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Aircraft identification from RCS measurement using an orthogonal transform

IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 2000年第2期147卷 93-102页

作者： Chan, YT Ho, KC Wong, SK Royal Mil Coll Canada Dept Elect & Comp Engn Kingston ON K7K 5L0 Canada Univ Missouri Dept Elect Engn Columbia MO 65211 USA Def Res Estab Ottawa Ottawa ON K1A 0Z4 Canada

A comparative study on target identification using the radar cross section (RCS) signature of an aircraft in both the frequency domain and the range domain is conducted. A maximum likelihood method is employed to perform the identification process. Generalised likelihood identification when the received RCS signal is attenuated by an unknown amount is also examined. Target identification could be quite computationally intensive since a large number of library reference signatures may have to be searched to declare an identification. The use of an orthogonal transform is proposed to reduce the computational requirement. It is found that the discrete cosine transform is very effective in compacting the RCS signature in the frequency domain, and the Haar transform is more efficient in the range domain. The application of orthogonal transforms can reduce the computational complexity by at least 50% while maintaining the same identification accuracy.

关键词： computational complexity Mathematical analysis Radar theory maximum likelihood estimation library reference signatures frequency-domain analysis RCS measurement aircraft identification maximum likelihood method radar cross section signature orthogonal transform target identification discrete cosine transforms Integral transforms in numerical analysis received RCS signal attenuation computational complexity reduction radar applications aircraft Haar transform discrete cosine transform identification accuracy frequency domain radar cross-sections range domain RCS signature Haar transforms generalised likelihood identification radar target recognition

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Novel multiuser ultra-wideband receiver based on adaptive modelling of generalised normal-Laplace distribution

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IET COMMUNICATIONS 2014年第17期8卷 3189-3201页

作者： An, Jinyoung Kim, Sangchoon Univ Ulsan Automobile Ship Elect Convergence Ctr Ulsan 680749 South Korea Dong A Univ Dept Elect Engn Pusan South Korea

This study takes a new receiving approach to detect an ultra-wideband (UWB) signal in the presence of multiple access interference (MAI). A generalised normal-Laplace (GNL) distribution is exploited for designing a novel multiuser UWB receiver. To more accurately comply with real statistical behaviours of the MAI-plus-noise in time-hopping multiple access UWB systems, a modified parameter estimator, which is an adaptive method of moments estimation (aMME), is proposed. In the existing studies, the analysis about GNL model shows appropriate results for UWB simulations, while it requires heavy complexity to obtain the precise distribution because of no existence of a closed-form probability density function (PDF) expression. To practically evaluate the GNL PDF, the fast Fourier transform, which can significantly reduce the computational complexity is considered. The GNL using the aMME outperforms the conventional matched filter UWB receiver, the soft-limiting receiver, the Gaussian-Laplace mixture receiver, the p-order metric receiver and the previous GNL receivers, especially in high SNR ranges. Furthermore, the presented GNL receiving method is applied to each finger of the conventional Rake receiver for signal detection in IEEE UWB multipath channels. The proposed Rake receiver based on the GNL distribution performs better than the conventional Rake receiver in multipath fading channels.

关键词： ultra wideband communication radio receivers statistical distributions signal detection radiofrequency interference multi-access systems parameter estimation method of moments computational complexity probability fast Fourier transforms multiuser ultra-wideband receiver adaptive modelling generalised normal-Laplace distribution UWB signal detection multiple access interference GNL distribution multiuser UWB receiver statistical behaviours MAI-plus-noise time-hopping multiple access UWB systems modified parameter estimator adaptive method of moments estimation closed-form PDF expression GNL probability density function fast Fourier transform FFT computational complexity reduction aMME algorithm matched filter UWB receiver soft-limiting UWB receiver GNL receiving method p-order metric receiver Gaussian-Laplace mixture UWB receiver signal-to-noise ratio Rake receiver IEEE UWB multipath channels multipath fading channels

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Peak-to-average power ratio reduction in orthogonal frequency division multiplexing system using differential evolution-based partial transmit sequences scheme

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IET COMMUNICATIONS 2012年第11期6卷 1483-1488页

作者： Hung, H. -L. Huang, Y. -F. Chien Kuo Technol Univ Dept Elect Engn Changhua 500 Taiwan Chaoyang Univ Technol Dept Informat & Commun Engn Taichung 407 Taiwan

