2. Research On Streaming Media Online Charging System

Research On Streaming Media Online Charging
System
ZhenGuo Kuang, Zhihui Ji
National Network New Media Engineering Research
Center, Institute of Acoustics, Chinese Academy of
Sciences
Graduate University of Chinese Academy of Sciences
Beijing 100049, PRChina
{kuangzg,jizh}@dsp.ac.cn
Abstract—Prepaid services require the billing system to offer
real-time billing and service control in streaming media
applications. However, current billing approaches suffer from
high risk of bad debts to operators or lack of the function of
service termination during service consumption. On the basis of
streaming media services’ features, a Streaming Media Online
Charging System (SMOCS) is developed in this paper. The online
charging process for typical streaming media service-VoD service
is proposed, and a performance optimization scheme by adopting
main memory database technology is provided to improve the
efficiency of online charging. When comparing with shared
memory schema, SMOCS obtains an obvious average processing
time reduction (by almost 95%), and it could effectively satisfy
real-time billing requirements of streaming media services.
Keywords-Online Charging System; streaming media; real-time
billing; main memory database; Diameter CC
I. INTRODUCTION
With the rapid development of network technology and
more and more needs of customers, the streaming media
services such as Mobile TV, Video-on-Demand (VoD) and
Internet TV spread rapidly. Service diversities and its complex
billing requirements are in need of more powerful billing
system [1].
The postpaid billing approach is rarely adopted by
operators for the following reasons: Firstly, it is difficult to
control bad debts caused by poor credit customers, which
causes huge losses to operators every year [2]; secondly,
customers can’t check their real-time balance and bill records
[1]. The quasi real-time billing approach is also called hot
billing, by which the billing system deducts service fees
immediately after the customer’s service consumption. Though
we can improve the performance of billing systems to shorten
the rebate cycle, the quasi real-time billing approach is
essentially an off-line billing approach and the fixed time
interval will cause operators to suffer higher risk. In addition, it
This work was undertaken at National Network New Media Engineering
Research Center, Institute of Acoustics, Chinese Academy of Sciences and the
Graduate University of Chinese Academy of Sciences, and was supported by
Hi-Tech Research and Development Program of PRChina under contract
number 2008AA01A317 and National Key Technology R&D Program of
PRChina under contract number 2008BAH28B04.
Hong Ni, Lei Liu
National Network New Media Engineering Research
Center, Institute of Acoustics, Chinese Academy of
Sciences
Beijing 100190, PRChina
{nih,liul}@dsp.ac.cn
lacks the function of service termination during the process of
customer consumption [2]. With the increase of service types
and Internet transactions, customers need to pay for valueadded
services provided by the third-party Content Provider or
Service Provider. So a large amount of expenses may arise
within a short time, and this increases arrearage risk further [3].
Online charging approach is realized by a mechanism that
whether customers can use the service or not depends on their
account balance. For example, the online charging of voice
service is implemented by means of intelligent network
through CAMEL protocol [8].
Obviously, postpaid billing approach or quasi real-time
billing approach can’t satisfy operators’ demands for the
control of bad debts; neither can they satisfy the customers’
demands for checking their real-time balance and bill records.
In this paper we analyze the shortcomings of existing billing
approaches at first; Then we propose a Streaming Media
Online Charging System (SMOCS) based on features of
streaming media services and their supporting networks [4][5]
and improve its real-time performance by adopting main
memory database technology. SMOCS ensures that streaming
media services are available only when customers have enough
balance. It also offers the function of inquiring real-time
balance and bill records, and provides the function of real-time
service termination during service consuming, which can
effectively satisfy the needs both of operators and customers.
The paper is organized as follows. The design of Streaming
Media Online Charging System is proposed in section 2. A
performance optimization scheme to improve overall
performance of the system is presented in section 3.
Experimental results are reported in section 4. Finally
conclusions are given in section 5.
II. THE DESIGN OF ARCHITECTURE OF SMOCS
In this section, we give a brief introduction to streaming
media and propose the framework of SMOCS. After in-depth
research on Authentication � Authorization and Accounting
(AAA) protocol, we adopt the Diameter Credit Control
protocol (DiameterCC) [7] in SMOCS to support prepaid
services. Finally, according to the framework of SMOCS, the
online charging process of VoD service is designed.
