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Combined algorithm of acquisition and anti-jamming based on SFT

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Journal of Systems Engineering and Electronics 2015年第3期26卷 431-440页

作者： Ying Ma xiangyuan bu Hangcheng Han Qiaoxian Gong School of Information and Electronics Beijing Institute of Technology

A communication and navigation receiver is required to remove hostile jamming signals and synchronize receiving signals effectively especially for satellite communication and navigation whose resources are becoming more and more limited. This paper proposes a novel signal receiving method by combining the pro- cesses of anti-jamming and synchronization to reduce the overall computationa~ complexity at the expense of slightly affecting the detection probability, which is analyzed in detail by derivations. Furthermore, this paper introduces sparse Fourier transformation （SFT） into the proposed algorithm to replace fast Fourier transfor- mation （FFT） so as to further reduce the calculation time especially in large frequency offset environments.

关键词： acquisition anti-jamming navigation sparse Fourier transformation (SFT).

Robust or nonrobust: On MC-DS-CDMA acquisition in LEO satellite communications

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Digital Communications and Networks 2023年第4期9卷 896-905页

作者： Entong Meng xiangyuan bu Jihong Yu Jianping An Xuanhe Yang School of Information and Electronics Beijing Institute of TechnologyBeijing100081China

Low Earth Orbit(LEO)satellite communications can provide global coverage in the sixth generation communication(6G)*** combat the strong Partial Band Interferences(PBIs)and multipath fading in LEO satellite communication systems,the Multicarrier Direct Sequence Code Division Multiple Access(MC-DS-CDMA)technique is a promising alternative to the traditional Single-carrier Direct Sequence Code Division Multiple Access(SC-DS-CDMA)system for its advantages of high bandwidth efficiency,superior interference rejection capability,and low complexity of parallel signal ***,limited studies have been conducted on the performance analysis of MC-DS-CDMA acquisition systems in the presence of a large Doppler shift,a unique characteristic of LEO satellite *** bridge this gap,we investigate the performance of MC-DS-CDMA systems with two-dimensional acquisition and noncoherent equal gain combining over Rician fading channel in the presence of the Doppler shift and *** performance metrics are detection probability and Mean Square Error(MSE)of the Doppler factor and ***,we derive the closed-form expressions for the MSE and the Probability Density Function(PDF)of the acquisition decision variable and obtain the detection *** conduct extensive numerical experiments to verify the theoretical analysis and performance gain of MC-DSCDMA over the *** results show that MC-DS-CDMA with two-dimensional acquisition is more robust to multipath Rician fading than ***,MC-DS-CDMA outperforms SC-DS-CDMA regarding the detection probability and MSE when combating the strong PBIs.

关键词： Satellite communications MC-DS-CDMA Acquisition performance Rician fading channel Partial band interference

A Novel Synchronization Method in Terahertz Large-Scale Antenna Array System

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Chinese Journal of Electronics 2021年第5期30卷 956-968页

作者： ZHENG Chen DING Xuhui LIU Dekang bu xiangyuan AN Sining School of Information and Electronics Beijing Institute of Technology Microwave Electronics Laboratory Department of Microtechnology and Nanoscience Chalmers University of Technology

We focus on the problems of the accurate time delay estimation, the design of training pilots,and hybrid matrix optimization within the large-scale antenna array Terahertz(THz) broadband communication system. In contrast to the existing researches based on narrow-band arrays, we hereby shed light on the time delay estimation of broadband arrays. In THz broadband communication systems, the data symbol duration is relatively short when comparing with the dimension of the antenna array. In large-scale antenna systems,signals received in each antenna are no longer different phase-shifted copies of the same symbol, but completely different symbols in which occasion traditional narrowband structure is no longer suitable. Based on the above conclusion, firstly, we put forward a system model based on large-scale antenna arrays and Time delay line(TDL)structure. Secondly, we deduce the Cramer-Rao lower bound(CRLB) of the time delay estimation, and present a time delay estimation algorithm that could reach the CRLB. Thirdly, by minimizing the CRLB, we address the design of the training pilot and optimized TDL structure under the condition of constant envelope training pilot and modulus TDL structure. Finally, we disclose the numerical simulation results. According to the simulation results, the aforementioned method is workable in reaching the CRLB,the TDL structure can significantly surpass that of the traditional model, and the optimal pilot design method outperforms the pseudo-random pilot structure.

