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Haze removal for unmanned aerial vehicle aerial video based on spatial-temporal coherence optimisation

IET IMAGE PROCESSING 2018年第1期12卷 88-97页

作者： Zhao, Xintao Ding, Wenrui Liu, Chunhui Li, Hongguang Beihang Univ Sch Elect & Informat Engn Beijing 100083 Peoples R China Beihang Univ Res Inst Unmanned Aerial Vehicle Beijing 100083 Peoples R China Collaborat Innovat Ctr Geospatial Technol Wuhan 430079 Hubei Peoples R China

Haze removal is a non-trivial work for unmanned aerial vehicle (UAV) aerial video processing, and challenges are mainly attributed to spatial-temporal coherence and computational efficiency. The authors propose a novel dehazing algorithm for hazy UAV aerial video and improve the classical dark channel prior approach with a bright region filling process to alleviate colour distortion in the recovered video, which enhances the spatial consistency. To achieve better temporal coherence, the authors constrain the atmospheric light estimation between adjacent frames by using a temporal filter. The authors also optimise the transmission calculation to reduce computational complexity. Experimental findings show that the proposed algorithm yields results superior to those obtained from previous methods. Compared with that in frame-by-frame dehazing, the processing time in the proposed method is reduced by 74.5%.

关键词： autonomous aerial vehicles video signal processing spatiotemporal phenomena optimisation computational complexity image filtering geophysical image processing image colour analysis unmanned aerial vehicle aerial video haze removal spatial-temporal coherence optimisation UAV aerial video processing computational efficiency dehazing algorithm classical dark channel prior approach bright region filling process colour distortion alleviate spatial consistency enhancement atmospheric light estimation temporal filter computational complexity reduction transmission calculation optimisation

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Interference-leakage based non-cooperative beamforming with low-dimensional approximation

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IET COMMUNICATIONS 2015年第8期9卷 1060-1067页

作者： Choi, Jinho Gwangju Inst Sci & Technol GIST Sch Informat & Commun Kwangju South Korea

In this study, the authors have studied downlink multiuser non-cooperative beamforming in a time-division duplexing-based multicell system with a non-linear Jacobi-like iterative algorithm, where each base station is to minimise the interference leakage to adjacent cells in forming beams with signal-to-interference-plus-noise ratio constraints for users in its cell. The resulting approach is referred to as altruistic non-cooperative beamforming (ANB). To reduce the computational complexity for ANB per cell, a low-dimensional beamforming approach, which can be easily solved as it has a standard downlink multiuser beamforming formulation, has also been considered at the expense of degraded performance.

关键词： cellular radio array signal processing interference suppression iterative methods computational complexity multiuser detection computational complexity reduction ANB signal-to-interference-plus-noise ratio interference leakage minimisation base station nonlinear Jacobi-like iterative algorithm time division duplexing-based multicell system downlink multiuser altruistic noncooperative beamforming low-dimensional approximation

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Coefficient reduction Method for Stopband Ripple Minimization of IFIR Filter

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IETE JOURNAL OF RESEARCH 2019年第2期68卷 799-813页

作者： Chandra, S. Sharma, A. Singh, G. K. Indian Inst Technol Dept Elect Engn Roorkee Uttar Pradesh India

This paper presents a technique for minimization of ripples of interpolated finite impulse response (IFIR) filter. Single-stage and two-stage IFIR filters are designed using the Remez exchange algorithm. The performance of these filters is improved by minimizing the ripples in the stopband region by discarding zero-valued coefficients. The proposed technique yields the desired filter response of IFIR filters matching closely with the required response of finite impulse response (FIR) filter in the passband and stopband regions, providing very low computational complexity and sharp transition width as compared to the conventional FIR filter. In comparison to other existing techniques, the proposed algorithm reduces the stopband ripples significantly (the distortion in the frequency domain is reduced up to 61.20%). As a result, the power losses in the filtered signal are reduced, thereby enhancing the sensitivity and its consistency during the filtering process.

