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Cooperative User-Scheduling and Resource Allocation Optimization for Intelligent Reflecting Surface Enhanced LEO Satellite Communication 被引量:1
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作者 Meng Meng Bo Hu +1 位作者 Shanzhi Chen Jianyin Zhang 《China Communications》 SCIE CSCD 2024年第2期227-244,共18页
Lower Earth Orbit(LEO) satellite becomes an important part of complementing terrestrial communication due to its lower orbital altitude and smaller propagation delay than Geostationary satellite. However, the LEO sate... Lower Earth Orbit(LEO) satellite becomes an important part of complementing terrestrial communication due to its lower orbital altitude and smaller propagation delay than Geostationary satellite. However, the LEO satellite communication system cannot meet the requirements of users when the satellite-terrestrial link is blocked by obstacles. To solve this problem, we introduce Intelligent reflect surface(IRS) for improving the achievable rate of terrestrial users in LEO satellite communication. We investigated joint IRS scheduling, user scheduling, power and bandwidth allocation(JIRPB) optimization algorithm for improving LEO satellite system throughput.The optimization problem of joint user scheduling and resource allocation is formulated as a non-convex optimization problem. To cope with this problem, the nonconvex optimization problem is divided into resource allocation optimization sub-problem and scheduling optimization sub-problem firstly. Second, we optimize the resource allocation sub-problem via alternating direction multiplier method(ADMM) and scheduling sub-problem via Lagrangian dual method repeatedly.Third, we prove that the proposed resource allocation algorithm based ADMM approaches sublinear convergence theoretically. Finally, we demonstrate that the proposed JIRPB optimization algorithm improves the LEO satellite communication system throughput. 展开更多
关键词 convex optimization intelligent reflecting surface leo satellite communication OFDM
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Delay-optimal multi-satellite collaborative computation offloading supported by OISL in LEO satellite network
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作者 ZHANG Tingting GUO Zijian +4 位作者 LI Bin FENG Yuan FU Qi HU Mingyu QU Yunbo 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第4期805-814,共10页
By deploying the ubiquitous and reliable coverage of low Earth orbit(LEO)satellite networks using optical inter satel-lite link(OISL),computation offloading services can be provided for any users without proximal serv... By deploying the ubiquitous and reliable coverage of low Earth orbit(LEO)satellite networks using optical inter satel-lite link(OISL),computation offloading services can be provided for any users without proximal servers,while the resource limita-tion of both computation and storage on satellites is the impor-tant factor affecting the maximum task completion time.In this paper,we study a delay-optimal multi-satellite collaborative computation offloading scheme that allows satellites to actively migrate tasks among themselves by employing the high-speed OISLs,such that tasks with long queuing delay will be served as quickly as possible by utilizing idle computation resources in the neighborhood.To satisfy the delay requirement of delay-sensi-tive task,we first propose a deadline-aware task scheduling scheme in which a priority model is constructed to sort the order of tasks being served based on its deadline,and then a delay-optimal collaborative offloading scheme is derived such that the tasks which cannot be completed locally can be migrated to other idle satellites.Simulation results demonstrate the effective-ness of our multi-satellite collaborative computation offloading strategy in reducing task complement time and improving resource utilization of the LEO satellite network. 展开更多
关键词 low Earth orbit(leo)satellite network computation offloading task migration resource allocation
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Survivability model of LEO satellite constellation based on GERT with limited backup resources
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作者 NIE Yuanyuan FANG Zhigeng +1 位作者 LIU Sifeng GAO Su 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第4期976-986,共11页
Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constell... Survivability is used to evaluate the ability of the satellite to complete the mission after failure,while the duration of maintaining performance is often ignored.An effective backup strategy can restore the constellation performance timely,and maintain good network communication performance in case of satellite failure.From the perspective of network utility,the low Earth orbit(LEO)satellite constellation survivable graphical eva-luation and review technology(GERT)network with backup satel-lites is constructed.A network utility transfer function algorithm based on moment generating function and Mason formula is proposed,the network survivability evaluation models of on-orbit backup strategy and ground backup strategy are established.The survivable GERT model can deduce the expected mainte-nance time of LEO satellite constellation under different fault states and the network utility generated during the state mainte-nance period.The case analysis shows that the proposed surviv-able GERT model can consider the satellite failure rate,backup satellite replacement rate,maneuver control replacement ability and life requirement,and effectively determine the optimal sur-vivable backup strategy for LEO satellite constellation with limi-ted resources according to the expected network utility. 展开更多
关键词 SURVIVABILITY low Earth orbit(leo)satellite constella-tion graphical evaluation and review technology(GERT) backup strategy
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OFDMA-Based Unsourced Random Access in LEO Satellite Internet of Things
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作者 Jiaqi Fang Gangle Sun +2 位作者 Wenjin Wang Li You Rui Ding 《China Communications》 SCIE CSCD 2024年第1期13-23,共11页
This paper investigates the low earth orbit(LEO)satellite-enabled coded compressed sensing(CCS)unsourced random access(URA)in orthogonal frequency division multiple access(OFDMA)framework,where a massive uniform plana... This paper investigates the low earth orbit(LEO)satellite-enabled coded compressed sensing(CCS)unsourced random access(URA)in orthogonal frequency division multiple access(OFDMA)framework,where a massive uniform planar array(UPA)is equipped on the satellite.In LEO satellite communications,unavoidable timing and frequency offsets cause phase shifts in the transmitted signals,substantially diminishing the decoding performance of current terrestrial CCS URA receiver.To cope with this issue,we expand the inner codebook with predefined timing and frequency offsets and formulate the inner decoding as a tractable compressed sensing(CS)problem.Additionally,we leverage the inherent sparsity of the UPA-equipped LEO satellite angular domain channels,thereby enabling the outer decoder to support more active devices.Furthermore,the outputs of the outer decoder are used to reduce the search space of the inner decoder,which cuts down the computational complexity and accelerates the convergence of the inner decoding.Simulation results verify the effectiveness of the proposed scheme. 展开更多
关键词 leo OFDMA satellite unsourced random access UPA
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Multi-network-region traffic cooperative scheduling in large-scale LEO satellite networks
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作者 LI Chengxi WANG Fu +8 位作者 YAN Wei CUI Yansong FAN Xiaodong ZHU Guangyu XIE Yanxi YANG Lixin ZHOU Luming ZHAO Ran WANG Ning 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第4期829-841,共13页
A low-Earth-orbit(LEO)satellite network can provide full-coverage access services worldwide and is an essential candidate for future 6G networking.However,the large variability of the geographic distribution of the Ea... A low-Earth-orbit(LEO)satellite network can provide full-coverage access services worldwide and is an essential candidate for future 6G networking.However,the large variability of the geographic distribution of the Earth’s population leads to an uneven service volume distribution of access service.Moreover,the limitations on the resources of satellites are far from being able to serve the traffic in hotspot areas.To enhance the forwarding capability of satellite networks,we first assess how hotspot areas under different load cases and spatial scales significantly affect the network throughput of an LEO satellite network overall.Then,we propose a multi-region cooperative traffic scheduling algorithm.The algorithm migrates low-grade traffic from hotspot areas to coldspot areas for forwarding,significantly increasing the overall throughput of the satellite network while sacrificing some latency of end-to-end forwarding.This algorithm can utilize all the global satellite resources and improve the utilization of network resources.We model the cooperative multi-region scheduling of large-scale LEO satellites.Based on the model,we build a system testbed using OMNET++to compare the proposed method with existing techniques.The simulations show that our proposed method can reduce the packet loss probability by 30%and improve the resource utilization ratio by 3.69%. 展开更多
