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 Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/27856

 Title: OVSF Code Assignment Strategies with Minimal Fragmentations for WCDMA Systems Authors: Chih-Min Chao Contributors: NTOU:Department of Computer Science and Engineering國立臺灣海洋大學:資訊工程學系 Keywords: Mobile computing;Personal communication services;Wireless communication;OVSF;WCDMA;3G Date: 2008 Issue Date: 2011-10-21T02:34:14Z Publisher: Computer Networks: The International Journal of Computer and Telecommunications Networking Abstract: Abstract:This paper handles the internal and external fragmentation problems of WCDMA systems using Orthogonal Variable Spreading Factor (OVSF) codes. Internal fragmentation occurs when the allocated data rate is larger than what is requested, while external fragmentation occurs when the OVSF code tree is too fragmented to support a call even if there is sufficient capacity remaining in the code tree. The key factor in solving these two problems is the OVSF code assignment strategy. Most works in the literature do not consider the time-varying and location-dependent channel conditions. In this paper, we formulate the fragmentation problem as a {\it multiple knapsack problem} where each OVSF code is considered as a knapsack. We propose single-code, time-shared strategies that %takes into account consider channel conditions while solving these fragmentation problems. Simulation results verify that our strategies efficiently use the precious wireless bandwidth. Relation: 52(12), pp.2331-2343 URI: http://ntour.ntou.edu.tw/handle/987654321/27856 Appears in Collections: [資訊工程學系] 期刊論文

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