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    题名: Simulation analysis and channel characteristics for outdoor wireless communications
    其它题名: 戶外無線通訊之系統通道特性分析與模擬研究
    作者: 杜定傑;Tu, Ting-chieh
    贡献者: 淡江大學電機工程學系博士班
    丘建青;Chiu, Chien-ching
    关键词: 路徑損失;錯誤率;分集;Path loss;bit error rate (BER);diversity
    日期: 2009
    上传时间: 2010-01-11 07:13:38 (UTC+8)
    摘要: 在本論文中所呈現的是戶外無線通訊系統的通道特性分析。然而在戶外的環境中,有許多阻擋物會干擾和減弱接收訊號的功率例如車輛樹木和建築物。所以我們的目的是要分析與了解戶外無線通訊系統的通道特性。
    在第三章中,我們利用2.5維的彈跳射線追蹤法來建立模擬的戶外環境。而且我們考慮了三種不同的天線形式來評估戶外環境中的路徑損失。而且藉由使用基因演算法,陣列天線的天線場型可以被改善具有良好的指向性和路徑損失的減少。
    在第四章所呈現的是在不同路徑和環境中,以不同極化方式來計算極化辨別率。極化分集是通常用於手持行動端以減少壓縮天線結構所帶來的衰減。極化分集可以藉由分析信號的交叉相關與極化來評估其適用性。如此可以幫助我們了解何種極化方式適用於 直視與非直視路線或都會與半都會環境。
    在第五章中在超寬頻系統裡討論有無車輛的情況的戶外通道特性。因為大部分研究超寬頻系統的論文都是考慮在室內環境中,必較少用於戶外環境中。所以本文中將超寬頻系統應用於戶外無線通訊以研究其通道特性。藉由結合2.5維射線追蹤法、快速反傅立葉轉換與何米特程序處理,可以計算出超寬頻的通道脈衝響應進而得到位元錯誤率的結果。所以我們用位元錯誤率與失效率來評估車輛在戶外超寬頻系統的影響。由於超寬頻系統所用的頻寬很大(3.1-10.6GHz),所以在時域中的時間解析度只有幾個十億分之一秒,如此我們便利用選擇性的rake 接收機技術來增加接收的訊號雜訊比進而減少多路徑效應。
    In this thesis, using different diversity techniques and different simulation environments for outdoor wireless communication systems are presented. However, more obstructions such vehicles, trees, and buildings will degrade the received signal in the outdoor environments. Our purpose is that analyzing and understanding the channel characteristics of outdoor wireless communication.
    In the Chapter 3, we use the 2.5D SBR-Image ray tracing method to set up the outdoor simulation environment. Moreover, we take account of different types of antenna arrays to evaluate path loss in the outdoor environment. Moreover, by using the genetic algorithm, antenna pattern can be improved to have a good directivity and the reduction of path loss.
    The Chapter 4 shows different polarization schemes to calculate the cross polarization discrimination (XPD) value in different routes and environments. Polarization diversity is one of the most promising techniques to reduce fading with a compact antenna configuration requiring only one antenna location for the mobile terminal. The applicability of polarization diversity can partly be evaluated to analyze signal cross correlation and cross polarization discrimination (XPD) values. It is helpful to understand what polarization is suitable for the LOS and NLOS routes or urban and semi-urban environments

    Finally, outdoor channel characteristics with and without traffic in Ultra-wideband system are presented. Most researches of UWB system are concentrated on indoor scenes, but we proposed applications for outdoor UWB systems. By combining with 2.5D SBR/Image method, inverse fast Fourier transform (IFFT) and Hermitian processing, the channel impulse response in the UWB system can be calculated to get the bit error rate. Bit error rate (BER) and outage probability can be used to evaluate the performance of outdoor UWB systems with and without traffic. Based on the large bandwidth of UWB systems, the scale of time resolution on the time domain is just about several nanoseconds. So we take account of the S-rake receiver technique to increase the signal-to-noise ratio (SNR) in order to reduce multipath effect.
    显示于类别:[電機工程學系暨研究所] 學位論文

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