The rapid advancement of the next generation of mobile communication technologies has set increasingly stringent demands on transmission quality, capacity, and rate. In this paper, we discuss the weighted sum rate (WS...
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The rapid advancement of the next generation of mobile communication technologies has set increasingly stringent demands on transmission quality, capacity, and rate. In this paper, we discuss the weighted sum rate (WSR) using intelligent reflecting surface (IRS) assisted rate-splitting multiple access (RSMA) for downlink multiuser multiple-input single-output (MISO) systems with consideration of phase quantization of IRS. The aim is to propose a scheme to obtain the maximum WSR by optimizing the equivalent beamforming matrix, quantized IRS phase shift matrix, and the common rate splitting scheme. To this end, an equivalent optimization scheme is designed on the basis of weighted minimum mean square error (WMMSE) algorithm, difference of convex sets (DCS) theory, Lagrange penalty and Taylor approximation, where the non-convex mixed continuous and discrete optimization problem is converted to three continuous convex optimization sub-problems and then worked out iteratively with the alternating optimization algorithm. We compare the maximum WSR achievable by quantized IRS-aided 1-layer-RSMA with three other multiple access (MA) technologies: dirty paper coding (DPC), non-orthogonal multiple access (NOMA), and multiuser linear precoding (MULP) under different signalto-noise ratio (SNR) scenarios. It is also found that the proposed method provides an improvement in WSR with the increase of the number of base station antennas, IRS reflective elements and phase quantization bits.
Clustering techniques play a pivotal role in unveiling the inherent structure of unlabeled data. When dealing with overlapping clusters, traditional hard clustering methods encounter challenges. As a representative of...
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Clustering techniques play a pivotal role in unveiling the inherent structure of unlabeled data. When dealing with overlapping clusters, traditional hard clustering methods encounter challenges. As a representative of soft clustering methods, Fuzzy K-Means (FKM) enables data points to be assigned different degrees of membership to multiple clusters, offering a solution to this problem. However, when dealing with high-dimensional data, the performance of FKM is often affected by redundant features and noise. To address this limitation, this paper introduces a Fuzzy K-Means Clustering with Reconstructed Information (FKMRI) method. This method combines the reconstruction term with a cluster weight variable to effectively capture the true nature of data structure, thereby enhancing the clustering capability of FKM in high-dimensional spaces. We theoretically analyze the convergence of the FKMRI algorithm and prove its time complexity to be O(c+P(c))nd2+cnd\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$O\left( (c+P(c)) n d<^>2+c n d\right)$$\end{document}. Finally, we evaluate the performance of FKMRI on standard benchmark datasets including Yale-32x32, Yale-64x64, ORL-32x32, and ORL-64x64. The results demonstrate that, in comparison to five current state-of-the-art algorithms (K-Means, FKM, Kernel-km, RSFKM, DFKM), FKMRI exhibits an average improvement of over 18% in terms of accuracy rate (ACC) and normalized mutual information (NMI). These findings convincingly validate the effectiveness and efficiency of the proposed algorithm in handling high-dimensional data clustering, providing valuable support for related research fields.
This letter investigates the use of pilot-based codebook artificial noise (PCAN) in Integrated Sensing and Communication (ISAC) systems to enhance physical layer security. ISAC technology integrates communication and ...
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This letter investigates the use of pilot-based codebook artificial noise (PCAN) in Integrated Sensing and Communication (ISAC) systems to enhance physical layer security. ISAC technology integrates communication and sensing through shared resources, emphasizing the need for secure strategies. PCAN allows the receiver to extract information from the pilot codebook, effectively removing interference and increasing secrecy capacity. The non-convex secrecy capacity optimization problem is addressed by decomposing it into simpler subproblems. A semidefinite relaxation (SDR) and alternating optimization algorithm is proposed to maximize secrecy capacity while maintaining sensing accuracy. Simulation results show significant improvements, particularly at low and moderate Signal-to-Noise Ratio (SNR), with consistent gains at high SNRs. This work underscores the role of optimization techniques in enhancing secure communication and balancing secrecy with sensing performance in ISAC systems.
