methods: 该文提出了一种名为 NoisE subspAce correcTion technique for MUltiple SIgnal Classification（NEAT-MUSIC）的自动准备方法，该方法基于 Correcting the noise subspace for accurate DOA estimation in the presence of gain-phase mismatches and beam-squint.
results: numerical results show that the proposed approach is effective.Abstract
Terahertz (THz) band is envisioned for the future sixth generation wireless systems thanks to its abundant bandwidth and very narrow beamwidth. These features are one of the key enabling factors for high resolution sensing with milli-degree level direction-of-arrival (DOA) estimation. Therefore, this paper investigates the DOA estimation problem in THz systems in the presence of two major error sources: 1) gain-phase mismatches, which occur due to the deviations in the radio-frequency circuitry; 2) beam-squint, which is caused because of the deviations in the generated beams at different subcarriers due to ultra-wide bandwidth. An auto-calibration approach, namely NoisE subspAce correcTion technique for MUltiple SIgnal Classification (NEAT-MUSIC), is proposed based on the correction of the noise subspace for accurate DOA estimation in the presence of gain-phase mismatches and beam-squint. To gauge the performance of the proposed approach, the Cramer-Rao bounds are also derived. Numerical results show the effectiveness of the proposed approach.
摘要
oterahertz (THz) 频率带被看作未来第六代无线系统的未来，因为它具有充足的带宽和非常窄的照射角度。这些特点是高分解能感应的关键因素，因此这篇论文研究了THz系统中的方向来源估计问题在获取资料时的两个主要错误源：1）获取阶段的偏差，这些偏差是由无线电路的差异引起的；2）照射角度的偏差，这是由不同子探频率生成的照射干扰所致。这篇论文提出了一个自动协调方法，即NoisE subspAce correcTion technique for MUltiple SIgnal Classification (NEAT-MUSIC)，以精确地估计方向来源的DOA。为了评估提案的表现，还 deriv了克拉默-拉欧 bounds。 numerics 结果显示了提案的有效性。
High-performance Power Allocation Strategies for Active IRS-aided Wireless Network
results: 对小规模IRS系统进行了 simulations，并证明了ESMPI-GA可以增加约0.5比特的性能提升，而TTE可以与TPA和固定PA策略相比，在低复杂度下达到更高的性能。Abstract
Due to its intrinsic ability to combat the double fading effect, the active intelligent reflective surface (IRS) becomes popular. The main feature of active IRS must be supplied by power, and the problem of how to allocate the total power between base station (BS) and IRS to fully explore the rate gain achieved by power allocation (PA) to remove the rate gap between existing PA strategies and optimal exhaustive search (ES) arises naturally. First, the signal-to-noise ratio (SNR) expression is derived to be a function of PA factor beta [0, 1]. Then, to improve the rate performance of the conventional gradient ascent (GA), an equal-spacing-multiple-point-initialization GA (ESMPI-GA) method is proposed. Due to its slow linear convergence from iterative GA, the proposed ESMPI-GA is high-complexity. Eventually, to reduce this high complexity, a low-complexity closed-form PA method with third-order Taylor expansion (TTE) centered at point beta0 = 0.5 is proposed. Simulation results show that the proposed ESMPI-GA harvests about 0.5 bit gain over conventional GA and 1.2 and 0.8 bits gain over existing methods like equal PA and Taylor polynomial approximation (TPA) for small-scale IRS, and the proposed TTE performs much better than TPA and fixed PA strategies using an extremely low complexity.
摘要
由于其内置的对双折射效应的战斗能力，活动智能反射表面（IRS）得到了广泛的应用。主要特点之一是需要电源供应，因此如何将总能量分配给基站（BS）和IRS以实现完全利用rate gain而带来的问题自然而然而来。首先，Signal-to-noise ratio（SNR）的表达式被 derivated为 beta [0, 1] 的函数。然后，为了提高传统的梯度升级（GA）的率性能，一种等间距多点初始化GA（ESMPI-GA）方法被提议。由于其在迭代GA中的慢Linear convergence，提议的ESMPI-GA高度复杂。最终，为了减少这种高复杂度，一种低复杂度的closed-form PA方法with third-order Taylor expansion（TTE） centered at point beta0 = 0.5被提议。 simulation results show that the proposed ESMPI-GA can harvest about 0.5 bit gain over conventional GA and 1.2 and 0.8 bits gain over existing methods like equal PA and Taylor polynomial approximation（TPA）for small-scale IRS，and the proposed TTE performs much better than TPA and fixed PA strategies using an extremely low complexity.
