卫星监测多波束天线技术研究

本文综述了三种主要形态的多波束天线,并分别给出其工作原理图,对三种基本多波束天线进行了性能比较.     

基于OPNET的卫星多波束天线仿真建模研究

多波束天线技术是卫星移动通信系统中的关键技术之一.研究卫星多波束天线的几何模型,推导卫星多波束天线方位角和俯仰角的计算公式,分析卫星多波束天线的辐射特性,总结了利用OPNET生成卫星多波束天线模型的方法,并建模实现了OPNET多波束天线模型,通过构建网络仿真场景仿真分析了卫星多波束天线覆盖区内用户SNR的分布特性,仿真结果表明OPNET多波束天线模型较好地模拟卫星多波束天线的辐射特性.     

一种Ka频段多波束天线设计研究

针对临近空间飞行器测控的需求,提出了一种Ka频段多波束天线。分析了天线的实现形式,讨论了偏馈馈源位置与覆盖区域的关系、焦径比对偏馈波束性能的影响以及副面大小对偏馈波束性能的影响。从中总结了规律,对天线的优化设计有一定的指导意义。     

Ka频段高通量卫星地面关口站13m天线馈源系统设计

本文介绍了新一代高通量卫星通信系统下,13m Ka频段地面关口站天线馈源系统的设计实例。经过开发设计,得到一款高性能、免调试、模块化的天线馈源系统,具有良好的驻波、轴比、损耗、隔离特性。文末给出天线系统和馈源网络的实测结果,该天馈系统目前在全球Ka频段关口站系统中投入使用达30余台套,由于优良的电气和结构性能,深受用户好评。     

一种Ka频段多波束天线的工程实现

针对近空间飞行器测控的需求,设计了一种Ka频段的宽角覆盖多波束天线。采用方喇叭作为馈源,通过馈源的横向偏焦,实现反射面天线的宽角覆盖;最后,仿真并研制了原理样机,进行了测试。测试结果表明,该多波束天线覆盖了±1.5°以上的空域,且在覆盖区内的增益差小于1.8 dB,实现了对探测空域的宽角高增益覆盖。样机的研制成功为后续的工程优化提供了重要的设计参考。     

采用相控阵馈电反射器的多波束天线

本文对相控阵馈电单反射器天线作了分析研究，并阐明了馈源单元数量是最重要的设计参数，计算出的辐射特性证实了相控阵馈电单反射器天线适用于大型多波束天线。     

GEO卫星多波束天线指向测量方法与误差分析

针对地球同步轨道(GEO)卫星的多波束天线指向问题,研究了一种精确测量卫星天线指向的方法。在卫星发射通道间存在固有耦合干扰的情况下,通过地面测量站接收GEO卫星多波束天线发射的正交信标信号,推导并建立了测量卫星天线指向的数学模型;系统分析了各种误差源对测量精度的影响。通过仿真分析证明了该方法的有效性和可行性,为工程实现提供了参考依据。     

卫星多波束天线技术的发展

本文综述了欧洲卫星多波束天线发展的新技术 ,对各种多波束反射面天线或阵列天线的反射面、馈源、波束成形网络、辐射贴片等的新理论、新技术、新应用作了述评。     

卫星赋形波束天线优化方法的改进

本文采用了最小ｐ乘法和Ｍｉｎｉｍａｘ法对卫星多波束天线的赋形问题进行了研究，提出了用归一化的功率偏差值作为目标函数，使各点的偏差得以平衡，权值的选取变得十分简单。同时根据上述两种方法的目标函数特点，采用了相应有效的算法。最后用一个偏置抛物面多波束天线对本文改进后的方法进行了验证，并和以前的方法进行了比较，说明用归一化的功率偏差值作为目标函数来研究天线的赋形问题是非常合适的     

LCMV方法在卫星多波束天线赋形中的应用

本文提出了用线性约束最小方差(LCMV)方法对卫星多波束天线进行赋形.它是通过在保证主瓣电平一定的条件下,使天线的辐射功率最小,来对卫星天线的方向图赋形.由于这种方法与目前常用的迭代方法不同,它是一种解析法,故它在赋形精度、运算效率方面都高于目前这些常用方法,同时不会出现不收敛的现象.最后用两个具有代表性的例子,分别对方形区域和中国本土进行赋形,证明了LCMV方法的优点.     

Per‐antenna power minimization in symbol‐level precoding for the multibeam satellite downlink

This paper addresses the problem of multiuser interference in the forward downlink channel of a multibeam satellite system. A symbol‐level precoding scheme is considered, to exploit the multiuser interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, a per‐antenna power minimization scheme is proposed, under quality‐of‐service constraints, for multilevel modulation schemes. The consideration of the power limitations individually for each transmitting radio frequency chain is a central aspect of this work, and it allows to deal with systems using separate per‐antenna amplifiers. Moreover, this feature is also particularly relevant for systems suffering nonlinear effects of the channel. This is the case of satellite systems, where the nonlinear amplifiers should be properly driven to reduce the detrimental saturation effect. In the proposed scheme, the transmitted signals are designed to reduce the power peaks, while guaranteeing some specific target signal‐to‐noise ratios at the receivers. Numerical results are presented to show the effectiveness of the proposed scheme, which is compared both with the state of the art in symbol‐level precoding and with the conventional minimum mean square error precoding approach.     

