T-MOBILE EXHIBIT 1007
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`

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`1922
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`Edited by G. Goos, J. Hartmanis and J. van Leeuwen
`
` Lecture Notes in Computer Science
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`

`

`Jon Crowcroft James Roberts
`Mikhail I. Smirnov (Eds.)
`
`
`
`Quality of Future
`Internet Services
`
`
`Berlin, Germany, September25-26, aie
`First COST 263 International Workshop,
`
`,
`
`QoflIS
`
`2
`
`000
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`Proceedings
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`
`
`Q}) Springer
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`

`

`Series Editors
`
`Gerhard Goos, Karlsruhe University, Germany
`Juris Hartmanis, Comell University, NY, USA
`Jan van Leeuwen, Utrecht University, The Netherlands
`
`VolumeEditors
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`COp
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`Cataloging-in-Publication Data applied for
`
`/
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`ff
`~ERSubject Classification (1998): C.2, H.4, H.3, J.1
`
`Jon Crowcroft
`University College London, Department of Computer Science
`GowerStreet, London WC1E 6BT,United Kingdom
`E-mail: jon.crowcroft@cs.ucl.ac.uk
`James Roberts
`France Telecom R&D
`38 rue de Général Leclerc, 92794 Issy-Moulineaux, Cedex 9, France
`E-mail: james.roberts@cnet.francetelecom.fr
`Mikhail I. Smirnov
`GMD FOKUS
`Kaiserin-Augusta Allee 31, 10589 Berlin, Germany
`E-mail: smirnov @fokus.gmd.de
`
`ae«feic./2
`
`__DieDeutsche Bibliothek - CIP-Einheitsaufnahme
`~
`Qualit)of future Internet services : first COST 263 international
`avprkshop ; proceedings/ QoflS 2000, Berlin, Germany, September
`25 - 26, 200. Jon Crowcroft ... (ed.). - Berlin ; Heidelberg ; New York ;
`Barcelona ; Hong Kong ; London ; Milan ; Paris ; Singapore ; Tokyo :
`Springef-2000
`tufé potes in computerscience ; 1922)
` EIBBN3-f40-41076-7
`oS
`}
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`FCONG
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`Voy
`\. 2
`
`ISSN 0302-9743
`ISBN 3-540-41076-7 Springer-Verlag Berlin Heidelberg New York
`
`This work is subject to copyright. All rights are reserved, whether the whole or part of the material is
`concemed,specifically therights oftranslation,reprinting,re-useofillustrations,recitation, broadcasting,
`reproduction on microfilms or in any other way, and storage in data banks. Duplication ofthis publication
`or parts thereofis permitted only underthe provisions ofthe German Copyright Law of September9, 1965,
`in its currentversion, and permission for use mustalways be obtained from Springer-Verlag. Violations are
`liable for prosecution under the German Copyright Law.
`Springer-Verlag Berlin Heidelberg New York
`a memberof BertelsmannSpringer Science+Business Media GmbH
`© Springer-Verlag Berlin Heidelberg 2000
`Printed in Germany
`Typesetting: Camera-ready by author, data conversion by DA-TeX Gerd Blumenstein
`Printed on acid-free paper
`SPIN: 10722832
`06/3142
`§43210
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`|>
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`ia
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`

`

`
`
`Table of Contents
`
`IX
`
`eveing and Scheduling
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`Qu
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`Boundsin a Network with Aggregate Scheduling eaiheacase acer earniaen sini EE bs
`. Charny and Jean-Yves Le Boudec
`anagement System for Differentiated-Services IP Routers ...... 14
`A Queue M
`Goncalo Quadros, Antonio Alves, Joao Silva, Henrique Matos,
`Bdmundo Monteiro and Fernando Boavida
`Modeling the Dynamicsof the RED Algorithm sCyRKN PARES RR OR eV
`Pasi E. Lassila and Jorma T. Virtamo
`
`CHMEANNATE
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`28
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`TCP, Flow and Congestion Control
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`0... 2-22... seeee eee eee esse eee es
`Random Early Marking .........
`Sanjeewa Athuraliya, Steven Low and David Lapsley
`A Markovian Model for TCP Analysis in
`a Differentiated Services Network ..
`Chadi Barakat and Bitan Altman
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`_amateas
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`43
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`..00
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`On the Feasibility of RSVP as General Signalling Interface ................
