according to [3]. . . . . . . . . . . . . . 12
2.4 UMTS data rates in different cells. . . . . . . . . . . . . . . . . 18
4.1 Query performance parameters in server and client code. . . . . 42
4.2 Inter-packet delay algorithm in server. . . . . . . . . . . . . . . 44
5.1 ISP A: GPRS Downlink with packet size of 128 bytes. . . . . . 52
5.2 ISP A: GPRS Uplink with packet size of 128 bytes. . . . . . . . 54
5.3 ISP B: GPRS Downlink with packet size of 128 bytes. . . . . . 59
5.4 ISP B: GPRS Uplink with packet size of 128 bytes. . . . . . . . 62
5.5 ISP A: UMTS Downlink with packet size of 480 bytes. . . . . . 73
5.6 ISP A: UMTS Uplink with packet size of 480 bytes. . . . . . . 75
5.7 ISP B: UMTS Downlink with packet size of 480 bytes. . . . . . 80
5.8 ISP B: UMTS Uplink with packet size of 480 bytes. . . . . . . 81
5.9 IEEE 802.11b with packet size of 1458 bytes. . . . . . . . . . . 86
5.10 IEEE 802.11g with packet size of 1458 bytes. . . . . . . . . . . 88
B.1 Excerpt from server trace file. . . . . . . . . . . . . . . . . . . . 107
C.2 Excerpt from client trace file. . . . . . . . . . . . . . . . . . . . 109
xvii
