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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
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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