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首页> 外文学位 >Analysis and Mitigation of Tropospheric Effects on Ka Band Satellite Signals and Estimation of Ergodic Capacity and Outage Probability for Terrestrial Links.
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Analysis and Mitigation of Tropospheric Effects on Ka Band Satellite Signals and Estimation of Ergodic Capacity and Outage Probability for Terrestrial Links.

机译：分析和减轻对流层对Ka波段卫星信号的影响，并估算地面链路的遍历容量和中断概率。

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摘要

The first part of this work covers the effect of the troposphere on Ka band (20-30 GHz) satellite signals. The second part deals with the estimation of the capacity and outage probability for terrestrial links when constrained to quadrature amplitude modulations.;The desire for higher data rates and the need for available bandwidth has pushed satellite communications into the Ka band (20--30 GHz). At these higher carrier frequencies the effects of scintillation and rain attenuation are increased. In regards to the effects of scintillation, the first part of this work quantifies, through the use of a multiple phase screen simulation model, the benefits of using two receive antennas to mitigate tropospheric-induced scintillation on Ka band satellite downlinks. Two representative turbulence profiles are considered, and cumulative distribution curves for scintillation-induced attenuation are generated for selection and maximal ratio combining schemes and compared to those for a single antenna. The results indicate that there can be significant diversity gains achieved by combining two antennas separated by only a short distance. Also, a comparison of simulation results with the results predicted by the basic Rytov approximation shows that at elevation angles greater than 10 degrees, Rytov theory can accurately predict performance benefits of antenna combining, but at elevation angles less than 10 degrees it is better to use multiple phase screen simulations to make performance predictions. In addition, the effects of scintillation-induced phase perturbations on the output power of large aperture antennas is examined. It is found that the output power degradation due to scintillation-induced phase perturbations is generally negligible and can be countered by the simple means of antenna tracking if necessary.;In regards to rain attenuation, this work developed simple methods for estimating the outage probability and outage capacity and ergodic capacity of satellite links due to rain fades. The rain-induced fades of a satellite link are often modeled with a log-log-normal distribution. Researchers have determined methods for calculating the outage probability for Shannon capacity for log-log-normal channels. However, in practical communications systems, the input signal is constrained to a discrete signalling set such as finite-size quadrature amplitude modulations. Under these conditions the outage probability with regards to the constrained capacity is a more accurate measure. A method is detailed in this work for tightly estimating the outage probability and outage capacity of satellite links with quadrature amplitude modulations. In addition this work derives a lower bound for the ergodic constrained capacity of log-log-normal channels. To date, no other method for calculating the outage probability, outage capacity, or a lower bound for the ergodic capacity for a log-log-normal channel with a finite-size quadrature amplitude modulation has been published. Also, this portion of the work quantifies the benefit of using receive diversity to mitigate rain fades, providing the gains in outage capacity due to the use of diversity for a tropical region and a fairly dry region under the constraint that practical constellations are transmitted. The above information and analysis methods provide