Physical layer security issue is investigated in Wireless Power Transfer Communication Network (WPCN) system, and the double Reconfigurable Intelligent Surface (RIS) are introduced to assist the system to improve comm...
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Physical layer security issue is investigated in Wireless Power Transfer Communication Network (WPCN) system, and the double Reconfigurable Intelligent Surface (RIS) are introduced to assist the system to improve communication security and reduce transmission power. The system operates in two phases: wireless energy transfer (WET) and wireless information transfer (WIT). First, the WET phase is conducted to address the issue of insufficient transmitter (TS) energy in the WIT phase, followed by utilizing RIS assistance during the WIT phase to achieve secure transmission at the physical layer. In the WIT phase, the presence of eavesdroppers and interference among multiple Internet of Things (IoT) devices, along with obstructed direct links from TS to IoT devices, reduce the system's security rate. Especially, we introduce double RIS deployed above TS and IoT devices, respectively. Compared to a single RIS, double RISs not only improves the communication system's coverage and data transmission rate but also enhances system security and efficiency. In the WET phase, since TS and power station (PS) belong to different service providers, we propose an energy trading and secure communication scheme assisted by double RIS based on Stackelberg game theory. The leader's strategy problem in this scheme is non-convex, hence decomposed into two subproblems. The first subproblem is independently solved using alternatingoptimization (AO) algorithm. The second subproblem is tackled with a block coordinate descent (BCD) based iterative algorithm, employing successive convex approximation (SCA) to solve each block-level subproblem. Finally, the numerical results demonstrate that the proposed scheme enhances the system's security rate, reduces the time required for wireless energy transfer (WET), and thereby improves overall system efficiency.
This paper investigates the over-the-air computation (AirComp) problem in a hybrid intelligent reflecting surface (IRS) and cell-free massive multiple-input multiple-output (CF-mMIMO) assisted digital twin system, whe...
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ISBN:
(纸本)9798350354720;9798350354713
This paper investigates the over-the-air computation (AirComp) problem in a hybrid intelligent reflecting surface (IRS) and cell-free massive multiple-input multiple-output (CF-mMIMO) assisted digital twin system, where multiple users offload their data to access points (APs) and central processing unit (CPU) via the IRS for data aggregation. We formulate a joint beamforming design, IRS phase shift optimization, and power allocation problem to minimize the mean squared error (MSE) of data aggregation. We solve the resultant non-convex optimization problem in three steps. First, we transform the original problem into two sub-problems. Then, we exploit a convex optimization framework to respectively determine the beamforming design, IRS phase shift optimization, and power allocation. Last, we propose an alternating optimization algorithm for finding the jointly optimized results. The simulation results demonstrate the effectiveness of the proposed scheme as compared with other benchmark schemes.
Unmanned aerial vehicles (UAVs) are widely used in wireless communication networks due to their rapid deployment and high mobility. However, in practical scenarios, the existence of obstacles and eavesdroppers will se...
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Unmanned aerial vehicles (UAVs) are widely used in wireless communication networks due to their rapid deployment and high mobility. However, in practical scenarios, the existence of obstacles and eavesdroppers will seriously interfere with the communication quality of the UAV network and produce a security risk. Thus, this paper combines reconfigurable intelligent surface (RIS) technology with UAVs to build a secure UAV communication network. Normally, a rotary-wing UAV (labeled as UAV-S) acting as a base station sends information signals to a legitimate user on the ground with RIS equipment. However, there is a passive eavesdropper on the ground who can steal the information. Therefore, a friendly UAV jammer (labeled as UAV-J) with a fixed location is introduced to send jamming signals to confuse the eavesdropper. The goal of this paper is to maximize the average secrecy rate of the communication network by jointly optimizing the flight trajectory, transmit power of the UAV-S and UAV-J, and phase shifter of the RIS. Since the constructed problem is highly nonconvex, an alternating optimization algorithm based on successive convex approximation techniques is proposed to solve the problem. Simulation results show that the proposed algorithm can achieve a higher secrecy rate in comparison with other schemes.
Here, the beamforming design for multiuser multiple-input and multiple-output (MIMO) downlink transmission aided by an intelligent reflecting surface (IRS) with discrete phase shifts is studied. The authors deduce a m...
