天地一体化信息网络中天基卫星网络架构设计

为了充分利用各种空间设施资源,提升天基信息网络覆盖与传输能力,分别从天基信息网络体系架构和逻辑功能架构角度进行了系统性设计。与以往天基网络的设计不同,该设计更注重各类卫星网络的深度融合应用,为此将网络虚拟化技术引入天基卫星网络。同时,还提出了解决新架构下卫星组网难题的方法,将电磁涡旋、卫星灵活载荷和边缘计算技术设计到天基网络。仿真表明,所提出的架构能有效提升频谱利用率和减少卫星网络信令开销。     

面向多波束卫星通信网络的步进跟踪方法

面向多波束覆盖的卫星通信网络,为解决相控阵用户终端位置姿态信息无法获取时程序跟踪卫星失效的问题,提出了一种步进扫描跟踪方法。在该方法中,终端仅需比较单个波束的信标接收能量即可判断波束指向,从而降低跟踪时延。在此基础上,为满足终端在动中通场景下的业务通信需求,进一步研究动态条件下的跟踪方法,并讨论跟踪时延的影响因素。实验结果表明,当终端位置姿态变化较小时,所提方法的跟踪性能接近程序跟踪。     

卫星网络中永久星间链路的设计方法研究

从星座设计角度出发,分析永久性星间链路存在的条件,解决了不同轨道面以及不同轨道高度卫星之间相对移动造成的星间链路频繁切换问题。根据卫星网络空间几何特性,提出了一种在卫星生存期内可以永久保持星间链路连接的星座设计方法,并对建立星间链路的条件进行了分析。通过数值分析方法得出了永久星间链路存在的条件,并通过实例加以验证。     

基于可延展带宽分配的卫星网络高可用性方案

随着IPTV等网络服务的蓬勃发展,以及地面互联网的接入与融合,针对空间信息网络的资源规划势在必行.同时,为了有效抵抗分布式拒绝服务(DDoS)攻击,可用性设计成为卫星正常运转的重要前提.提出了基于网络带宽资源分配的DDoS攻击防御体系,建立了有效的卫星网络拓扑结构模型,并引入了路由状态数据包的概念,设计了相应的卫星网络路由协议.在此基础上,阐述了具有延展性的网络带宽分配机理及其实现方式.根据安全性分析与实验评估结果,提出方案可在有效防范敌手攻击的同时,保障带宽资源的可延展分配,同时方案具备良好的实现性能.     

面向LEO卫星网络的高效路由算法

由于卫星星上处理以及存储能力有限,随着卫星网络的规模越来越庞大,迫切需要一种简单高效的路由算法.为此,提出了一种基于网络拥塞程度感知的路由策略(Network Congestion-Aware Routing Algorithm,NCARA).NCARA路由策略在网络处于非拥塞状态时采用Dijkstra算法寻路,网络拥...     

QoS handover management for multimedia LEO satellite networks

Low earth orbit (LEO) satellite systems gained considerable interest towards the end of the previous decade by virtue of some of the appealing features that are endowed with, such as low propagation delay and the ability to communicate with handheld terminals. However, after the limited commercial success of the first networks of this kind, future satellite networks are now conceived as complementary rather than competitive to terrestrial networks. In this paper, we focus on one of the most influential factors in system performance, that is, the handover of a call. First, we provide a succinct review of the handover strategies that have been proposed in the literature. Then we propose two different satellite handover techniques for broadband LEO satellite systems that capitalize upon the satellite diversity that a system may provide. The proposed schemes cater for multimedia traffic and are based on the queuing of handover requests. Moreover, a deallocation scheme is also proposed according to which capacity reservation requests are countermanded when the capacity that they strive to reserve is unlikely to be used. Simulation studies further document and confirm the positive characteristics of the proposed handover schemes.     