A differential evolution (DE)-based partial transmit sequence (PTS) scheme for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems has been proposed. PTS techniques can improve the PAPR statistics of an OFDM signals, but the considerable computational complexity for the required search through a high-dimensional vector space is a potential problem for the implementation in practical systems. The DE is an efficient and powerful population-based stochastic search technique for solving optimisation problems over continuous space, which has been widely applied in many scientific and engineering fields. Thus, to reduce the complexity for searching phase weight vector and to improve the PAPR statistics, the authors introduce DE, to search the optimal phase weight factors. The simulation results show that the proposed DE-based PTS obtains an excellent PAPR performance with a low computational complexity.

关键词： optimisation problem PAPR statistics peak-to-average power ratio reduction Optimisation techniques orthogonal frequency division multiplexing system continuous space searching phase weight vector Modulation and coding methods OFDM systems OFDM modulation optimal phase weight factors powerful population-based stochastic search technique DE-based PTS scheme differential evolution-based partial transmit sequence scheme high-dimensional vector space computational complexity evolutionary computation PAPR reduction computational complexity reduction

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Partial phase weighting selected mapping scheme for peak-to-average power ratio reduction in orthogonal frequency division multiplexing system

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IET COMMUNICATIONS 2015年第2期9卷 147-155页

作者： Wang, Lingyin Liu, Ju Univ Jinan Sch Informat Sci & Engn Jinan 250022 Peoples R China Shandong Univ Sch Informat Sci & Engn Jinan 250100 Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian 710071 Peoples R China

As one of the most attractive schemes, selected mapping (SLM) provides an effective solution for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) system. However, in conventional SLM (CSLM), the large number of inverse fast Fourier transform (IFFT) operations are required for achieving the satisfactory PAPR reduction performance, which results in the large computational complexity. In this study, a partial phase weighting SLM (PPW-SLM) for PAPR reduction in OFDM system is proposed. In the proposed PPW-SLM, partial phase weighting method and the properties of IFFT are employed for simplifying the calculations of IFFTs and obtaining good PAPR reduction performance. Theoretical analysis and simulation results show that, compared with CSLM, the proposed PPW-SLM can obtain a significant computational complexity reduction in similar PAPR reduction performance.

关键词： OFDM modulation inverse transforms fast Fourier transforms computational complexity partial phase weighting selected mapping scheme peak-to-average power ratio reduction orthogonal frequency division multiplexing system selected mapping OFDM system conventional SLM CSLM inverse fast Fourier transform IFFT operations PPW-SLM partial phase weighting method PAPR reduction performance theoretical analysis theoretical simulation computational complexity reduction

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Minimisation of image watermarking side effects through subjective optimisation

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IET IMAGE PROCESSING 2013年第8期7卷 733-741页

作者： Golestani, Hossein Bakhshi Ghanbari, Mohammed Sharif Univ Technol Dept Elect & Comp Engn Tehran Iran Univ Essex Sch Comp Sci & Elect Engn Colchester CO4 3SQ Essex England

This study investigates the use of structural similarity index (SSIM) on the minimised side effect to image watermarking. For the fast implementation and more compatibility with the standard discrete cosine transform (DCT)-based codecs, watermark insertion is carried out on the DCT coefficients and hence an SSIM model for DCT-based watermarking is developed. For faster implementation, the SSIM index is maximised over independent 4 x 4 non-overlapped blocks, but the disparity between the adjacent blocks reduces the overall image quality. This problem is resolved through optimisation of overlapped blocks, but, the higher image quality is achieved at a cost of high computational complexity. To reduce the computational complexity while preserving the good quality, optimisation of semi-overlapped blocks is introduced. The authors show that while SSIM-based optimisation over overlapped blocks has as high as 64 times the complexity of the 4 x 4 non-overlapped method, with semi-overlapped optimisation the high quality of overlapped method is preserved only at a cost of less than 8 times the non-overlapped method.

