Table Of ContentManfred Taferner . Ernst Bonek
Wireless Internet Access over GSM and UMTS
Springer-Verlag Berlin Heidelberg GmbH
Manfred Taferner . Ernst Bonek
Wireless Internet Access
over GSM and UMTS
With 136 Figures
, Springer
Dipl.-Ing. Dr. Manfred Taferner
Neunkirchen, Austria
Dipl.-Ing. Dr. Ernst Bonek
Wien, Austria
Die Deutsche Bibliothek -CIP-Einheitsaufnahme
Taferner, Manfred:
Wireless Internet Access over GSM and UMTS I Manfred Taferner; Ernst Bonek. - Berlin;
Heidelberg; New York; Barcelona; Hong Kong; London; Milan; Paris; Tokyo:
Springer, 2002
ISBN 978-3-642-07643-5 ISBN 978-3-662-04771-2 (eBook)
DOI 10.1007/978-3-662-04771-2
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Preface
We dedicate this book to students 0/ computer science who want to under
stand why the radio channel is at the heart of mobile communications, be it
data or voice, and to students 0/ communications engineering looking for an
introduction to the structure of the Internet protocols, and their application
to mobile radio. We also welcome the practicing engineer' working for mobile
network operators and infrastructure suppliers, and the application program
mer looking for the underlying reasons for the problems they encounter in
their daily work.
Given that convergence of the information technology and communica
tions worlds has been talked about for almost 20 years, there is still surpris
ingly little knowledge among specialists of each others' fields. Data communi
cations over radio, notably Internet access, however, requires fuH understand
ing of both fields. Internet protocols have been designed for fixed networks.
There bit errors are so rare that interrupted transmission almost inevitably
means congestion. In contrast, the radio channel constitutes a bottleneck for
mobile data communications in that it introduces bit errors even at modest
data rates.
This book is based on the doctoral thesis of one of us (M. Taferner).
The work leading to this thesis has been generously sponsored by Mobilkom
Austria, a highly innovative and successful mobile network operator in one
of Europe's most competitive markets (at the time of writing, Austria boasts
a mobile phone penetration of 83%). However, we hast.en to say that the
views put forward in this book are solely ours, and in no way reflect the
views of Mobilkom Austria or Telekom Austria. They are not even based on
experience with Mobilkom's network alone, as we have measured our data in
different Austrian networks.
It is our pleasure to thank Mobilkom Austria for 12 years of cooperation
between Telekom/Mobilkom Austria and the Institut für Nachrichtentechnik
und Hochfrequenztechnik of Technische Universität Wien. We have appre
ciated the continual challenge that has deepened our understanding of the
actual needs of an operator. It is probably unjust to give special thanks to
just a few persons, but we gratefuHy acknowledge the assistance of Kurt Ehe
moser, Thomas Ergoth, and Alexander Schneider in technical matters, and
of Werner Wiedermann and Reinhard Kuch (formerly with Telekom Austria)
VI Preface
in all matters relating to the cooperation. We also thank our colleagues
Klaus Hugl, Klaus Kopsa and Elmar Trojer for numerous expert discussions.
Furthermore, our thanks are due to Georg Löffelmann who contributed the
simulations of Chap. 5.6, and Günther Pospischil for help in setting up the
measurements.
The benefits of the Internet as we perceive them (instant information
retrieval, connectivity at will) will not become universally accepted unless
the Internet really becomes ubiquitous, Le. accessible from mobile terminals.
So, in a way, the future success of the Internet is intimately tied to that of
mobile radio. Although Japan had a slow start with the acceptance of mobile
communications, it is now the largest and fastest growing market in mobile
data services. It shows the world the path to the mobile Internet. In Europe,
the Scandinavian countries and Austria seem to have the best preconditions
for a rapid spreading of the mobile Internet.
We hope that both protocol and system designers, and application pro
grammers working on the 3rd and 4th generations of mobile radio will learn
from the successes and deficiencies of earlier generations. If this book con
tributes a little to this goal, then it will have served its purpose well.
