Ka频段卫星通信信道建模及系统性能仿真

本文给出了卫星通信系统设计,建模和仿真的一般方法,重点是Ka频段卫星通信信道的建模及仿真,我们首先分析了Ka频段卫星通信信道的统计特性,建立了信道的统计模型,然后在此基础上建立了Ka频段卫星通信信道及系统的仿真模型,并进行了系统性能的仿真,最后利用分析法分析推导了相干BPSK信号在Ka频段的系统性能,并与仿真结果进行了比较,得出了有用的结论。     

基于OPNET的Ka频段卫星信道仿真建模与研究

针对Ka频段卫星通信信道中电波传播特性的研究,通过引入SAM模型和新的影响因子,包括雨滴大小、云雾及大气吸收等,分析了降雨及多因子对信道的影响,建立了Ka频段卫星通信信道仿真模型,并基于OPNET平台进行仿真。此模型能够更好地提供清晰的数学表达式．对卫星信道的研究提供了可靠数据。     

数字卫星广播中CPM与QPSK调制性能仿真分析

在介绍分析卫星广播Ka波段信道特点并建立信道仿真模型的基础上,使用Matlab软件对四相相移键控(QPSK)和连续相位调制(CPM)在Ka波段信道中的性能进行了仿真比较,指出在数字卫星广播应用中CPM调制具有更强的优势和应用前景.     

卫星移动通信信道LR2模型及系统性能分析

在对卫星移动通信信道传播特性进行分析的基础上,综合目前提出的各种卫星移动信道传播模型,提出了一种新的Lognormal—Rice—Rayleigh模型(简称LR^2模型)。从该模型可以推导到其它各种经典的卫星移动信道传播模型,并且具有良好的全波段特性(从UHF到Ka)和实际逼真度。还给出了LR^2模型从UHF到Ka各个波段的仿真效果和参数优化公式,全面分析了与信道模型有关的各种参数如电平通过率(LCR)、平均衰落时长(AFD)、相位分布、误码率、块差错率等,为信道模型的应用作了较全面的阐述。     

串行级联Turbo码在Ka频段卫星通信中的仿真研究

在分析Ka频段静止卫星信道特点的基础上,建立了信道仿真模型并进行了基带仿真,研究了不同天气条件下静止卫星通信系统的误比特率性能,基于这一模型通过仿真研究了串行级联Turbo码在静止卫星信道条件下的性能。仿真结果表明,除了中雨、雷雨等恶劣天气状况之外,在通常的天气条件下,串行级联Turbo码可以提供约10dB左右的编码增益,可有效改善系统性能。     

Ka频段卫星通信网传播衰落效应研究

Ka频段卫星作为未来卫星通信发展的主要频段，但其面临的信道衰落是比较严重的，因此对信道传播衰落效应进行研究是十分必要的。本文在对Ka频段卫星通信的信道模型分析的基础上，利用分析法导出了相干BPSK信号在Ka频段的系统性能，并进行仿真，得出了明确的结论。     

有效的Ka波段移动卫星信道综合模型研究

为了更加准确地描述卫星移动通信信道的衰落特性,提出了一种新的Ka波段卫星移动通信信道综合模型。首先在分析移动卫星信道传播特性的基础上,考虑多径衰落、阴影遮蔽及天气影响等因素,建立了服从Gaussian分布的大气空间模型,推导出服从Rice、Rayleigh和Lognormal联合分布的地面信道模型。然后利用卫星信道环境中大气空间部分与地面部分对信道特性的影响是彼此相互独立的性质,提出了一种在大气空间持续影响下的移动卫星信道衰落特性综合模型。并就不同天气条件和不同阴影遮蔽程度下,综合模型的误码率特征与系统误码率理论上限进行仿真对比,得出了相一致的结果,验证了该信道综合模型的合理性和正确性。     

星载SAR双程信道建模与仿真实现

目前卫星移动通信的信道研究主要集中在星-地单程链路对无线电波传播的影响,而在星载SAR回波信号的无线传播环境中,信号需要经过星-地和地-星的双程传播,2次穿越大气层,且要经过地面目标的反射。因此,有必要针对星载SAR的这个特点,建立星载SAR的信道模型,为回波信号的模拟提供参考。在经典的卫星移动通信信道模型C.Loo模型的基础上,考虑星-地和地-星链路损耗及地面后向散射系数,推导了星载SAR星-地-星双程链路的理论信道模型,并利用正弦和方法设计了与理论模型相对应的仿真模型,通过仿真验证了理论模型和仿真模型的一致性。     

Ka频段卫星通信的信道特性与仿真技术

分析了ka频段静止卫星通信和移动卫星通信的信道特点;研究了信号经过两类信道后的幅度和相位概率分布;给出了适合Ka频段通用的信道仿真模型。利用该模型,通过Montecarlo仿真采用BPSK调制信号对静止卫星的通信信道进行了计算机仿真,得出了仿真结果。     

Ka频段数字卫星广播系统抗上行干扰性能分析

文章研究了基于DVB-S标准的Ka频段数字卫星广播系统抗上行干扰的性能。首先介绍了Ka频段同步卫星通信信道特点,然后对系统抗上行干扰的性能进行了分析并给出了系统误比特率的计算公式,在考虑天气影响条件下,对几种干扰样式下系统的性能进行了仿真分析,仿真表明：黑云天气对系统性能的影响最大;同时4PSK干扰较其他几种干扰样式对系统性能的影响更大。     

