The advancement of Rydberg atoms in quantum information technology is driving a paradigm shift from classical radio-frequency (RF) receivers to Rydberg atomic receivers. Capitalizing on the extreme sensitivity of Rydb...
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The advancement of Rydberg atoms in quantum information technology is driving a paradigm shift from classical radio-frequency (RF) receivers to Rydberg atomic receivers. Capitalizing on the extreme sensitivity of Rydberg atoms to external electromagnetic fields, Rydberg atomic receivers are capable of realizing more precise radio-wave measurements than RF receivers to support high-performance wireless communication and sensing. Although the atomic receiver is developing rapidly in quantum-physics domain, its integration with wireless communications is at a nascent stage. In particular, systematic methods to enhance communication performance through this integration are yet to be discovered. Motivated by this observation, we propose in this paper to incorporate Rydberg atomic receivers into multiple-input-multiple-output (MIMO) communication, a prominent 5G technology, as the first attempt on implementing atomic MIMO receivers. To begin with, we provide a comprehensive introduction on the principles of Rydberg atomic receivers and build on them to design the atomic MIMO receivers. Our findings reveal that signal detection of atomic MIMO receivers corresponds to a non-linear biased phase retrieval (PR) problem, as opposed to the linear Gaussian model adopted in classical MIMO systems. Then, to recover signals from this non-linear model, we modify the Gerchberg-Saxton (GS) algorithm, a typical PR solver, into a biased GS algorithm to solve the biased PR problem. Moreover, we propose a novel Expectation-Maximization GS (EM-GS) algorithm to cope with the unique Rician distribution of the biased PR model. Our EM-GS algorithm introduces a high-pass filter constructed by the ratio of Bessel functions into the iteration procedure of GS, thereby improving the detection accuracy without sacrificing the computational efficiency. Finally, the effectiveness of the devised algorithms and the feasibility of atomic MIMO receivers are demonstrated by theoretical analysis and numerica
Impact monitoring technology plays a critical role in ensuring the structural integrity and safety of thin-walled engineering structures in service. This article presents a novel hybrid direction of arrival (DoA)-time...
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Impact monitoring technology plays a critical role in ensuring the structural integrity and safety of thin-walled engineering structures in service. This article presents a novel hybrid direction of arrival (DoA)-time difference of arrival (TDoA) method for impact localization on thin-walled engineering structures using sensor clusters. The methodology involves placing two sensor clusters on the structure to capture impact signals. Subsequently, narrowband Lamb wave signals at a specific frequency are extracted from impact signals using continuous wavelet transform (CWT). The normalized variance sequence (NVS) approach is then used to determine the TDoA, and phase differences are calculated to estimate the DoA. The DoA-based spatial beamforming focusing (SBF) technique and TDoA-based hyperbolic locus imaging algorithm are used for impact imaging. An imaging fusion step is introduced to combine the results of the two imaging techniques, accurately determining the impact location. Experimental validation of the proposed method is conducted through impact tests on three distinct structures: a large-scale plate, a complex riveted stiffened plate, and a 3-D thin-walled cylindrical structure. A comparative analysis with two existing methods demonstrates the superior imaging resolution and localization accuracy of the proposed approach, which remains effective even in the presence of measurement noise. In addition, the effects of sensor type, shape, and configuration on the localization results are discussed. This research contributes to the advancement of impact localization technology for thin-walled structures, with potential applications in structural health monitoring and safety assessment.
The proposed parallel mechanisms (PMs) differ from conventional PMs in that they can achieve the same mobility with fewer active joints. The general motion principle of the proposed new mechanism has been proposed. Ba...
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The proposed parallel mechanisms (PMs) differ from conventional PMs in that they can achieve the same mobility with fewer active joints. The general motion principle of the proposed new mechanism has been proposed. Based on the Newton iterative method and neural network approaches, a method is put forward to obtain the continuous forward solution for the new PMs. Since the posture adjustment of the moving platform is realized through the active branch adjusting the passive branches one by one in sequence, the adjustment sequence of passive branches and step size of the passive branch in each adjustment for any end posture of the new PM is optimized, with the workspace as the constraint and minimizing the number of adjustment times as the goal. The structure of the 7SPS is designed and prototype experiments are conducted. Experiment results have shown that the proposed PM can achieve the original mobility while significantly reducing the number of actuators.