`Martin Karsten, Jens Schmitt, Nicole Beriér and Ralf Steinmetz
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`Field-Trial of Dynamic SLA in Diffserv-Capable Network ..............5: 117
`Naoto Morishima, Akimichi Ogawa, Keijiro Ehara and Youki Kadobayashi
`
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`The Direct Adjustment Algorithm:
`A TCP-Friendly Adaptation Scheme
`Dorgham Sisalem and Henning Schulzrinne
`On ACK Filtering on a Slow Reverse Channel ....-..... 025-505 sseeeuneees
`Chadi Barakat and Eitan Altman
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`.. 68
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`80
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`End-to-End
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`Design, Implementation and Test of a RSVP Agent Based
`on.a-Generic QoS API svia
`Esteve Majoral-Coma, Xavier Martinez-Alvarez, Angel Luna-Lambies
`and Jordi Domingo-Pascual
`
`..93
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`105
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`Xx
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`Table of Contents
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`
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`.129
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`141
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`Traffic Engineering, QoS Routing
`Choosing the Objectives for Traffic Engineering in
`IP Backbone Networks Based on Quality-ofService Requirements ...---:
`Fabrice Poppe, Sven Van den Bosch, Paloma de La Vallée-Poussin,
`Hugo Van Hove, Hans De Neve and Guido Petit
`On the Cost of Using MPLSfor Interdomain Traffic scuwuaeaneseen ease
`Steve Uhlig and Olivier Bonaventure
`Mechanisms for Inter-domain QoS Routing
`in Differentiated Service Networks
`Peng Zhang and Raimo Kantola
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`QoS Measurements and Measurement Based QoS Mechanisms
`Priority Queueing Applied to Expedited Forwarding:
`A Measurement-Based Analysis . SUR
`Tiziana Ferrari, Giovanni Pau and Carla Raffaelli
`QoS/GOS Parameter Definitions and Measurement
`in IP/ATM Networks ..---.++20rercrerrnene Sepen eee yale
`Jorma Jormakka and Kari Heikkinen
`QoS Assessment and Measurementfor End-to-End Services ..--:
`Torsten Bissel, Manfred Bogen, Christian Bonkowski and Dieter Strecker
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`208
`The Fairness Challenge in Computer Networks ...--
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`Robert Denda, Albert Banchs and Wolfgang Effelsberg
`A Multi-color Marking Scheme to Achieve Fair Bandwidth Allocation ....
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`Kenny Pauwels, Stefaan De Cnodder and Omar Ellouma
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`Traffic Phase Effects with RED and Constant Bit Rate
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`UDP-Based Traffic ..-..
`Jérg Diederich, Thorsten Lohmar, Martina Zitterbart and Ralf Keller
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`Adaptation
`Adaptive Hybrid Error Control for IP-Based Continuous
`Media Multicast Services -..-.++-+rsssertspe enn Logeees
`Georg Carle, Henning Sanneck and Mirko Schramm
`Efficient Shaping of User-Specified QoS Using Aggregate-Flow Control ....259
`Huan Ren and Kihong Park
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`Fairness
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`balan acts 167
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`. 182
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`.. 194
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`221
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`(ewes ulee xeenn 245
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`e Construction ofHeterogeneous Multicast Distribution ‘Trees
`cnn Active Network ...ccseccvsccrseensy eee
`Naoki Wakamzya, Masayuki Murata and
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`272
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`Table of Contents
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`285
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`312
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`d Huw Oliver
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`qraffic Classes and Charging
`An Approach to Support Traffic Classes in IP Networks ...-.-ssrer0
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`Goncalo Quadros, Antonio Alves, Edmundo Monteiro and
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`ng in the Future Internet ....--++300
`Fernando Boavida
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`Framework for Prici r and Klaus Wehrle
`Blements of an Open
`Ritter, Jochen Schille
`Jan Gerke, Hartmut
`d Billing Models for GSM and
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`n of Charging an
`Evolutio
`pile Internet Services
`Future Mo
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`David Hutchison an
`John Cushnie,
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`Resource Utilization and Performance
`LiveVideo Scheduling in Differentiated Services Internet ..----e.rrr324
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`Themistoklis Rapsomanikis
`Virtual Routers: A Novel Approach for QoS Performance
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`Florian Baumgartner and Torsten Braun
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`DSRUP: A Resource Updating Protocol for
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`the Differentiated Services Gnvitoritiient: csavevernnnentaeerreneneeeene
`Joo Ghee Lim, Brahim Bensaou and Kee Chaing Chua
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`Internet Charging
`Keynote Talk: Internet Grade ooOE
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`Andrew M. Odlyzko
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`btspdtWETGOS ~--sivnannstdarcnensnnrsnzense semen nae”
`Georg Carle
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`Evaluation ..---- 336
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`348
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`360
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`361
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`ete TBE tens earn <medtunsnieasspacton aby fees RSENS
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`367
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`

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`Evolution of Charging andBilling Models for GSM and
`Future Mobile Internet Services
`
`John Cushnie’, David Hutchison’, and Huw Oliver’
`
`1 Distributed Multimedia Research Group
`Lancaster University, UK
`{j.cushnie,d.h}@lancaster.ac.uk
`2 Internet Research Institute
`HP Labs, Bristol, UK
`heo@hplb.hpl.hp.com
`
`Abstract. Mobile telephone communications and the Internet are
`converging and may eventually operate on a common technical
`platform, using TCP/IP networks as the main backbone medium.
