隧道环境下无线信道特性仿真分析

发布时间：2018-06-05 17:36

本文选题：隧道 + 射线跟踪　；参考：《北京交通大学》2017年硕士论文

【摘要】：随着城市规模扩大和人口数量增加,地铁已经成为城市居民出行的主要交通工具,同时便携式通信设备的普及使得人们对出行时的通信需求越来越高。在地下轨道交通中,隧道是一种主要场景,而隧道与开放环境下的信道特征截然不同。隧道作为一种受限空间,其电波传播会存在各种反射、透射、折射,以及锁孔效应,导致信道恶化。为了建立高效可靠的无线通信系统,需要对隧道环境下无线信道特性进行深入研究。本团队在北京交通大学隧道中心和江苏南通中天科技集团隧道实验室进行了两次实际测量,并使用射线跟踪法对实际测量场景进行仿真。通过对比大尺度衰落特性,发现仿真结果与实测结果有较高的一致性,二者均方根误差约为4dB,可以认为射线跟踪法能够对隧道环境下大尺度衰落进行准确预测。通过对比信道冲激响应,发现实测与仿真结果在时延和衰落上有较好的吻合度,因此可以认为使用射线跟踪法仿真得到的信道冲激响应是准确的。通过射线跟踪法对隧道模型进行扩展仿真。在文中构建的隧道下,2.4GHz和5.9GHz的路径损耗指数分别为1.418和1.438,阴影衰落服从正态分布。对比长直隧道和弯曲隧道下的路径损耗,结果表明弯曲隧道的路径损耗比长直隧道略大。发射天线位于弯曲隧道内侧时比位于外侧时路径损耗大,并且两者的差值与收发天线之间的距离成正比。多天线技术是提高信道容量的重要技术,对比单天线与2×2天线,结果表明多天线可以很大程度上提高容量。本文引进车体模型,研究车体对MIMO系统的影响,与无车体的情况相比,有车体时接收端角度扩展较大,天线之间的相关性较小,容量较大。随着天线数目的增加,信道容量增加明显,但无车时信道容量与瑞利信道容量的差值随天线数目的增加急剧变大,而有车情况下差值变化不显著。当天线间隔增大时无车情况下的信道容量增大,有车的情况下并没有明显的变化。
[Abstract]:With the expansion of the city scale and the increase of population, subway has become the main means of transportation for urban residents, and the popularity of portable communication equipment makes people more and more need to travel. In underground rail transit, tunnel is a main scene, and the channel characteristics of tunnel and open environment are very different. As a limited space, the propagation of radio waves in a tunnel will have a variety of reflection, transmission, refraction, and keyhole effect, which leads to the deterioration of the channel. In order to establish an efficient and reliable wireless communication system, it is necessary to study the wireless channel characteristics in tunnel environment. The team conducted two actual measurements at the Tunnel Center of Beijing Jiaotong University and the Tunnel Laboratory of Jiangsu Nantong Zhongtian Science and Technology Group and simulated the actual measurement scene by ray tracing method. By comparing the characteristics of large-scale fading, it is found that the simulation results are in good agreement with the measured results, and the root-mean-square error between them is about 4 dB. It can be considered that the ray tracing method can accurately predict the large-scale fading in tunnel environment. By comparing the channel impulse response, it is found that the measured results are in good agreement with the simulation results in terms of time delay and fading. Therefore, the channel impulse response simulated by ray tracking method is considered to be accurate. The extended simulation of tunnel model is carried out by ray tracing method. The path loss exponents of the tunnel constructed in this paper are 1.418 and 1.438 at 2.4 GHz and 1.4 38, respectively, and the shaded fading suits are distributed from normal to normal. The results show that the path loss of the curved tunnel is slightly larger than that of the long straight tunnel. The path loss of the transmitting antenna is larger when it is located inside the curved tunnel than at the outside, and the difference between them is proportional to the distance between the transmitting and receiving antennas. Multi-antenna technology is an important technique to improve the channel capacity. Compared with single antenna and 2 脳 2 antenna, the results show that multi-antenna can improve the capacity to a large extent. In this paper, a carbody model is introduced to study the effect of car-body on MIMO system. Compared with car-body, the angle expansion of the receiving end is larger, the correlation between antennas is smaller and the capacity is larger when there is a car-body. With the increase of the number of antennas, the channel capacity increases obviously, but the difference between the channel capacity and Rayleigh channel capacity increases sharply with the increase of the number of antennas, but the difference does not change significantly with the increase of the number of antennas. When the antenna spacing increases, the channel capacity increases without vehicle, but there is no obvious change in the case of vehicle.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN92

【参考文献】