超寬頻多輸入多輸出系統模型之建構與量測

Abstract

近幾年高傳輸速率特別受到重視，例如第三代行動通訊的標準如WCDMA和UWB。基於需要較高的傳輸速率，我們結合UWB和MIMO的特性。本論文介紹在UWB MIMO系統中，傳播環境中的傳輸端與接收端的距離、本地散射體、相鄰的天線間距及天線的擺放方式對通道容量及相關性的影響。此外在本論文中也提出了適用於室內UWB MIMO的通道模型，此通道模型主要是先找出UWB的特性再根據802.11n通道模型去做結合的動作。 在本論文中，吾人發現了下列幾個現象：(1)在具有雜亂回波的環境下，在不同的接收距離下並不會對通道容量有任何影響; (2)在有本地散射體的環境下，通道容量會高於沒有本地散射體的環境; (3)通道容量會隨著天線單元間距的增加而增加，但在超過0.5波長後，天線單元間距對於通道容量就沒有顯著的影響; (4)在直接波存在的情況下，天線的擺放方式對通道容量是有影響的; (5)因為高相關性所造成的通道容量損失，會隨著SNR的增加而獲得補償; (6)在採用S-V模型的UWB系統中，可觀察到在直接波存在的情況下，參數Γ衰減的比沒有直接波存在的情況快; (7)我們發展的室內UWB MIMO通道模型，經由與量測結果的比較結果發現我們的通道模型是可適用於UWB MIMO系統。

Recent years have seen the emergence of high data rate, third generation wideband wireless communication standards like wideband code division multiple access (W-CDMA) and UWB radio. Motivated by the ever increasing demand for higher wideband wireless data rates, we consider multiple antenna communication over the UWB wireless channel (UWB-MIMO). In this thesis, we will introduce the capacity and correlation properties of UWB-MIMO channels and analyze the measured UWB-MIMO channel data to investigate the effects of propagation range, local scatterer, antenna spacing and array orientation effect. And in order to propose a set of channel models applicable to indoor UWB-MIMO systems. We first present the characterization of UWB channels for indoor environment with above measured data. Then we base on 802.11n channel model to develop the UWB-MIMO channel model. In this research, some phenomena are revealing and listed as following (1) Propagation distance effect: Capacity is independent of Tx-Rx distance in the LOS/NLOS with heavy clutter. (2) Local scatterers effect: In the environment with local scatterers, the capacity is higher than the environment without local scatterers under LOS and NLOS condition. (3) Antenna spacing effect: The UWB-MIMO capacity increases as the antenna spacing increases and it saturates when the spacing is larger than 0.5λ. (4)Antenna array orientation effect: Capacity for perpendicular antenna array is higher than parallel antenna array in LOS condition. But in NLOS condition, capacity is higher for perpendicular antenna array in a guided environment. (5) Capacity Loss: The relative channel capacity loss due to the effect of high antenna correlation is reduced as SNR increases. (6) From the parameter of S-V model in UWB radio channel model, we can see that Γ decay faster in the LOS condition than in the NLOS condition. (7) The UWB-MIMO channel model has been proved to be effective and accurate.