室內多輸入多輸出通道容量之量測與分析

Abstract

無線通訊系統為了達到高速率傳輸，近年來發展了發射端與接收端都使用多單元天線的架構，稱之多輸入多輸出系統。該系統於多路徑環境下可利用路徑的低相關性達到相當高的通道容量。本論文採用頻域向量通道響應系統模擬四對四的多輸入多輸出系統，於台灣國立交通大學工程四館內對非波導性環境進行通道響應實地量測並計算其通道容量與相關特性。對於通道容量而言，吾人發現於非波導性環境中，天線間距以及主導波都有很大的影響。然而陣列擺向只在主導波存在的環境下有顯著的影響，傳輸接收端的距離則是沒有影響。對於相關特性而言，相關特性跟周遭環境有很大的關連。由於接收端是固定的，因此相同環境下接收端相關係數的變化很少。與通道容量相似，於非波導性環境中，天線間距以及主導波都有很大的影響。然而陣列擺向只在主導波存在的環境下有顯著的影響，傳輸接收端的距離則是沒有影響。另外吾人發現相關係數與通道容量呈現負相關的現象，正如預期所料。

Recent years, in order to achieve high data rate transmission, wireless communication systems developed architecture used multiple elements antennas at transmitting end and receiving end called MIMO (Multiple Input Multiple Output). MIMO system is able to achieve very high channel capacity if the correlations among the radio channels are small. In the thesis the 4x4 MIMO channel frequency response is measured at 5.3GHz with 100MHz bandwidth in non-“wave guiding” environment. Use the data and information theory, the channel capacity and the correlation properties are evaluated. It is found that antenna spacing and dominant path have strong effects on the channel capacity. However, the antenna orientation significantly affects only in the scenario when dominant path exists. It seems that the Tx-Rx distance effect is not significant. For the exploration of the effect on correlation properties, it strongly correlates with local environment. It is found that the correlation coefficient and the channel capacity are inverse correlation, as expected.