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Dissertation angenommen durch: University Duisburg-Essen,
Campus
Duisburg, Faculty of Engineering Sciences, Department Electrical and
Electronic Engineering and Information Technology, 2003-10-23
BetreuerIn: Prof.
Dr. -Ing Axel Hunger ,
University Duisburg-Essen, Campus Duisburg, Faculty of Engineering
Sciences, Department Electrical and Electronic Engineering and
Information Technology
GutachterIn: Assoc. Prof. Dr. Mahamod Ismail ,
Universiti
Kebangsaan Malaysia, Bangi, Malaysia, Faculty of Engineering,
Department of Electrical Engineering
GutachterIn: Prof. Dr.
-Ing. Axel Hunger , University Duisburg-Essen, Campus Duisburg, Faculty
of Engineering Sciences, Department Electrical and Electronic
Engineering and Information Technology
Schlüsselwörter in Englisch: Active Networks,
Streaming Multimedia
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Abstrakt in Englisch
A problem in today’s Internet
infrastructure may occur when a streaming
multimedia application is to take place. The information content of
video and audio signals that contain moving or changing scenes may
simply be too great for Internet clients with low bandwidth capacity if
no adaptation is performed.
In order to satisfactorily reach clients with various bandwidth
capacities some works such as receiver-driven multicast and resilient
overlay networks (RON) have been developed. However these efforts
mainly call for modification on router level management or place
additional layer to the Internet structure, which is not recommended in
the nearest future due to the highly acceptance level and widely
utilization of the current Internet structure, and the lengthy and
tiring standardization process for a new structure or modification to
be accepted.
We have developed an improved active network approach for distributed
and dynamic streaming multimedia environment with heterogeneous
bandwidth, such as the case of the Internet. Friendly active network
system (FANS) is a sample of our approach. Adopting application level
active network (ALAN) mechanism, FANS participants and available media
are referred through its universal resource locator (url). The system
intercepts traffic flowing from source to destination and performs
media post-processing at an intermediate peer. The process is performed
at the application level instead of at the router level, which was the
original approach of active networks. FANS requires no changes in
router level management and puts no additional requirement to the
current Internet architecture and, hence, instantly applicable.
In comparison with ALAN, FANS possesses two significant differences.
From the system overview, ALAN requires three minimum elements:
clients, servers, and dynamic proxy servers. FANS, on the other hand,
unifies the functionalities of those three elements. Each of peers in
FANS is a client, an intermediate peer, and a media server as well.
Secondly, FANS member’s tracking system dynamically detects the
existence of a newly joined computers or mobile device, given its url
is available and announced. In ALAN, the servers and the middle nodes
are priori known and, hence, static. The application level approach and
better performance characteristics distinguished also our work with
another similar work in this field, which uses router level approach.
The approach offers, in general, the following improvements:
• FANS promotes QoS fairness, in which clients with lower bandwidth are
accommodated and receive better quality of service • FANS introduces a
new algorithm to determine whether or not the involvement of
intermediate peer(s) to perform media post-processing enhancement
services is necessary. This mechanism is important and advantageous due
to the fact that intermediate post-processing increases the delay and,
therefore, should only be employed selectively.
• FANS considers the size of media data and the capacity of client’s
bandwidth as network parameters that determine the level of quality of
service offered.
By employing the above techniques, our experiments with the Internet
emulator show that our approach improves the reliability of streaming
media applications in such environment.
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