宽带卫星移动信道的研究与模拟实现
发布时间：2018-11-07 16:50
【摘要】：陆地移动通信系统飞速发展,第四代陆地移动通信系统已经开始大规模组网并且商用,第五代也开始了全面的研究,数据传输速率和载波频率都在不断提高。同时,卫星移动通信系统也发展到了以提供高速宽带Internet的接入和无线多媒体通信服务的第三代,卫星移动通信系统正朝着信号宽带化和载波的高频化演进。宽带信号将经历频率选择性衰落,引起码间串扰,使得信号波形失真,而卫星系统中的高频载波在通过大气层与地面站进行信息传输时将不可避免地受到大气吸收损耗、降雨衰减、电离层闪烁等影响。因此,宽带卫星移动信道特性的研究对于提高宽带卫星系统服务质量具有重要意义,本文从以下几方面进行研究。首先,分析了无线电波的传播机制,包括多径效应、阴影遮蔽、多普勒频移的形成原因及其对电波信号的影响,并研究高频信号在星地链路传播过程中大气损耗、降雨衰减对其影响,并对这些影响进行量化分析,建立统计模型,对成都地区的降雨衰减进行了计算机仿真实现,对比分析了星地之间的通信仰角、工作频率和降雨率对降雨衰减的不同影响,给出了Rician、Rayleigh和Lognormal概率分布函数的推导及其物理意义。然后,介绍了宽带卫星移动信道与传统的窄带卫星移动信道的区别,研究了宽带信号频率选择性衰落的形成原因,给出了基于广义平稳非相关散射模型的宽带卫星移动信道冲击响应函数,进一步建立了基于抽头延迟线原理的宽带卫星移动信道模型,重点研究了成形滤波法、正弦波叠加法和随机数生成法模拟平坦性衰落信道并进行了计算机仿真实现,对正弦波叠加法进行了改进,对于每个正弦波的频移和相移引入随机性,使得模拟得到的平坦性衰落序列更符合实际情况,对建立的宽带卫星移动信道分别从时域和频域进行了仿真分析,并和实测数据进行了统计特性的对比,验证了所提模型的正确性。最后,设计并实现了基于STK和MATLAB GUI的宽带卫星移动信道模拟器。该模拟器的信道模型采用本文建立的基于抽头延迟线的宽带卫星移动信道模型,对使用到的STK卫星工具包进行了二次开发,利用其强大的分析报告能力实时地计算出卫星通信仰角、多普勒频移和星地链路距离,并通过与MATLAB的联合仿真将这些数据实时传送到信道模拟器中,既可以形象地观测卫星运行轨迹,还可在信道模拟器上分析其信道传输特性和链路特性,具有较高的实用价值。
[Abstract]:With the rapid development of land mobile communication systems, the fourth generation of land mobile communication systems have begun to form a large-scale network and commercial, the fifth generation has also started a comprehensive study, the data transmission rate and carrier frequency are constantly improving. At the same time, the satellite mobile communication system has been developed to provide high-speed broadband Internet access and wireless multimedia communication services of the third generation, the satellite mobile communication system is moving towards signal broadband and carrier high-frequency evolution. Wideband signals will undergo frequency-selective fading, causing inter-symbol crosstalk, resulting in distortion of signal waveforms, while high-frequency carriers in satellite systems will inevitably suffer from atmospheric absorption losses when transmitting information through the atmosphere to earth stations. Rain attenuation, ionospheric scintillation and so on. Therefore, the research on the characteristics of broadband satellite mobile channel is of great significance to improve the quality of service of broadband satellite system. Firstly, the propagation mechanism of radio wave is analyzed, including multipath effect, shadow shadowing, Doppler frequency shift and its influence on radio wave signal, and the atmospheric loss of high frequency signal in the process of satellite and ground link propagation is studied. The influence of rainfall attenuation on it is analyzed quantitatively, and a statistical model is established. The computer simulation of rainfall attenuation in Chengdu area is carried out, and the elevation angle of communication between satellites and ground is compared and analyzed. The effects of operating frequency and rainfall rate on rainfall attenuation are different. The derivation of probability distribution function of Rician,Rayleigh and Lognormal and its physical significance are given. Then, the difference between wideband satellite mobile channel and traditional narrowband satellite mobile channel is introduced, and the reason of frequency selective fading of wideband signal is studied. The impulse response function of wideband satellite mobile channel based on generalized stationary uncorrelated scattering model is given. The wideband satellite mobile channel model based on tap delay line principle is further established. Sine wave superposition method and random number generation method are used to simulate flat fading channel and computer simulation is carried out. The sine wave superposition method is improved to introduce randomness into frequency shift and phase shift of each sine wave. The flattening fading sequence obtained by simulation is more in line with the actual situation. The established wideband satellite mobile channel is simulated and analyzed in time domain and frequency domain respectively, and the statistical characteristics of the established channel are compared with the measured data. The correctness of the proposed model is verified. Finally, a broadband satellite mobile channel simulator based on STK and MATLAB GUI is designed and implemented. The channel model of the simulator adopts the wideband satellite mobile channel model based on tap delay line established in this paper. The second development of the STK satellite toolkit is carried out. The satellite communication elevation angle, Doppler frequency shift and satellite-ground link distance are calculated in real time by using its powerful analytical reporting ability, and these data are transmitted to the channel simulator in real time through the joint simulation with MATLAB. Not only can the satellite track be observed vividly, but also the channel transmission and link characteristics can be analyzed on the channel simulator, which is of high practical value.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.23