关键词 low-Earth-orbit(leo)satellite network satellite communication load balance multi-region scheduling latency optimization
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Covert LEO Satellite Communication Aided by Generative Adversarial Network Based Cooperative UAV Jamming
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作者 Shi Jia Li Xiaomeng +2 位作者 Liao Xiaomin Tie Zhuangzhuang Hu Junfan 《China Communications》 SCIE CSCD 2024年第9期27-39,共13页
In this paper,we study the covert performance of the downlink low earth orbit(LEO)satellite communication,where the unmanned aerial vehicle(UAV)is employed as a cooperative jammer.To maximize the covert rate of the LE... In this paper,we study the covert performance of the downlink low earth orbit(LEO)satellite communication,where the unmanned aerial vehicle(UAV)is employed as a cooperative jammer.To maximize the covert rate of the LEO satellite transmission,a multi-objective problem is formulated to jointly optimize the UAV’s jamming power and trajectory.For practical consideration,we assume that the UAV can only have partial environmental information,and can’t know the detection threshold and exact location of the eavesdropper on the ground.To solve the multiobjective problem,we propose the data-driven generative adversarial network(DD-GAN)based method to optimize the power and trajectory of the UAV,in which the sample data is collected by using genetic algorithm(GA).Simulation results show that the jamming solution of UAV generated by DD-GAN can achieve an effective trade-off between covert rate and probability of detection errors when only limited prior information is obtained. 展开更多
关键词 covert communication generative adversarial network leo satellite UAV jammer
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A Parallel Discrete Event Simulation Engine for the Low-Earth-Orbit Satellite Constellation Networks
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作者 Su Hailong Liu Yaoqi +3 位作者 Zhou Yiqing Shi Jinglin Li Hongguang Qian Manli 《China Communications》 SCIE CSCD 2024年第8期264-275,共12页
Low-Earth-Orbit satellite constellation networks(LEO-SCN)can provide low-cost,largescale,flexible coverage wireless communication services.High dynamics and large topological sizes characterize LEO-SCN.Protocol develo... Low-Earth-Orbit satellite constellation networks(LEO-SCN)can provide low-cost,largescale,flexible coverage wireless communication services.High dynamics and large topological sizes characterize LEO-SCN.Protocol development and application testing of LEO-SCN are challenging to carry out in a natural environment.Simulation platforms are a more effective means of technology demonstration.Currently available simulators have a single function and limited simulation scale.There needs to be a simulator for full-featured simulation.In this paper,we apply the parallel discrete-event simulation technique to the simulation of LEO-SCN to support large-scale complex system simulation at the packet level.To solve the problem that single-process programs cannot cope with complex simulations containing numerous entities,we propose a parallel mechanism and algorithms LP-NM and LP-YAWNS for synchronization.In the experiment,we use ns-3 to verify the acceleration ratio and efficiency of the above algorithms.The results show that our proposed mechanism can provide parallel simulation engine support for the LEO-SCN. 展开更多
关键词 CONSTELLATION low earth orbit satellite ns-3 null-message parallel discrete-event simulation
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Segment routing for traffic engineering and effective recovery in low-earth orbit satellite constellations
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作者 Shengyu Zhang Xiaoqian Li Kwan Lawrence Yeung 《Digital Communications and Networks》 SCIE CSCD 2024年第3期706-715,共10页