1-4244-2424-5/08/$20.00 ©2008 IEEE 309
ICCS 2008

A. A brief introduction to streaming media
Streaming media refers to the continuous audio/video
stream being transmitted and broadcasted on data network
according to time sequence. With the progress of 3G networks
and the improvement of network condition, the streaming
media services develop rapidly and attract more and more
attention. There has been a streaming media subject- "highperformance
information broadband network 3TNet" subject
that belongs to China’s "863 project". Beginning with typical
broadband streaming media services such as Internet TV, VoD,
High Definition TV, Time-Shifted TV and so on, the subject
established a high-performance, WAN (MAN) broadband
demonstration network 3TNet which is applicable to real-time
transmission of Internet TV and other media streams, and it
was deployed in the Yangtze-River-Delta region. It is so far the
largest integrated application platform for IPv6 interactive
multimedia broadband network.
B. Architecture of Streaming Media Online Charging System
The function of Online Charging System (OCS) is to
response to charging requests in real time, finish rating
according to billing policies, give feedbacks after deducting
corresponding service fees and generate billing details.
Furthermore, OCS ought to monitor customers’ account
balance and control service consumption in real time. In the
specification of R5 & R6, 3GPP proposed OCS and defined the
reference framework of OCS for IMS network [6]. The OCS
proposed by 3GPP is aimed at charging requirements of
telecom services and it is complex to support CAMEL
protocol. However, streaming media services have their own
features as multimedia, personalized interaction,
humanization, and their supporting networks are almost IPbased
broadband networks. In order to make the SMOCS
support streaming media services more effective and the
system be more scalable and more compatible, we design a
Common Interface Function (CIF) module to unify the
interaction with external devices, add the Session Management
module to monitor charging request session information and
adopt DiameterCC protocol to interact with streaming media
service control servers. On the principle of the separation
between billing control and billing applications, according to
function requirements of OCS in streaming media applications,
taking advantage of 3GPP’s related research achievements
[14], we designed architecture of Streaming Media Online
Charging System and it consists of Common Interface module,
Charging module, Account Balance Management module,
Charging gateway module, Rating module and Session
Management module. The detailed architecture of SMOCS is
shown in Figure 1.
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Figure 1. Framework of the Streaming Media Online Charging System
Access Convergence Router (ACR) and Media Server (MS)
are service control network elements in streaming media
application systems. They interact with SMOCS by
DiameterCC Protocol and realize the online charging function
in coordination. ACR in the backbone of network controls the
multicast of Internet TV, High Definition TV, Broadband
access, etc. MS around the edge of Metropolitan Area Network
(MAN) provides streaming service of VoD, Time-Shifted TV,
Time-shift VoD and other stream services for terminals.
SMOCS specifies a CIF module to unify the interaction with
external network devices and enhance the system’s
compatibility. CIF module interacts with external network
devices through DiameterCC Protocol and IPDR [10] file for
real-time billing information and billing details respectively;
Charging function module is one of control modules and it
supports charging function based on session, beater and events;
Rating function module is the charge calculation module and it
supports charging calculation for a variety of services through
configuration of billing rules; Main function of Account
Balance Management Function (ABMF) is monitoring
customers’ account balance, including reserving/releasing
account balance, deducting service fees, inquiring real-time
balance, etc. When a customer’ balance is below a dynamically
calculated threshold based on the customer’s level and history
bill records, the module reminds the customer to recharge
through short messages or E-mails; Main function of Session
Management Function (SMF) is to establish/close sessions,
monitor status of sessions and maintain session information;
According to pre-determined strategy in SMOCS, charging
Gateway produces IPDR files for further dealings in
accounting system [8].
