天線陣列幾何結構對無線通訊系統效能分析與最佳化

Abstract

行動通訊系統中，多路徑造成的通道衰落會影響傳輸的可靠度，使傳輸品質及速率受到限制，而多輸入多輸出系統能利用衰落通道間獨立的特性，空間分集及空間多工技術來提高傳輸品質及速率，然天線間的空間相關性會造成通道間不再獨立，使得傳輸品質及速率受到影響。而由於天線陣列的幾何結構會影響空間相關性，因此在此首先在第二章推導二維擴散之空間相關性公式，及三維擴散之空間相關性公式。第三至六章則使用粒子群最佳化演算法，藉由第二章推導之空間相關性公式，在一定範圍內搜尋擁有最大通道容量之最佳化天線陣列，並且實驗模擬常見之均勻分布線性陣列、均勻分布圓形陣列同心圓陣列這三種天線陣列架構，討論空間相關性對通道容量及位元錯誤率之影響，並比較相同大小之天線陣列間效能的差異，以及其與該情況最佳之天線陣列之差距。

In mobile radio communication systems, channel fading caused by multipath propagation influences the reliability of information transmission. To provide higher transmission quality and spectral efficiency, MIMO greatly migrates the impact of the channel impairment. However, the spatial correlation between the elements of antenna array significantly affects transmission quality and spectral efficiency. Therefore, the spatial correlation characteristics for different array geometries must be considered. For modeling the spatial correlation properties, the spatial correlation functions under 2-D spreading and 3-D spreading environments are derived in chapter 2. A optimization method of array geometry is provided in chapter 3 to chapter 6, which searching the optimal array geometry for maximizing channel capacity using particle swarm optimization. The performance analyses of using uniform linear array (ULA), uniform circular array (UCA), concentric ring array (CRA), and the optimal array are also provided in chapter 3 to chapter 6, considering the effect of spatial correlation and comparing the ergodic channel capacity and bit error rate between these different array geometries.