WCDMA 系統下增波器對整體容量之最佳化演算法

Abstract

在類比及二代行動通訊中，增波器已被廣泛使用於聲音、低速率傳輸和簡訊 (short message)。而緊接而來的第三代行動通訊除了支援高傳輸速率同時也要求高通訊品質。因此，增波器無論在加強訊號強度、服務質量(Quality of Service)的需求或是成本的考量上，都可帶來長足的提升。但由於增波器會帶來嚴重的干擾，因此在佈建和運作時必須加以限制。在本篇論文中，主要的目的為調整增波器以最佳化系統效能。首先將探討增波器在三種不同環境下的使用對系統效能的影響，由此歸結出適用最佳化的環境。接著，以數學推導出最佳化的式子，將其轉為線性問題，對多蜂巢式系統進行最佳化處理，調整各種參數，例如增波器的增益、訊雜比（SINR）的門檻等等，抑制蜂巢間嚴重的干擾及提升整體的效益。在論文中會提出另外一個演算法以逼近最佳化的結果，讓我們可以更加了解調制增波器參數的準則。模擬結果顯示出增波器在無外來可變動的干擾下，能夠有效的提高使用者的SINR並且增加頻帶效率；而在多蜂巢系統下，則可以平衡系統容量及使用者訊雜比的牽制關係。

Repeaters have been employed on analogue and 2G generation mobile networks, which are designed to support voice, low data rates and short messages. The 3G mobile systems are designed to support high speed internet access with high transmission quality. The use of repeaters, to enhance the weak RF signals, taking the quality of service and costs into consideration is important. However repeater can enlarge interference and we must manage the deployment and the gain of repeater under tight control. In the thesis the main target is to optimize the system performance by appropriately adjusting repeater parameters. We first investigate the influence of repeater at three different kinds of scenarios to find a case in which optimization can be applied. Later the optimization formula is proposed and turned into a linear problem. We then do optimization on multi-cell system by adjusting parameters, i.e. repeater gain, SINR threshold etc, to suppress severe interference and improve system performance. An algorithm is proposed to give a more specifically criterion to adjust the parameters. The simulation results show repeater can effectively enhance user SINR and spectrum efficiency at no other-cell-variation interference circumstance and balance the tradeoff between system capacity and user SINR.