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Efficient nonlinear companding scheme for substantial reduction in peak-to-average power ratio of OFDM

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Journal of Systems engineering and Electronics 2015年第5期26卷 924-931页

作者： Kasun Bandara Atul Sewaiwar Yeon-Ho Chung department of information and communications engineering Pukyong National University

Orthogonal frequency division multiplexing(OFDM)produces a high peak-to-average power ratio(PAPR) that adversely affects high-speed OFDM data transmission. In order to reduce the high PAPR, an efficient nonlinear companding transform(NCT) function is proposed. With the proposed NCT function,the compression and expansion weights can be applied independently with suitably chosen function parameter values. As a result, the proposed function can easily maintain the average signal power approximately unchanged during the companding *** this regard, the proposed function is superior to previously proposed schemes. Also, the simulations show the outstanding PAPR reduction performance of the proposed function. It is demonstrated that the proposed scheme performs well with nonlinear transmitter amplifiers and delivers superior error performance, compared with error function and exponential function based schemes.

关键词： companding orthogonal frequency division multiplexing(OFDM) peak-to-average power ratio(PAPR)

Robust Transmission Design for Federated Learning Through Over-the-Air Computation

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China communications 2025年第03期 65-75页

作者： Hamideh Zamanpour Abyaneh Saba Asaad Amir Masoud Rabiei School of Electrical and Computer engineering College of Engineering University of Tehran department of Electrical engineering and Computer Science York University

Over-the-air computation(AirComp) enables federated learning(FL) to rapidly aggregate local models at the central server using waveform superposition property of wireless channel. In this paper, a robust transmission scheme for an AirCompbased FL system with imperfect channel state information(CSI) is proposed. To model CSI uncertainty, an expectation-based error model is *** main objective is to maximize the number of selected devices that meet mean-squared error(MSE)requirements for model broadcast and model aggregation. The problem is formulated as a combinatorial optimization problem and is solved in two ***, the priority order of devices is determined by a sparsity-inducing procedure. Then, a feasibility detection scheme is used to select the maximum number of devices to guarantee that the MSE requirements are met. An alternating optimization(AO) scheme is used to transform the resulting nonconvex problem into two convex subproblems. Numerical results illustrate the effectiveness and robustness of the proposed scheme.

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Discovering High-Quality Threaded Discussions in Online Forums

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Journal of Computer Science & Technology 2014年第3期29卷 519-531页

作者： Jung-Tae Lee Min-Chul Yang Hae-Chang Rim department of Computer and radio communications engineering Korea UniversitySeoul 136-713Korea

Archives of threaded discussions generated by users in online forums and discussion boards contain valuable knowledge on various topics. However, not all threads are useful because of deliberate abuses, such as trolling and flaming, that are commonly observed in online conversations. The existence of various users with different levels of expertise also makes it difficult to assume that every discussion thread stored online contains high-quality contents. Although finding high-quality threads automatically can help both users and search engines sift through a huge amount of thread archives and make use of these potentially useful resources effectively, no previous work to our knowledge has performed a study on such task. In this paper, we propose an automatic method for distinguishing high-quality threads from low-quality ones in online discussion sites. We first suggest four different artificial measures for inducing overall quality of a thread based on ratings of its posts. We then propose two tasks involving prediction of thread quality without using post rating information. We adopt a popular machine learning framework to solve the two prediction tasks. Experimental results on a real world forum archive demonstrate that our method can significantly improve the prediction performance across all four measures of thread quality on both tasks. We also compare how different types of features derived from various aspects of threads contribute to the overall performance and investigate key features that play a crucial role in discovering high-quality threads in online discussion sites.