Low-Earth Orbit Satellite Constellations(LEO-SCs)provide global,high-speed,and low latency Internet access services,which bridges the digital divide in the remote areas.As inter-satellite links are not supported in in... Low-Earth Orbit Satellite Constellations(LEO-SCs)provide global,high-speed,and low latency Internet access services,which bridges the digital divide in the remote areas.As inter-satellite links are not supported in initial deployment(i.e.the Starlink),the communication between satellites is based on ground stations with radio frequency signals.Due to the rapid movement of satellites,this hybrid topology of LEO-SCs and ground stations is time-varying,which imposes a major challenge to uninterrupted service provisioning and network management.In this paper,we focus on solving two notable problems in such a ground station-assisted LEO-SC topology,i.e.,traffic engineering and fast reroute,to guarantee that the packets are forwarded in a balanced and uninterrupted manner.Specifically,we employ segment routing to support the arbitrary path routing in LEO-SCs.To solve the traffic engineering problem,we proposed two source routings with traffic splitting algorithms,Delay-Bounded Traffic Splitting(DBTS)and DBTS+,where DBTS equally splits a flow and DBTS+favors shorter paths.Simu-lation results show that DBTS+can achieve about 30%lower maximum satellite load at the cost of about 10%more delay.To guarantee the fast recovery of failures,two fast reroute mechanisms,Loop-Free Alternate(LFA)and LFA+,are studied,where LFA pre-computes an alternate next-hop as a backup while LFA+finds a 2-segment backup path.We show that LFA+can increase the percentage of protection coverage by about 15%. 展开更多
关键词 Fast reroute Low-earth orbit satellite constellation Segment routing Traffic engineering Traffic splitting
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For LEO Satellite Networks: Intelligent Interference Sensing and Signal Reconstruction Based on Blind Separation Technology
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作者 Chengjie Li Lidong Zhu Zhen Zhang 《China Communications》 SCIE CSCD 2024年第2期85-95,共11页
In LEO satellite communication networks,the number of satellites has increased sharply, the relative velocity of satellites is very fast, then electronic signal aliasing occurs from time to time. Those aliasing signal... In LEO satellite communication networks,the number of satellites has increased sharply, the relative velocity of satellites is very fast, then electronic signal aliasing occurs from time to time. Those aliasing signals make the receiving ability of the signal receiver worse, the signal processing ability weaker,and the anti-interference ability of the communication system lower. Aiming at the above problems, to save communication resources and improve communication efficiency, and considering the irregularity of interference signals, the underdetermined blind separation technology can effectively deal with the problem of interference sensing and signal reconstruction in this scenario. In order to improve the stability of source signal separation and the security of information transmission, a greedy optimization algorithm can be executed. At the same time, to improve network information transmission efficiency and prevent algorithms from getting trapped in local optima, delete low-energy points during each iteration process. Ultimately, simulation experiments validate that the algorithm presented in this paper enhances both the transmission efficiency of the network transmission system and the security of the communication system, achieving the process of interference sensing and signal reconstruction in the LEO satellite communication system. 展开更多
关键词 blind source separation greedy optimization algorithm interference sensing leo satellite communication networks signal reconstruction
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HOI延迟对LEO卫星简化动力学POD的影响 被引量:2
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作者 张兵良 方卓 +1 位作者 李珊珊 曾彬 《导航定位与授时》 CSCD 2024年第1期79-86,共8页
通常使用无电离层(IF)线性组合(LC)消除低地球轨道(LEO)卫星简化动力学精密定轨(POD)一阶电离层延迟误差,忽略了高阶电离层(HOI)延迟误差。随着LEO卫星POD技术的发展,计算不同轨道高度的HOI延迟并探索其变化已成为进一步提高POD精度的... 通常使用无电离层(IF)线性组合(LC)消除低地球轨道(LEO)卫星简化动力学精密定轨(POD)一阶电离层延迟误差,忽略了高阶电离层(HOI)延迟误差。随着LEO卫星POD技术的发展,计算不同轨道高度的HOI延迟并探索其变化已成为进一步提高POD精度的重要手段。首先,使用国际参考电离层-2016(IRI-2016)和国际地磁参考场第13代(IGRF-13)模型,计算电离层穿刺点(IPP)位置和地磁场强度。其次,使用平滑星载GNSS数据计算电离层斜路径总电子含量(STEC)。然后,分别计算GOCE、GRACE-A和SWARM-A/B卫星的二阶和三阶电离层延迟。最后,评估了HOI延迟对LEO卫星重叠轨道分析、卫星激光测距(SLR)检核和精密科学轨道(PSO)比较结果的影响。实验结果表明:HOI延迟对LEO卫星简化动力学POD的影响大约在毫米至厘米的数量级上;HOI延迟对LEO卫星简化动力学POD外符合精度的影响分别达到0.92,0.22,0.21和0.18 mm;随着LEO卫星轨道高度的增加,HOI延迟对LEO卫星简化动力学POD的影响减小。 展开更多
关键词 leo卫星 HOI延迟 简化动力学POD 轨道高度
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LEO多星座增强BDS精密单点定位性能评估
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作者 刘婧 郝金明 +3 位作者 杨颜 周蕊 谢建涛 焦博 《测绘科学技术学报》 2024年第5期464-469,共6页
