Coordinated Resource Allocation for Satellite-Terrestrial Coexistence Based on Radio Maps

Coexistence of satellite and terrestrial wireless communication systems in the same frequency band is quite promising for addressing the challenge of spectrum scarcity. To cope with the inevitable inter-system interference, radio resource allocation at both sides should be carefully re-optimized. In this paper, we focus on a scenario where a satellite communication system and a terrestrial distributed antenna system(DAS) coexist via spectrum sharing. We particularly utilize the radio map(RM) to reduce the system overhead for channel acquisition. Based on the large-scale channel state information at the transmitter(CSIT), which is derived from the RM, we propose an optimized power allocation scheme to improve the achievable sum rate of the terrestrial system. For the satellite side, an opportunistic user scheduling scheme is presented, to reduce the harmful leakage interference to the terrestrial mobile users. Simulation results demonstrate that the proposed RM-based coordination scheme can significantly promote the performance of satellite terrestrial coexistence, although the small-scale channel fading has been ignored in the formulated optimization.

Low Altitude Satellite Constellation for Futuristic Aerial-Ground Communications

This paper discusses the significance and prospects of low altitude small satellite aerial vehicles to ensure smooth aerial-ground communications for next-generation broadband networks.To achieve the generic goals of fifthgeneration and beyondwireless networks,the existing aerial network architecture needs to be revisited.The detailed architecture of low altitude aerial networks and the challenges in resource management have been illustrated in this paper.Moreover,we have studied the coordination between promising communication technologies and low altitude aerial networks to provide robust network coverage.We talk about the techniques that can ensure userfriendly control and monitoring of the low altitude aerial networks to bring forth wireless broadband connectivity to a new dimension.In the end,we highlight the future research directions of aerial-ground communications in terms of access technologies,machine learning,compressed sensing,and quantum communications.

SIRIUS Satellite radio卫星收音机

车载收音机一直是车内信息和娱乐的来源之一。目前美国SIRIUS卫星广播公司已经推出了主要针对汽车族的数字卫星广播，节目多达120多个，内容无所不包，不仅音质奇佳，而且接受地域几乎不受任何限制。

Satellite RFI mitigation on FAST

As the most sensitive single-dish radio telescope,the Five-hundred Aperture Spherical radio Telescope(FAST)is very susceptive to radio frequency interference(RFI)from active radio services.Moreover,due to the rapid development of space applications and research,satellite interference has become one of the main RFI sources for FAST,particularly at the L band.Therefore,we have developed several measures to mitigate satellite RFI.On the one hand,an antenna with 4.5-meter diameter has been constructed and installed at the FAST site to detect the satellite interference in the frequency band between 1 to 5 GHz.Meanwhile,we have developed a satellite RFI database based on the FAST sky coverage,the observing frequency bands,and known satellite systems.By combining the satellite RFI monitoring antenna and the database,we have established a satellite RFI mitigation system.With this system,we can not only track satellites to collect their characteristics and update the database but also help the observer to program the observing plan by predicting satellite interference.During the practical observation of FAST at the L band,the feasibility of this system to mitigate satellite RFI has been proved.In particular,the system effectively avoids strong satellite interference from entering the main beam of the telescope and causing receiver saturation.

Total Electron Content and Anomalous Appearance of GPS Satellites as Pointers to Epicentre Identification of Major Japan Earthquake of 2011

The paper presents an analysis of variations in Total Electron Content (TEC) observed through Global Positioning System (GPS) at Guwahati (26?10'N, 91?45'E), in relation to the Japan Earthquakes (EQs) of March 9 and 11, 2011. For this purpose, the azimuthal positions and trajectories of abnormally increased number of satellites at the epicentre location appearing into the Field Of View (FOV) of GPS antenna at Guwahati and consequent pseudo enhancement in TEC are taken as inputs. The paper discusses how the analysis results could provide warning alarms of two earthquakes possibly one on March 8 or 9 and the other on March 11 or 12, 2011 with epicenter positions around 135?E to 145?E and 35?N to 40?N, that coincides with location of Japan Earthquakes. A projected forecast on EQ magnitude of M > 8.5 is also made. The explanations to the observed modifications in TEC features and abnormal increase in number of satellites are purported to be the result of coupling between lithosphere and troposphere forced in by pre-earthquake processes that had spread the zone of activities to as far as Guwahati.

Wideband Modeling of Land-Mobile-Satellite Channel in Built-Up Environment

This paper presents a propagation model for land-mobile-satellite (LMS) wideband radio channel in built-up environment. The model characterizes the behavior of the radio channel, under shadowing and multipath effects due to buildings, with variation of the elevation angle of the satellite. The wideband parameters (coherent bandwidth and time delay spreading) for LMS channel, in residential and urban environments, are computed. These parameters can be considered as a measure of the amount of ISI (inter-symbol interference) of the radio channel, which distorts the received signal and accordingly increases the bit error rate. The calculated values for these parameters using our model, show very good agreement with the corresponding measured ones, which accordingly shows the validity of the developed model for radio channel design in satellite mobile communication systems.