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Here, the beamforming design for multiuser multiple-input and multiple-output (MIMO) downlink transmission aided by an intelligent reflecting surface (IRS) with discrete phase shifts is studied. The authors deduce a minimum signal-to-interference-plus-noise-ratio (SINR) maximization fairness problem with the transmit beamformer, the receive beamformer and IRS phase shifts as optimization variables, which is generally NP-hard. Hence, an alternating optimization algorithm based on the gradient extrapolated majorization-minimization (GEMM) approach is employed to solve the above problem. Specifically, when the transmit beamformer and reflective phase shift are fixed, the authors give an optimal closed expression for the receive beamformer. Then, the receive beamformer is fixed, and the minimum SINR maximization problem at the transmitter is transformed into a power minimization problem. Finally, under the zero-forcing (ZF) transmitter beamformer, the GEMM algorithm is used to optimize the reflective phase shift. Simulation results show that by comparing to existing methods, the proposed GEMM algorithm can almost achieve the same performance with lower complexity.
With the development of 6G, millimeter wave communication has received extensive attention. Due to the characteristics of wireless transmission, information secrecy transmission is facing significant challenges. This ...
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ISBN:
(纸本)9798350311143
With the development of 6G, millimeter wave communication has received extensive attention. Due to the characteristics of wireless transmission, information secrecy transmission is facing significant challenges. This paper uses the physical layer security (PLS) to explore the information secrecy transmission. Specifically, we use Intelligent Reflecting Surface (IRS) to control the wireless propagation environment and improve the secrecy rate of millimeter wave communication. The active beamforming matrix of the base station and the passive beamforming matrix of the IRS are optimized to achieve the maximum secrecy rate. We deduce the closed form solution of active beamforming and the approximate optimal solution of passive beamforming. An alternatingoptimization (AO) algorithm is applied to solve the non-convex optimization problem. Simulation results verify the convergence and effectiveness of the algorithm, which can obtain nearly twice the secrecy rate gain of the benchmark algorithm.
Wireless powered communication networks (WPCNs) are a promising technology for low-power wireless communication. Intelligent reflecting surfaces (IRSs) have recently emerged as a potential solution for enhancing the p...
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ISBN:
(纸本)9789819947416;9789819947423
Wireless powered communication networks (WPCNs) are a promising technology for low-power wireless communication. Intelligent reflecting surfaces (IRSs) have recently emerged as a potential solution for enhancing the performance of WPCNs. This paper presents a comparative study of active IRSs with passive IRSs for maximizing the throughput in WPCNs. We propose an alternatingoptimization (AO)-based a near-optimal solution for maximizing the throughput in WPCNs by exploiting the active capabilities of the IRS. Our proposed algorithm is based on a joint optimization of the time allocation and the reflection coefficients and phase shift matrices of the active IRS. We evaluate the performance of the proposed algorithm and compare it with a passive IRS-assisted system. Simulation results demonstrate that the proposed algorithm achieves a higher throughput compared to the passive IRS-assisted system. Our findings highlight the potential of active IRSs for enhancing the performance of WPCNs and provide insights into the design of efficient and reliable wireless communication systems.
An additive noise channel is considered, in which the distribution of the noise is nonparametric and unknown. The problem of learning encoders and decoders based on noise samples is considered. For uncoded communicati...
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An additive noise channel is considered, in which the distribution of the noise is nonparametric and unknown. The problem of learning encoders and decoders based on noise samples is considered. For uncoded communication systems, the problem of choosing a codebook and possibly also a generalized minimal distance decoder (which is parameterized by a covariance matrix) is addressed. High probability generalization bounds for the error probability loss function, as well as for a hinge-type surrogate loss function are provided. A stochastic-gradient based alternating-minimization algorithm for the latter loss function is proposed. In addition, a Gibbs-based algorithm that gradually expurgates an initial codebook from codewords in order to obtain a smaller codebook with improved error probability is proposed, and bounds on its average empirical error and generalization error, as well as a high probability generalization bound, are stated. Various experiments demonstrate the performance of the proposed algorithms. For coded systems, the problem of maximizing the mutual information between the input and the output with respect to the input distribution is addressed, and uniform convergence bounds for two different classes of input distributions are obtained.
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