关键词： computational complexity discrete cosine transforms minimisation image watermarking image watermarking side effect minimisation subjective optimisation structural similarity index standard DCT-based codecs watermark insertion DCT coefficients SSIM model independent nonoverlapped blocks image quality reduction computational complexity reduction semioverlapped block optimisation

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Transceiver design for cooperative non-orthogonal multiple access systems with wireless energy transfer

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IET COMMUNICATIONS 2016年第15期10卷 1947-1955页

作者： Sun, Ruijin Wang, Ying Wang, Xinshui Zhang, Yuan Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Beijing 100876 Peoples R China

In this study, an energy harvesting (EH)-based cooperative non-orthogonal multiple access (NOMA) system is considered, where node S simultaneously sends independent signals to a stronger node R and a weaker node D. The authors focus on the scenario that the direct link between S and D is too weak to meet the quality of service (QoS) of D. Based on the NOMA principle, R, the stronger user, has prior knowledge about the information of the weaker user, D. To satisfy the targeted rate of D, R also serves as an EH decode-and-forward relay to forward the traffic from S to D. In the sense of equivalent cognitive radio concept, R viewed as a secondary user assists to boost D's performance, in exchange for receiving its own information from S. Specifically, transmitter beamforming, power splitter and receiver filter are jointly designed to maximise R's rate with the predefined QoS constraint of D and the power constraint of S. Since the problem is non-convex, they propose an iterative approach to solve it. Moreover, a zero-forcing based low-complexity solution is also presented. Simulation results demonstrate that, both two proposed schemes have better performance than the direction transmission.

关键词： radio transceivers cooperative communication multi-access systems radiofrequency power transmission energy harvesting array signal processing radiofrequency filters concave programming quality of service computational complexity iterative methods decode and forward communication relay networks (telecommunication) filtering theory transceiver design energy harvesting-based cooperative nonorthogonal multiple access system NOMA principle wireless energy transfer quality-of-service QoS EH decode-and-forward relay cognitive radio concept secondary user transmitter beamforming design power splitting ratio optimisation receiver filter design computational complexity reduction iterative approach zero-forcing based solution nonconvex problem

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Linear transceiver design with intercarrier interference reduction for multiple-input-multiple-output with orthogonal frequency division multiplexing systems

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IET COMMUNICATIONS 2014年第8期8卷 1384-1392页

作者： Qian, Fengyong Leung, Shu-hung Mai, Ruikai Zhu, Yuesheng City Univ Hong Kong State Key Lab Millimeter Waves Dept Elect Engn Hong Kong Hong Kong Peoples R China Peking Univ Shenzhen Grad Sch Commun & Informat Secur Lab Beijing Peoples R China

In this study, a joint design of precoder and equaliser of a linear transceiver for multiple-input-multiple-output system with orthogonal frequency division multiplexing in the presence of intercarrier interference (ICI) is presented. The matrix structures of the precoder and equaliser are banded for the sake of reducing the computational complexity and feedback overhead from the receiver to the transmitter. The design criterion is to minimise the mean-squared error subject to a total transmitted power constraint of which the power is allocated over space and frequency domains in the precoder. The authors use the Karush-Kuhn-Tucker conditions to derive an iterative procedure to obtain a convergent solution and a closed-form procedure for the optimal full transceiver. Numerical results show that the banded precoder is an efficient scheme to improve the bit error rate (BER) of the transceiver by simply increasing its band size and can provide better BER performance than that of the existing jointly designed full transceiver in the presence of ICI. With small band sizes, the proposed transceiver can give performance close to that of the jointly designed full transceiver but with lower implementation complexity and feedback overhead to the transmitter.

关键词： OFDM modulation intercarrier interference radio transceivers interference suppression MIMO communication precoding matrix algebra equalisers communication complexity feedback least mean squares methods minimisation channel allocation frequency-domain analysis iterative decoding error statistics joint linear transceiver design intercarrier interference reduction multiple input multiple output orthogonal frequency division multiplexing OFDM multiplexing precoder matrix structure ICI BER performance band size bit error rate banded precoder iterative procedure KarushaEuro"KuhnaEuro"Tucker conditions space domain analysis frequency domain analysis power allocation mean squared error minimisation transmitter receiver feedback overhead reduction computational complexity reduction equaliser matrix structure

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Robust blind beamforming using neural network

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IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 2000年第1期147卷 41-46页

作者： He, Z Chen, Y DSP Division Department of Radio Engineering Southeast University Nanjing People's Republic of China

Many blind beamforming algorithms, such as C-CAB, use cyclostationarity to estimate the steering vector and adaptively obtain the LCMV optimum solution. However, LCMV methods are sensitive to the mismatch caused by the uncalibration array or estimate error. After discussion of this mismatch, a robust blind beamforming algorithm is presented in the paper. Implemented as a neural network, this algorithm reduces computational complexity for real-time use. Computer simulations verify the analysis.

