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。     

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。     

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频段移动卫星通信TC-OFDM性能研究

建立了一种改进型的Ka频段移动卫星信道模型,并将Turb0编码和正交频分复用(OFDM)技术应用于Ka频段移动卫星通信中.通过在不同天气下的仿真比较,TC-OFDM系统在误码率为10-4时,可得到4.7-12.0dB的增益,降低了系统的衰减裕量,提高了系统的性能.     

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。     

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/EHF频段卫星信道传输特性研究

为了获取更高的可用带宽,使用更小的天线口径并获得更强的抗干扰能力,Ka频段在军事卫星通信系统中已经得到广泛的使用,并正在向EHF频段发展。在Ka频段的卫星通信系统已经被建立,但更高的EHF频段对卫星通信系统来讲仍是一个尚待研究的领域。EHF频段降雨损耗、多普勒频移等因素对系统设计所造成的影响必须充分考虑,因此对EHF频段的信道特性分析是未来极高频卫星通信系统设计的关键之一。在研究Ka频段信道传输特性的基础上,对EHF频段的信道传输特性作了初步的研究和探索。     

UWB卫星通信系统与窄带系统互扰分析

UWB技术在卫星通信领域推广应用的瓶颈是UWB卫星通信系统与窄带系统的互扰问题。研究了正弦调制高斯脉冲在卫星信道应用的时频域特性,提出了Ka频段UWB卫星通信信道模型,建立UWB卫星通信仿真系统,研究了UWB卫星通信系统和窄带系统在互扰条件下的误码特性,得到了影响互扰的关键因素,提出了适合卫星通信信道传输的UWB信号设计参数,论证了UWB卫星通信系统与窄带系统共享频谱的可行性。     

高效频谱调制在Ka频段卫星通信系统中的仿真

研究了高效频谱调制方式MPSK及MQAM在Ka频段固定卫星通信中的应用及其性能。在综合考虑了卫星信道的特性以及带限、非线性失真、邻道干扰和高斯噪声等因素影响的基础上,给出了系统BER性能分析及仿真结果。     

Ka频段卫星通信雨衰特性分析与改进措施研究

Ka频段卫星通信中,降雨引起的信号衰减对通信链路的通断起着非常重要的作用。本文详尽分析了Ka频段卫星通信信道的电波传播特性,重点分析了降雨对卫星通信的影响,并提出了Ka频段抗雨衰的各种对策。     

Dual-Space Diversity over Land Mobile Satellite Channels Operating in the L and K Frequency Bands

Land mobile satellite communication systems at Ka/K band (30/20 GHz) are attracting more and more attention to researchers because of its frequency band availability and the possibility of using small earth stations and satellite antennas for the systems. However, the Ka/K-band communications also give significant challenges in the system design due to severe channel impairments expected from the satellite links. In this paper, K-band channel characteristics are studied and compared with those at L band. The channel is modeled as Rayleigh multipath fading with the line-of-sight (LOS) component following a lognormal distribution. The first and second-order statistics of the fading channel are studied. Dual-space diversity reception is investigated to combat the flat channel fading. The bit error rate performance of coherent binary phase shift keying (BPSK) with ideal bit and carrier phase synchronization over the fading channel at K band is evaluated theoretically and verified by computer simulations in the case with and without diversity reception.     

Assessment of spatial and temporal properties of Ka/Q band earth‐space radio channel across Europe using Alphasat Aldo Paraboni payload

The upcoming migration of satellite services to higher bands, namely, the Ka‐ and Q/V‐bands, offers many advantages in terms of bandwidth and system capacity. However, it poses challenges as propagation effects introduced by the various atmospheric phenomena are particularly pronounced in these bands and can become a serious constraint in terms of system reliability and performance. This paper presents the goals, organisation, and preliminary results of an ongoing large‐scale European coordinated propagation campaign using the Alphasat Aldo Paraboni Ka/Q band signal payload on satellite, performed by a wide scientific consortium in the framework of a European Space Agency (ESA) project. The main objective of this activity is the experimental characterisation of the spatial and temporal correlation over Europe of the radio channel at Ka and Q band for future modelling activities and to collect data for development and testing of fading mitigation techniques.     

