Channel Measurements and Transmission Simulation for Taiwan High Speed Rail Wireless Communication

通道特性是無線通訊中最重要的參數之一。傳統上藉由通道探測機獲得通道參數，例如：功率延遲數據、通道頻率響應、都卜勒(Doppler)頻譜等。通道探測機利用銣原子鐘可以讓傳送端與接收端在一段時間之內達到完美的同步，而且有能力去偵測功率延遲數據、通道頻率響應、都卜勒頻譜，配合天線陣列還能取得電波來向。在本篇論文中，我們利用正交分頻多工技術配合訊號產生器及頻譜分析儀提出一個正交分頻多工之通道量測系統替代昂貴且笨重的通道探測機。此外我們將用此系統在台灣高速鐵路的戶外與隧道環境下進行量測。整體的系統模型與所使用的儀器設備，量測時的環境與系統參數都有詳細的描述。我們也呈現量測的結果與分析，並且與模擬或理論做比較。路徑衰減、延遲數據、錯誤率、都卜勒效應都是我們分析的重點。道內的通訊配合光纖以增加整個基地站涵蓋範圍，我們也對隧道內之光載無線通信(Radio-over-Fiber)量測並分析其結果。最後我們將量測結果配合台灣所使用的全球互通微波存取(WiMAX)系統參數，模擬實際通訊傳輸時會產生的現象，模擬結果也可作為未來台灣高鐵寬頻通訊系統建立的參考。The important factor of the wireless communication is the channel characteristic. Conventionally, channel characteristic can be fully investigated by channel sounder, e.g., PDP (Power delay profile), CFR (Channel frequency response), and DS (Doppler spectrum). Due to several associated equipments, channel sounder has almost perfect synchronization between transmitter (TX) and receiver (RX), and capability to detect PDP, CFR, DS and AOA (angle of arrival) of transmit signal by antenna array. n this thesis we make use of the orthogonal frequency division multiplexing technique (OFDM) and present an OFDM-based channel measurement system and demonstrate results measured in Taiwan High Speed Rail (THSR) environments. The system model and used equipments will be shown up. We focus the data analysis on the path loss, delay profile, bits error rate (BER), DS. The measured results are compared with simulation. For the communication system, BER and throughput are two major factors that affect the system performance. We consider the actual condition of WiMAX to develop the simulation scenario. The simulation result can contribute to the THSR wireless communication system.Abstract Iontents IIIist of Figures Vist of Tables IXhapter 1 Introduction 1.1 Motivation 1.2 Thesis Overview 2hapter 2 OFDM-based Channel Measurement System 5.1 System Description 6.2 Synchronization 11.2.1 Preamble structure 12.2.2 Packet Detection 14.2.3 Symbol Timing Offset 16.3 Channel Estimation 18.3.1 Pilot signal 19.3.2 Equalization 20.4 Measurement methods 23.4.1 Channel Characteristics 23.4.2 Equipments Setup 27.5 Fast Fading Environment Simulation 29.5.1 AOA measurement 32.5.2 Voltage Controlled Oscillator (VCO) 34hapter 3 Channel measurement on Taiwan High Speed Rail 37.1 Measurement scenario 38.1.1 The experiment routes 39.1.2 The experiment equipments 40.2 Channel measurements 41.2.1 Measured channel characteristics 42.2.2 Channel Modeling 45.3 Data analysis 47.3.1 Propagation loss 47.3.2 Comparison with standardized channel model 54.3.3 CP ratio & Normalized CFO 56hapter 4 Channel measurement in Song Shan Tunnel 57.1 Measurement scenario 57.1.1 The experiment routes 58.1.2 Experiment Equipments 60.2 Data analysis 62.2.1 Measured channel characteristics 62.2.2 Channel Modeling 64.2.3 Propagation loss 65.3 Measurement with Radio over Fiber 67.3.1 Down link data analysis 69.3.2 Up link data analysis 76hapter 5 Transmission Simulations 83.1 Simulation for Radio over Fiber 83.1.1 Simulation Scenario 84.1.2 Simulation Result 86.2 Simulation for Doppler transition 90.2.1 Simulation Scenario 90.2.2 Simulation Result 92hapter 6 Conclusions 95ppendix 97eferences 12