针对不同构型的低轨星座(LEO)增强北斗卫星导航系统BDS的精密单点定位PPP性能开展研究。通过IGS高、中、低纬度6测站实测数据、精密轨道及钟差产品,生成BDS、“鸿雁”HY、“微厘空间”CS精密星历、卫星钟差、观测量等实验仿真数据,构建... 针对不同构型的低轨星座(LEO)增强北斗卫星导航系统BDS的精密单点定位PPP性能开展研究。通过IGS高、中、低纬度6测站实测数据、精密轨道及钟差产品,生成BDS、“鸿雁”HY、“微厘空间”CS精密星历、卫星钟差、观测量等实验仿真数据,构建了LEO增强BDS PPP数学模型,实现了BDS、BDS+HY、BDS+CS、BDS+HY+CS不同组合PPP。实验结果表明,在10、60 min静态PPP定位精度以及平均可视卫星数、PDOP值等方面均有不同程度的提升,HY对高纬度KIRU站改善效果显著,收敛时间减至2 min以内,CS对低纬度FAA1站测站收敛时间的提升最大,从46 min 50 s缩短至2 min,HY+CS增强BDS的效果最好,10 min定位精度均能达到毫米级,除FAA1站外其他测站均收敛在1 min以内。 展开更多
关键词 低轨卫星导航增强 北斗卫星导航系统 精密单点定位 定位精度 收敛时间
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LEO卫星系统对GSO卫星系统干扰规避技术研究
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作者 韩晓娱 刘昊昱 +1 位作者 张世层 王丽冲 《计算机与网络》 2024年第1期74-79,共6页
近年,低地轨道(Low Earth Orbit,LEO)卫星星座繁荣发展,LEO卫星系统和地球静止轨道(Geosynchronous Orbit,GSO)卫星系统同频共用情况非常普遍,同频段内LEO卫星系统需要规避GSO卫星系统的上下行干扰。LEO卫星系统对GSO卫星系统干扰规避... 近年,低地轨道(Low Earth Orbit,LEO)卫星星座繁荣发展,LEO卫星系统和地球静止轨道(Geosynchronous Orbit,GSO)卫星系统同频共用情况非常普遍,同频段内LEO卫星系统需要规避GSO卫星系统的上下行干扰。LEO卫星系统对GSO卫星系统干扰规避方法和策略包含调整指向、更改频率、降低功率和关闭波束。在对系统干扰规避模式及干扰区域情况进行仿真基础上,结合LEO卫星系统特点,提出经过规避区域时切换信关站或者馈电链路关闭下行波束的方案。用户链路结合相控阵天线特点,信令波束通过上注星载相控阵天线波位表实现干扰规避;业务波束通过上注干扰规避区域对应的地面网格编码实现干扰规避,提出不同链路干扰规避实施方案和实现流程。 展开更多
关键词 leo卫星系统 干扰规避 信令波束 业务波束 相控阵天线
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Jamming-Aided Secure Communication in Ultra-Dense LEO Integrated Satellite-Terrestrial Networks 被引量:2
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作者 Yongpeng Shi Jiajia Liu +1 位作者 Jiadai Wang Yijie Xun 《China Communications》 SCIE CSCD 2023年第7期43-56,共14页
The ultra-dense low earth orbit(LEO)integrated satellite-terrestrial networks(UDLEO-ISTN)can bring lots of benefits in terms of wide coverage,high capacity,and strong robustness.Meanwhile,the broadcasting and open nat... The ultra-dense low earth orbit(LEO)integrated satellite-terrestrial networks(UDLEO-ISTN)can bring lots of benefits in terms of wide coverage,high capacity,and strong robustness.Meanwhile,the broadcasting and open natures of satellite links also reveal many challenges for transmission security protection,especially for eavesdropping defence.How to efficiently take advantage of the LEO satellite’s density and ensure the secure communication by leveraging physical layer security with the cooperation of jammers deserves further investigation.To our knowledge,using satellites as jammers in UDLEO-ISTN is still a new problem since existing works mainly focused on this issue only from the aspect of terrestrial networks.To this end,we study in this paper the cooperative secrecy communication problem in UDLEOISTN by utilizing several satellites to send jamming signal to the eavesdroppers.An iterative scheme is proposed as our solution to maximize the system secrecy energy efficiency(SEE)via jointly optimizing transmit power allocation and user association.Extensive experiment results verify that our designed optimization scheme can significantly enhance the system SEE and achieve the optimal power allocation and user association strategies. 展开更多
关键词 ultra-dense leo satellite integrated satellite-terrestrial network physical layer security cooperative jamming
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Beam Position and Beam Hopping Design for LEO Satellite Communications 被引量:1
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作者 Leyi Lyu Chenhao Qi 《China Communications》 SCIE CSCD 2023年第7期29-42,共14页
The numbers of beam positions(BPs)and time slots for beam hopping(BH)dominate the latency of LEO satellite communications.Aiming at minimizing the number of BPs subject to a predefined requirement on the radius of BP,... The numbers of beam positions(BPs)and time slots for beam hopping(BH)dominate the latency of LEO satellite communications.Aiming at minimizing the number of BPs subject to a predefined requirement on the radius of BP,a low-complexity user density-based BP design scheme is proposed,where the original problem is decomposed into two subproblems,with the first one to find the sparsest user and the second one to determine the corresponding best BP.In particular,for the second subproblem,a user selection and smallest BP radius algorithm is proposed,where the nearby users are sequentially selected until the constraint of the given BP radius is no longer satisfied.These two subproblems are iteratively solved until all the users are selected.To further reduce the BP radius,a duplicated user removal algorithm is proposed to decrease the number of the users covered by two or more BPs.Aiming at minimizing the number of time slots subject to the no co-channel interference(CCI)constraint and the traffic demand constraint,a low-complexity CCI-free BH design scheme is proposed,where the BPs having difficulty in satisfying the constraints are considered to be illuminated in priory.Simulation results verify the effectiveness of the proposed schemes. 展开更多
