DS/CDMA 蜂巢式行動電話網路中向下鏈路的功率控制

Abstract

本篇論文探討 CDMA 蜂巢式行動電話網路中向下鏈路（基地台－－＞行動 台）功率控制方法之設計。向下鏈路通信中，存在著距離遠近的問題以及 多路由短期信號衰褪效應，在基地台必需有效且及時地調整傳輸功率以維 護良好的通信品質，在此我們提出兩個向下鏈路的功率控制機制；一是多 重調度式 SIR 型，另一是分散式平衡法則，我們對於上述的 CDMA蜂巢式 行動電話網路建立一個電腦模擬環境，在這個模擬的環境中包含了整個 CDMA 蜂巢式行動電話的網路架搆，譬如基地台的位置，行動台的地理分 布，以及都卜勒效應和短期信號衰褪效應等。我們探討系統參數對系統效 能的影響並設計其最佳的系統參數。最後，我們比較這兩個向下鏈路的功 率控制機制的系統效能以及它們的應用範疇。 In this paper, the down-link (base station $\rightarrow$ mobile station) power control in a CDMA cellular mobile radio communication network is designed. For down-link communication, there arises a near-far problem and has a multipath short-term fading. The transmitting power of the base station must be effectively adjusted in real time fashion in order to achieve good communication quality. We will propose two down-link power control mechanisms. One is the multiple-step SIR-based power control mechanism, and the other is the distributed balancing power control mechanism. We construct a simulation environment for the above mentioned CDMA cellular mobile radio network; the simulation environment includes the CDMA cellular mobile radio network configuration, the position of the base stations, the geographical distributions for the mobile stations, the Doppler effect, and the short-term fading,$\cdots$,etc. We investigate how the system performance is affected by system parameters and design the optimal parameters for the two down-link power control mechanisms. Addtionally, we compare these two down-link power control mechanisms and discuss their application ranges.