C. Research on the AAA protocol
The Remote Authentication Dial In User Service
(RADIUS) protocol is one of the most popular AAA protocols
and it is widely used for its simpleness, easy management and
nice expansibility. However, RADIUS protocol can’t be
adapted to current networks for its own defects, such as
transmission by the unreliable UDP protocol, simple package
drop mechanism, without rules about retransmission and the
concentrated billing service mechanism. So the Diameter
protocol [10] is proposed. The Diameter protocol provides a
safe, reliable and scalable framework for various authentication
authorization and accounting services, and it can be applied to
practical applications conveniently. Compared to RADIUS
protocol, Diameter protocol has a nice mechanism to handle
transmission failure, the ability to rapidly detect the receiving
peer, and a better package drop mechanism. In addition, it
supports end-to-end security and makes authenticates and
authorizes for each session to ensure security. Based on
Diameter, DiameterCC protocol defines a billing mechanism
for prepaid services, adopts credit control mechanism to realize
session based charging, bearer based charging and event based
charging. And it satisfies billing requirements for prepaid
services. Therefore, SMOCS designed in this paper interacts
with external network devices by this protocol to realize online
charging function.

D. Online charging process of VoD service
According to framework of SMOCS shown in Figure1, we
take VoD service as an example to discuss online charging
process of streaming media services. The detailed online
charging process of VoD service is shown in Figure 2. The
process includes six sub-processes: Sub-process 6 assesses the
customer’s account balance and the accumulated usage of the
service. Sub-process 7 calculates charges of the charging
request; Sub-process 8 deducts service fees from the
customer’s account; Sub-process 11 produces IPDR files
according to billing detail information; Sub-process 13 refunds
after customer‘s service failures; Sub-process 14 reminds the
customer to recharge when the account balance is below a
dynamically-calculated threshold.
III. PERFORMANCE OPTIMIZATION OF SMOCS
There are a lot of data accessing operations during the
process of online charging, so the efficiency of data accessing
operations plays an important part in real-time performance of
SMOCS. In addition, the SMOCS has been an important part
Figure 2. The detailed online charging process of VoD service
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Obviously, MSOCS has the following advantages: Firstly,
SMOCS adopts advanced DiameterCC protocol to support
streaming media prepaid services, which avoids the complexity
of supporting CAMEL protocol and security problems caused
by AAA protocol; Secondly, the CIF module unifies the
interaction with external network devices, which enhances
compatibility of the system; Furthermore, the SMF module
manages the online charging session information and it is
convenient to support multi-services and flexible billing
policies in SMOCS. Finally, ABMF reminds the customer to
recharge, when the customer’s balance is below a dynamically
calculated threshold based on customer’s level and history bill
records, and this function greatly reduces service terminations
due to insufficient balance, while reducing the pressure on
SMOCS caused by real-time service control.
of streaming media service platform and has direct impact on
the use of normal services, and thus it is requested to offer
higher performance in security, real-time, reliability, etc. To
improve the efficiency of data accessing operation and overall
performance of SMOCS, we provide a system performance
optimization schema in this section.

A. Summary of data accessing methods
The widely used data accessing methods including Open
Database connectivity (ODBC) method, sharing memory
method [11] and the main memory database method [12], etc.
The introductions to them are as follows.
By ODBC method, data updating and inquiry are realized
by Database Management System (DBMS) and the data
needed in applications is accessed from the database through
ODBC. Data management and transaction assurance are
implemented by DBMS, which greatly reduces the difficulty
of application development. Data accessing relies on DBMS
by this method, so the delay of SMOCS’s response to charging
requests will increase and concurrency performance of
SMOCS will be limited by the overall performance of used
database.
By sharing memory method, the data storied in shared
space of main memory is provided for all processes and we
don’t have to save more copies. The relatively stable or readonly
data can be rapidly accessed through shared memory. The
application program does the data updating procedure and
ensures the consistency of the data between shared memory
and database, and thus it increases the difficulty to the
development of application program. By this method we can
access stable data easily, but can’t handle the frequent data
updating procedure effectively in SMOCS.
By main memory database method, almost all data are
stored in main memory to be operated directly. Architecture of
main memory database has been re-designed on the basis of all
data in main memory, and corresponding improvement has
been made in data cache mechanism, fast algorithms, parallel
operations, etc. So the data processing speed of main memory
database is 10 to 100 times that of traditional database. Main
memory database such as TimesTen [13] and eXtremeDB has
been widely used in applications.