`Mobile telephones are converging to Internet terminals, allowing the
`user access to email, Web browsingandall the other Internet services
`currently available from a desktop computer environment. In order to
`provide improved infrastructure for Global System for Mobile (GSM)
`based Internet services using 2™ and 3 generation (2G and 3G) the
`mobile network providers have the requirement to generate revenue for
`the services they provide. To do this the mobile network providersfirst
`need to capture the charging and billing data from the network. This
`paper describes the evolution of the GSM telephone networks and
`future mobile Internet services, via the General Purpose Radio Service
`(GPRS) and Universal Mobile Telecommunication System (UMTS).
`The methods for collecting the charging and billing information and
`charging models for processing this data into subscriber bills are
`discussed. A selection ofproposed Internet charging models are applied
`to the mobile network market and their relative suitability is examined.
`Keywords: 1G, 2G, 3G, GSM, GPRS, UMTS, Charging, Billing, Mobile, Internet.
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` 1
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`Introduction
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`The Global System for Mobile (GSM) was
`first
`introduced in 1992
`approximately 23 million subscribers, rising to over 200 million in 1999 on Over
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`GSM networks [1]. The aim was to provide a global mobile telephonenetwO
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`could be implemented using standard building blocksnot tied to specific ha
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`vendors. The uptake of GSM by subscribers is far higher than any
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`predictions andtypifies the 1990's and the increasing need for personal mob:
`1 generation (1G} GSM mobile networksprovide subscribers with high 444
`communications and low bandwidth data connections for FAX, Short
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`J. Crowcroft, J. Roberts, and M. Smirnov (Eds.); QoflS 2000, LNCS 1922, pp. 3 12-323, 200
`© Springer-Verlag Berlin Heidelberg 2000
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`Evolution of Charging and Billing Models
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`313
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`Service (SMS)andfull dial-in connection to the Internet for email and web browsing,
`usually requiring a mobile computer or intelligent handset. The addition of overlay
`communication protocols, such as Wireless Application Protocol (WAP) [2], allow
`mobile handsets on 1G GSM networks to be used for secure connection applications
`such as mobile banking and other transaction based services. International roaming
`agreements between the numerous mobile network providers allow subscribers to be
`reachable almost anywhere in the world where there is GSM coverage using the same
`telephone number and handset. Satellite based services such as GlobalStar [3] and
`ICO [4] allow GSM subscribers to further expand their network coverage and
`availability using the same mobile communications infrastructure. The increasing use
`of mobile telephones and devices for data communication drives the need from the
`market for a fast, reliable and available infrastructure. GSM proposesto provide the
`required infrastructure using 2™ and 3" (2G and 3G) generation GSM which
`introduce new technology that allows increased data bandwidths and new data
`services [1]. 2G GSM introduces the General Packet Radio Service (GPRS) and 3G
`GSM introduces the Universal Mobile Telecommunication System (UMTS).
`The introduction of 2G and 3G GSMtechnology brings convergence ofGSM mobile
`networks with the Internet. Packet Switching [5]is being introduced as the switching
`mechanism for data calls and Internet sessions,
`in contrast with the currentcircuit
`switching implementations currently used in 1G GSM and fixed line telephony
`networks. The 2G and 3G technologies deliver the same services available from the
`desktop Internet
`today,
`including email, secure transactions and Web browsing
`becomeavailable on mobile devices, using the standard infrastructure of the Internet.