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.     

Channel Capacity Statistics of an Interfered Broadband Satellite Link

Satellite communication networks play an important role in the “digital divide” problem, by offering broadband services everywhere in the world. The ever increasing demand for multimedia services has led to the use of Ku, Ka and V band in modern satellite communication networks. In these frequency bands, rain attenuation is the most dominant propagation fading mechanism. Moreover, interference due to propagation phenomena deteriorates the performance of the satellite links and should be taken into account for the reliable design of satellite communication networks. In this paper, an analytical physical mathematical propagation model is presented for the prediction of channel capacity statistics of a dual-polarized interfered broadband satellite link. Rain attenuation spatial inhomogeneity is incorporated in the analysis with the employment of correlated slant paths. The obtained numerical results show the significance of these effects to channel capacity estimation. Finally, the proposed model may be used towards the optimum utilization of the satellite channel capacity by means of adaptive fade mitigation schemes.     

一种低损耗波导高通滤波器的设计方法

针对Ka频段卫星通信系统中对阻收滤波器的工程应用需求,提出一种低损耗波导高通滤波器的设计方法。利用波导低频截止特性及阶梯阻抗变换法,在软件中进行建模仿真优化后,通过参数扫描得到一个合理的设计方案。实物测试结果表明通带25～28 GHz插入损耗＜0.4 dB;阻带22～23 GHz抑制＞40 dB,是一款可应用于实际工程的高性能滤波器。     

多场景卫星通信信道动态建模与仿真实现

面向智慧海洋、智慧农业等垂直行业场景的广覆盖无线接入需求,低轨卫星通信因其可靠的连接性、更宽广的覆盖能力以及超大带宽连接的巨大潜力而成为了下一代移动通信技术的重要组成部分.目前,针对低轨卫星通信的系统性信道建模流程与仿真方法仍相对匮乏,对于低轨卫星信道的高动态特性仍缺乏有效的建模方法,且大多模型仅能支持单场景通信环境.基于此,本文提出了一种模块化、高动态的多场景卫星通信信道建模机制,并据此设计实现了一套动态卫星信道建模仿真系统.该系统实现了流程化的建模思路,并引入了基于卫星信道高动态特性的动态参数更新方法.所设计的卫星通信信道建模与仿真机制能够生成卫星通信的信道大、小尺度参数与信道冲激响应,且对不同场景具有较好的适用性.     

Novel down link rain fade mitigation technique for Ka‐band multibeam systems

Rain fades at Ka‐Band degrades the link quality and performance significantly. Several rain fade mitigation techniques for Ka‐band satellite systems are being investigated to improve the channel capacity. Methods such as power control and adaptive waveform techniques have been proposed for use in the uplink as they are capable of straightforward implementation. A novel down link power control technique for multi‐beam Ka‐band system has been proposed in this paper. It is based on the use of multi‐port amplifier, which is commonly used for dynamic power sharing of the beams depending upon the traffic. Payload architecture for multi‐beam coverage using multi‐port amplifiers has been designed for the proposed technique. The simulation results to compensate for the rain fade attenuation of one beam by sharing the unused power from other beams have been presented Copyright © 2006 John Wiley & Sons, Ltd.     

Ka宽频带卫星通信馈源系统

作为下一代Ka频段卫星通信系统的关键天馈设备,新研制了一种高性能Ka宽频带卫星通信地球站四端口圆极化馈源系统,文章介绍了该馈源系统的方案特点及关键部件的选取原则,并给出实测结果。测试结果表明馈源系统在19.2~21.2 GHz的接收频带、29.0~31.0 GHz的发射频带内具有优良的性能,轴比小于0.5 dB、回波损失小于-21 dB,整体技术指标达到了国际先进水平。