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Solar system interplanetary communication networks:architectures, technologies and developments

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Science China(Information Sciences) 2018年第4期61卷 19-44页

作者： Peng WAN Yafeng ZHAN Xiaohan PAN space center Tsinghua University

With the development of deep space exploration technologies, main space agencies all over the world are working hard to develop the solar system interplanetary communication networks(SSICN). SSICN is a perspective communication networking system characterized by high data rate, high intelligent and perfect interconnection, which could provide the deep-space mission control and scientific application with the convenient, reliable and secure data transmission services. Following the introduction of future deep space exploration prospect, this paper analyzes the similarities and differences for three networks, terrestrial internet, near Earth space networks and SSICN, then discusses the key technologies and research trends of SSICN in details, and finally proposes the suggestions for the construction of future Chinese SSICN.

关键词： deep space exploration SSICN system architecture physical transmission network access up-layer application time synchronization

Spectral Coexistence between LEO and GEO Satellites by Optimizing Direction Normal of Phased Array Antennas

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China Communications 2018年第6期15卷 18-27页

作者： Chen Zhang Jin Jin Hao Zhang Ting Li Tsinghua Space Center Tsinghua University Technology and Engineering center for space Utilization Chinese Academy of Sciences

This paper addresses the spectral coexistence between LEO constellation and GEO belt for global distributed earth stations. A specific method is introduced to mitigate the in-line interference by tilting the direction normal of phased array antennas of LEO satellites, and the optimal direction is found by solving a non-linear programming problem. The simulation results prove that the proposed approach leads to greater link availability while guaranteeing the desired received signal level especially for low-latitude earth stations.

关键词：狮子座 GEO 天线数组光谱共存卫星优化

Trajectory Planning for OTFS-Based UAV Communications

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China Communications 2023年第1期20卷 114-124页

作者： Rui Han Jiahao Ma Lin Bai Tsinghua Space Center Tsinghua UniversityBeijing 100084China School of Cyber Science and Technology Beihang UniversityBeijing 100191China

Unmanned aerial vehicles(UAVs)have attracted growing research interests in recent years,which can be used as cost-effective aerial platforms to transmit collected data packets to ground access points(APs).Thus,it is crucial to investigate robust airto-ground(A2G)wireless links for high-speed UAVs.However,the A2G wireless link is unstable as it suffers from large path-loss and severe Doppler effect due to the high mobility of UAVs.In order to meet these challenges,we propose an orthogonal time frequency space(OTFS)-based UAV communication system to relief the Doppler effect.Besides,considering that the energy of UAV is limited,we optimize the trajectory planning of UAV to minimize the energy consumption under the constraints of bit error rate(BER)and transmission rate,where the Doppler compensation is taken into account.Simulation results show that the performance of OTFS-based UAV system is superior to orthogonal frequency division multiplexing(OFDM)-based UAV systems,which can accomplish transmission tasks over shorter distances with lower energy consumption.

关键词： orthogonal time frequency space(OTFS) orthogonal frequency division multiplexing(OFDM) unmanned aerial vehicle(UAV) 6G trajectory planning

On-orbit real-time magnetometer bias determination for micro-satellites without attitude information

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Chinese Journal of Aeronautics 2015年第5期28卷 1503-1509页

作者： Zhang Zhen Xiong Jianping Jin Jin Department of Precision Instrument Tsinghua University space center Tsinghua University

Due to the disadvantages such as complex calculation, low accuracy of estimation, and being non real time in present methods, a new real-time algorithm is developed for on-orbit mag- netometer bias determination of micro-satellites without attitude knowledge in this paper. This method uses the differential value approach. It avoids the impact of quartic nature and uses the iterative method to satisfy real-time applications. Simulation results indicate that the new real-time algorithm is more accurate compared with other methods, which are also tested by an experiment system using real noise data. With the new real-time algorithm, a magnetometer calibration can be taken on-orbit and will reduce the demand for computing power effectively.

关键词： Magnetometer bias：On-orbit determinationMicro-satellite Attitude-independent Real-time

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系统视角下的6G通信创新展望

Engineering 2023年第12期31卷 19-24页

作者： Ning Ge Chunxiao Jiang Jianhua Lu Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research center for Information Science and Technology Tsinghua UniversityBeijing 100084China Tsinghua Space Center Tsinghua UniversityBeijing 100084China

The history of wireless communications can be divided into two eras.The first was a discovery-inspired era,initiated by the great physicist Maxwell’s discovery of the classical theory of electromagnetism,while the second was a technology-driven era that began with Marconi’s creation of the first practical world-wide radio-based wireless telegraph system,Shannon’s information theory,and the later invention of cellular mobile communications from the first generation(1G)to the fourth(4G).Nowadays,the fifth generation(5G)is regarded as a leading information and communication technology.

