Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/7035
標題: W-CDMA系統下之有效率的速率與能量控制:Cross Layer Design
A Cross Layer Design for Efficient Rate and Power Control in W-CDMA System
作者: 吳學曜
Wu, Hsueh-Yao
關鍵字: Quality of Service;服務品質;Radio Resource Allocation;W-CDMA;Rate Allocation Scheme;Multiple Step-Size Power Control;無線資源分配;展頻系統;速率分配;能量控制
出版社: 電機工程學系
摘要: 
若要保證多媒體服務的成功,QoS就必須小心的處置,在W-CDMA網路下,RRA是控制QoS的機制中所不可或缺的,而其中最重要的就是速率分配以及能量控制。我們在媒體存取控制層提出一套速率分配的方法;首先,將通道與緩衝器的狀況區分成六種情況,每種情況都有其對應的分數,我們再結合這兩種分數來做為分配速率的參數。接下來,依照通道與緩衝器的危機程度區分成六種情況,每種情況也都有其對應的分數,我們再結合這兩種分數來做為危機程度的參數。最後,我們利用所計算出來的兩種參數做為分配速率的依據,目標是所分配的速率能在相同的QoS條件下,可使平均的封包遺失率降至最低。由於重新分配速率的緣故,以致於SNR值在同時間會有劇烈的變動,因此我們另外在實體層提出一套能量控制的方法來改善此效應。我們將在最後對於所提出的方法作一個效能上的分析,並展示此方法在封包遺失率上有較佳的效能。

To ensure the success of wireless multimedia service, quality of service (QoS) has to be implemented with care. Radio resource allocation (RRA) is one of the most important issue and is essential in wireless networks. Among the elements of RRA, both rate allocation and power control play important roles in multimedia W-CDMA networks. A rate allocation power control scheme is proposed to take considerations at both the channel state and the buffer state in MAC layer. First, channel state and buffer state are divided into six conditions. The score of each condition is determined by two kinds of allocation parameter. Second, the score of risk parameter is determined by the score of both channel risk state and buffer risk sate. Third, based on allocation parameter and risk parameter, we propose a rate allocation scheme for wireless multimedia W-CDMA systems, which aims at minimizing average packet dropping rate while maintaining QoS requirement of all active mobiles. Finally, we also apply a multiple step-size power control method which can avoid large variation of SNR while the rate allocation scheme is activated. The simulation results show that the efficiency and performance of the proposed rate allocation scheme and multiple step-size power control can effectively decrease average packet dropping rate.
URI: http://hdl.handle.net/11455/7035
Appears in Collections:電機工程學系所

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