B. Performance optimization of Streaming Media Online
Charging System based on Main Memory Database
Through the analysis of data accessing methods above, we
can greatly improve the efficiency of data accessing. It is
realized by adopting main memory database to manage
customers’ basic information, account balance, accumulated
usage and fees, session information, and billing detail
information in SMOCS. This can greatly improve the speed of
online charging, concurrency and real-time performance of
SMOCS. So a main memory database function (MMDB
Function) module is added to SMOCS’s framework to manage
data information, which not only can reduce the difficulty of
developing SMOCS, but also improve overall performance of
the system. Integrated with main memory database, new
framework of SMOCS is shown in Figure 3.
Making use of main memory database, the new SMOCS
has the following additional advantages:
• Data accessing speed of SMOCS can be improved
greatly due to the storage of account balance, the
accumulated usage and fee, and session information in
main memory;
312
• The main memory database not only improves the
speed of data accessing, but also ensures the data
integrity and reliability by its own copy mechanism
and security strategy;
• For large-scale concurrent charging requests and
shared data accessing, adopting lock mechanism in
main memory database, SMOCS ensures that multithreads/processes
can access critical data safely, and
thus reduces the difficulty of system development.
Figure 3. Framework of SMOCS based on main memory database
IV. EXPERIMENTAL RESULTS
To verify reasonableness of SMOCS’s framework and
performance optimization results of the system, the functions
and performance of the system are tested, with the emphasis
on the average online charging response time. Description of
the test is as follows.
• Oracle9i and Oracle Times Ten In-Memory Database
7.0.5 as database were used respectively. The database
and SMOCS were deployed on two different servers in
the LAN.
• The online charging process of VoD service was
tested. There were 10,000 videos charged by times,
each video was charged differently and every
customer’s ceiling charges are less than��10 within
an account cycle.
• A condition of 100,000 customers sending 100,000
charging requests in all was simulated, and the
customers’ basic information and account balance
were stored in database. The session information and
billing details produced during the online charging
process were saved into database.
• The online charging process was simplified as
initializing a session, accessing customer’s account
balance and accumulated usage, rating, deducting
service fees and generating billing details, the
processing time of online charging was recorded in the
test and the average processing time was computed.
The test includes the following two groups:
• Shared memory scheme. The SMOCS loaded the
customers’ basic information and account balance,
price information of videos and other data at startup,

and then initialized customers’ accumulated usage and
fees. Session information, balance updating and billing
detail information were saved into database during the
process of online charging.
• Main memory database scheme. The main memory
database processed the loading and storing data such
as customers’ account balance, accumulated usage and
fees, session information, billing detail information
and so on. The SMOCS modules accessed data
through standard interface.
Four groups of experimental results are shown in Figure 4
and we can draw the conclusions: optimized by main memory
database, the average processing time of online charging of
SMOCS is reduced by almost 95%, comparing with shared
memory schema. In use of main memory database technology,
SMOCS can effectively access data during online charging
process, which enhances the concurrency and real-time
performance of SMOCS. Therefore, a great improvement of
the system’s overall performance is achieved.
Figure 4. Average processing time of Online Charging of SMOCS
V. CONCLUSIONS
In streaming media applications, post-paid billing approach
and quasi-real-time billing approach can’t satisfy streaming
media operators’ demand for the control of bad debts, neither
can they satisfy customers’ demand for checking their realtime
balance and bill records. Prepaid services paid monthly
are not widely accepted for their relatively high monthly rent,
due to unrestricted amount of service usage. The disadvantages
of existing billing approaches and practical requirements of
streaming media services are analyzed firstly. And then
SMOCS is proposed according to features of streaming media
services and their supporting networks. Furthermore the online
charging process of typical streaming media service-VoD
service is introduced. Finally by using main memory database
technology, an optimization scheme is provided to improve
overall performance of the system. According to the
experimental results, SMOCS obtains an obvious reduction on
the average processing time of online charging. SMOCS can
effectively support the development of streaming media
services and be helpful to make a rapid promotion for
streaming media services.
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ACKNOWLEDGMENT
This work is supported by Hi-Tech Research and
Development Program of China under contract number
2008AA01A317 and National Key Technology R&D
Program of China under contract number 2008BAH28B04,
their support is highly appreciated. The authors would like to
thank the anonymous reviewers. Their valuable comments
have significantly improved the quality of this paper. Their
efforts are highly appreciated.
[1]
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