`In order for the mobile networks to be able to offer these additional services to the
`customersthere is a requirementfor the recovery ofthe infrastructure investmentcost.
`This is a prime justification and motivation for charging and billing for telephone
`network usage together with the need for generating commercial profits for telephone
`network shareholders and companies. Charging may also be used to provide
`congestion control in under-provisioned and over-subscribed networks.
`2G and 3G GSM networks present the operators with many charging andbilling
`challenges. The experience gained with charging andbilling with GPRS will prove
`valuable when UMTSis being rolled out
`in GSM networks. There are various
`proposed economic and technical models for charging andbilling for Internet usage.
`Most of these are equally suitable for charging and billing of mobile network traffic,
`especially with 2G and 3G GSM systems.
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`2 GSM Mobile Networks andthe Future Internet
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`1G GSM networks[1] provide high quality digital telephony with low bandwidth data
`communications for FAX and SMS. GSM networks are typically multi-vendor and
`consist of a layered architecture including the mobile handsets, the telephone network
`and the subscriber invoices and bills. The Base Station and the Network Subsystems
`are often referred to as the Operational Network (ON), and is usually physically
`distributed around the area of coverage of the GSM network. The ON elements are
`often sited remotely with wide area networking (WAN) connectivity to the rest of the
`network to allow centralised remote administration of the network. The Base
`
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`John Cushnie etal.
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`314
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`
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`Transmitter Stations (BTS) and the Base Station Controllers (BSC) provide the air
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`interface for GSM, whichis then circuit switched [5] using the industry standard SS7
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`switching by the Mobile Switching Centers (MSCs) in the ON. Additional Gateway
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`MSCsallow switching to other mobile and fixed line telephone networks, providing
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`interconnection and roaming. Billing tickets for all calls made in the network are
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`produced on the MSCs, based on subscriber Ids in the network.
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`The Operational Support Systems (OSS) provides the interface to the customer
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`invoices
`and bills,
`and normally includes
`systems
`for billing,
`subscriber
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`administration, GSM Subscriber Identification Module (SIM) chipcard production,
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`fraud detection, voicemail and off-line data-mining and analysis systems. Most
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`mobile networks de-couple the ON from the OSS using Mediation Systems or
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`Mediation Devices (MD). These systems are used to collect billing data from the ON
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`and also to manage the subscriber databases in the ON elements.
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`The collection of the billing data is normally via high-speed communicationlinks
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`using reliable data protocols such as File Transfer and Management (FTAM)and
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`X.25. Once billing data is collected centrally it can be processed into subscriber
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`invoices andbills using dedicated billing systems and the mobile network’s charging
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`tariffs. The billing data can also be further processed by additional data-mining
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`systems to detect subscriber’s usage patterns, possible fraud detection and subscriber
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`profile surveying.
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`With 2G GSM the General Packet Radio Service (GPRS) [1,6,7] is introduced
`
`providing an overlay service for Internet access that shares the sameair interface as
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`1G GSM. The design goal behind GPRS is to provide high-speed Internet data
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`communications for mobile devices and subscribers using the existing 1G GSM air
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`interface,
`thereby minimising the cost
`impact on the existing installed network
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`infrastructure. GPRS is implemented in an existing GSM network with the addition of
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`two new ONelements the Signalling GPRS Service Node (SGSN) and the Gateway
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`GPRS Service Node (GGSN).
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`Additional modifications to the existing BTS and BSC to include Packet Control
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`Units are also required so that the network is GPRS aware. The two new ON elements
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`provide the interface between the GSM air interface and the TCP/IP network used for
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`the GPRS specific traffic, (i.e. Internet sessions used for email, http, ftp etc). GPRS
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`has the advantages ofdigital telephony of GSM combined with increased bandwidth
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`over the air interface for data traffic. The GGSN and SGSNin the ON provide the
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`switching for the mobile data sessions and use packet switching [5]. GPRS data
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`sessions are routed by the MSCs as for 1G GSM with the SGSN and GGSNrouting
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`the Internet sessions to the TCP/IP network, using packet switching [5]. Packet
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`switching makes full use of the available bandwidth of the underlying network, but
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`often has a reduced Quality of Service, and is suited to ‘bursty’ network traffic
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`including Internet protocols such as http, ftp, email etc, where guaranteed qualities of
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`service are not a top priority.