关键词： computational complexity reduction IFIR filter Narrow band filter Sharp transition width Stopband ripples

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Effective Frame Selection for Blind Source Separation Based on Frequency Domain Independent Component Analysis

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2014年第3期E97A卷 784-791页

作者： Mizuno, Yusuke Kondo, Kazunobu Nishino, Takanori Kitaoka, Norihide Takeda, Kazuya Nagoya Univ Grad Sch Informat Sci Nagoya Aichi 4648603 Japan Yamaha Corp Ctr Corp Res & Dev Iwata 4380192 Japan Mie Univ Grad Sch Engn Tsu Mie 5148507 Japan

Blind source separation is a technique that can separate sound sources without such information as source location, the number of sources, and the utterance content. Multi-channel source separation using many microphones separates signals with high accuracy, even if there are many sources. However, these methods have extremely high computational complexity, which must be reduced. In this paper, we propose a computational complexity reduction method for blind source separation based on frequency domain independent component analysis (FDICA) and examine temporal data that are effective for source separation. A frame with many sound sources is effective for FDICA source separation. We assume that a frame with a low kurtosis has many sound sources and preferentially select such frames. In our proposed method, we used the log power spectrum and the kurtosis of the magnitude distribution of the observed data as selection criteria and conducted source separation experiments using speech signals from twelve speakers. We evaluated the separation performances by the signal-to-interference ratio (SIR) improvement score. From our results, the SIR improvement score was 24.3 dB when all the frames were used, and 23.3 dB when the 300 frames selected by our criteria were used. These results clarified that our proposed selection criteria based on kurtosis and magnitude is effective. Furthermore, we significantly reduced the computational complexity because it is proportional to the number of selected frames.

关键词： dodecahedral microphone array frequency domain independent component analysis computational complexity reduction signal to interference ratio improvement

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Joint resource allocation with subcarrier pairing in cooperative OFDM DF multi-relay networks

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IET COMMUNICATIONS 2015年第1期9卷 78-87页

作者： Li, Xueyi Zhang, Qi Zhang, Guangchi Cui, Miao Yang, Liang Qin, Jiayin Guangdong Univ Technol Sch Informat Engn Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Dept Elect & Commun Engn Guangzhou 510006 Guangdong Peoples R China China Elect Technol Grp Corp 7 Res Inst Guangzhou 510310 Guangdong Peoples R China

For conventional subcarrier pairing scheme in cooperative orthogonal frequency division multiplexing decode-and-forward multi-relay networks, to avoid interference, each subcarrier pair (SP) is assigned to a single relay. Over a specific subcarrier, the destination receives signals transmitted from the relay. In this study, to better exploit the degrees of spatial freedom, the authors propose to assign each SP to multiple relays. Thus, over a specific subcarrier, the destination receives signals transmitted from multiple relays. Under the total network power constraint, to maximise the sum transmission rate, they propose a joint resource allocation scheme, in which they jointly optimised the four types of resources: assisting relays selection, transmission mode selection, subcarrier pairing and power allocation. They further propose a suboptimal algorithm which can significantly reduce the computational complexity of the aforementioned optimal allocation scheme with sacrificing little on the performance. It is shown from simulation results that the author's proposed schemes have significant performance improvement over the resource allocation schemes in the literature.

关键词： cooperative communication relay networks (telecommunication) OFDM modulation resource allocation subcarrier pairing scheme cooperative orthogonal frequency division multiplexing SP decode-and-forward multirelay networks interference avoidance degrees of spatial freedom total network power constraint OFDM computational complexity reduction performance improvement suboptimal algorithm power allocation transmission mode selection relays selection joint resource allocation scheme sum transmission rate

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Mean-based reciprocity calibration in TDD massive MIMO systemInspec keywordsOther keywords

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IET COMMUNICATIONS 2020年第22期14卷 4038-4047页

作者： Kumar, Varun Patra, Sarat Kumar Singh, Poonam Natl Inst Technol Elect & Commun Rourkela India Indian Inst Informat Technol Vadodara India Natl Inst Technol Rourkela India