本文编号：2316959
[Abstract]:With the rapid development of land mobile communication systems, the fourth generation of land mobile communication systems have begun to form a large-scale network and commercial, the fifth generation has also started a comprehensive study, the data transmission rate and carrier frequency are constantly improving. At the same time, the satellite mobile communication system has been developed to provide high-speed broadband Internet access and wireless multimedia communication services of the third generation, the satellite mobile communication system is moving towards signal broadband and carrier high-frequency evolution. Wideband signals will undergo frequency-selective fading, causing inter-symbol crosstalk, resulting in distortion of signal waveforms, while high-frequency carriers in satellite systems will inevitably suffer from atmospheric absorption losses when transmitting information through the atmosphere to earth stations. Rain attenuation, ionospheric scintillation and so on. Therefore, the research on the characteristics of broadband satellite mobile channel is of great significance to improve the quality of service of broadband satellite system. Firstly, the propagation mechanism of radio wave is analyzed, including multipath effect, shadow shadowing, Doppler frequency shift and its influence on radio wave signal, and the atmospheric loss of high frequency signal in the process of satellite and ground link propagation is studied. The influence of rainfall attenuation on it is analyzed quantitatively, and a statistical model is established. The computer simulation of rainfall attenuation in Chengdu area is carried out, and the elevation angle of communication between satellites and ground is compared and analyzed. The effects of operating frequency and rainfall rate on rainfall attenuation are different. The derivation of probability distribution function of Rician,Rayleigh and Lognormal and its physical significance are given. Then, the difference between wideband satellite mobile channel and traditional narrowband satellite mobile channel is introduced, and the reason of frequency selective fading of wideband signal is studied. The impulse response function of wideband satellite mobile channel based on generalized stationary uncorrelated scattering model is given. The wideband satellite mobile channel model based on tap delay line principle is further established. Sine wave superposition method and random number generation method are used to simulate flat fading channel and computer simulation is carried out. The sine wave superposition method is improved to introduce randomness into frequency shift and phase shift of each sine wave. The flattening fading sequence obtained by simulation is more in line with the actual situation. The established wideband satellite mobile channel is simulated and analyzed in time domain and frequency domain respectively, and the statistical characteristics of the established channel are compared with the measured data. The correctness of the proposed model is verified. Finally, a broadband satellite mobile channel simulator based on STK and MATLAB GUI is designed and implemented. The channel model of the simulator adopts the wideband satellite mobile channel model based on tap delay line established in this paper. The second development of the STK satellite toolkit is carried out. The satellite communication elevation angle, Doppler frequency shift and satellite-ground link distance are calculated in real time by using its powerful analytical reporting ability, and these data are transmitted to the channel simulator in real time through the joint simulation with MATLAB. Not only can the satellite track be observed vividly, but also the channel transmission and link characteristics can be analyzed on the channel simulator, which is of high practical value.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.23
【参考文献】
相关期刊论文 前2条
1 陈秀廷，段少华，张乃通;三状态信道模型在卫星移动通信系统中的应用研究[J];哈尔滨工业大学学报;1998年01期
2 雍明远;梁俊;袁小刚;;宽带移动卫星通信信道模型研究[J];通信技术;2009年01期
，本文编号：2316959
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