Memory AMP for Generalized MIMO: Coding Principle and Information-Theoretic Optimality
paper_authors: Yufei Chen, Lei Liu, Yuhao Chi, Ying Li, Zhaoyang Zhang for: This paper focuses on developing an information-theoretically optimal low-complexity receiver for generalized multiple-input multiple-output (GMIMO) systems.methods: The proposed receiver uses a message passing algorithm called MAMP, which is a low-complexity variant of the optimal OAMP/VAMP receiver. The paper also develops a simplified single-input single-output variational state evolution (VSE) to analyze the achievable rate of MAMP.results: The paper shows that the proposed MAMP receiver achieves the same performances as the optimal OAMP/VAMP receiver with 0.4% of the time consumption for large-scale systems. Additionally, the paper proves the information-theoretic optimality of MAMP and establishes an optimal coding principle to maximize the achievable rate. Numerical results show that the finite-length performances of MAMP with practical optimized LDPC codes are 0.5-2.7 dB away from the associated constrained capacities.Abstract
To support complex communication scenarios in next-generation wireless communications, this paper focuses on a generalized MIMO (GMIMO) with practical assumptions, such as massive antennas, practical channel coding, arbitrary input distributions, and general right-unitarily-invariant channel matrices (covering Rayleigh fading, certain ill-conditioned and correlated channel matrices). The orthogonal/vector approximate message passing (OAMP/VAMP) receiver has been proved to be information-theoretically optimal in GMIMO, but it is limited to high-complexity LMMSE. To solve this problem, a low-complexity memory approximate message passing (MAMP) receiver has recently been shown to be Bayes optimal but limited to uncoded systems. Therefore, how to design a low-complexity and information-theoretically optimal receiver for GMIMO is still an open issue. To address this issue, this paper proposes an information-theoretically optimal MAMP receiver and investigates its achievable rate analysis and optimal coding principle. Specifically, due to the long-memory linear detection, state evolution (SE) for MAMP is intricately multidimensional and cannot be used directly to analyze its achievable rate. To avoid this difficulty, a simplified single-input single-output variational SE (VSE) for MAMP is developed by leveraging the SE fixed-point consistent property of MAMP and OAMP/VAMP. The achievable rate of MAMP is calculated using the VSE, and the optimal coding principle is established to maximize the achievable rate. On this basis, the information-theoretic optimality of MAMP is proved rigorously. Numerical results show that the finite-length performances of MAMP with practical optimized LDPC codes are 0.5-2.7 dB away from the associated constrained capacities. It is worth noting that MAMP can achieve the same performances as OAMP/VAMP with 0.4% of the time consumption for large-scale systems.