`In addition to introducing TCP/IP packet switching
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`GPRS equipped mobile networks mayroll in IPv6 [8] as the preferred IP protocol.
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`This will allow the large number of addressable network nodes that will be required
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`whenthere is a high saturation ofmobile devices requiring Internet connectivity.
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`The GGSN and SGSNproducebilling tickets andstatistical data relating to Internet
`traffic usage generated by GPRS calls andsessions.
`
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`

`Evolution of Charging and Billing Models
`
`315
`
`2G and 3G GSMbringswith it a new set of parametersto the challenge of billing and
`charging subscribers for using the GSM mobile networks. Mobile network subscribers
`are normally charged on a time and usage basis for the high quality telephony. With
`2G and 3G GSMthere are new possibilities to charge the subscribers for how much
`data or bandwidth they use in the network, in addition to the amount of talk-time
`consumed. This shares commonality with the possibilities currently being proposed
`for Internet charging andbilling. Asin the Internet the cost of packet counting may
`be more expensive than the value of the packets being counted. These new challenges
`need to be met and addressed by the network operators.
`3G GSM mobile networks arrive with the introduction of Universal Mobile
`Telecommunication System (UMTS). This will be based on the standard ON and OSS
`GSMarchitecture with the addition of UMTSspecific Network Elements.It will build
`on the infrastructure installed for GPRS with a marked increase in maximum
`bandwidth to 2Mbits/sec [1].
`Supported applications for 2G and 3G GSM may involve Internet intensive activities
`such as web browsing and email communication, as well as traditional mobile
`telephony. Table 1 shows a comparison of the bandwidth and communication rates
`achievable with the different generations of GSM networks[1].
`
`Table 1. GSM Architecture Generations
`
`Generation
`
`—
`Year
`
`Technology
`
`Max. Data Bandwidth
`
`
`1° | 1992
`Voice
`N/A
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`
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`1%
`1995
`SMS & Mobile Data & FAX
`9.6 Kb/sec Internet via Modem
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`GPRS
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`115 Kb/secDirectIntemetconnection
`
`oe | 2001
`
`an
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`2002/3
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`UMTS
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`2 Mb/sec Direct Internet connection
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`The introduction of GPRS is considered a stepping stone to the promises and
`functionality of UMTS and high-speed access to Internet services and Networking.
`Many mobile network operators view the experience to be gained with GPRSand the
`associated billing issues essential for the implementation of systems for UMTSasit
`may be too late to leam when UMTSis implemented and available for the mass
`market. The systems and methods developed for GPRS charging andbilling need to
`be compatible with the requirements of UMTSto ensure preservation of investment,
`infrastructure and knowledge.
`
`3
`
`Infrastructure for Charging andBilling
`
`In order to charge for mobile telephony services the network operator has to first
`capture the network usage of all of the network’s users including subscribers and
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`John Cushnieet al.
`316
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`roaming subscribers. This usage data then needs to be processedandthen set against
`the billing and charging modelsandtariffs in use.
`Billing tickets need to be collected and processed centrally so that the subscriberbills
`can be produced. Thecollection ofbilling tickets is often done by a mediation system,
`These systems may also carry out vendor specific translations on the billing ticket
`formats so that multi-vendor ONs can be implemented, or to allow the native billing
`tickets to be used on commercialbilling system, or on other centralised OSS systems
`used for data-mining. The heterogeneous nature ofmost mobile networks may be very
`problematic with many different file formats and standards being involved. Onceal]
`the billing tickets have been collected and pre-processed into a standard formatthat
`the billing and other OSS systems can understand they may them be used to produce
`the invoices andbills for the subscribers.
`The ETSI [1] standards recommend a Charging Gateway Function (CGF)to handle
`the billing record generation. Twobilling records are generated, one by the GGSN for
`the Internet part and one by the SGSNfor the mobility (radio) part.
`Current GSM billing systems have difficulties implementing charging for 1G GSM
`non-voice services and it
`is unlikely that existing billing systems will be able to
`processthe large numberofnewvariables introduced with 2G and 3G networks.