Wien, AIanfred Taferner
August 2001 Ernst Bonek
Contents
1. Introduction.............................................. 1
2. Protocols for Internet Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Data Link Layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Serial Line Internet Protocol, SLIP. . . . . . . . . . . . . . . . . 8
2.1.2 Point to Point Protocol, PPP . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Network Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11
2.2.1 Internet Protocol, IP ............................. 11
2.2.2 Internet Protocol, Version 6, IPv6 . . . . . . . . . . . . . . . . .. 13
2.2.3 Mobile IP .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15
2.2.4 Cellular IP ...................................... 17
2.3 Transport Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
2.3.1 Transmission Control Protocol, TCP . . . . . . . . . . . . . . .. 19
2.3.2 User Datagram Protocol, UDP . . . . . . . . . . . . . . . . . . . .. 27
2.4 Application Layer ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28
2.4.1 Hypertext Transport Protocol, HTTP. . . . . . . . . . . . . .. 28
2.5 Wireless Application Protocol, WAP . . . . . . . . .. . . . . . . . . . . . .. 30
2.5.1 Architecture Overview . . . . . . . . . . . . . . .. . . . . . . . . . . . .. 30
2.5.2 Transport Layer. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. 32
2.5.3 Security Layer .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33
2.5.4 Transaction Layer . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. 35
2.5.5 Session Layer . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. 36
2.5.6 Application Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37
2.5.7 WAP Push Architecture. . . . . . . . .. . . . . .. . . . . . . . . . .. 40
2.5.8 Comparison WAP vs. Internet Protocol Stack. . . . . . .. 41
3. Data Transmission in GSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
3.1 Circuit-Switched Data ..................... . . . . . . . . . . . .. 47
3.1.1 Basics........................................... 47
3.1.2 Radio Link Protocol (RLP) . . . . . . . . . . . . . . . . . . . . . . .. 50
3.1.3 Interworking Function (IWF) . . . . . . . . . . . . . . . . . . . . .. 51
3.1.4 High-Speed Circuit-Switched Data (HSCSD) . . . . . . . .. 54
3.2 Packet-Switched Data, General Packet Radio Service (GPRS) 55
3.2.1 System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 55
VIII Contents
3.2.2 Services......................................... 56
3.2.3 Radio Interface .................................. 58
3.2.4 Protocol Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 61
3.3 Link Level Simulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 68
3.3.1 Implementation Details ........................... 69
3.3.2 Channel Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 73
3.3.3 Simulation Results ............................... 75
3.3.4 Summary........................................ 79
3.4 Link Layer Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 81
3.5 Summary.............................................. 88
4. Data Transmission in UMTS ............................. 91
4.1 Core Network (CN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 91
4.1.1 Release'99 Core Network . .. . . . . . . .. . . .. . . . . .. . . . .. 91
4.1.2 ATM-based Core Network . . . . . . . . . . . . . . . . . . . . . . . .. 93
4.1.3 All IP Network ................................... 94
4.2 Access Network, UMTS Terrestrial Radio Access Network
(UTRAN) ............................................. 95
4.3 Protocol Architecture ................................... 100
4.3.1 Overall Protocol Architecture (User Plane) .......... 100
4.3.2 Radio Interface Protocol Architecture ............... 101
4.4 UMTS Bearer Services and QoS .......................... 109
4.5 Differences from GSM-GPRS ............................ 112
5. TCP in Wireless Environments ........................... 115
5.1 General Problems ...................................... 115
5.1.1 TCP Behavior on Packet Loss ..................... 115
5.1.2 TCP Behavior on Temporary Disconnections ........ 118
5.1.3 Interactions with Link Layer ....................... 120
5.1.4 Asymmetrie Services .............................. 122
5.2 Suggested Solutions from Literature ...................... 124
5.2.1 End-to-end proposals ............................. 125
5.2.2 Split-Connection Proposals ........................ 128
5.2.3 Link Layer Proposals ............................. 131
5.3 Packet Length for Optimum Throughput .................. 133
5.3.1 Basic Context .................................... 134
5.3.2 Throughput Efficiency ............................ 135
5.3.3 Optimum Packet Length .......................... 139
5.3.4 Conclusions ...................................... 143
5.4 TCP over GSM-CSD, Simulations and Measurements ....... 143
5.4.1 Simulation Müdel für GSM-CSD ................... 144
5.4.2 Simulation Results for GSM-CSD .................. 146
5.4.3 Measurement Setup for GSM-CSD .................. 152
5.4.4 Measurement Results for GSM-CSD ................ 155
5.4.5 Summary and Conclusions ......................... 172
Contents IX
5.5 TCP over GSM-GPRS, Simulations ....................... 177
5.5.1 Simulation Model for GSM-GPRS .................. 177
5.5.2 Simulation Results for GSM-GPRS ................. 184
5.5.3 Discussion and Conclusions ........................ 204
5.6 TCP over UMTS, Simulations ............................ 209
5.6.1 Simulation Model for TCP /IP over UMTS .......... 209
5.6.2 Simulation Results for TCP /IP over UMTS .......... 211
5.6.3 Summary and Conclusions ......................... 222
6. Summary and Conclusions ................................ 225
6.1 Wireless Application Protocol ............................ 226
6.2 GSM and GSM-GPRS Radio Link ........................ 227
6.3 GSM-GPRS VS. UMTS Packet-Switched Data .............. 227
6.4 TCP Performance in Wireless Environments ............... 229
6.4.1 Problems of TCP and Suggested Solutions ........... 229
6.4.2 TCP Packet Length for Optimum Throughput ....... 231
6.4.3 GSM Circuit-Switched Data ....................... 232
6.4.4 GSM Packet-Switched Data (GPRS) ................ 233
6.4.5 UMTS Packet-Switched Data ...................... 234
6.5 General Comments ..................................... 235
A. List of Acronyms ......................................... 239
B. Glossary .................................................. 243
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
Index ......................................................... 255