Dual-input single-output (DISO) radio frequency (RF) power amplifiers (PAs) have gathered significant interest for highly efficient amplification of modulated signals. DISO PAs provide advantages over their single-inp...
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Dual-input single-output (DISO) radio frequency (RF) power amplifiers (PAs) have gathered significant interest for highly efficient amplification of modulated signals. DISO PAs provide advantages over their single-input single-output (SISO) counterparts, both for design and operation. However, contrary to SISO, driving DISO PAs requires an extraction of the optimum driving signals to maximize the power-added efficiency (PAE), and some input conditions can easily make the PA operate in a nonsafe region. This article presents algorithms to safely derive these optimal input signals. Two types of algorithms are proposed, which are dubbed "exploration" and "extraction";the exploration algorithm finds a safe operation region of the DISO PA from minimal a priori information on the device under test;the extraction algorithm finds the optimal input drive from the exploration algorithm data. These algorithms are tested and validated in simulation and measurement for different DISO PA architectures.
Faulty array sensors pose a significant challenge in accurately determining the target angles in bistatic multiple-input multiple-output (MIMO) radar systems. To remedy this, we propose a novel method utilizing atomic...
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Faulty array sensors pose a significant challenge in accurately determining the target angles in bistatic multiple-input multiple-output (MIMO) radar systems. To remedy this, we propose a novel method utilizing atomic norm regularized tensor completion for joint estimates of the direction of departure (DOD) and direction of arrival (DOA). We first develop a third-order covariance tensor model for the sensor array data in bistatic MIMO radar and cast the reconstruction of missing entries caused by faulty array sensors as a low-rank tensor completion (LRTC) problem with structurally missing entries. By leveraging the Vandermonde structure inherent in the factor matrices from the CANDECOMP/PARAFAC (CP) decomposition of the covariance tensor, we impose atomic norm constraints on the factor vectors to formulate an atomic norm regularized tensor completion model. Then, an efficient optimization algorithm based on the alternating direction method of multipliers (ADMM) is developed to solve the proposed model. Moreover, to enforce the Vandermonde structure of the factor matrices, we integrate difference coarray processing to rectify the factor matrices during iterations. Finally, joint estimates of DOD and DOA are obtained by applying the estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm to the Toeplitz matrices derived from the optimized vectors. Extensive simulations demonstrate that the proposed algorithm achieves superior angle estimation accuracy and computational efficiency compared to state-of-the-art algorithms when handling array sensor failures.
Grant-free transmission and cell-free communication are vital in improving coverage and quality-of-service for massive machine-type communication. This paper proposes a novel framework of joint active user detection, ...
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Grant-free transmission and cell-free communication are vital in improving coverage and quality-of-service for massive machine-type communication. This paper proposes a novel framework of joint active user detection, channel estimation, and data detection (JACD) for massive grant-free transmission in cell-free wireless communication systems. We formulate JACD as an optimization problem and solve it approximately using forward-backward splitting. To deal with the discrete symbol constraint, we relax the discrete constellation to its convex hull and propose two approaches that promote solutions from the constellation set. To reduce complexity, we replace costly computations with approximate shrinkage operations and approximate posterior mean estimator computations. To improve active user detection (AUD) performance, we introduce a soft-output AUD module that considers both the data estimates and channel conditions. To jointly optimize all algorithm hyper-parameters and to improve JACD performance, we further deploy deep unfolding together with a momentum strategy, resulting in two algorithms called DU-ABC and DU-POEM. Finally, we demonstrate the efficacy of the proposed JACD algorithms via extensive system simulations.
This article investigates a direction-of-arrival (DOA) estimation method for underwater acoustic arrays in non-Gaussian impulsive noise environments. Traditional DOA estimation methods for underwater acoustic arrays t...
