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。     

一种Ka/EHF双频段圆极化器的设计

为了获得更大的通信容量,卫星通信频率将由Ku/Ka向更高的Ka/EHF频段发展,Ka/EHF双频段圆极化器是EHF卫星通信系统中的关键技术之一。设计了一种Ka/EHF双频段波导圆极化器,同时提出了一种新颖的Ka/EHF双频段极化分解器,该圆极化器和极化分解器获得了良好的驻波比和相位特性。借助仿真软件对圆极化器和极化分解器的尺寸和结构进行了优化,并进行了加工和测试。测试结果与仿真结果吻合较好,对所提出圆极化器和极化分解器的性能进行了验证。     

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。     

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。     

EHF频段卫星通信特点与关键技术分析

随着Ka频段卫星通信系统的逐步建立与普及,为获得更多的通信资源,需要建立更高频段的EHF频段卫星系统,该频段的射频器件、卫星链路等相比传统卫星通信系统均有其自身特点,是未来设计EHF卫星系统必须考虑的问题。文章分析了典型卫星链路和链路中各环节需要的关键技术。     

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。     

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。     

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频段卫星通信系统降雨衰减分析

Ka频段卫星通信因其具有可提供的带宽大(3.5GHz)、通信容量大、波束窄、终端尺寸小,轨道平面内可容纳的卫星多和抗干扰能力强等优势成为未来卫星通信的必然趋势。Ka频段卫星通信面临的一个巨大挑战在于它受气象因素的影响大,这一度使研究人员认为Ka频段卫星通信是不可能实现的。降雨、闪烁、大气吸收等因素都会导致Ka频段地空链路信道质量的恶化。根据Ka频段卫星通信的特点,分析了降雨衰减的特性,提出了几种抗雨衰的办法。     

Ka频段卫星通信自适应传输技术

随着经济的日益发展,传统的C频段、Ku频段已经无法满足生活和社会活动的通信需求,因此带宽更大的Ka频段成为近年来的发展方向.由于通信信道条件对Ka频段卫星通信的影响很大,所以克服通信质量的干扰成为Ka频段通信的主要工作.本文在Ka频段卫星通信中给予LDPC码的自适应编码调制(ACM)技术及功率控制技术进行了研究.     

LEO/MEO卫星通信系统发展展望

本简述了LEO/MEO卫星通信系统的主要特点，并介绍了几个典型的LEO/MEO卫星通信系统，如Iridium、Globalstar、ICO、Teledesic、Skybridge系统。还从星座、频率、星上处理及星际链路、无线技术、网络技术等方面讨论了LEO/MEO卫星通信系统的发展趋势和研究热点。     

The Alphasat Aldo Paraboni scientific and communication experiments at Ka and Q/V bands in Austria

The use of higher frequencies for satellite multimedia communication systems calls for research of the atmospheric propagation effects at these bands (rain, cloud and gaseous attenuation, scintillation, and depolarization). Alphasat was successfully launched on 25 July 2013. This largest and most powerful European telecommunication satellite carries, besides a commercial payload belonging to the mobile satellite communication provider Inmarsat, several Technology Demonstration Payloads (TDPs) from ESA. One of them is the Aldo Paraboni payload (TDP5) for Q/V‐band communication and Ka/Q‐band propagation experiments. These experiments explore future applications in satellite communication and measure how the Earth's atmosphere affects the propagation of electromagnetic waves. Under ESA contract, JOANNEUM RESEARCH designed, developed, and operates a Q/V‐band communication ground station and a Ka/Q‐band propagation terminal. The experimental site is equipped with ancillary equipment including a multifrequency radiometer profiler, a 2D video disdrometer (2DVD), and meteorological stations. This paper reports on the experimental setup, data processing, and obtained results.     

Q/V频段卫星通信发展现状与关键技术分析

随着航天技术的发展与用户对大通信容量、高传输带宽的迫切需求,GEO-HTS、NGSO-HTS快速发展,全球各大卫星运营商纷纷申请使用Q/V频段进行馈电链路传输。针对Q/V高频段在抗雨衰损耗和射频器件成熟度方面存在的短板,对国外搭建的Q/V频段卫星通信试验系统以及所采用的抗雨衰技术、射频器件技术进行了简要介绍,综合提出了上行功率控制、自适应编码调制和智能网关分集等抗雨衰技术以及固态功放、空间功率合成和预失真线性化等高频段射频技术,旨在提升通信系统的建设和运行效率,从而为国内Q/V频段卫星通信系统的建设提供了一定的建设思路。     

30/20-GHz domestic satellite communication system in the public communication network of Japan: Design and operation