Chinese Surveying and Control Network for Earth-Orbit Satellites and Deep Space Detection

The relationship between the surveying and contro l network(CSN) for earth-orbit satellite and spatial geodesy, and the relationshi p between the CSN for deep space celestial bodies and detectors, and deep space detection are briefly summarized, and so are the basic technical needs of the de ep space surveying and control network(DSN). Then, the techniques, the constitue nts and the distributing of Chinese satellite CSN (CSCSN) and other radio observ ing establishments in China are introduced. Lastly, with the primary CSCSN and o ther observing establishments, some projects for China to rebuild a more perfect CSCSN, and to establish a DSN are analyzed and stated.

Conspiracy Determines World War III with Reference to Several Windows’ Channel in Connection with Earth Observation Satellite

Thermonuclear reaction exerts its influence of X-emission to produce several windows’ channel in the presence of an oscillator under electrical relay circuit with a decisive importance to a radiofrequency Earth observation satellite. Indian Television Network (National Channel) has introduced a radiofrequency accelerator to produce X-emission at resonance with an activation of artificial human environment under relay analogy in the presence of an Earth observation satellite. Thermonuclear reaction communicates several windows’ channel via Earth observation satellite. Star Television network communicates an artificial human environment under the influence of a relay circuit with different pulse code units of human brain with an active influence of an artificial sensation to generate the loss of humanity around the world.

Quantum Nature of Distortion and Delay of Satellite Signals II

A detailed analysis of the influence of Rydberg states to the behavior of GPS satellite signals in the D and E atmospheric layers has been carried out. It is demonstrated that these states are the main reason for the GPS signal distortion. It is shown that the behavior of satellite signals is associated with the spectral characteristics of the UHF radiation of the Rydberg states depending on the geomagnetic conditions of ionosphere. The foundations of the quantum theory of distortion and delay of GPS satellite signal propagation through D and E atmospheric layers are analyzed and expounded. The problem reduces to the resonant scattering of photons, moving in the electromagnetic field of the signal, to the Rydberg complexes populated in a two-temperature non-equilibrium plasma. The processes of creation of additional photons because of stimulated emission and resonance scattering of photons are considered. In the present work, the quantum theory of the propagation of a satellite signal in the Earth’s upper atmosphere, firstly earlier proposed by the same authors, is described in detail. The general problems of the theory and possible theoretical and applied consequences are discussed. It is explained that two main processes occurring here, are directly related to the resonant quantum properties of the propagation medium. The first process leads to a direct increase in the power of the received signal, and second—to a shift in the signal carrier frequency??and the time delay??of its propagation. The main reasons of the processes are scattering of the Rydberg electron by the ion core and presence of the neutral medium molecule in the intermediate autoionization states of the composite system populated by the strong non-adiabatic coupling of electron and nuclear motions. The main purposes of our investigation are the physical justification of the formation of parameters ?and??using the quantum dynamics of the electron behavior in the intermediate state of the Rydberg complex A**M and the estimation of the quantities of??and??in the elementary act of elastic (Rayleigh) photon scattering.

面向FAST的卫星电磁干扰监测技术研究与实现

来自人造卫星的信号是射电天文观测面临的主要射频干扰(radio frequency interference,RFI)之一,这些RFI会将天文信号掩埋,为天文信号的搜寻和分析带来困扰。为了缓减卫星对天文观测的影响,我们在之前的工作中为500 m口径球面射电望远镜(Five-hundred-meter Aperture Spherical radio Telescope,FAST)开发了卫星电磁干扰监测软件,主要包括卫星数据库、观测模块和监测模块。近年来随着多个巨型卫星星座的规划发射以及望远镜观测模式的增多,卫星对射电天文观测的影响更为复杂,已有的软件已经不能满足实际的需要。为此,本文在单个卫星干扰分析的基础上提出了卫星星座的干扰评估方法,并对已有监测软件进行了升级,升级后卫星数据库覆盖更多的在轨卫星及星座信息且能够自动化更新,观测模块能够支持更多种观测模式下的卫星过境预测和干扰评估。在实际天文观测中,通过接在FAST接收机上的频谱仪数据对软件的干扰预测结果进行了实验验证,结果证明升级后的软件能够在多种观测模式下预测可能威胁的卫星以及对应的过境时间,为望远镜观测规划的调整、卫星干扰的规避和接收系统的保护提供重要的支撑。