关键词： online forum discussion board thread quality

Dark channel prior based blurred image restoration method using total variation and morphology

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Journal of Systems engineering and Electronics 2015年第2期26卷 359-366页

作者： Yibing Li Qiang Fu Fang Ye Hayaru Shouno College of information and Communication engineering Harbin Engineering University department of information and Communication engineering University of Electro-Communications

The blurred image restoration method can dramatically highlight the image details and enhance the global contrast, which is of benefit to improvement of the visual effect during practical ap- plications. This paper is based on the dark channel prior principle and aims at the prior information absent blurred image degradation situation. A lot of improvements have been made to estimate the transmission map of blurred images. Since the dark channel prior principle can effectively restore the blurred image at the cost of a large amount of computation, the total variation （TV） and image morphology transform （specifically top-hat transform and bottom- hat transform） have been introduced into the improved method. Compared with original transmission map estimation methods, the proposed method features both simplicity and accuracy. The es- timated transmission map together with the element can restore the image. Simulation results show that this method could inhibit the ill-posed problem during image restoration, meanwhile it can greatly improve the image quality and definition.

关键词： image restoration dark channel prior total variation (TV) morphology transform

An Effective Intrusion Detection System Based on the FSA-BGRU Hybrid Model

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China communications 2025年第2期22卷 188-198页

作者： Deng Zaihui Li Zihang Guo Jianzhong Gan Guangming Kong Dejin School of Electronic and Electrical engineering Wuhan Textile UniversityWuhan 430200China School of Computer Science and Artificial Intelligence Wuhan Textile UniversityWuhan 430200China School of Physics and Electronic information engineering Hubei Engineering UniversityXiaogan 432000China

Intrusion detection systems play a vital role in cyberspace *** this study,a network intrusion detection method based on the feature selection algorithm(FSA)and a deep learning model is developed using a fusion of a recursive feature elimination(RFE)algorithm and a bidirectional gated recurrent unit(BGRU).Particularly,the RFE algorithm is employed to select features from high-dimensional data to reduce weak correlations between features and remove redundant features in the numerical feature ***,a neural network that combines the BGRU and multilayer perceptron(MLP)is adopted to extract deep intrusion behavior ***,a support vector machine(SVM)classifier is used to classify intrusion *** proposed model is verified by experiments on the NSL-KDD *** results indicate that the proposed model achieves a 90.25%accuracy and a 97.51%detection rate in binary classification and outperforms other machine learning and deep learning models in intrusion *** proposed method can provide new insight into network intrusion detection.

关键词： bidirectional GRU feature selection intrusion detection system multilayer perceptron recursive feature elimination support vector machine

A Multi-Task Learning Framework for Joint Sub-Nyquist Wideband Spectrum Sensing and Modulation Recognition

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China communications 2025年第1期22卷 128-138页

作者： Dong Xin Stefanos Bakirtzis Zhang Jiliang Zhang Jie department of Electronic and Electrical engineering University of SheffieldSheffield S102TNUnited Kingdom department of Computer Science and Technology University of CambridgeCambridge CB21TNUnited Kingdom College of information Science and engineering Northeastern UniversityShenyang 110819China Ranplan Wireless Network Design Ltd. Cambridge CB233UYUnited Kingdom

The utilization of millimeter-wave frequencies and cognitive radio(CR)are promising ways to increase the spectral efficiency of wireless communication ***,conventional CR spectrum sensing techniques entail sampling the received signal at a Nyquist rate,and they are not viable for wideband signals due to their high *** paper expounds on how sub-Nyquist sampling in conjunction with deep learning can be leveraged to remove this *** this end,we propose a multi-task learning(MTL)framework using convolutional neural networks for the joint inference of the underlying narrowband signal number,their modulation scheme,and their location in a wideband *** demonstrate the effectiveness of the proposed framework for real-world millimeter-wave wideband signals collected by physical devices,exhibiting a 91.7% accuracy in the joint inference task when considering up to two narrowband signals over a wideband ***,the proposed data-driven approach enables on-the-fly wideband spectrum sensing,combining accuracy,and computational efficiency,which are indispensable for CR and opportunistic networking.

