第五代行動通訊系統功率控制方法之研究

Abstract

在我們提出的第五代蜂巢式系統[1]，就像分碼多重進接的系統一樣，所有的使用者都在相同的頻段傳送資料，所以任何過多的傳送功率都會增加此系統中整體的干擾。我們的系統在沒有功率控制的情況下，無法達到較好的鏈路品質和系統容量。為了克服在上行傳輸中的遠近問題，我們採用開迴路功率控制，使得被同一台基地台服務的使用者，到達基地台的訊號有相同的接收功率。而上行功率控制的效能則由功率控制誤差來評估。在下行傳輸中的功率控制是為了增加系統的容量。我們做了在理想的訊號干擾比平衡下，系統容量的分析和模擬。最後，本篇論文也模擬在實際系統中，閉迴路功率控制在下行傳輸中所能達到的系統容量。

In the proposed 5G cellular system [1], all users use the same frequency band to transmit data; like CDMA systems, any excessive transmit power will increase the overall interference. Without power control mechanisms, better link quality and system capacity cannot be achieved in the proposed 5G cellular system. We adopt open-loop power control in uplink transmission for combating near-far problem so that equal signal power from the mobiles can be received by the same BS. The performance of uplink power control is evaluated by power control error. Power control in downlink transmission is used to increase system capacity. We make a simplified analysis and simulation to evaluate the capacity of a downlink system with ideal SIR balancing. Besides, the downlink capacity with a practical closed-loop power control method is verified by computer simulation in this thesis.