COSMIC-2近实时廓线反演对流层延迟及其质量分析

为了进一步提高全球大气探测和极端天气预报的精度,提出一种气象、电离层与气候星座观测系统2代(COSMIC-2)近实时廓线反演对流层延迟方法:指出随着气象、电离层与气候星座观测系统2代(COSMIC-2)掩星探测深度的加深,通过掩星手段为地表全球卫星导航系统(GNSS)观测站提供近实时先验天顶对流层延迟(ZTD)产品成为可能;采用COSMIC-2掩星Level 2近实时产品wetPf2大气湿度廓线获取掩星ZTD,并以欧洲中期数值天气预报中心第五代再分析资料(ERA5)作为参考,分高程、纬度、季节评估其反演精度。结果表明,COSMIC-2掩星反演天顶对流层延迟ZTD整体精度较高,10 km高程以下全球定位系统(GPS)信号反演ZTD精度较格洛纳斯卫星导航系统(GLONASS)信号更优;掩星反演ZTD精度随高程增加而提升,在0~1 km高程范围内精度最低,均方根(RMS)分别为11.33 mm(GPS)、11.54 mm(GLONASS);中低纬度区域(25°N—35°N)反演ZTD精度低于低纬(15°N—25°N)和中纬(35°N—45°N)区域,其中中纬区域精度最高,RMS分别为4.74 mm(GPS)、4.70 mm(GLONASS);掩星反演ZTD精度同样受季节影响,GPS/格洛纳斯全球卫星导航系统(GLONASS)双模信号均在夏季反演精度最差,冬季反演精度最高,冬季RMS分别为4.15 mm(GPS)、4.18 mm(GLONASS)。

基于软件无线电的通信卫星柔性测试技术

针对通信卫星有效载荷地面测试系统专用化程度高、人员操作性差、软件兼容性低、迭代更新成本高的问题,文章提出一种基于软件无线电的卫星柔性测试技术,发挥软件无线电支持高级语言编程和灵活程度高的特点,将不同通信卫星有效载荷体制以软件自定义实现的方式统型到通用的硬件平台,设计可用于各型通信卫星有效载荷测试的通用化地面测试设备,实现卫星有效载荷测试技术经济一体化。经在卫星移动通信载荷和航空监视载荷中实际测试验证,结果表明:基于软件无线电的卫星柔性测试设备满足通信卫星有效载荷的测试需求,可为软件无线电技术在卫星测试领域的探索和应用提供参考。

卫星通信在广播电视领域的应用研究

以卫星通信在广播电视领域的应用为研究重点,首先全面介绍卫星通信相关理论知识,包括卫星通信的定义和特点、工作原理、不同类型等,其次重点分析卫星通信在广播电视领域的优势和挑战,最后深入探讨卫星通信在广播电视方面的具体应用,包括在4K/8K超高清节目传输、应急广播、新闻报道等领域的应用,并举例说明,以期为广播电视与卫星通信的深度融合提供参考。

基于舰艇平台授时技术现状及发展研究

为了解军用授时技术现状及发展,结合基于舰艇平台的授时技术对自身及编队时间统一能力的深刻影响,对国内外军用授时技术发展现状进行了相应的研究。通过对授时基本技术、授时技术在国内舰艇的应用、国外军用授时技术发展等方面的理论研究,概括了基于舰艇平台的授时技术现状及发展情况,最后总结提出了我国未来授时技术的发展方向以及需要大力加强无外部授时源方法研究,旨在为未来军用授时技术的发展研究提供一定的参考。

基于RCS不同海况双基雷达最优角度分析

雷达散射截面(RCS,Radar Cross Section)用于表征雷达目标对照射电磁波反射特性,在被动雷达系统中,雷达散射截面是判断能否检测到目标的一个重要参数。针对以广播电视卫星为外辐射源的被动雷达系统对海面目标进行检测的问题,仿真了目标和海面的双基地雷达散射截面(RCS),分析外辐射源-仿真对象-接收机位置关系对雷达散射截面(RCS)的影响,讨论了目标和海面的雷达散射截面(RCS)与角度的关系,对被动雷达系统如何选择外辐射源具有一定参考价值。

气象小卫星发展的回顾与展望

气象卫星对地观测是大气、空间气象要素观测的重要手段.近年来,气象小卫星发展迅猛,引起对地观测领域的广泛关注.回顾了目前国内外具有重要影响力的气象小卫星星座的设计思路和布局,在已经实现的对降水、云雨粒子和大气温湿度廓线等重要气象要素的探测能力基础上,提出并阐述了未来中国气象小卫星的发展构想.中国将打造具有前沿技术验证能力、科学试验能力、星座协同和即时定制能力的气象小卫星星座,与大平台系列风云气象卫星互联互通,共同作为数字太空系统的天基感知节点,形成大小结合、星地统筹、协同观测、综合应用的气象卫星发展新格局,为气象高质量发展提供新的技术支撑.

基于非正交多址接入的星空地多用户认知网络性能研究

卫星通信(SatCom)因其强大的生存能力和无缝覆盖的独特优势,能够弥补地面通信网络受地形限制、覆盖范围小等短板,在当前和未来的无线通信系统中具有重要的地位。此外,空中辅助通信由于其在星地网中的灵活性和可扩展性,具有很高的研究价值。为克服星空地网络(ISATN)中频谱短缺问题,认知无线电(CR)和非正交多址接入(NOMA)被用于提高频谱利用率和传输性能。因此,该文研究了基于NOMA的星空地认知网络(CISATN)的性能,考虑多用户场景,分别得到了主网络和次级网络的中断概率(OP)的准确表达式和高信噪比下的渐进表达式,并给出了这两个网络的分集增益。最后,通过蒙特卡罗仿真验证了理论推导的正确性,并分析了关键变量对系统指标的影响。