Software-Defined Space-Air-Ground Integrated Network Architecture with the Multi-Layer Satellite Backbone Network

Under the background of the rapid development of ground mobile communication,the advantages of high coverage,survivability,and flexibility of satellite communication provide air support to the construction of space information network.According to the requirements of the future space information communication,a software-defined Space-Air-Ground Integrated network architecture was proposed.It consisted of layered structure satellite backbone network,deep space communication network,the stratosphere communication network and the ground network.The Space-Air-Ground Integrated network was supported by the satellite backbone network.It provided data relay for the missions such as deep space exploration and controlled the deep-space spacecraft when needed.In addition,it safeguarded the anti-destructibility of stratospheric communication and assisted the stratosphere to supplement ground network communication.In this paper,algorithm requirements of the congestion control and routing of satellite backbone protocols for heterogeneous users’services were proposed.The algorithm requirements of distinguishing different service objects for the deep space communication and stratospheric communication network protocols were described.Considering the realistic demand for the dynamic coverage of the satellite backbone network and node cost,the multi-layer satellite backbone network architecture was constructed.On this basis,the proposed Software-defined Space-Air-Ground Integrated network architecture could be built as a large,scalable and efficient communication network that could be integrated into space,air,and ground.

Distributed Contact Plan Design for Multi-Layer Satellite-Terrestrial Network

In multi-layer satellite-terrestrial network, Contact Graph Routing(CGR) uses the contact information among satellites to compute routes. However, due to the resource constraints in satellites, it is extravagant to configure lots of the potential contacts into contact plans. What's more, a huge contact plan makes the computing more complex, which further increases computing time. As a result, how to design an efficient contact plan becomes crucial for multi-layer satellite network, which usually has a large scaled topology. In this paper, we propose a distributed contact plan design scheme for multi-layer satellite network by dividing a large contact plan into several partial parts. Meanwhile, a duration based inter-layer contact selection algorithm is proposed to handle contacts disruption problem. The performance of the proposed design was evaluated on our Identifier/Locator split based satellite-terrestrial network testbed with 79 simulation nodes. Experiments showed that the proposed design is able to reduce the data delivery delay.

一种中高轨混合的多层卫星骨干网络架构设计

卫星骨干网络将向宽带与中继融合方向发展,为陆、海、空、天基用户提供全球骨干传输、宽带接入、全域通联等服务。该文针对全域用户通联的新需求,创新采用“卫星骨干网络/全域用户接入”模型,提出一种具有层内、层间星间链路的中高轨混合的多层卫星骨干网络架构(3GEO+3IGSO/24MEO)。对该架构的全域覆盖性计算分析,得出该多层卫星骨干网络能够实现地球表面到地球同步轨道高度(约36000 km)全域100%覆盖,并为全域用户提供多重接入能力。进一步对路径数、最少跳数、最小时延等关键网络性能指标分析比较,说明了该架构中轨卫星与高轨卫星之间存在层间星间链路的必要性。分析结果表明:该架构能够满足全域宽带接入和全球骨干传输的需求。

面向未来星地激光骨干链路可靠组网的云预测技术研究

为解决星地骨干链路组网过程中,激光链路因受到云层干扰而出现的阻塞、中断等影响通信质量的问题,提出了一种基于随机森林算法的云预测技术,训练出高准确率、高提前量的预测模型。预测模型以随机森林为基本算法,与云量相关的气象参数集合为数据集,经过基本模型搭建、两轮超参数优化三个步骤,可以有效提高模型预测准确率。实验结果表明,对有云无云情况的预测准确率达到90%以上,而加入了预测模型的组网系统可以有效降低链路中断次数,提高链路容量。

Markov approximation for multilayered selection in satellite network

A satellite network system comprises three layers of satellites:LEO(Low Earth Orbit),MEO(Middle Earth Orbit)and GEO(Geostationary Orbit).In the system,users can choose a layer according to their demands,including QoS(Quality of Service),congestion,energy cost,etc.The utility that users gain will change when they access satellites in different layers.The mobility of satellites in the LEO and MEO leads to frequent handover among satellites in the same layer.These characteristics of multi-layered satellite networks make it possible for us to exploit the optimal distribution of users,which will maximize the utility of the entire satellite network.While the proposed problem is an NP-hard problem,we analyze the system based on the Markov chain and use the Markov approximation to approach the maximum utility.In addition,we use the count down and select algorithm to implement the process of Markov chain.The simulation results validate the convergence of the Markov approximation.In addition,the gap between the approximate value and optimal values decreases with an increase inβ,which is a positive constant in Markov formulation,according to the simulation results.

空间骨干网络体系架构与关键技术研究

空间骨干网络是由天、空、地中大型骨干节点组成的综合性一体化网络,是构建空间信息网络的核心支撑。在介绍了欧美关于空间信息网络研究现状的基础上,分析了空间骨干网络的相关特性和总体需求,提出了整个网络的体系架构和协议框架;该网络可划分为天基、空基和地基骨干网络3部分,各层以IP技术为基本协议架构,通过星间、星空、星地、空空、空地和地面链路实现互联互通;重点研究了基于多层卫星网络的天基骨干网络以及基于无线Mesh的空基骨干网络;最后,探讨了空间骨干网络的组网结构、路由协议、数据传输、异构兼容、网络管理等多项关键技术。对未来空间骨干网络构建具有一定的参考意义。

地震行业地面骨干网与应急卫星通信网互联路由设计方案的探讨

本文介绍了地震行业地面骨干网与应急卫星通信网的运行现状及互联存在的路由问题,讨论了实现两网互联的路由设计目标和策略,根据OSPF协议与BGP协议的特点和适用范围,提出了统一互联的接入方法,以及联合使用OSPF和BGP协议解决两网互联路由问题的具体方案,经网络仿真平台测试证明,该方案切实可行,效果良好。

卫星网络骨干节点通信冲突算法研究

针对卫星网络中骨干节点多对通信中通信所引发的资源冲突问题,为了提高卫星的工作效率与合理分配通信时间,提出了一种新的解决方法——遗传模拟退火算法(GASA)。算法克服了遗传算法(GA)容易陷入局部最优解的缺陷,同时也解决了模拟退火算法(SA)收敛速度慢的问题。首先利用STK创建了卫星网络模型,模拟了四颗低轨卫星(LEO)向一颗高轨卫星(GEO)通信的场景,然后采用OPNET建立通信冲突模型,并对GASA、GA和SA三种算法进行了仿真。仿真结果表明算法在保证一定吞吐量的前提下,冲突率和延时优于GA和SA算法。