模糊式蜂巢選擇及適應性重整機制於階層式蜂巢系統通道分配之研究
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2007
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Abstract
由於訊務量劇烈的增加，使得行動通訊中的無線通道變得極為珍貴而需被謹慎的分配。通道配置上，除可利用通道分配技術來增加頻譜使用率，同時亦可利用階層式的架構，增加蜂巢的覆蓋面積，以提升通道使用率。因此，本論文將探討運用於階層式蜂巢網路上通道分配之改進方式。本研究設計的通道分配處理器為運用模糊演算法及適應性重整的機制，妥善分配資源以供行動台使用。其中處理器分三個部分：模糊路徑選擇器、模糊蜂巢選擇器，及通道分配評估器。設計架構主體，首先以模糊聚類方式依基地台可利用程度，決定所欲傳輸的路徑，藉此降低搜尋時間。接著以模糊演算法依行動台移動速度及蜂巢內有效資源決定所要分配的蜂巢層，以降低新呼叫阻塞率。為了避免移動速度慢的行動台佔用巨蜂巢內資源，以及快速行動台交遞率的增加，將採用適應性重整機制，重新選擇合適的蜂巢層，以降低交遞率。
經模擬得知，相較於使用門檻值控制機制，本研究所使用的方法平均改善13.48％阻塞率及56.48％的交遞率，故證明本研究所提方法，在解決通道分配問題上確實有明顯較佳之效能。
Since the traffic in mobile communication system increase rapidly, the radio channels are unable to meet the demand and must be assigned more accurately. It is possible to improve the channel allocation efficiency by upgrading the utility rate of spectrum. Further, the flexible application of hierarchical structure can be used to increase the coverage area and improve the utility rate of channels. In this thesis, Fuzzy Path Selector was developed to make path selection to meet the property of balanced-load cellular network. Fuzzy Cell Selector then was used to determine the cellular layer according to the velocity of MS and the resource state of cells to reduce the blocking rate. Third, Channel Assignment Evaluator was used to do adaptive repacking for reducing the dropping rate. The simulation results of proposed strategy in this thesis improved the blocking rate of 13.48% and the handoff rate of 56.48％ compared to traditional threshold controlling mechanism. It can be a better choice for improving channel allocation efficiency.
Since the traffic in mobile communication system increase rapidly, the radio channels are unable to meet the demand and must be assigned more accurately. It is possible to improve the channel allocation efficiency by upgrading the utility rate of spectrum. Further, the flexible application of hierarchical structure can be used to increase the coverage area and improve the utility rate of channels. In this thesis, Fuzzy Path Selector was developed to make path selection to meet the property of balanced-load cellular network. Fuzzy Cell Selector then was used to determine the cellular layer according to the velocity of MS and the resource state of cells to reduce the blocking rate. Third, Channel Assignment Evaluator was used to do adaptive repacking for reducing the dropping rate. The simulation results of proposed strategy in this thesis improved the blocking rate of 13.48% and the handoff rate of 56.48％ compared to traditional threshold controlling mechanism. It can be a better choice for improving channel allocation efficiency.
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階層式蜂巢網路, 通道分配技術, 模糊蜂巢分配, 適應性重整機制, Hierarchical Cellular System, Channel Assignment Scheme, Fuzzy Cellular Assignment, Adaptive Repacking Mechanism