功率控制一直是分碼多重存取(CDMA)無線網路系統中一個很重要
的課題。在分碼多重存取通訊系統中，每一位使用者擁有各自獨特的
展頻碼來做為使用者之間傳輸的保護以及區分，進而達到更佳的頻譜
使用效益。然而，在有頻道衰減與干擾的環境中，會導致了多重路徑
干擾(MAI)和遠近問題(near-far problem)，這些問題會限制住系統
通訊品質及使用者容量。因此功率控制被提出來對付這些問題，利用
功率的調節來克服干擾的影響，達到較有效益的通訊品質。
本篇論文提出ㄧ個結合雙迴路控制設計的CDMA系統，此系統利用模
糊邏輯控制及多目標最佳化控制器調整目標訊雜比(target SINR)和
傳輸功率(transmission power)。之前的功率控制方法考慮達到每個
使用者所需求的訊雜比(SINR)目標值來維持良好的通訊服務品質
(QoS) ，或是減少傳輸功率來降低整體網路干擾。在本文當中，我們
利用多目標(Multi-ojective)觀念，整合上面所需要的設計目標。再
利用多目標最佳化方法，根據不同的通道情形調整目標比重值。此外
透過陰影系統(shadow system)和H_infty濾波器補償傳輸延遲的問
題並估測出傳輸功率，數個模擬的範例將驗證所提出方式的可行性及
優越的性能表現。

Power control is an important issue for code division multiple access (CDMA) systems to achieve higher communication link quality. In this study, an adaptive
two-loop power control scheme for CDMA systems is proposed. It includes an outer-loop controller and an inner-loop controller. A fuzzy logic controller (FLC) is designed to determine the target SINR for the required quality of service (QoS) in the outer loop to prevent vicious cycle, reduce target SINR tracking time, and lower outage probability. A shadow system with an H∞ filter (SS-H∞)
is used to compensate round-trip delay and uncertainty in the inner loop via a multi-objective (MO) optimization method.
Through MO optimization, the best compromise between target SINR tracking and the minimization of power consumption can be achieved. Combining these controllers in the outer loop and the inner loop, the proposed scheme can achieve a better performance in comparison with other existing schemes in CDMA communication systems.

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