Interruption Tolerance Routing Strategy for Space Information Network

Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will consume considerable time(compared with ground networks)derived from long ISL delay and flooding between hundreds or even thousands of satellites.During the network convergence/update stage,the lack of up-to-date forwarding information may cause severe packet loss.Considering the fact that ISL handovers for close-to-earth constellation are predictable and all the ISL handover information could be stored in each satellite during the network initialization,we propose a self-update routing scheme based on open shortest path first(OSPF-SUR)to address the slow route convergence problem caused by frequent ISL handovers.First,for predictable ISL handovers,forwarding tables are updated according to locally stored ISL handover information without link state advertisement(LSA)flooding.Second,for unexpected ISL failures,flooding could be triggered to complete route convergence.In this manner,network convergence time is radically descended by avoiding unnecessary LSA flooding for predictable ISL handovers.Simulation results show that the average packet loss rate caused by ISL handovers is reduced by 90.5%and 61.3%compared with standard OSPF(with three Hello packets confirmation)and OSPF based on interface state(without three Hello packets confirmation),respectively,during a period of topology handover.And the average endto-end delay is also decreased by 47.6%,9.6%,respectively.The packet loss rate of the proposed OSPF-SUR does not change along with the increase of the frequency of topology handovers.

Research of multi-path routing based on network coding in space information networks

A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks. On the basis of traditional multi-path routing, the algorithm uses a random linear network coding strategy to code data pack- ets. Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together. The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding. Meanwhile, the algorithm also adopts the flow distribution strategy based on time delay to balance network load. Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate, reduce packet delay, and enhance network performance.

Concurrent Reconfiguration of Resource-Oriented Emergency TT&C Mission Planning for Space Information Networks

The scale expansion of the space information networks(SINs)makes the demands for tacking,telemetry and command(TT&C)missions increase dramatically.An increasing number of missions and a sharp conflict of resources make it much more challenging to schedule missions reasonably.In order to ensure both the mission completion rate of the high concurrent emergency missions and the performance of regular missions,a conflict degree scheduling algorithm based on transfer strategy(CDSA-TS)is proposed concurrently reconfiguring multi-dimensional resources reasonably.Furthermore,we design an emergency mission planning algorithm based on simulated annealing algorithm(EMPA-SA)to increase the probability of jumping out of the trap through the iterative neighborhood searching strategy and destabilization.Finally,we design a simulation system to verify the network performance in terms of the integrated weights of completed missions and the time consumption of the proposed algorithms.We also investigate the impact of the scheduling strategy for emergency missions on regular missions to improve the overall network performance,which provides guidance for emergency mission planning in the future for the large scale constellation oriented SINs.

Architecture and critical technologies of space information networks

Focusing on its main requirements and challenges and by analyzing the characteristics of different space platforms,an overall architecture for space information networks is proposed based on national strategic planning and the present development status of associated technologies.Furthermore,the core scientific problems that need to be solved are expounded.In addition,the primary considerations and a preliminary integrated demonstration environment for verification of key technologies are presented.

Utilization and Analysis of Resource Mobility in Space Information Networks

In space information networks,resource mobility is an important factor affecting the network performance,which not only results in challenges in resource management but also brings opportunities to the improvement of network service capability.In order to explore the restriction and improvement mechanism of resource mobility on network performance,we firstly use the time-expanded resource relationship graph to represent the moving behavior of multidimensional resources and the collaborative relationship between different resources.Then by jointly considering the number of disjoint resource combinations,the length of moving time window,and the parameter of resource independence,we propose(k,n,L)degree of freedom on resource combination as a metric measuring performance gain resulted from resource mobility.Furthermore,the analysis of resource mobility is transformed into the problem of finding disjoint paths in the graph,and the tradeoff relationship between QoS requirements of task and resource mobility utilization is discussed.Finally,the tradeoff between the gain of resource mobility utilization and the payment of service process delay is revealed through simulation.

