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Seunghwa Lee and Eunseok Lee+
School of Information and Communication Engineering
Sungkyunkwan University
Suwon 440-746, South Korea
Context-adaptive services for overcoming various limitations of mobile environment
have become important. They have the potential to maintain appropriate service levels
according to the changing environment. However, most existing studies concentrate on
adaptation modules in a single system: client, proxy, or server. Hence, these systems suffer
from a concentrated workload when the number of users increases. This causes response
time delays to user requests. This paper proposes a novel adaptation system that
performs adaptation over distributed systems. The proposed system monitors the condition
of each system using adaptation modules that are deployed on the client, proxy, and
server, and selects the appropriate system on which to perform the adaptation. Therefore,
the proposed system responds rapidly and stabilizes the system operation, even when
overload is increased, such as by the increase in the number of user requests. We implemented
a prototype of the system in order to evaluate it, and tested the distributed processing
for multimedia content adaptation, simulating the overload on the server. We
compared the proposed system with the existing adaptation approaches, in terms of the
response time and system stability, and confirmed the effectiveness of the system through
these experimental results.
Received February 19, 2008; revised May 1, 2008; accepted July 10, 2008.
Communicated by Suh-Yin Lee.
* This work was supported by the Ministry of Knowledge Economy ITRC Program in Korea, and a result of
Basic Research Program of the Korea Science and Engineering Foundation. IITA-2008-(C1090-080-0046),
grant No. R01-2006-000-10954-0.
+ Corresponding author.