Non-reciprocity limits the potential of time division duplexing (TDD) massive multiple-input and multiple-output (MIMO) systems. Due to the reciprocal channel, there is no need for downlink (DL) pilot transmission implies computational complexity reduction and saving precious time resources. In this study, the DL channel matrix is estimated using the uplink channel matrix by a novel reciprocity calibration technique. Non-reciprocity arises due to the hardware mismatch (HM) across the base station (BS) and the user terminal (UT)/both. Its detrimental effect causes amplitude and phase impairment in the downlink signal transmission. Since a massive MIMO network has a large number of antenna elements across the BS, hence the instantaneous HM coefficient cannot be determined accurately. For solving such a problem, the authors use the statistical response of the hardware unit. Considering a complex Gaussian hardware response across each antenna terminal, the probability density function (PDF) of amplitude and phase mismatch is derived. They also derive the joint PDF of amplitude and phase mismatch, considering the HM. Simulation results address the sensitivity and complexity for evaluating the sum-rate capacity under three linear precoders (matched filter, regularized zero-forcing, and zero-forcing), which validate their effectiveness in this scenario.

关键词： radio receivers computational complexity interference suppression precoding wireless channels calibration radiofrequency interference MIMO communication matrix algebra antenna arrays linear codes TDD massive MIMO system nonreciprocity limits time division duplexing massive multiple‐ input reciprocal channel downlink pilot transmission computational complexity reduction saving precious time resources DL channel matrix uplink channel matrix novel reciprocity calibration technique hardware mismatch base station BS user terminal detrimental effect phase impairment downlink signal transmission massive MIMO network antenna elements instantaneous HM coefficient statistical response hardware unit complex Gaussian hardware response antenna terminal phase mismatch sensitivity

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Low-complexity design framework of all-pass filters with application in quadrature mirror filter banks design

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IET SIGNAL PROCESSING 2017年第3期11卷 239-249页

作者： Jou, Yue-Dar Lin, Zhan-Pei Chen, Fu-Kun ROC Mil Acad Dept Comp & Informat Sci Kaohsiung 830 Taiwan ROC Mil Acad Dept Elect Engn Kaohsiung 830 Taiwan Southern Taiwan Univ Sci & Technol Dept Comp Sci & Informat Engn Tainan 710 Taiwan

Digital all-pass filters design problem can be simplified by solving a set of linear equations associated with a Toeplitz-plus-Hankel matrix in the least-squares sense. Consequently, the Cholesky decomposition or split Levinson technique can be appropriately used to obtain the optimal solution. In this study, the determination of the set of linear equations to calculate the all-pass-based quadrature mirror filter banks is achieved by exploiting some trigonometric identities and the frequency sampling method. The proposed simplification allows for expressing a sum of sinusoids by a single expression. The simulation results indicate that the presented new and simpler closed-form expressions of the Toeplitz-plus-Hankel associated matrices can achieve accurate performance with a considerable reduction in computational complexity.

关键词： channel bank filters computational complexity all-pass filters quadrature mirror filters least squares approximations Toeplitz matrices Hankel matrices computational complexity reduction Toeplitz-plus-Hankel associated matrices closed-form expressions frequency sampling method trigonometric identities optimal solution split Levinson technique Cholesky decomposition least-squares method linear equations digital all-pass filter design problem quadrature mirror filter bank design low-complexity design framework

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computationally efficient adaptive algorithm for resource allocation in orthogonal frequency-division multiple-access-based cognitive radio networks

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IET COMMUNICATIONS 2015年第12期9卷 1442-1449页

作者： Raeis, Mahdi Shahtalebi, Kamal Forouzan, Amir Reza Univ Isfahan Dept Elect Engn Esfahan *** Iran

In this study, the authors examine resource allocation in an orthogonal frequency-division multiple-access-based cognitive radio (CR) network which dynamically senses primary users (PUs) spectrum and opportunistically uses available channels. The aim is resource allocation such that the CR network throughput is maximised under the PUs maximum interference constraint and cognitive users (CUs) transmission power budget. This problem is formulated as a mixed-integer non-linear programming problem which is MATHEMATICAL SCRIPT CAPITAL NP-hard in general and infeasible to solve in real-time. To reduce the computational complexity, the authors decouple the problem into two separate steps. After initial power allocation, in the first step, an adaptive algorithm is employed to assign subcarriers to the CUs toward throughput maximisation by using these initial powers. In the second step, power is allocated optimally to the assigned subcarriers. Simulation results show that the proposed method nearly achieves the optimal solution in a small number of iterations meaning significant reduction in the computational complexity.