摘要
本文研究了下一代无线通信中复杂通信场景下的通信理论最佳化。文章关注实际假设，如大量天线、实用 canal coding、任意输入分布和通用右特征不变Channel矩阵（包括劳仑辐射、一些不良conditioned和相关的 Channel矩阵）。文章证明了OAMP/VAMP接收器是GMIMO中信息理论最佳的，但它具有高复杂度LMMSE的限制。为解决这个问题，文章提出了一种低复杂度内存approximate message passing（MAMP）接收器，并证明其是信息理论最佳的。文章还研究了MAMP接收器的可达率分析和最佳编码原则。由于MAMP接收器的长期线性探测，其SE的维度是复杂的多dimensional，直接使用SE无法分析其可达率。为了避免这种困难，文章提出了基于MAMP和OAMP/VAMP的单输入单出力variational SE（VSE），并证明了VSE的可达率分析。文章还使用VSE计算了MAMP接收器的可达率，并确定了最佳编码原则以优化可达率。在这基础上，文章证明了MAMP接收器的信息理论最佳性。numerical results表明，使用实用LDBCodes的MAMP接收器在finite length系统中的性能与相关的受限容量相差0.5-2.7dB。另外，MAMP接收器可以在大规模系统中实现与OAMP/VAMP相同的性能，但它的计算时间只需0.4%。
Coverage Hole Elimination System in Industrial Environment
paper_authors: Mervat Zarour, Shreya Tayade, Sergiy Melnyk, Hans D. Schotten
for: 这 paper 旨在避免indoor环境中的覆盖洞，以确保自动导向车 (AGV) 的稳定连接。
methods: 该 paper 提出了一个框架，该框架使用支持向量机 (SVM) 分类模型确定覆盖洞的位置，并构建了一个二进制覆盖洞地图，以避免覆盖洞。AGV 的再规划路径由最短覆盖洞free路径优化。
results: 研究发现，如果在 ahead of time 知道覆盖洞的位置，AGV 的再规划路径可以更短并且更优化。Abstract
The paper proposes a framework to identify and avoid the coverage hole in an indoor industry environment. We assume an edge cloud co-located controller that followers the Automated Guided Vehicle (AGV) movement on a factory floor over a wireless channel. The coverage holes are caused due to blockage, path-loss, and fading effects. An AGV in the coverage hole may lose connectivity to the edge-cloud and become unstable. To avoid connectivity loss, we proposed a framework that identifies the position of coverage hole using a Support- Vector Machine (SVM) classifier model and constructs a binary coverage hole map incorporating the AGV trajectory re-planning to avoid the identified coverage hole. The AGV's re-planned trajectory is optimized and selected to avoid coverage hole the shortest coverage-hole-free trajectory. We further investigated the look-ahead time's impact on the AGV's re-planned trajectory performance. The results reveal that an AGV's re-planned trajectory can be shorter and further optimized if the coverage hole position is known ahead of time
摘要
文章提出了一种框架，用于 indentify和避免工厂内部环境中的覆盖洞。我们假设了一个位于工厂地面的边缘云控制器，跟随自动导向车(AGV)的运动通过无线频道进行通信。覆盖洞是由堵塞、路径损失和折射效应引起的，AGV在覆盖洞中可能会失去与边缘云的连接，导致不稳定。为了避免连接损失，我们提出了一种框架，使用支持向量机(SVM)分类模型确定覆盖洞的位置，并构建一个二进制覆盖洞地图，包括AGV的轨迹重新规划以避免所确定的覆盖洞。AGV的重新规划轨迹是通过优化和选择最短覆盖洞自由轨迹来实现。我们进一步调查了AGV的重新规划轨迹表现的影响因素，结果显示，如果在先知道覆盖洞位置，AGV的重新规划轨迹可以更短并更优化。
Federated Learning via Active RIS Assisted Over-the-Air Computation
results: simulations 表明，使用活动RIS可以比pasive RIS更有效地减少梯度聚合错误，提高联合学习系统的稳定性和性能。Abstract
In this paper, we propose leveraging the active reconfigurable intelligence surface (RIS) to support reliable gradient aggregation for over-the-air computation (AirComp) enabled federated learning (FL) systems. An analysis of the FL convergence property reveals that minimizing gradient aggregation errors in each training round is crucial for narrowing the convergence gap. As such, we formulate an optimization problem, aiming to minimize these errors by jointly optimizing the transceiver design and RIS configuration. To handle the formulated highly non-convex problem, we devise a two-layer alternative optimization framework to decompose it into several convex subproblems, each solvable optimally. Simulation results demonstrate the superiority of the active RIS in reducing gradient aggregation errors compared to its passive counterpart.