关键词： adaptive estimation array signal processing computational complexity Simulation, modelling and identification Signal processing and detection computer simulations covariance analysis robust blind beamforming Neural nets blind beamforming algorithms Signal processing theory computational complexity reduction steering vector estimation neural network C-CAB linearly constrained minimum variance cyclostationarity LCMV optimum solution estimate error improved Hopfield network Hopfield neural nets

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Passive Synthetic Aperture Radar Imaging Using Kalman Reflection Coefficients Estimation Algorithm with DVB-T Signal

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JOURNAL OF REAL-TIME IMAGE PROCESSING 2021年第6期18卷 2097-2109页

作者： Ansari, Farzad Samadi, Sadegh Mohseni, Reza Shiraz Univ Technol Shiraz Iran

In this paper, a new method is presented for image formation in a Multistatic Passive Synthetic Aperture Radar (SAR), whose receiver is moving and transmitters are stationary in a multistatic structure, and the signal used to create the image is DVB-T. The proposed method uses multiple transmitters of opportunity to improve the range resolution of a Passive SAR. First, a linear observation model is developed for multistatic structure of the Passive SAR system. Then, the image of the underlying scene is obtained through a new Kalman-based estimation algorithm. In this algorithm, range migration error is completely corrected, and the use of Kalman recursive filter reduces the computational complexity of the reflection coefficients estimation algorithm. Experimental results indicate that the proposed algorithm is effective.

关键词： Real time processing computational complexity reduction DVB-T signal Estimation Kalman recursive filter Linear model Passive synthetic aperture radar

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Simplified QR-decomposition based and lattice reduction-assisted multi-user multiple-input-multiple-output precoding scheme

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IET COMMUNICATIONS 2016年第5期10卷 586-593页

作者： Fang, Shu Wu, Jian Lu, Chengyi Yue, Zong-di Han, Yuan-chao Univ Elect Sci & Technol China Dept Natl key Lab Commun Chengdu 611731 Peoples R China

Future wireless communication systems require more and more antennas at the transceiver to improve the achievable rates. Multi-user multiple-input multiple-output (MU-MIMO) technique is regarded as a potential technique to serve large number of users simultaneously to further increase the achievable rates in MIMO systems. If the number of antennas at the transceiver is large, the computational complexity of precoding becomes the bottleneck and a big challenge in MU-MIMO system. In this paper, a simplified QR decomposition with lattice reduction assisted MU-MIMO precoding scheme named S-QR-LR is proposed as a low-complexity MU-MIMO transmission scheme. The simplified QR decomposition method is delicately designed and operated twice for the proposed precoding scheme not only to achieve good performance but also reduce the computational complexity significantly. The proposed S-QR-LR scheme first uses the simplified QR decomposition operation to balance the multi-user interference and the noise. Then, the proposed S-QR-LR precoding scheme utilizes the simplified QR decomposition method again with the assist of lattice reduction to obtain the precoding gain to further improve the performance with low computational complexity. Analytical and simulation results show that the proposed S-QR-LR precoding scheme achieves best performance among the existing precoding schemes, but requires the lowest computational complexity.

关键词： multiuser channels MIMO communication radio transceivers antenna arrays linear codes precoding least mean squares methods singular value decomposition computational complexity lattice theory simplified QR-decomposition MU-MIMO precoding scheme lattice reduction-assisted MU-MIMO precoding scheme multiuser multiple-input-multiple-output technique future wireless communication systems transceiver achievable rate improvement computational complexity reduction block diagonalisation linear precoding scheme singular value decomposition operations LR-S-GMI precoding scheme generalised minimum mean square error channel inversion utilisation large matrix pseudo-inverse computation S-QR-LR precoding scheme LR-assisted MU-MIMO precoding scheme low-complexity MU-MIMO transmission precoding gain

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