Abstract
Orthogonal Variable Spreading Factor (OVSF) code assignment is a fundamental problem in Wideband Code-Division Multiple-Access (W-CDMA) systems, which plays an important role in third generation mobile communications. In the OVSF problem, codes must be assigned to incoming call requests with different data rate requirements, in such a way that they are mutually orthogonal with respect to an OVSF code tree. An OVSF code tree is a complete binary tree in which each node represents a code associated with the combined bandwidths of its two children. To be mutually orthogonal, each leaf-to-root path must contain at most one assigned code. In this paper, we focus on the online version of the OVSF code assignment problem and give a 10-competitive algorithm, improving the previous O(h)-competitive result, where h is the height of the code tree, and also another recent constant-competitive result, where the competitive ratio is only constant under amortized analysis and the constant is never determined. Finally, we also improve the lower bound of the problem from 3/2 to 5/3.
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Chin, F.Y.L., Ting, H.F., Zhang, Y. (2007). A Constant-Competitive Algorithm for Online OVSF Code Assignment. In: Tokuyama, T. (eds) Algorithms and Computation. ISAAC 2007. Lecture Notes in Computer Science, vol 4835. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-77120-3_40
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DOI: https://doi.org/10.1007/978-3-540-77120-3_40
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-77118-0
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