Nippon Telegraph and Telephone Public Corporation (NTT) initiated the world's first 30/20-GHz domestic satellite communication system for commercial use, using CS-2s launched from Japan in 1983. This system utilizes TDMA digital communication in the trunk transmission route of the public communication network, which includes interregional-center routes and main-island-to-remoteisland routes. Small transportable earth stations enable easy access to the public communication network from any place in Japan. The adoption of the 30/20-GHz band enables use of a compact on-board antenna that has a shaped beam that effectively covers the main islands of Japan. It also enables the use of high-performance, compact antennas at the earth stations. These antennas can easily be installed on the roof of telephone offices or set on motor vehicles. One apparent disadvantage of using the 30/20-GHz band is rain attenuation. However, NTT has realized a commercial system that is affected very little by rain attenuation. This was accomplished by utilizing high-performance radio equipment and by concentrating on appropriate system design. Adoption of the 30/20-GHz band is quite significant because the wide bandwidth available enables construction of high-capacity economical transmission systems. It also enables use of small antennas, which allow construction of high-speed digital direct-to-user transmission systems using small earth stations. These expand the application of the domestic satellite communication system to even small service areas. Therefore, NTT considers satellite communication to be of primary importance for its proposed digital communication network, and has begun research on a high-capacity, economical, multibeam communication satellite system using the 30/20-GHz band. This paper describes the 30/20-GHz band radio technology, digital communication technology utilizing high-speed TDMA, and operational technology in the public communication network.     

Trellis-coded dpsk with multiple-symbol viterbi decoding over mobile satellite channel at K and L bands

Mobile satellite communication systems at K_a/K band (30/20 GHz) are attractive because of their large bandwidth availability and potentiality to support smaller earth-stations and satellite antennas compared with L-band (1·6/1·5 GHz) systems. In this paper, multiple-symbol Viterbi decoding and dual-space equal-gain diversity reception for trellis-coded differential M-ary phase-shift-keying (DPSK) modulation are investigated as two mitigation techniques for severe channel impairments expected from a land mobile satellite communication channel at K band and, for comparison purposes, at L band. The multiple-symbol Viterbi decoder (MSVD) is a modified Viterbi decoder with inputs from multiple differential detectors. The channel is modelled as Rayleigh distributed multipath fading with a lognormally distributed line-of-sight (LOS) component due to shadowing. Four trellis-coded modulation (TCM) schemes are studied. The dependency of the system performance improvement on the decoder structure, the TCM scheme, and the system RF frequency band is presented.     

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.     

20, 30 GHz Band Cassegrain Earth Station Antenna for the Japanese Domestic Satellite Communication System

An 11.5 m 30/20 GHz band Cassegrain antenna has been developed for a Japanese domestic satellite communication system earth station. In order to form an economical satellite communication network, the earth station antenna is required to be installed on the top of a telephone office building in a large city. Therefore, interference with terrestrial radio relay systems and antenna load on a building become the most important problems to be investigated. Considering the satellite position in geostationary orbit, a limited steerable system combined with a two-jackscrew drive mechanism is employed to lighten and simplify the antenna structure. Measured antenna aperture efficiencies are 72% in 20 GHz band and 68% in 30 GHz band. Measured wide angle radiation patterns satisfy the CCIR recommendation level. TheG/Tof the antenna at the feed horn port is measured to be 53.9 dB/K atEl = 45degat 18.75 GHz. Interference with the 20 GHz band terrestrial radio relay system in extremely near field was experimentally studied. Results show that the terrestrial system's antennas can be installed closely up to about 20 m without serious interference.     

A new view of millimeter-wave satellite communication

Italian satellite results have broad implications for millimeter-wave satellite communication. We apply their results to high-elevation satellite systems, and find that attractive frequencies extend well beyond the Ka band, to emphasize 40-47 and 85-98 GHz     

自适应TDMA抗雨衰对策在Ka波段卫星通信中的应用

自适应TDMA是一种非常有效的Ka波段卫星通信抗雨衰对策。本文研究了自适应TDMA的解决方案，包括地球站结构、帧结构安排、系统体系结构和链路质量估计及其传输。本文可以为Ka波段卫星通信设计人员提供TDMA系统设计的参考。     

具有双陷波特性的蜂窝结构分形超宽带天线

提出了一款具有双陷波特性的蜂窝结构分形超宽带（ultra-wideband，UWB）天线，采用二阶蜂窝结构作为辐射贴片和缺陷地结构接地板实现良好的超宽带特性.通过在辐射贴片上挖去正六边形和矩形宽缝隙并引入对称鱼钩形枝节，在馈线处刻蚀倒U形窄缝隙产生了3.27~4.27 GHz和7.2~8 GHz两个频段的陷波特性.天线在2.8~11.6 GHz的频段内，可有效抑制WiMAX、C波段卫星和X波段卫星窄带系统的干扰.仿真和实测结果基本吻合，表明该天线适合应用于各种UWB通信系统.