Clustering strategies for multicast precoding in multibeam satellite systems

Next generation multibeam SatCom architectures will heavily exploit full frequency reuse schemes along with interference management techniques, eg, precoding or multiuser detection, to drastically increase the system throughput. In this framework, we address the problem of the user selection for multicast precoding by formulating it as a clustering problem. By introducing a novel mathematical framework, we design fixed/variable size clustering algorithms that group users into simultaneously precoded and served clusters while maximising the system throughput. Numerical simulations are used to validate the proposed algorithms and to identify the main system‐level trade‐offs.     

An online power allocation algorithm based on deep reinforcement learning in multibeam satellite systems

Dynamic power allocation (DPA) is the key technique to improve the system throughput by matching the offered capacity with that required among distributed beams in multibeam satellite systems. Existing power allocation studies tend to adopt the metaheuristic optimization algorithms such as the genetic algorithm. The achieved DPA cannot adapt to the dynamic environments due to the varying traffic demands and the channel conditions. To solve this problem, an online algorithm named deep reinforcement learning‐based dynamic power allocation (DRL‐DPA) algorithm is proposed in this paper. The key idea of the proposed DRL‐DPA lies in the online power allocation decision making other than the offline way of the traditional metaheuristic methods. Simulation results show that the proposed DRL‐DPA algorithm can improve the system performance in terms of system throughput and power consumption in multibeam satellite systems.     

Design of next generation high throughput satellite communication system based on beam-hopping

Beam-hopping technology provides a basis for flexible allocation and efficient utilization of satellite resources,and it is considered as a key technology of the new generation of high-throughput satellite.With the goal of service-driven,efficient utilization of resources and on-demand coverage of hot spots area,from the aspects of system architecture,communication system,working mechanism,resource allocation method and beam-hopping pattern design,user access strategy,air interface protocol design and system workflow,a top-down feasibility and technical foundation was provided for the design of a new generation of high-throughput satellite communication system based on beam hopping.Finally,it meet the requirements of flexible and mobile information service for the space-earth integration network,as well as the demand of the space-based backbone network with high reliability and large capacity transmission.     

卫星天线的自动跟踪技术研究

天线自动跟踪技术是卫星移动通信系统的关键技术,其核心问题是天线对卫星的快速捕获和自动跟踪.文中采用了新的步进跟踪算法,进一步提高了系统的跟踪速度和精度.     

Coarse recovery of carrier frequency and symbol timing in multibeam satellite channels

A multibeam concept under full frequency reuse is a major prerequisite for high throughput satellite systems. The resulting interference problems might be tackled by appropriately designed precoding or multiuser detection schemes. However, before such powerful techniques are applicable, the most important transmission parameters have to be recovered successfully. In the context of this paper, a feedback structure for joint control of carrier frequency and symbol timing is investigated for a multibeam scenario, which has been developed in some previous work by the authors for a single user link. It is to be noticed that we describe a recovery method for a multibeam satellite network with suitably selected interference mitigation techniques; as a consequence, all cochannels are assumed to be aligned in frequency and time to the reference beam; other signal models are out of scope and not addressed in this contribution.     

Ku、Ka频段龙伯透镜馈源阵列技术研究

针对卫星通信中龙伯透镜天线不同频段的馈源并排放置导致最大波束指向的偏移,无法实现多频段馈源上、下行跟踪同一颗卫星,提出了馈源阵列馈电的方法。通过辐射口面采用介质杆天线取代喇叭以改进馈源,此方法减小了馈源的阵间距,利于馈源组阵。结果表明:利用馈源组阵技术可以解决波束偏焦问题,实现多频段收发同一颗卫星的目的,同时也分析了阵列馈源馈电对天线增益和效率的影响。     

Simulation and analysis of node throughput using smart antenna in wireless mesh networks

Smart antenna technology is introduced to wireless mesh networks. Smart antennas based wider-range access medium access control (MAC) protocol (SWAMP) is used as MAC protocol for IEEE 802.11 mesh networks in this study. The calculation method of node throughput in chain and arbitrary topology is proposed under nodes fairness guarantee. Network scale and interference among nodes are key factors that influence node throughput. Node distribution pattern near the gateway also affects the node throughput. Experiment based on network simulator-2 (NS-2) simulation platform compares node throughput between smart antenna scenario and omni-antenna scenario. As smart antenna technology reduces the bottle collision domain, node throughput increases observably.     

船载卫通站天线控制单元引导计算异常的解决

某船载卫通站天线控制单元( ACU)在一次任务海域使用捷联惯导( SINS)作为数据源引导计算时出现了卫星捕获异常情况。针对该问题,从分析船载卫通站卫星捕获原理入手,详细比对了各类引导源的数据格式与异同点,结合以往工程经验进行问题排查定位,提出了相应的解决方案并完成了ACU软件的修改完善和测试验证。试验结果表明,采用所提方法,问题定位准确,解决方案简单有效、可行性强,可为类似问题的解决提供参考。     

基于Simulink仿真的用户星天线控制系统分析

为满足中继卫星系统对天线指向精度的要求,首先描述了天线指向控制概念,对用户星与中继卫星星间链路的建立过程进行了分析,并且设计了星上自主控制方案,在Simulink环境下对所设计的天线指向控制系统进行了数学仿真,最后通过对仿真结果的分析验证了用户星天线控制系统的跟踪性能。