Topological design,routing and capacity dimensioning for ISL networks in broadband LEO satellite systems

This paper considers the network design of intersatellite link (ISL) networks in broadband LEO satellite systems, where the major challenge is the topology dynamics. First, a general method to design convenient ISL topologies for connection‐oriented operation is presented, and a reference topology for numerical studies is derived. A permanent virtual topology is then defined on top of the orbiting physical one, thus forming a framework for discrete‐time dynamic traffic routing. On this basis, heuristic and optimization approaches for the combined routing and dimensioning task, operating on discrete time steps, are presented and their performance is numerically compared. It is shown that minimizing the worst‐case link capacity is an appropriate target function, which can be formulated as linear optimization problem with linear constraints. Using linear programming (LP) techniques, the dimensioning results are clearly better than with simple heuristic approaches. Copyright © 2001 John Wiley & Sons, Ltd.     

卫星载荷软件的层次化设计

介绍了卫星技术的发展对未来载荷软件设计的要求,提出了层次化设计这样一种新的思路.通过对载荷软件功能的分析、提炼和抽象,将载荷软件划分为相对独立的3个层次,即系统层、协议层和应用层,采用这样的分层架构设计,可以最大限度地实现软件的高内聚、低耦合,提高软件的可移植性、可重用性和可靠性,节省研制时间及成本.     

面向全球能源互联网的天空地协同卫星通信网络架构

全球能源互联网的监测、调度、授时、同步及定位等业务均需要能提供广域覆盖、泛在灵活接入服务的可靠通信网络。针对该需求,首先分析阐述全球能源互联背景下各种新型业务需求及其特点,并总结各种业务的共性数据特征;然后论述卫星通信技术的特点以及与全球能源互联网业务特点与数据传输需求的高度契合性,最终提出融合卫星通信网络的全球能源互联网天空地协同网络体系架构。其以IP技术为基础,各层网络通过星间、星地、星空、空空、空地以及地面有线、无线链路连接起来,构建全球覆盖的一体化网络体系。     

Ku-Band satellite data networks using very small aperture terminals—part II: System design

In this part of the paper on Ku-band VSAT networks, the issue of overall system design is considered. After discussing possible system architectures, primary attention is given to the star network configuration in which customer-premise VSATs communicate with a central hub station, co-located with, or terrestrially connected to a host computer. The component elements of a Ku-band star network for interactive data applications are discussed and the critical items from the point-of-view of performance, capacity and cost are identified. An analytical model for the network, which combines delay-throughput characterization of the multi-access inbound and TDM outbound channels with satellite link analysis is described. The analytical model is exercised over a range of typical system component, traffic model and performance objective scenarios to provide a set of general design guidelines. These guidelines are useful for evaluating the trade-offs between key system elements (channel access unit, modem, VSAT antenna and satellite), VSAT traffic message length parameters and the performance objectives (average and peak network response time and availability). The results are used to address the issue of multi-access protocol selection over a range of scenarios typical of 1.2 or 1.8m VSAT-based interactive networks using current commercial Ku-band satellites. The results show that interactive star networks are often limited by satellite power rather than bandwidth, so that the use of simple contention access for VSATs may not imply a significant system capacity penalty.     

Virtual fully connected WDM network: A high-performance single-hop architecture for metropolitan area networks

With the widespread use of broadband access technologies and the development of high-speed Internet backbones, the requirement for high-performance metropolitan area networks (MANs) is increasing. Traditional ring- or star-based metro networks are costly to scale up to high speed and cannot recover from multiple failures, while backbone solutions are too expensive to fit into the cost-sensitive metro market. This paper proposes a virtual fully connected (VFC) architecture for metro networks to provide high-performance node-to-node all-optical transportation. The architecture emulates a fully connected network by providing optical channels between node pairs without intermediate buffering, and thus realizes single-hop transportation and avoids expensive packet routers. In addition, a scheduling algorithm is developed for medium access control and dynamic bandwidth allocation, which achieves 100% throughput and provides a fairness guarantee. Simulations show that the VFC network achieves good performance under both uniform and non-uniform loads.     

Survey of outdoor and indoor architecture design in TVWS networks

To understand the utilizability of TV white spaces (TVWS), a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that: in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components: TV spectrum identification, access point (AP) discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.     