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This article investigates a direction-of-arrival (DOA) estimation method for underwater acoustic arrays in non-Gaussian impulsive noise environments. Traditional DOA estimation methods for underwater acoustic arrays typically presume that underwater environmental noise follows a Gaussian distribution. This assumption can lead to a significant degradation in estimation accuracy, or even failure, in underwater environments where non-Gaussian impulsive noise is predominant, thereby limiting the detection capabilities of underwater acoustic arrays. To address this issue, this study employs a method based on mixture correntropy, which maximizes the mixture correntropy of the residual fitting error matrix for subspace decomposition of the received data matrix, effectively filtering out impulsive noise. Considering the signalprocessing performance of correntropy and mixture correntropy depends on the selection of the kernel width, this article introduces a novel adaptive method for updating the kernel width. This method updates the kernel width in each iteration based on the residual fitting error value, setting the square of the kernel width to the sum of the squares of a preset kernel width and the residual fitting error modulus. This approach retains the simplicity and robustness of the maximum mixture correntropy criterion (MMCC) algorithm while enhancing the convergence rate and achieving a lower steady-state excess mean square error. Furthermore, this study applies the classical multiple signal classification (MUSIC) algorithm for DOA estimation. Finally, simulations and sea trials have substantiated the correctness and effectiveness of the method proposed in this article.
Three fundamental problems are addressed for distributed detection networks regarding the maximum of performance/detection loss. The losses obtained are, first, due to the choice of decision rule in parallel sensor ne...
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Three fundamental problems are addressed for distributed detection networks regarding the maximum of performance/detection loss. The losses obtained are, first, due to the choice of decision rule in parallel sensor networks (general-case vs identical decisions), second, due to the choice of network architecture (serial vs parallel), and third, due to the choice of quantization rule (centralized vs decentralized). Previous results, if available, for all these three problems are restricted to the statement that the loss is "small" over some specific examples. The key principles underlying this study are delineated as follows. First, there is a surjection from all simple hypothesis tests to the receiver operating characteristic (ROC) curve. Second, the ROC can be well modeled with linear splines. Third, considering splines with only a finite number of line segments, in fact, on the order of the total number of sensors, is sufficient to determine the maximum loss. Leveraging these principles, infinite-dimensional optimization problems are reduced to their finite-dimensional equivalent forms. The equivalent problems are then numerically solved to obtain the theoretical bounds.
The high-resolution TOA estimation of multipath channel is essential for many areas while the resolution of conventional algorithms is constrained by the system bandwidth. With the advancement of communication technol...
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The high-resolution TOA estimation of multipath channel is essential for many areas while the resolution of conventional algorithms is constrained by the system bandwidth. With the advancement of communication technology, more applications demand higher positioning accuracy, yet single-band systems are restricted by their limited bandwidth. To address this, we consider utilizing decentralized multi-band signals to obtain a larger available bandwidth for high-resolution TOA estimation. Taking dual-band signals as an example, we exploit the dual-band coherent subspace and propose a novel subspace-based high-resolution TOA estimation algorithm. The proposed algorithm does not require parameter matching with high complexity and is suitable for the existing dual-band communication systems. We also derive the Cram & eacute;r-Rao Bound (CRB) for the dual-band signal model. Simulation results show that the performance of the proposed algorithm is better than existing subspace-based algorithms available for dual-band signals and converges to the derived CRB.
In the 6G network, integrating broadcasting and mobile networks will significantly improve the transmission capability. Considering the excellent error-correction performance, polarized-adjusted convolutional (PAC) co...
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In the 6G network, integrating broadcasting and mobile networks will significantly improve the transmission capability. Considering the excellent error-correction performance, polarized-adjusted convolutional (PAC) codes are promising for ensuring reliable data transmission in 6G broadcasting services. However, the inherent high decoding latency of PAC codes poses challenges for seamless switching between broadcasting and mobile services. In this paper, we propose a simplified fast list (SFL) PAC decoder, which jointly exploits the node thresholds and adaptive path-pruning technology to reduce the decoding latency while maintaining high reliability. Firstly, we present a novel path expansion rule based on the node thresholds to avoid unnecessary computations. Secondly, the introduction of the adaptive path-pruning technology efficiently reduces the number of sorting operations. Moreover, we implement the proposed decoder on general purpose processors (GPPs) by software. Simulation results show that the proposed SFL decoding algorithm significantly reduces the decoding latency by up to 75.18% compared to the state-of-the-art (SOTA) work with no noticeable degradation in error-correction performance. Software implementation of the proposed decoder achieves an 18.80% improvement in throughput performance over the SOTA PAC software decoder.
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