关键词 beam hopping(BH)design beam position(BP)design low earth orbit(leo) low latency satellite communications
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A Positioning Method and Realization on Single Satellites in Different Orbits Using TDOA 被引量:1
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作者 Laiding Zhao Xun Zhu +1 位作者 Gengxin Zhang Zhaowen Wang 《China Communications》 SCIE CSCD 2023年第7期108-121,共14页
The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and freque... The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value. 展开更多
关键词 different orbit time-sharing non-convex optimization single satellite TDOA
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Resource allocation for uplink grant-free access in beam-hopping based LEO satellite systems
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作者 张梦莹 YANG Xiumei BU Zhiyong 《High Technology Letters》 EI CAS 2023年第2期140-147,共8页
The low earth orbit(LEO) satellite system provides a promising solution for the global coverage of Internet of Things(IoT) services.Confronted with the sporadic uplink transmission from massive IoT terminals, this wor... The low earth orbit(LEO) satellite system provides a promising solution for the global coverage of Internet of Things(IoT) services.Confronted with the sporadic uplink transmission from massive IoT terminals, this work investigates the grant-free access scheme and resource allocation algorithm for the beam-hopping(BH) based LEO satellite systems.To improve the packet success rate, the time slots are pre-allocated to each cell according to the number of terrestrial terminals and the probability of packet arrival.When the packets arrive, the terrestrial terminals perform contention-free or contention-based grant-free access with packet repetition in the time slots allocated to their cells.The analytical expression of the packet collision probability for the grant-free access scheme is derived to provide reference for the resource allocation.To reduce the computational complexity, a heuristic resource allocation algorithm is proposed to minimize the maximum cell packet collision probability in the system.Simulation results show that the proposed resource allocation scheme achieves lower packet collision probability and higher resource utilization ratio when compared with the uniform resource allocation scheme. 展开更多
关键词 low earth orbit(leo)satellite system grant-free access beam-hopping(BH) resource allocation collision
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Analysis on Connectivity of Inter-Orbit-Links in a MEO/LEO Double-Layer Satellite Network 被引量:3
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作者 王振永 李集林 +1 位作者 郭庆 顾学迈 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第4期340-345,共6页
As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network (DLSN) with MEO satellites and LEO satellites is proposed. The Inter-Orb... As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network (DLSN) with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links (IOLs) between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle. 展开更多
关键词 double-layer satellite network MEO/leo inter-orbit-links CONNECTIVITY
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NOMA-Based Collaborative Beam Hopping Frequency Allocation Mechanism for Future LEO Satellite Systems
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作者 Fei Zheng Zhao Pi +2 位作者 Zou Zhou Miao Ye Hongbing Qiu 《China Communications》 SCIE CSCD 2023年第6期321-338,共18页
Low Earth orbit(LEO) satellite systems provide terrestrial users with services that are not limited by geographical location. However, the conflict between existing allocation schemes and the business variability betw... Low Earth orbit(LEO) satellite systems provide terrestrial users with services that are not limited by geographical location. However, the conflict between existing allocation schemes and the business variability between beams is becoming increasingly prominent. Beam hopping technology allows for a more flexible and versatile approach to satellite resource allocation. This paper proposes a beam hopping pattern optimization scheme that jointly considers the interference threshold distance and beam service priority, reducing the inter-beam co-channel interference(CCI). In