`An added complication for GPRS charging is the overlap and convergence to the
`Internet and the multitude of diverse systems connectedto it. In addition to the inter-
`charging between the mobile and fixed telephone networks inter-charging between
`the mobile networks and Internet providers will be required and this will add to the
`operational costs of running the 2G and 3G services in parallel to the 1G GSM
`network. With the already proposed Internet charging models the inter-charging
`between the mobile and Internet network providers has the potential to become very
`complicated and may include requirements for additional billing and charging
`systems for the required accounting. The addition of GPRS to the GSM mobile
`network modifies the call flows for Internet packet data as in Figure 1 and includes
`the required gateway to Internetservices and external networks:
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`ied Fig. 1. GSM 2G GSM Call Flow with GPRS
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`317
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` Evolution of Charging and Billing Models
`
`Network operators may also have packet counting systems in the network that will
`produce additional billing and charging information that may require processing by
`the billing systems.
`The GPRSrelated billing tickets may be ofa different format to the ones produced by
`the MSCs and may includedata on the amounts of packets exchanged during GPRS
`sessions. Extensions to the mediation methods may be implementedforthe collection
`and pre-processing of the GPRSrelated billing tickets that may then be fed to the
`billings systems. For 3G there will be the addition of UMTS Mobile Switching
`Centers (UMSC) for UMTSspecific traffic.
`Oncethebilling ticket information has been collected from the network the mobile
`network requires a billing and charging system to make sense of all the data and
`produce the invoices and bills for the subscribers, and also to produce the cross-
`charge data for partner network providers. The actual cost of providing and
`maintaining such a billing system may be anything up to 50% of the total
`infrastructure investment and annual turnover of the mobile network. The billing
`system therefore needs to be able to provide a good deal of added value to make the
`investment worthwhile. This provides a valid justification for simplifying the billing
`function and investigating the use of charging models based on fixed price
`subscriptions and bulk purchaseoftalk time and data bandwidth in the network.
`Most mobile network operators currently offer contract subscriptions, which include a
`line rental element plus a contract rate for telephony airtime, usually based on call
`duration. In addition to the contract subscriptions the network operators offer “pre-
`paid’ contracts where the subscriber pre-pays for the airtime used in the network.
`From a commercial viewpoint pre-paid makes sense for the network operators, since
`they will receive payment from subscribers prior to the consumption of resources.
`This simplifies revenue collection, but with the downside of increased complexity in
`the ON to prevent subscribers from over-spending on their ‘pre-paid’ subscription.
`With the addition of Internet access via GPRS and UMTSexisting mobile network
`subscriptions need to be extendedto include charging for the Internet services used by
`the subscribers. Just how to charge for the Internet services offered to and used by the
`subscribers is the major challenge to the mobile networkproviders.
`In most commercial environments some kind offraud is normally present. Mobile
`networks are no exception. The vast array ofbilling ticket information produced by
`the ON in mobile networks can be processed offline and used effectively for fraud
`detection. Again the infrastructure investments for such systems are high and their
`added value has to be proved. Fraud detection fits quite nicely into the billing and
`charging models and they often go hand in hand. An example of fraud in GSM
`networks is the running up oflarge bills on stolen mobile phones. This can be
`detected using the billing data and the mobile phone being used can be blockedin the
`network, but incurs a high cost in the real-time monitoring of the networktraffic data
`and the associated systems and staff. With the addition of 2G and 3G GSM the
`opportunity for fraud increases and the network operators need to be aware of the
`different kinds of fraud that are possible and may occur.
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`Metered Charging
`This pricing modelis already in use with many Internet service providers (ISPs) and
`European mobile and fixed line telephone networks. The model involves charging the
`subscriber for the connection to the service provider on a monthly basis and then
`charging for metered usage ofthe service. The usageis usually measured in units of
`time and there is often a ‘free’ period of usage included with the monthly fee,
`Variations on this model include having scaled subscription charges that increase with
`the metered usage.
`in 2G and 3G GSM networks may become commercially
`The use of this model
`problematic since subscribers may leave GPRSsessions open endlessly without the
`handset being powered on. Metered charging based on time for such usage may prove
`prohibitive. However, if the usage is based on other session parameters, for example
`number of packets transmitted/received,
`then the commercial impact becomesless
`and the model maybeusable in mobile networksfor data.
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`Fixed Price Charging
`This pricing modelis similar to that used by some USfixedline telephone networks
`for localcall charging. The network service provider sets a fixed rental charge for the
`telephone connection andall local calls are then free of charge with metered charging
`used for long-distancecalls.
`The advantage of this charging modelis that call data for local calls does not need to
`be collected and processed, providing a commercial saving for the network operator
`in the billing systems and mediation systemsinfrastructure.