A hierarchical autonomous system based space information network architecture and topology control

SIN(Space Information Network)has recently emerged as a promising approach to solving the collaboration difficulty among current space programs.However,because of the SIN’s large scale,high component complexity,and dynamic characteristics,designing a proper SIN architecture is challenging.Firstly,we propose a novel SIN architecture,which is composed of GEO(Geostationary Earth Orbit)satellites as backbone network nodes,LEO(Low Earth Orbit)or other types of satellites as enhanced coverage nodes,and high-altitude platforms to meet the service requirements of emergency or hot-spot applications.Unlike most existing studies,the proposed architecture is AS(Autonomous-System)based.We decouple the complex SIN into simpler sub-networks using a hierarchical AS model.Then,we propose a topology control algorithm to minimize the time delay among sub-AS networks.We prove that the proposed algorithm achieves logical k-connectivity provided that the original physical topology has k-connectivity.Simulation results validate the theoretic analysis and effectiveness of the algorithm.

Survey on key security technologies for space information networks

SIN(Space Information Network)is expected to play an increasing role in providing real-time,flexible,and integrated communication and data transmission services in an efficient manner.Nowadays,SIN has been widely developed for position navigation,environment monitor,traffic management,counter-terrorism,etc.However,security is a major concern in SIN,since the satellites,spacecrafts,and aircrafts are susceptible to a variety of traditional/specific network-based attacks,including eavesdropping,session hijacking,and illegal accessing.The network architecture and security issues of SIN were reviewed.Various security requirements were discussed that should be considered when designing SIN.And existing solutions proposed to meet these requirements were surveyed.The key challenges and key technologies that still require extensive research and development for securing SIN were indentifed.

Intrusion-detection model integrating anomaly with misuse for space information network

In recent years,following the development of space commutation,space information has become a critical part in space information network and will play a very significant role in winning future information war.A space information network with characteristics such as complex structure,special communication requirement,long delay,dependence on remote maintenance,and fragile ecological environment contains enormous security risks.Therefore,ensuring space information network safety is important.Intrusion-detection model as an important part of a network security system becomes a hot issue in space network security.We propose an intrusion-detection method that integrates anomaly with misuse,which supports automatic updates from a remote ground,and design a distributed intrusion-detection model of space information network.

An Anti-Quantum Authentication Protocol for Space Information Networks Based on Ring Learning with Errors

With the continuous development of satellite communication and Internet of things technology,more and more devices can access space information networks(SIN)and enjoy satellite services everywhere in the world.However,due to the openness of the air-to-ground channel,the device will face a series of security threats when accessing SIN,such as replay attacks,eavesdropping attacks,impersonation attacks,and man-in-the-middle attacks.These security threats will lead to illegal entity access and further endanger the reliability and availability of the system.Although scholars have proposed many enhanced security access authentication protocols,most of them have been proved to have security vulnerabilities.In addition,with the development of quantum computing,the previous authentication protocols based on some asymmetric cryptographic mechanisms such as discrete logarithm and elliptic curve cryptographic mechanisms may face new security challenges.In this context,this paper proposes a novel antiquantum access authentication protocol based on ring learning with errors(RLWE),which meets more security requirements and greatly reduces the authentication delay through prenegotiation.Through the security analysis and performance analysis,it is shown that our protocol can be more suitable for delaysensitive IoT devices to access SIN while ensuring higher security.

Resource Mobility Aware Hybrid Task Planning in Space Information Networks

In this paper,a resource mobility aware two-stage hybrid task planning algorithm is proposed to reduce the resource conflict between emergency tasks and the common tasks,so as to improve the overall performance of space information networks.Specifically,in the common task planning stage,a resource fragment avoidance task planning algorithm is proposed,which reduces the contention between emergency tasks and the planned common tasks in the next stage by avoiding the generation of resource fragments.For emergency tasks,we design a metric to quantify the revenue of the candidate resource combination of emergency tasks,which considers both the priority of the tasks and the impact on the planned common tasks.Based on this,a resource mobility aware emergency task planning algorithm is proposed,which strikes a good balance between improving the sum priority and avoiding disturbing the planned common tasks.Finally,simulation results show that the proposed algorithm is superior to the existing algorithms in both the sum task priority and the task completion rate.