useful tools for satellite system planners.;The second part of this work examines terrestrial communication links, which can suffer greatly from channel fading or shadowing. Two common statistical models for channels are the Rayleigh distribution and the log-normal distribution. The goal of this second part of the work was to develop a simple method for tightly estimating the ergodic capacity and outage probability of these two channel types when used with quadrature amplitude modulated signalling sets. Specifically an innovative method was developed for estimating the ergodic constrained capacity for Rayleigh and log-normal channels with and without antenna combining. The expressions facilitate straightforward computation of outage probability as well. Researchers have determined methods for calculating the ergodic Shannon capacity for log-normal and Rayleigh channels for single and multiple receive antenna systems. However, in practical communications systems, the input signal is constrained to a discrete signalling set such as finite-size quadrature amplitude modulation constellations. Under these conditions the ergodic constrained capacity is a more accurate measure. The method detailed in this work provides a uniform expression for computing the ergodic capacity, both Shannon and constrained, of Rayleigh and log-normal channels with and without antenna combining. The expressions facilitate straightforward computation of outage probability as well. Both the noise-limited and interference-limited cases are studied. To date, no other method for estimating the outage probabilities for the constrained capacity of Rayleigh or log-normal channels has been published for either the noise-limited case or interference-limited case. Also, no method for estimating the ergodic constrained capacity of a log-normal channel or of an interference-limited Rayleigh channel has appeared in the literature. The analysis methods and information for terrestrial links developed in the second part of this work provide useful tools for the designers of wireless communication systems in general and have particular application to cellular mobile and ultra-wideband systems.
机译：这项工作的第一部分介绍了对流层对Ka波段（20-30 GHz）卫星信号的影响。第二部分讨论了在受限于正交幅度调制时地面链路的容量和中断概率的估计;对更高数据速率的需求以及对可用带宽的需求已将卫星通信推向了Ka频段（20--30 GHz） ）。在这些较高的载波频率下，闪烁和雨衰的影响增加了。关于闪烁的影响，本工作的第一部分通过使用多相屏幕仿真模型来量化使用两个接收天线来减轻对流层引起的Ka波段卫星下行链路上闪烁的好处。考虑了两个代表性的湍流曲线，并为选择和最大比率组合方案生成了闪烁诱发衰减的累积分布曲线，并与单个天线的方案进行了比较。结果表明，通过组合仅相隔很短距离的两个天线，可以获得明显的分集增益。此外，将仿真结果与基本Rytov近似预测的结果进行比较，结果表明，在仰角大于10度时，Rytov理论可以准确地预测天线组合的性能优势，但是在仰角小于10度时，最好使用多相屏幕模拟以做出性能预测。另外，研究了闪烁引起的相位扰动对大孔径天线输出功率的影响。发现由于闪烁引起的相位扰动而导致的输出功率降级通常可以忽略不计，并且在必要时可以通过简单的天线跟踪手段来抵消。关于降雨衰减，这项工作开发了简单的方法来估计断电概率和雨衰导致卫星链路的中断容量和遍历容量。雨水引起的卫星链路衰落通常以对数-对数正态分布建模。研究人员已经确定了用于计算对数对数正态信道的香农容量中断概率的方法。然而，在实际的通信系统中，输入信号被约束到离散的信令集，例如有限尺寸的正交幅度调制。在这些条件下，关于受约束容量的中断概率是更准确的度量。在这项工作中详细介绍了一种方法，用于通过正交幅度调制紧密估计卫星链路的中断概率和中断容量。此外，这项工作得出了对数对数正态通道的遍历约束能力的下界。迄今为止，还没有其他方法可以计算出具有有限尺寸正交幅度调制的对数对数正态信道的中断概率，中断容量或遍历容量的下限。而且，这部分工作量化了使用接收分集来减轻雨衰的好处，由于在实际星座传输的约束下，热带地区和相当干燥的地区使用了分集，从而提供了中断容量的收益。以上信息和分析方法为卫星系统规划者提供了有用的工具。这项工作的第二部分研究了地面通信链路，这些链路可能会受到信道衰落或阴影的严重影响。通道的两种常见统计模型是瑞利分布和对数正态分布。工作的第二部分的目的是开发一种简单的方法，用于与正交幅度调制信号集一起使用时，严格估算这两种信道类型的遍历容量和中断概率。专门开发了一种创新方法，用于估计有无天线组合情况下瑞利和对数正态信道的遍历约束能力。这些表达式也方便了中断概率的直接计算。研究人员已经确定了用于计算单接收天线系统和多接收天线系统的对数正态和瑞利信道的遍历香农容量的方法。但是，在实际的通信系统中，输入信号被约束到离散的信令集，例如有限尺寸的正交幅度调制星座图。在这些条件下，遍历约束能力是一种更准确的度量。这项工作中详述的方法提供了一个统一的表达式，用于计算在有天线合并和无天线合并的情况下，瑞利和对数正态信道的香农容量和受约束的遍历容量。这些表达式也方便了中断概率的直接计算。研究了噪声受限和干扰受限的情况。至今，对于噪声受限的情况或干扰受限的情况，没有其他方法可以估计瑞利信道或对数正态信道的受约束容量的中断概率。而且，文献中还没有用于估计对数正态信道或受干扰限制的瑞利信道的遍历约束能力的方法。在这项工作的第二部分中开发的用于地面链路的分析方法和信息通常为无线通信系统的设计人员提供有用的工具，并且特别适用于蜂窝移动和超宽带系统。

著录项

  • 作者

    Enserink, Scott Warren.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 151 p.
  • 总页数 151
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:42:29

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