(1+ε)-competitive algorithm for online OVSF code assignment with resource augmentation

  • Authors:

  • Yuichi Asahiro;Kenta Kanmera;Eiji Miyano

  • Affiliations:

  • Department of Information Science, Kyushu Sangyo University, Fukuoka, Japan 813-8503;Department of Systems Design and Informatics, Kyushu Institute of Technology, Fukuoka, Japan 820-8502;Department of Systems Design and Informatics, Kyushu Institute of Technology, Fukuoka, Japan 820-8502

  • Venue:
  • Journal of Combinatorial Optimization
  • Year:
  • 2013

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Abstract

This paper studies the online Orthogonal Variable Spreading Factor (OVSF) code assignment problem with resource augmentation introduced by Erlebach et al. (in STACS 2004. LNCS, vol. 2996, pp. 270---281, 2004). We propose a (1+1/驴)-competitive algorithm with help of (1+驴驴驴)lg驴 h trees for the height h of the OVSF code tree and any 驴驴1. In other words, it is a (1+驴)-competitive algorithm with help of (1+驴1/驴驴)lg驴 h trees for any constant 0驴≤1. In the case of 驴=1 (or 驴=1), we obtain a 2-competitive algorithm with 2lg驴 h trees, which substantially improves the previous resource of 3h/8+2 trees shown by Chan et al. (COCOON 2009. LNCS, vol. 5609, pp. 358---367, 2009). In another aspect, if it is not necessary to bound the incurred cost for individual requests to a constant, an amortized (4/3+驴)-competitive algorithm with (11/4+4/(3驴)) trees for any 0驴≤4/3 is also designed in Chan et al. (COCOON 2009. LNCS, vol. 5609, pp. 358---367, 2009). The algorithm in this paper gives us a new trade-off between the competitive ratio and the resource augmentation when 驴驴3 (or 驴≤1/3), although the incurred cost for individual requests is bounded to a constant.