摘要
在这篇论文中，我们提出使用可活动重配置智能表面（RIS）来支持无线计算（AirComp）启发的联合学习（FL）系统中可靠的梯度聚合。一种分析联合学习的收敛性质表明，在每轮训练中最小化梯度聚合错误是关键的，以减少收敛差距。因此，我们设计了一个优化问题，目标是最小化这些错误，通过同时优化无线传输设计和RIS配置。为处理这个非常不对称的问题，我们开发了一个两层代替优化框架，将其分解成多个可优化的几何问题，每个问题都可以优化到最优解。实验结果表明，活动RIS可以比其适应性较强的pasive counterpart更好地减少梯度聚合错误。
NOMA Enabled Multi-Access Edge Computing: A Joint MU-MIMO Precoding and Computation Offloading Design
paper_authors: Deyou Zhang, Meng Wang, Shuo Shi, Ming Xiao
for: 这个研究targets computation offloading and transmit precoding co-design for multi-access edge computing (MEC), where multiple MEC users (MUs) equipped with multiple antennas access the MEC server in a non-orthogonal multiple access manner.
methods: 以jointly optimizing computational frequency, offloading ratio, and precoding matrix的方式， minimize the total energy consumption of all MUs while satisfying latency constraints.
results: simulation results validate the convergence of the proposed method and demonstrate its superiority over baseline algorithms.Abstract
This letter investigates computation offloading and transmit precoding co-design for multi-access edge computing (MEC), where multiple MEC users (MUs) equipped with multiple antennas access the MEC server in a non-orthogonal multiple access manner. We aim to minimize the total energy consumption of all MUs while satisfying the latency constraints by jointly optimizing the computational frequency, offloading ratio, and precoding matrix of each MU. For tractability, we first decompose the original problem into three subproblems and then solve these subproblems iteratively until convergence. Simulation results validate the convergence of the proposed method and demonstrate its superiority over baseline algorithms.
摘要
Here's the text in Simplified Chinese:这封信函数探索了多接点边缘计算（MEC）中多个MEC用户（MU）通过多antenna访问MEC服务器的非对称多接点访问方式。我们目标是使所有MU的总能耗降低到最低，同时满足响应时间约束，通过对每个MU的计算频率、下载比率和 precoding 矩阵进行共同优化。为了使问题更加可解，我们首先将问题分解成三个互相独立的习题，然后在迭代 até convergence 的过程中解决这些习题。实验结果证明了我们提出的方法的可行性和基eline算法相比的优越性。
Distributed Parameter Estimation with Gaussian Observation Noises in Time-varying Digraphs
results: 该论文表明，提出的估计器可以 garantía 每个感知器都能够估计真实的参数值，即使任何一个感知器不能够估计。这需要网络拓扑的union集在固定长度的间隔上具有强连接性，并且感知器们必须共同满足一个协作 persistentexcitation（PE）条件，这条件relax traditional PE condition。数字Examplefinally提供了证明结果。Abstract
In this paper, we consider the problem of distributed parameter estimation in sensor networks. Each sensor makes successive observations of an unknown $d$-dimensional parameter, which might be subject to Gaussian random noises. The sensors aim to infer the true value of the unknown parameter by cooperating with each other. To this end, we first generalize the so-called dynamic regressor extension and mixing (DREM) algorithm to stochastic systems, with which the problem of estimating a $d$-dimensional vector parameter is transformed to that of $d$ scalar ones: one for each of the unknown parameters. For each of the scalar problem, both combine-then-adapt (CTA) and adapt-then-combine (ATC) diffusion-based estimation algorithms are given, where each sensor performs a combination step to fuse the local estimates in its in-neighborhood, alongside an adaptation step to process its streaming observations. Under weak conditions on network topology and excitation of regressors, we show that the proposed estimators guarantee that each sensor infers the true parameter, even if any individual of them cannot by itself. Specifically, it is required that the union of topologies over an interval with fixed length is strongly connected. Moreover, the sensors must collectively satisfy a cooperative persistent excitation (PE) condition, which relaxes the traditional PE condition. Numerical examples are finally provided to illustrate the established results.