Land mobile satellite channel measurements and modeling

This paper, tutorial in nature, describes the effort of many investigators who have and still are conducting channel measurements and modeling for land mobile satellite communications. Various channel measurement results, ranging from ultrahigh frequency to Ka-band, are given. Many statistical channel models and simplified models that have been developed are referred to. Some of the models are applicable to geostationary and nongeostationary communications satellites. A statistical model developed by Loo (1985) is described in detail, as well as its extension to modeling land mobile satellite communications at Ka-band. This was accomplished by including a Gaussian probability density function to account for weather conditions. Also, practical computer-generated statistical channel models are given. These computer models should facilitate the estimation of performance of satellite communications systems     

Ka-band land mobile satellite channel model incorporating weathereffects

A Ka-band land mobile satellite (LMS) channel model which is able to take into account weather impairments is proposed. The statistics of the received signal and the BER performance of the system under the proposed channel model are obtained and compared with the results generated using Loo's weather-affected LMS channel model. The proposed Ka-band (20/30 GHz) LMS channel model is shown to be more reasonable as it gives realistic results     

基于Ka频段的自适应MIMO调制算法

这里研究了一种应用于Ka频段卫星通信信道的自适应多输入多输出(MIMO,multiple-Input multiple-Out-put)调制算法,不同于一般Ka频段卫星通信的信道衰减补偿算法,该算法主要是能根据不同天气条件,利用MIMO系统的接收信噪比自适应的转换调制方式,以维持一定的目标比特率为目标,从而获取较高的系统吞吐量。仿真结果表明,该算法能有效应对Ka频段固定卫星通信信道下的严重信道衰落,兼顾系统性能和频谱效率,得到较高的吞吐量。     

Ka-band Satellite Channel Model in Deep Space Relaying Network

In this paper, a Ka-band satellite channel in deep space relaying networks is modelled based on propagation environments, considering weather impairments, shadowing, Doppler shift and solar scintillation together. The whole deep space channel is divided into three different parts based on the network architecture, which is a special case of the multi-state channel model applicable for a non-uniform propagation environment.     

Ka频段卫星信道的衰减特性

在Ka及以上高频段卫星通信系统中,其链路信号的衰减很严重,主要是大气、降雨、闪烁对卫星信道的影响。本文主要研究了雨衰和对流层闪烁产生衰减的机理与特性,提出雨衰采用DAH模型,闪烁采用Van de Kamp模型。然后根据实测气象数据,计算我国各参考站点的雨衰和闪烁值。为抗衰减对策的提出提供理论依据,为工程设计提供具体的参考数据。     

The application of S-band polarimetric radar measurements toKa-band attenuation prediction

In September 1993, the National Aeronautics and Space Administration's Advanced Communications Technology Satellite (ACTS) was deployed into a geostationary orbit near 100° W longitude. The ACTS satellite employs two Ka-band beacons, one at 20.185 GHz and another at 27.505 GHz. Impairments due to rain attenuation and tropospheric scintillations will significantly affect new technologies for this spectrum. Heavy rain at Ka-band can easily produce 30 dB of attenuation along the propagation path. Propagation experiments being conducted in seven different climatic zones involve multiyear attenuation measurements along the satellite-Earth slant path. Measurements in the B2 climatic zone are made with an ACTS propagation terminal located in northeast Colorado. In order to gain move understanding about the physical processes that are responsible for Ka-band attenuation, the Colorado State University CHILL S-band polarimetric radar is used to take radar measurements along the slant path. The Colorado Front Range experiences a variety of weather conditions throughout the year ranging from upslope rain conditions to winter storms. Four such events measured along the slant path are illustrated in this paper. They include two convective cases and two “bright-band” cases. The S-band polarimetric radar data is used to initialize radar-based attenuation-prediction models, which are applied to the four precipitation events described. The comparisons of predicted attenuation to measured attenuation are quite good. It was also found during the course of the experiment that water droplets standing on the antenna surface can cause appreciable attenuation at Ka-band frequencies. That finding needs to be recognized in future model development and statistical analysis     

Measurement and Modeling of the Land Mobile Satellite Channel at Ku-Band

This paper presents the results of a measurement campaign conducted in the winter of 2002 around the city of Munich in southern Germany. The primary goal was to evaluate the link performance of the land mobile satellite channel at Ku-band and to characterize the temporal behavior of the channel to help in the evaluation of different fade mitigation techniques for future mobile satellite systems that aim at employing this frequency band. To achieve this objective, first- and second-order channel statistics will be presented, the outage probability of the channel analyzed, and a Markov-chain-based narrowband channel model proposed.     

阴影环境下陆地移动卫星信道的模型研究

陆地移动卫星信道通常用全阴影模型和部分阴影模型进行分析。本文利用全阴影模型的研究结论,就实际陆地移动卫星信道部分阴影模型的仿真问题,拟合了模型参数与卫星仰角之间的关系。通过统计特性的数值计算,验证了部分阴影模型与全阴影模型的一致性。     

A new simple model for land mobile satellite channels: first- and second-order statistics

We propose a new shadowed Rice (1948) model for land mobile satellite channels. In this model, the amplitude of the line-of-sight is characterized by the Nakagami distribution. The major advantage of the model is that it leads to closed-form and mathematically-tractable expressions for the fundamental channel statistics such as the envelope probability density function, moment generating function of the instantaneous power, and the level crossing rate. The model is very convenient for analytical and numerical performance prediction of complicated narrowband and wideband land mobile satellite systems, with different types of uncoded/coded modulations, with or without diversity. Comparison of the first- and the second-order statistics of the proposed model with different sets of published channel data demonstrates the flexibility of the new model in characterizing a variety of channel conditions and propagation mechanisms over satellite links. Interestingly, the proposed model provides a similar fit to the experimental data as the well-accepted Loo's (1985) model but with significantly less computational burden.