the cluster area, a non-orthogonal multiple access(NOMA)-based collaborative beam hopping(NCBH) scheme is proposed to minimize the cell-edge user(CEU) interference. Since there is a difference in channel gain between the CEU and cellcenter user(CCU), this scheme forms a NOMA cluster to perform power domain multiplexing and formulates a NOMA cluster pairing strategy according to the user location to reduce the CCI of the CEU. After NOMA cluster pairing, the optimal carrier frequency of the NOMA cluster is selected by a reinforcement learning algorithm. The simulation results verify the excellent performance of the proposed NCBH scheme regarding the user’s received power, transmission rate, and outage probability. 展开更多
关键词 leo satellite beam hopping NOMA resource allocation
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LEO-RAN切片场景联合用户关联和动态资源分配算法 被引量:2
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作者 陈赓 邢治薇 +1 位作者 沈斐 曾庆田 《通信学报》 EI CSCD 北大核心 2024年第2期173-187,共15页
为了解决6G天地一体化网络的资源高效利用问题,提出了一种面向高密度低地球轨道卫星-无线接入网(LEO-RAN)切片场景的联合用户关联和动态资源分配算法。考虑不同切片的最小速率、最大时延及资源比例等约束,以频谱效率(SE)和不同切片服务... 为了解决6G天地一体化网络的资源高效利用问题,提出了一种面向高密度低地球轨道卫星-无线接入网(LEO-RAN)切片场景的联合用户关联和动态资源分配算法。考虑不同切片的最小速率、最大时延及资源比例等约束,以频谱效率(SE)和不同切片服务水平协议(SLA)满意率(SSR)的加权和作为优化目标,建立用户关联和资源分配的联合优化问题。首先设计基于多智能体深度确定性策略梯度(MADDPG)的网络切片算法确定切片资源比例,然后采用基于拉格朗日对偶的用户关联算法确定最优的用户关联策略,最后通过轮询调度机制将资源分配给用户。仿真结果表明,所提算法在满足不同切片差异化SLA的同时能够有效提高SE。与基于MADDPG-RA、MATD3-LG、MATD3-RA、MASAC-LG和MASAC-RA算法相比,所提算法系统效用分别提升了2.0%、2.3%、5.7%、8.7%和9.4%。 展开更多
关键词 leo卫星通信 网络切片 用户关联 多智能体深度确定性策略梯度 系统效用
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Simulation for MSS-2 low-perigee elliptical orbit satellites:an example of lithospheric magnetic field modelling
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作者 Yi Jiang Nils Olsen +1 位作者 JiaMing Ou Qing Yan 《Earth and Planetary Physics》 EI CSCD 2023年第1期151-160,共10页
A future constellation of at least four geomagnetic satellites(designated Macao Scientific Satellite-1(MSS-1)and Macao Scientific Satellite-2(MSS-2))was recently proposed,to continue high-quality geomagnetic observati... A future constellation of at least four geomagnetic satellites(designated Macao Scientific Satellite-1(MSS-1)and Macao Scientific Satellite-2(MSS-2))was recently proposed,to continue high-quality geomagnetic observations in the post-Swarm period,focusing especially on collecting data that will provide a global,three-dimensional survey of the geomagnetic field.In this paper,we present a simulation of two years of orbits(2020.01.01-2022.01.01)of two satellites(tentatively denoted as MSS-2)that are constellated in elliptical(200×5,300 km)low-perigee orbits.By comparing error variances of Gauss coefficients,we investigate the sensitivity of lithospheric magnetic field modelling to data collected from various satellite orbits,including a near circular reference orbit of 300×350km,and elliptical orbit of 180×5,300 km,220×5,300 km,200×3,000 km and 200×1,500 km.We find that in two years the two MSS-2 satellites can collect 35,000 observations at altitude below 250 km,data that will be useful in advancing the quality of lithospheric magnetic field modelling;this number of observations reflects the fact that only 4.5%of the flight time of these satellites will be below250 km(just 6.4%of their flight time below 300 km).By combining observations from the MSS-2 satellites’elliptical orbits of 200×5,300km with observations from a circular reference orbit,the variance of the geomagnetic model can be reduced by a factor of 285 at spherical harmonic degree n=200 and by a factor of 1,300 at n=250.The planned lower perigee of their orbits allows the new satellites to collect data at unprecedentedly lower altitudes,thus dramatically improving the spatial resolution of satellite-derived lithospheric field models,(up to 80%at n=150).In addition,lowering the apogee increases the time interval during which the satellites fly at near-Earth altitudes,thus improving the model predictions at all spherical harmonic degrees(around 52%-62%at n=150).The upper limit of the expected improvement to the field model at the orbital apogee is not as good as at the perigee.However,data from the MSS-1 orbit can help fill the gap between data from the MSS-2 orbits and from the circular reference orbit for the low-degree part of the model.The feasibility of even lower-altitude flight requires further discussion with satellite engineers. 展开更多
关键词 elliptical orbit satellite orbit simulation lithosphere field modelling spherical harmonics
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