Verification of a GPRS Charging System
in a Simulated Test Environment
Author: Kirsi Koskenheimo
Supervisor: Prof. Raimo Kantola
Contents
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Background and Goals
Flexible Charging in GGSN
Simulated Test Environment
Simulations and Results
Conclusions
Further Development
© Ericsson AB 2006
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Background and Goals
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Problem
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GGSN (Gateway GPRS Support Node) support starting at Finland
 Lack of knowledge about node, simulators and charging
How to solve it
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© Ericsson AB 2006
Familiarize with GGSN, simulators and flexible charging
Setting up a test network
 GGSN
 Outline (charging node simulator)
 Trembler (SGSN & MS/UE simulator)
 Sgsnemu (SGSN emulator)
 Dummynet (delay, queue and bandwidth limitation
simulator)
 Ethereal (network protocol analyzer)
Investigate the suitability of simulated test environment to testing
of flexible charging
 What is possible to test with simulators in test
environment?
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Flexible Charging in GGSN
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Until now, PS charging often based on flat rate (monthly fee)
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Flat rate pricing not enough especially on QoS network
Traditional charging volume and byte based
3GPP specification of Flow Based Charging (FBC)
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© Ericsson AB 2006
Possibility to separately charge services that use the same bearer
Identification of charging data
 Based on QoS
 Based on traffic destination
Charging rules
 Separate rules based on Access Point Name (APN)
 Separate rules for UL and DL
 Separate rules for users
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Different Browsing Areas
Free Area
Portal home
News Area
News
Search
Promotions
Customer Care
Sports
Business
Internet Area
International
Rest of the Internet
Ring tones
Clips
Games
Downloads Area
© Ericsson AB 2006
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Flexible Charging in GGSN
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Ericsson solution: Service Aware Charging & Control (SACC)
Enables charging based on different price levels
Pre- and Postpaid Charging
Byte- and Block-Based Charging
Time- and Volume-Based Charging (kuva)
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Simulated Test Environment
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Simulations and Results
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Determination of Test Cases
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Cover a wide range of GGSN charging
Focus on prepaid users
Tested functionalities
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© Ericsson AB 2006
Traffic filtering
Identification of Prepaid users
Charging at different time of day (ToD)
Service authorization (roaming, time)
Byte- and Block-Based charging
Time- and Volume-Based charging
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Simulations and Results
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Problems faced
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© Ericsson AB 2006
Lack of components
 (Not possible to generate all situations that exist in real life)
 Not possible to filter traffic
Some exact messages
 Not possible to perform with used simulators
Charging Data Records (CDR)
 No stable system
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Simulations and Results
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Results
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© Ericsson AB 2006
Simulated test environment is applicable to the testing of SACC
charging
Basic SACC functions were tested successfully with simulators.
 Traffic was filtered correctly
 Prepaid users were identified correctly
 Rating was dependent of ToD
 Services could be authorized successfully
 Services could be charged correctly based on time or
volume
 Services could be charged correctly based on byte or
block
Basic functionalities can be more easily performed with simulators
than with real charging nodes
More complex testing can also be executed but it requires more
knowledge of charging and coding.
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Conclusions
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A diverse test environment was set up, although all testing
possibilities were not used.
Knowledge of the SACC solution, the simulators and GGSN
configuration was obtained
The features that can be tested in the simulated test environment
were found and tested.
The created test environment enables more versatile testing than
what was performed in this thesis.
© Ericsson AB 2006
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Further Development
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More specific testing
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Specific message creation
 In hexadecimal format
Different rates for specific days (e.g. weekends)
 In hexadecimal format
Use of other PCs and simulators
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© Ericsson AB 2006
Sgsnemu
 Traffic generation
Dummynet
 Propagation delays
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Thank You
 Comments?
 Questions?
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Additional Slides
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3GPP Specification vs. Ericsson
Solution
PRS/
CRF
EUS
CCS/
CCF
SURP
SRAP/Gx
GGSN/TPF
CCF = Credit Control Function
CCS = Credit Control Server
CRF = Charging Rules Function
EUS = External Update Server
GGSN = Gateway GPRS Support Node
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SCAP/Gy
PRS = Policy and Rating Server
SCAP = Service Charging Application Protocol
SRAP = Service Rating Application Protocol
SURP = Subscription Update Request Protocol
TPF = Traffic Plane Function
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Time-Based Block Charging
Inactivity time period: 3 blocks (B)
User is charged in: B1, B2, B3, B4, B9
User will not be charged for: B5, B6, B7, B8
(time between the 2nd and the 3rd charging event is larger than 3B)
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Volume-Based Block Charging
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