关键词： OFDM modulation time-domain analysis time delay estimation algorithm narrow-band arrays constant envelope training pilot frequency estimation synchronisation hybrid matrix optimization different phase-shifted copies completely different symbols THz broadband communication systems large-scale antenna systems optimal pilot design method Terahertz large-scale antenna array system modulus TDL structure occasion traditional narrow-band structure channel estimation large-scale antenna array Terahertz broadband communication system optimized TDL structure data symbol duration CRLB large-scale antenna arrays array signal processing pseudorandom pilot structure broadband arrays system model accurate time delay estimation antenna arrays Time delay line structure delay estimation

All-Digital Self-Interference Cancellation in Zero-IF Full-Duplex Transceivers

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China Communications 2016年第11期13卷 27-34页

作者： Lu Tian Shuai Wang Zhiheng Cheng xiangyuan bu School of Information Science and Electronics Beijing Institute of Technology

In this paper,a general scheme in digital self-interference cancellation at baseband for zero-IF full-duplex transceivers is presented. We model the self-interference signals specifically with only the nonlinear distortion signals falling in receiving band considered. A joint estimation algorithm is proposed for compensating the time delay and frequency offset taking into account the IQ amplitude and phase imbalances from mixers. The memory effect and nonlinear distortion are adaptively estimated by the de-correlated normalized least mean square(DNLMS) algorithm. Numerical simulation results demonstrate that the proposed self-interference cancellation scheme can efficiently compensate the self-interference and outperform the existing traditional solutions.

关键词： communication systems full-duplex transceivers self-interference cancellation IQ imbalance de-correlated normalized least mean square algorithm

Predictive Decision and Reliable Accessing for UAV Communication in Space-Air-Ground Integrated Networks

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China Communications 2022年第1期19卷 166-185页

作者： Bowen Zeng Zhongshan Zhang Xuhui Ding xiangyuan bu Jianping An School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

The cooperation of multiple Unmanned Aerial Vehicles(UAVs) has become a promising scenario in Space-Air-Ground Integrated Networks(SAGINs) recently due to their widespread applications,where wireless communication is a basic necessity and is normally categorized into control and nonpayload communication(CNPC) as well as payload communication. In this paper, we attempt to tackle two challenges of UAV communication respectively on establishing reliable CNPC links against the high mobility of UAVs as well as changeable communication conditions, and on offering dynamic resource optimization for Quality-of-Service(QoS) guaranteed payload communication with variable link connectivity. Firstly, we propose the concept of air controlling center(ACC), a virtual application equipped on the infrastructure in SAGINs, which can collect global information for estimating UAV trajectory and communication channels. We then introduce the knapsack problem for modelling resource optimization of UAV communication in order to provide optimal access points for both CNPC and payload communication. Meanwhile, using the air controlling information, predictive decision algorithm and handover strategy are introduced for the reliable connection with multiple access points. Simulation results demonstrate that our proposal ensures an approximate always-on reliable accessing of communication links and outperforms the existing methods against high mobility,sparse distribution, and physical obstacles.

关键词： space-air-ground integrated networks UAV communication air communication controlling predictive decision reliable accessing

Adaptive suppression of passive intermodulation in digital satellite transceivers

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Chinese Journal of Aeronautics 2017年第3期30卷 1154-1160页

作者： Lu TIAN Hangcheng HAN Wenhui CAO xiangyuan bu Shuai WANG School of lnJormation Science and Electronics Beijing Institute of Technology Bering 100081 China

For the performance issues of satellite transceivers suffering passive intermodulation interference,a novel and effective digital suppression algorithm is presented in this *** contrast to analog approaches,digital passive intermodulation（PIM） suppression approaches can be easily reconfigured and therefore are highly attractive for future satellite communication systems.A simplified model of nonlinear distortion from passive microwave devices is established in consideration of the memory *** multiple high-order PIM products falling into the receiving band can be described as a bilinear predictor function.A suppression algorithm based on a bilinear polynomial decorrelated adaptive filter is proposed for baseband digital signal *** consideration of the time-varying characteristics of passive intermodulation,this algorithm can achieve the rapidness of online interference estimation and low complexity with less consumption of *** simulation results show that the algorithm can effectively compensate the passive intermodulation interference,and achieve a high signal-to-interference ratio gain.

