李學智臺灣大學：電機工程學研究所葉大千Yeh, Ta ChienTa ChienYeh2007-11-262018-07-062007-11-262018-07-062005http://ntur.lib.ntu.edu.tw//handle/246246/53090隨著無線通訊技術的應用增加，高傳輸率己經變成一個重要的研究課題。多輸入多輸出型態是其中一種達成方法。首先，我們研究室內環境的通道特性來設計一個更好的多輸入多輸出系統。我們觀察到因為接收到的信號雜訊比變小了，所以阻擋直接波無法提昇系統容量。另外，我們證明了在高信號雜訊比時，多輸入多輸出技術在增加通道容量的表現上會比相位陣列天線表現的還要好。之後，我們基於奇異值分解來建立了三種四輸入四輸出正交分頻多工系統的架構。這三種架構可以分類為:(1)四個子通道全利用 (2)只利用三個子通道 (3)使用可適應位元與功率分配的演算法來傳送資料。我們證明了去除有最小奇異值(singular value)的子通道而只利用三個子通道來傳輸資料是一種簡單的改進效能方法。另外，使用可適應位元與功率分配可以有效地增加傳輸率並且使不同接受位置的位元錯誤率更穩定。As the increase of applications of wireless communications, high transmit rate becomes an important research topic. The Multiple-Input-Multiple-Output architecture is one of the solutions. In order to design a better MIMO system in the indoor environments, we study the characteristics of channels. We observe that blocking LOS doesn’t increase the capacity because the receiver SNR is reduced. We also demonstrate that MIMO techniques are more effective in increase channel capacity than phased array techniques at high SNR. Then, we build up three architectures of a 4x4 MIMO OFDM system which are categorized as (1) using all four sub-channels, (2) using only three sub-channels and (3) using adaptive bit and power loading algorithms for data transmission. We demonstrate that using only three sub-channels by discarding the sub-channel with the smallest singular value is a simple method to improve the performance. Using the adaptive bit and power loading algorithm can effectively increase the data rate and make BER stable at different Rx locations.Abstract I Contents III List of Figures V List of Tables Ⅷ Chapter 1 Introduction 1 Chapter 2 Ray tracing with SBR approach 5 2.1 Description of the Program 5 2.2 Vector Effective Antenna Height and Complex Receiving Amplitude b4 6 2.2.1 Vector Effective Antenna Height (VEH) 6 2.2.2 Complex Receiving Amplitude b4 7 2.3 The SBR-Image Method 9 2.3.1 Generation of ray tube 9 2.3.2 Direct, Reflected and Transmitted Fields 11 2.4 Verification of the SBR-Image Method 15 2.4.1 An empty room 15 2.4.2 Two adjacent empty rooms 18 2.4.3 Two adjacent empty rooms using hertzian dipole 20 2.5 Summary 21 Chapter 3 The Characteristics of Some MIMO Indoor Channels 23 3.1 Fundamentals of MIMO Systems 23 3.1.1 Channel Model 24 3.1.2 MIMO Capacity Analysis 25 3.2 Simulation environment 27 3.2.1 Parameters of Channel characteristics 29 3.3 Eigenvalue and capacity for MIMO Radio Channel 33 3.3.1 the effect between element spacing 0.5λand 1λ 37 3.3.2 Capacity using waterfilling power allocation policy 40 3.3.3 Compare capacity using MIMO with using phased array at different SNR 43 Chapter 4 Transmission Performance of MIMO OFDM using SVD in Different Indoor Environments 47 4.1 MIMO OFDM 47 4.1.1 Basic concept of OFDM 47 4.1.2 SVD-MIMO System 48 4.1.3 Signal model MIMO-OFDM using SVD architecture 50 4.1.4 Condition number 56 4.2 Adaptive bit and power loading algorithm for OFDM systems 59 4.3 Summary 67 Chapter 5 Conclusion 69 Reference 71en-US多輸入多輸出型態射線追蹤法通道MIMORay tracingchannelthesis