非静止轨道卫星网络间下行数据传输同频干扰的分析方法

本文根据已有的静止卫星网络之间的同频干扰计算方法,考虑非静止卫星网络下行数传的特点,提出了一种估算非静止卫星网络间下行数传的同频同向干扰的方法。该方法通过对离散化时间的仿真,可以从强度和频度两方面综合考察干扰的效果,从而能较全面地衡量上述的干扰情形。     

面向6G的卫星通信网络架构展望

分析和研究了未来6G卫星网络架构并提出了设想。首先介绍国内外星地融合的研究现状,结合6G网络的愿景、需求和6G网络架构的当前研究成果,总结了6G网络架构的技术特征;然后通过对人工智能（AI）在通信领域的研究和应用分析,以及AI在6G网络中关键作用的深入挖掘,提出了AI赋能的6G卫星通信网络总体架构、接入网架构及核心网架构的设想,同时提出了分阶段演进和分步骤实现的建设思路,最后对基于区块链的6G卫星通信网络韧性鲁棒机制进行了技术探讨。     

低轨卫星网络的航点分段路由及业务性能分析

提出一种基于卫星航点的分段路由（waypoint-segmentrouting,WSR）算法，WSR算法以可预测的卫星网络拓扑运动周期为基础，根据卫星节点链路状态确定卫星航点的位置；利用分段路由灵活规划分组传输路径的机制，提前响应网络拓扑变化，计算得到一条不受网络拓扑快照切换影响的传输路径。基于NS-3仿真平台进行仿真实验，设置源节点与目标节点在反向缝同侧与不同侧两种场景，选取优化链路状态路由（optimized link state routing,OLSR）算法和最短路径算法与WSR进行时延抖动与分组丢失率的对比分析。实验证明WSR与OLSR相比，两种场景下最大时延抖动分别降低46 ms与126 ms，分组丢失率分别降低30%和21%，并且能够解决拓扑快照切换导致分组传输路径中断的问题。     

A three-stage architecture for very large packet switches

This paper proposes a three-stage broadband packet switch architecture with more than 16,000 ports for a future central office. The switch is constructed by interconnecting many independent switch modules of small size which can be implemented using modifications of various well-studied switch fabric designs. Channel grouping is used to provide multiple paths for each input-output pair in order to decrease delay and increase throughput. We show that, for a given size, switch modules with channel grouping are simpler to realize than those without channel grouping. A datagram packet routeing approach is adopted in order to avoid table look-up that would be required by virtual-circuit routeing. Ways of preserving the sequence integrity of packets under this situation are presented. Performance analyses show that a 32,768 x 32,768 switch with acceptable performance can be constructed based on switch fabrics of no more than 128 ports.     

一种改进的宽带卫星网络MAC协议

为了提高宽带卫星网络上行信道资源的利用率,同时保障多媒体业务的不同服务质量要求,需要采用合适的媒体接入控制协议。BTDAMA可以显著减少自相似业务的等待时延,并且提高了资源利用率。但它没有区分业务类型,不能保证高优先级业务的服务质量,也造成了一定程度上资源的浪费。在BTDAMA的基础上提出了一种基于业务优先级的带宽分配算法,针对不同的业务类型采用不同的分配方案,不仅保证了各类业务的服务质量,同时提高了资源利用率。     

低轨卫星通信网络中改进的综合加权接入算法

针对用户终端有效与可靠接入低轨卫星通信网络的需求,基于现有的接入算法,综合考虑了卫星对用户终端的覆盖时间、卫星空闲信道数以及卫星接收信号的信噪比因素,提出了一种改进的综合加权接入算法,对该算法的目标函数和参数进行了设计与计算.仿真结果表明,采用改进的综合加权接入算法,新呼叫阻塞率和强制中断率等性能都得到了明显的改善.     

通信卫星星座优化设计综述

通信卫星星座优化设计是构建通信星座系统的关键环节。对通信卫星星座设计中的优化模型和优化算法进行了综述和展望。首先,建立了通信卫星星座设计的一般优化模型;然后,从覆盖性能、星间链路和系统成本三个方面对优化模型中优化变量、目标函数和约束条件的构建进行了综述;之后,介绍了卫星星座设计中常用的三大类多目标优化算法,归纳总结了4种主流算法的主要特征,并比较分析了它们应用于卫星星座设计的优缺点;最后,指出了现有通信卫星星座优化设计中存在的问题及发展趋势。