关键词： wireless communication theory

Outage Performance of Non-Orthogonal Multiple Access Based Unmanned Aerial Vehicles Satellite Networks

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China Communications 2018年第5期15卷 1-8页

作者： Ting Qi Wei Feng Youzheng Wang Tsinghua Space Center Tsinghua University tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University

With rapid development of unmanned aerial vehicles(UAVs), more and more UAVs access satellite networks for data transmission. To improve the spectral efficiency, non-orthogonal multiple access(NOMA) is adopted to integrate UAVs into the satellite network, where multiple satellites cooperatively serve the UAVs and mobile terminal using the Ku-band and above. Taking into account the rain fading and the fading correlation, the outage performance is first analytically obtained for fixed power allocation and then efficiently calculated by the proposed power allocation algorithm to guarantee the user fairness. Simulation results verify the outage performance analysis and show the performance improvement of the proposed power allocation scheme.

关键词：卫星网络存取多重车辆天线直角性能分配算法

Measures for Error Avalanche and Energy Avalanche Effect in Secure Wireless Fieldbus Systems

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China Communications 2019年第2期16卷 202-214页

作者： Bohua Li Yukui Pei Department of Electronic Engineering Tsinghua University Beijing National Research center for Information Science and Technology Tsinghua Space Center Tsinghua University Research Institute of tsinghua University in Shenzhen

The wireless fieldbus is a vital part in present industrial automatic controls and software-defined systems. Accompanying, security is an upcoming problem determines its future leapfrog development. Wireless fieldbus systems can be made secure by encrypting the data. Unfortunately, the diffusion character of encryption brings significant vulnerabilities in terms of deteriorated error performance and energy efficiency. In this paper, we first propose an AES-dependent Hsiao(AD-Hsiao) code to improve the error correction capability, which leverages the prior information of data similarity and AES decryption to assist syndrome decoding. Then, we develop "Random Coset" scheme to reduce energy consumption. Based on mapping written data into several data candidates, this scheme lessens the number of bits written to memory and thereby boosts the write energy efficiency. Simulation results show that the AD-Hsiao code can correct majority of double errors in a single codeword with limited latency and area cost as the Hamming code. Moreover, the(72,64) AD-Hsiao code improves the reliability by 102 over the(72,64) Hamming code at 8 dB AWGN channel, and also exceeding the high cost(78,64) BCH code. In addition, the "Random Coset" improves energy efficiency by 6.6～14% than the current scheme while re-quires small ROM storage.

关键词： wireless fieldbus system security reliability energy efficiency AES-dependent Hsiao(AD-Hsiao)code Random Coset

BER Performance Analysis of Asynchronous NOMA with Arbitrary Phase Offset

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China Communications 2022年第11期19卷 195-208页

作者： Chang Liu Sheng Wu Chunxiao Jiang Hongwen Yang School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Tsinghua Space Center Tsinghua UniversityBeijing 100084China

An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.

关键词： non-orthogonal multiple access(NOMA) asynchronous transmission jointly optimal(JO)maximum likelihood(ML)detection successive interference cancellation(SIC) bit error rate(BER)

QoE-Driven Social Aware Caching Placement for Terrestrial-Satellite Networks

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China Communications 2018年第10期15卷 60-72页

作者： Guiting Zhong Jian Yan Linling Kuang Tsinghua Space Center Tsinghua University Beijing 100084 China Beijing National Research center for Information Science and Technology China

In remote terrestrial-satellite networks, caching is a very promising technique to alleviate the burden of space cloudlet(e.g., cache-enabled satellite user terminal) and to improve subscribers' quality of experience(Qo E) in terms of buffering delay and achievable video streaming rate. In this paper, we studied a Qo E-driven caching placement optimization problem for video streaming that takes into account the required video streaming rate and the social relationship among users. Social ties between users are used to designate a set of helpers with caching capability, which can cache popular files proactively when the cloudlet is idle. We model the utility function of Qo E as a logarithmic function. Then, the caching placement problem is formulated as an optimization problem to maximize the user's average Qo E subject to the storage capacity constraints of the helpers and the cloudlets. Furthermore, we reformulate the problem into a monotone submodular optimization problem with a partition matroid constraint, and an efficient greedy algorithm with 1-1 e approximation ratio is proposed to solve it. Simulation results show that the proposed caching placement approach significantly outperforms the traditional approaches in terms of Qo E, while yields about the same delay and hit ratio performance compare to the delay-minimized scheme.

关键词：缓冲能力社会关系放置卫星网络陆上用户终端驾驶