关键词： Adaptive digital filters Intermodulation model Interference suppression Passive devices Satellite communication systems

Impact of Phase Noise on TDMS Based Calibration for Spaceborne Multi-Beam Antennas

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China Communications 2018年第3期15卷 128-136页

作者： Yujie Lin xiangyuan bu Shuai Wang Yuan Chai Jianping An School of Information and Electronics Beijing Institute of Technology Institute of Telecommunication Satellite China Academy of Space Technology

For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in practice, random phase noise imposed by noisy local oscillators can cause significant performance degradation in TDMS-based calibration systems. Characterization of phase noise effects is therefore crucial for practical applications. In this paper, we analyze the impact of phase noise on the calibration performance for a MBA system. Specifically, we derive the relationship between the probability of correct amplitude/phase estimation and various practical factors involving the signal-to-noise ratio(SNR), the standard deviation of phase noise, the given tolerance region, and the length of the spreading code. The results provide high efficiency for evaluating the calibration performance of the MBAs based on TDMS, especially for precisely anticipating the impact of phase noise. Finally, the accuracy of the derived results is assessed by simulations in different scenarios.

关键词： multi-beam antenna calibration phase noise time division multiplexed switching

A Novel Angle of Arrival Tracking Method in Large-Scale-Array Systems

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China Communications 2022年第9期19卷 171-190页

作者： Chen Zheng Dekang Liu Xuhui Ding xiangyuan bu Zhongshan Zhang School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

In this paper,we investigate the problem of angle of arrival(AOA)tracking for the largescale array in terahertz(THz)communication,which has a large size and a narrow beam,highly demanding an accurate angle *** the one hand,the system usually adopts a hybrid structure with limited radio-frequency(RF)chains,which increases the difficulty of angle estimation;on the other hand,the rapid mobility of users also brings new challenges to angle *** address the above challenges,a two-stage tracking framework is proposed in this paper,which employs the random phase matrix and orthogonal long pilots in the first stage to reduce the complicated multi-user estimation to multiple single-user estimations,followed by using both wide and narrow beams in the second stage to serve high-speed and low-speed ***,a generalized-approximated-message-passing(GAMP)method is proposed for facilitating a low-accuracy estimation of the angles,followed by adopting a modified expectation-maximization(EM)algorithm based phase estimation to unbiased estimate the instantaneous angle with the help of high-gain characteristics of the *** proposed structure can not only simplify the estimation complexity,but also improve the estimation accuracy due to its capability of transferring the non-linear problem of angle observation into a linear gaussian *** addition,the Kalman tracking framework is employed for performing a continuous angle *** results show that the angle estimation based on the random phase matrix in the initial stage can obtain a high enough estimation accuracy,while the GAMP algorithm implemented in the second stage can quickly capture the angle range under the Rayleigh *** performance of the proposed EM-based tracking method is shown to outperform the traditional extended Kalman filter(EKF)method.

关键词： angle tracking hybrid MIMO communications analog matrix

Network for hypersonic UCAV swarms

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Science China(Information Sciences) 2020年第4期63卷 112-139页

作者： Shixun LUO Zhongshan ZHANG Shuai WANG Shuo ZHANG Jibo DAI xiangyuan bu Jianping AN School of Information and Electronics Beijing Institute of Technology National Key Laboratory of Science and Technology on Aerospace Intelligence Control Beijing Aerospace Automatic Control Institute

Unmanned combat aerial vehicles(UCAVs) that swarm with both autonomous decision-making and cooperative attacking have been regarded as revolutionary elements of modern warfare. In such a swarm,inter-group connectivity must be ensured in a network to maintain a collective consensus. In recent years,academia and industry have made many efforts to achieve common tactical data link systems and commercial drone networks. However, the existing results have difficulty meeting the needs of cooperative autonomous UCAV swarms with both hypersonic mobility and time sensitivity in severe confrontation scenarios. In this article, we conduct an in-depth investigation of the network used for the hypersonic UCAV swarms,which can be considered as a special form of mobile wireless network. Furthermore, faced with specific functional demands, we summarize the main challenges of designing this dedicated network. In addition,a comprehensive survey of potential solutions for the network design is presented. Lastly, we discuss the possible capabilities of the network given the current forefront of technology, as well as remaining challenges and open issues.

关键词： military communication machine-to-machine communications multi-UCAV networks ad hoc networks wireless mesh networks unmanned aerial vehicles cross layer design