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Algorithms 2009, 2(3), 953-972; doi:10.3390/a2030953
Article

Improving the Competitive Ratio of the Online OVSF Code Assignment Problem

1
 and 2,*
1 Academic Center for Computing and Media Studies, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan 2 Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
* Author to whom correspondence should be addressed.
Received: 7 May 2009 / Revised: 14 July 2009 / Accepted: 14 July 2009 / Published: 17 July 2009
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Abstract

Online OVSF code assignment has an important application to wireless communications. Recently, this problem was formally modeled as an online problem, and performances of online algorithms have been analyzed by the competitive analysis. The previous best upper and lower bounds on the competitive ratio were 10 and 5/3, respectively. In this paper, we improve them to 7 and 2, respectively. We also show that our analysis for the upper bound is tight by giving an input sequence for which the competitive ratio of our algorithm is 7 ― ε for an arbitrary constant ε > 0.
Keywords: online OVSF code assignment; online algorithm; competitive analysis online OVSF code assignment; online algorithm; competitive analysis
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Miyazaki, S.; Okamoto, K. Improving the Competitive Ratio of the Online OVSF Code Assignment Problem. Algorithms 2009, 2, 953-972.

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