Simulation Analysis and Channel Characteristics for Outdoor Wireless Communications

• Main Authors: Ting-Chieh Tu, 杜定傑
• Other Authors: Chien-Ching Chiu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/68713868387444434817

博士 === 淡江大學 === 電機工程學系博士班 === 97 === 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.