关键词： automated modulation classification cognitive radio convolutional neural networks deep learning spectrum sensing sub-Nyquist sampling

Color image encryption scheme based on chaotic systems

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The Journal of China Universities of Posts and Telecommunications 2018年第2期25卷 39-48页

作者： Min Xiangshen Fan Jiulun Zhang Xuefeng Ren Fang department of communications and information engineering Xi'an University of Posts and Telecommunications

To improve the security of the color image encryption scheme,a color image encryption scheme based on chaotic systems is proposed. Firstly, the proposed scheme sets the color image as a three-dimensional matrix which is scrambled by affine transformation. Second, the Logistic chaotic sequence applied to generate the control parameter and auxiliary key is used to encrypt the three-dimensionaL matrix. Here, we mainly focus on two methods for encryption processes. One is to generate a chaotic sequence by Logistic map and Henon map, which is used to perform XOR operation with the scrambled components R＇, G＇, B＇ respectively. The other one is to adopt a binary Logistic sequence to select the pixel position for the scrambled components R＇, G＇, B＇ image, and then applying the Henon map and Logistic map with the auxiliary key to perform the replacement encryption. Based on this, an encrypted image is synthesized. Simulation results show that the proposed image encryption scheme can implement better encryption and achieve higher security performance.

关键词： color image cncryption chaotic systems affine transformation Logistic map Henon map security performance

Cancelable palmprint template generating algorithm based on adaptive threshold

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The Journal of China Universities of Posts and Telecommunications 2019年第1期26卷 1-11页

作者： Min Xiangshen Fan Jiulun Zhang Xuefeng department of communications and information engineering Xi'an University of Posts and Telecommunications

Aiming at the problem of low recognition rate and poor security in the process of palmprint identity authentication,a cancelable palmprint template generating algorithm is proposed,which is based on local Gabor directional pattern with adaptive threshold by mean(m LGDP),difference local Gabor directional pattern with adaptive threshold by mean(m DLGDP)and feature fusion of *** this method,the feature code of the image is segmented and the feature vectors are extracted and *** the Bloom filter is used to achieve many-toone mapping and the location scrambling of palmprint ***,the scrambling result matrix and the user key are irreversibly transformed by the convolution operation to obtain a revocable template of the palmprint *** theoretical and experimental results analysis show that,in the case of key loss,the method of feature fusion can enhance the diversity of the original palmprint template effectively,improve the recognition rate efficiently,and have better security.

关键词： cancelable palmprint template Gabor adaptive threshold feature fusion

A Lightweight ABE Security Protection Scheme in Cloud Environment Based on Attribute Weight

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Computers, Materials & Continua 2023年第8期76卷 1929-1946页

作者： Lihong Guo Jie Yang Haitao Wu department of information and communications engineering Nanjing Institute of TechnologyNanjing211167China

Attribute-based encryption(ABE)is a technique used to encrypt data,it has the flexibility of access control,high security,and resistance to collusion attacks,and especially it is used in cloud security ***,a large number of bilinear mappings are used in ABE,and the calculation of bilinear pairing is *** there is the problem of low *** the other hand,the decryption key is not uniquely associated with personal identification information,if the decryption key is maliciously sold,ABE is unable to achieve accountability for the *** practical applications,shared message requires hierarchical sharing in most cases,in this paper,we present a message security hierarchy ABE scheme for this ***,attributes were grouped and weighted according to the importance of attributes,and then an access structure based on a threshold tree was constructed according to attribute *** method saved the computing time for decryption while ensuring security and on-demand access to information for *** addition,with the help of computing power in the cloud,two-step decryption was used to complete the access,which relieved the computing and storage burden on the client ***,we simulated and tested the scheme based on CP-ABE,and selected different security levels to test its *** security proof and the experimental simulation result showthat the proposed scheme has high efficiency and good performance,and the solution implements hierarchical access to the shared message.

关键词： Attribute-based encryption cloud security message hierarchy attribute weight access control