Design for the simulation of space based information network

Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.

Design and Experimental Demonstration of Software Defined Space Optical Network (SDSON) Architecture Based on Cloud Platform

Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation positioning and science exploration. In this paper, the architecture of Software Defined Space Optical Network (SDSON) based on cloud platform is designed by means of Software Defined Optical Network (SDON) and cloud services. The new architecture combining centralized and distributed management-control mechanism is a multi-layer and multi-domain architecture with powerful computing and storage ability. Moreover, reliable service and unreliable service communication models employed in the space information network are proposed considering the characteristic of Disruption/Delay Tolerant Network (DTN). Finally, the functional verification and demonstration are performed on our optical experimental network platform.

Technologies and applications of free-space optical communication and space optical information network

Free-space optical communication and space optical information network offer many more superiorities over optical fiber,RF,or microwaves communication techniques,with higher data transfer rate,smaller platforms to launch and lower costs.A comprehensive overview on the architectures of the space high-speed optical information network was provided.In fundamental system,networking approach and operation mechanisms of the space optical information network were fully emphasized to be discussed a lot.The interactions of light waves and microwave network have been outlined.A blueprint for space optical information network technology is presented to be used in various communication fields in the future.

网络学习空间平台的规划与设计——以未来教育空间站为例

网络学习空间平台是一个以教师、学生和家长为服务对象的网络化社交学习平台,能够建立优质教育资源的共建共享机制,让教师在网络上开展教学和教研活动,让学生进行个性化学习,推进教学方式与学习方式变革,实现教育的公平均衡发展。网络学习空间平台是实现"网络学习空间人人通"的重要支撑,因此规划和设计好网络学习空间平台,对我国教育信息化建设有非常重要的意义。本文参考国际空间站的设计理念,以未来教育空间站为例,详细论述了网络学习空间平台的发展构想,通过对网络学习空间平台发展目标、功能价值定位和技术定位等方面进行建设规划,进一步分析设计出网络学习空间平台横向和纵向两个方向的逻辑架构层次关系,并总结得到网络学习空间平台的建设策略。

Space-air-ground integrated vehicular network for connected and automated vehicles:Challenges and solutions

Unlimited and seamless coverage as well as ultra-reliable and low-latency communications are vital for connected vehicles,in particular for new use cases like autonomous driving and vehicle platooning.In this paper,we propose a novel Space-Air-Ground integrated vehicular network(SAGiven)architecture to gracefully integrate the multi-dimensional and multi-scale context-information and network resources from satellites,High-Altitude Platform stations(HAPs),low-altitude Unmanned Aerial Vehicles(UAVs),and terrestrial cellular communication systems.One of the key features of the SAGiven is the reconfigurability of heterogeneous network functions as well as network resources.We first give a comprehensive review of the key challenges of this new architecture and then provide some up-to-date solutions on those challenges.Specifically,the solutions will cover the following topics:(1)space-air-ground integrated network reconfiguration under dynamic space resources constraints;(2)multi-dimensional sensing and efficient integration of multi-dimensional context information;(3)real-time,reliable,and secure communications among vehicles and between vehicles and the SAGiven platform;and(4)a holistic integration and demonstration of the SAGiven.Finally,it is concluded that the SAGiven can play a key role in future autonomous driving and Internet-of-Vehicles applications.

基于共享网络空间的物理演示实验教学平台

基于教育信息化背景,利用网络服务运营商提供免费和共享信息技术服务的客观条件,提出了一种全新的物理演示实验利用方案。这一方案通过创建基于共享网络空间的物理演示实验教学平台,一方面有助于解决传统物理演示实验使用过程中所遇到的时域和地域受限问题;另一方面有助于推进传统演示实验与信息技术相融合问题,适应数字化时代,学生微课化、碎片化学习行为的需要。通过创建基于"360 Cloud+Faisco"的演示实验网络教学平台的等具体措施,对这一方案进行教学实践,为翻转课堂模式下物理演示实验的利用,提供借鉴参考。