`Disadvantages of this model include no added revenue for the service providers in
`times of above average usage on the network, and congestion may also become an
`issue if the network is under provisioned for the number of possible subscribers at
`peak times. This provides a strong argumentfor using chargingandbilling to improve
`congestion control by dissuading subscribers from using the network through higher
`cost for the provided services.
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`318 John Cushnie etal.
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`4 Charging Models
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`There are many charging models that have been proposed [9] for the current and
`future Internet as well as thosetraditionally employed by the mobile and fixed line
`telephone networks. Most, if not all, of the Internet charging models are equally
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`applicable for use in the mobile networks, especially with the introduction of 2G and
`3G GSM systems. Below is a discussion of someof the proposed charging models,
`and how they can be adapted to the mobile network markets.
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`Packet Charging
`Packet Charging is specific to Packet Switching [5] networks and involves the
`capturing and counting the number of packets exchanged in a session. This is 4
`proposed methodof metering Internettraffic and being able to cross-charge between
`networks
`as well as
`ISP and mobile subscribers. This model
`requires
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`unplementation of packet counting systems in the network and complex billing
`systems that can process the packet data on a subscriber and customerbasis.
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`Evolution of Charging and Billing Models
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`The advantage of this method of charging is that the absolute usage ofthe network
`and services can be metered, calculated andbilled for very accurately, as long as the
`packetinformation can be capturedefficiently.
`The major disadvantage of Packet Chargingis that the cost of measuring the packets
`may be greater than their actual value, both from an infrastructure investment and
`additional network traffic viewpoint. This maylead to packet charging being used as
`a policing tool to ensure that network bandwidth is used efficiently and not over
`consumed by the network subscribers, rather than as a direct charging model.
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`Expected Capacity Charging
`This charging model[9] allows the service providerto identify the amount of network
`capacity that any subscriber receives under congested conditions, agreed on a usage
`profile basis, and charge the subscriber an agreed price for that level of service. The
`subscribers are charged for their expected capacity and not the peak capacity rate of
`the network. Charging involves using a filter at the user network interface to tag
`excesstraffic: this traffic is then preferentially rejected in the network in the case of
`network congestion but
`is not charged for; charges are determined by the filter
`parameters.
`This model has the advantagethatthe price to the subscriberis fixed and predictable
`whichin turn permits the network provider to budget correctly for network usage. The
`expected capacity model also gives the network provider a more stable modelof the
`long-term capacity planning for the network. This model fits is well with mobile
`networks and the administration of the agreed expected capacity would be done as
`part of the normal subscriber administration tasks.
`One disadvantageis that the network operator hasto police the actual capacity of the
`network used by subscribers and act accordingly by limiting the subscribers service to
`whathas been purchased, or by invoicing the subscriber for the extra capacity used,
`on a meteredtariff for example.
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`Edge Pricing
`Proposed in [10] this model charges for the usageat the ‘edge’ of the network scope
`for the subscriber, rather than along the expected path of the source and destination of
`the calling session. The networks in turn then cross-charge each other for the usage at
`the network ‘edges’.
`Edge pricing refers to the capture of the local charging
`information. Once captured the information can be used for any kind of charging
`including metered, fixed or expected capacity, for example. Past research [13] has
`shown that much ofthe observed congestion on the Internet is at the edges of the
`individual networks that make up the Internet. The use of edge pricing may be
`effective as a policing method to monitor and alert the network operators to such
`congestion.
`This approach has the advantagethatall session data can be captured locally and does
`not involve exchangingbilling data with other networks and partners for subscriber
`billing, as for current roaming arrangements between mobile networks.
`A disadvantage with this modelis the lack of visibility of the routing via external
`networks andthe costs ofthat traffic to both networks. The cost of collection of the
`data may again also be an influencing factor in the selection of this method, as for
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`Packet Charging above. The cost ofcollecting the edge usage information may be in
`excess ofthe value ofthe collected information.
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`Paris-Metro Charging
`This charging model, proposed in [11], introducesthe concept oftravel class, as used
`on public transport systems, to network traffic and relies on providing differentiateg
`levels of service based on customer usage pricing only. The scheme assumes that
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`become self-regulating at periods of high usage. When the network becomes
`congested and all the capacity in first class is filled subscribers may downgrade to
`second class to improvetheir own network performance,
`This charging model may work well
`in GPRS and UMTSnetworks and allow
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`subscribers to prioritise network traffic,
`for e