关键词： computational complexity cognitive radio OFDM modulation frequency division multiple access channel allocation wireless channels radiofrequency interference nonlinear programming integer programming iterative methods resource allocation computationally efficient adaptive algorithm resource allocation orthogonal frequency division multiple access cognitive radio network CR network throughput maximization primary user spectrum radio channel PU maximum interference constraint cognitive users CU transmission power budget mixed integer nonlinear programming problem NP-hard problem computational complexity reduction power allocation iteration method

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Speed up of Video Enhancement based on Human Perception

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SIGNAL IMAGE AND VIDEO PROCESSING 2014年第7期8卷 1199-1209页

作者： Bruni, Vittoria De Canditiis, Daniela Vitulano, Domenico Univ Roma La Sapienza Fac Engn Dept SBAI I-00161 Rome Italy CNR Ist Applicaz Calcolo M Picone I-00185 Rome Italy

This paper presents SUVEHP (speed up of video enhancement based on human perception), a human perception-based model oriented to reduce the computational time of digital video restoration. In particular, two specific hypothesis tests able to classify degraded frame regions are proposed. Classification is performed in agreement with regions visual significance in order to enable or inhibit motion compensated enhancement. The level of the proposed hypothesis tests is theoretically assessed. Moreover, extensive experimental results on video sequences affected by additive Gaussian noise show that SUVEHP speeds up some standard motion compensated denoisers up to 60%, preserving or even slightly increasing both the objective and subjective visual quality of the restored sequences.

关键词： Human visual system Block classification computational complexity reduction Image and video enhancement

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Adaptive power allocation strategies for distributed space-time coding in cooperative MIMO networks

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IET COMMUNICATIONS 2014年第7期8卷 1141-1150页

作者： Peng, Tong de Lamare, Rodrigo C. Schmeink, Anke Univ York Dept Elect Commun Res Grp York YO10 5DD N Yorkshire England Rhein Westfal TH Aachen Inst Theoret Informat Technol D-52056 Aachen Germany

Adaptive power allocation (PA) algorithms with different criteria for a cooperative multiple-input multiple-output network equipped with distributed space-time coding are proposed and evaluated. Joint constrained optimisation algorithms to determine the PA parameters and the receive filter are proposed for each transmitted symbol in each link, as well as the channel coefficients matrix. Linear receive filter and maximum-likelihood detection are considered with amplify-and-forward and decode-and-forward cooperation strategies. In these proposed algorithms, the elements in the PA matrices are optimised at the destination node and then transmitted back to the relay nodes via a feedback channel. The effects of the feedback errors are considered. Linear minimum mean square error expressions and the PA matrices depend on each other and are updated iteratively. Stochastic gradient algorithms are developed with reduced computational complexity. Simulation results show that the proposed algorithms obtain significant performance gains as compared with existing PA schemes.

关键词： channel allocation space-time codes cooperative communication MIMO communication channel coding filtering theory matrix algebra maximum likelihood detection amplify and forward communication decode and forward communication optimisation error statistics feedback stochastic processes gradient methods least mean squares methods adaptive power allocation strategy distributed space-time coding cooperative multiple input multiple output network joint constrained optimisation algorithm PA parameter determination symbol transmission channel coefflcients matrix linear receive filter maximum likelihood detection amplify and forward cooperation strategy decode and forward cooperation strategy destination node PA matrix optimisation relay nodes feedback channel feedback error linear minimum mean square error iterative method stochastic gradient algorithm computational complexity reduction

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