摘要
在这篇论文中，我们考虑了分布式参数估计问题在感知网络中。每个感知器在不知道的 $d$-维参数上进行连续观测，这个参数可能受到 Gaussian 随机噪声的影响。感知器们想要推断真实的参数值，通过合作来实现这一目标。为此，我们首先将动态扩展和混合（DREM）算法推广到随机系统中，将 $d$ 维参数估计问题转化为 $d$ 个整数估计问题。每个整数问题中，我们提供了 combinaison-then-adapt（CTA）和 adapt-then-combination（ATC）扩散基于估计算法，其中每个感知器在其内部邻域中进行结合步骤，并进行适应步骤来处理流动观测数据。在网络结构和刺激因子的弱条件下，我们证明了我们提出的估计器可以使每个感知器推断出真实的参数值，即使任何一个感知器不能做出准确的估计。特别是，需要网络上的union topologys over an interval with fixed length是强连接的。此外，感知器们需要共同满足一个合作 persistentexcitation（PE）条件，这些条件相对于传统PE条件更加宽松。最后，我们提供了数字例子，以 Illustrate 我们的结论。
Integrated Sensing, Communication, and Computing for Cost-effective Multimodal Federated Perception
results: 实验结果表明，提出的资源调度策略能够有效地提高MFP网络的学习性能和稳定性，同时减少资源成本。Abstract
Federated learning (FL) is a classic paradigm of 6G edge intelligence (EI), which alleviates privacy leaks and high communication pressure caused by traditional centralized data processing in the artificial intelligence of things (AIoT). The implementation of multimodal federated perception (MFP) services involves three sub-processes, including sensing-based multimodal data generation, communication-based model transmission, and computing-based model training, ultimately relying on available underlying multi-domain physical resources such as time, frequency, and computing power. How to reasonably coordinate the multi-domain resources scheduling among sensing, communication, and computing, therefore, is crucial to the MFP networks. To address the above issues, this paper investigates service-oriented resource management with integrated sensing, communication, and computing (ISCC). With the incentive mechanism of the MFP service market, the resources management problem is redefined as a social welfare maximization problem, where the idea of "expanding resources" and "reducing costs" is used to improve learning performance gain and reduce resource costs. Experimental results demonstrate the effectiveness and robustness of the proposed resource scheduling mechanisms.
摘要
sixth-generation (6G) 边缘智能 (EI) 中的 federated learning (FL) 是一种经典的 Paradigm, which alleviates privacy leaks and high communication pressure caused by traditional centralized data processing in the artificial intelligence of things (AIoT). The implementation of multimodal federated perception (MFP) services involves three sub-processes, including sensing-based multimodal data generation, communication-based model transmission, and computing-based model training, ultimately relying on available underlying multi-domain physical resources such as time, frequency, and computing power. How to reasonably coordinate the multi-domain resources scheduling among sensing, communication, and computing, therefore, is crucial to the MFP networks. To address the above issues, this paper investigates service-oriented resource management with integrated sensing, communication, and computing (ISCC). With the incentive mechanism of the MFP service market, the resources management problem is redefined as a social welfare maximization problem, where the idea of "expanding resources" and "reducing costs" is used to improve learning performance gain and reduce resource costs. Experimental results demonstrate the effectiveness and robustness of the proposed resource scheduling mechanisms.Note: Please note that the translation is in Simplified Chinese, which is one of the two standard versions of Chinese used in mainland China. If you prefer Traditional Chinese, I can provide that version as well.
Textile-based conformable and breathable ultrasound imaging probe
results: 实验结果显示，fabricated的纺织品基材探针具有低的flexural rigidity（$0.066 \times 10^{-4} N \cdot m^2/m）和高的空气通过率（$11.7 cm^3 / cm^2 \cdot s）。在人类 neck 的实验中，探针能够监测通过皮肤的血管径和 internal jugular vein 的 diameter 变化，这些变化可能会预悟 health issues 如arteriosclerosis 和 dehydration。Abstract
Daily monitoring of internal tissues with conformable and breathable ultrasound (US) imaging probes is promising for early detection of diseases. In recent years, textile substrates are widely used for wearable devices since they satisfy both conformability and breathability. However, it is not currently possible to use textile substrates for US probes due to the reflection or attenuation of US waves at the air gaps in the textiles. In this paper, we fabricated a conformable and breathable US imaging probe by sandwiching the US elements between two woven polyester textiles on which copper electrodes were formed through electroless plating. The air gaps between the fibers at the electrode parts were filled with copper, allowing for high penetration of US waves. On the other hand, the non-electrode parts retain air gaps, leading to high breathability. The fabricated textile-based probe showed low flexural rigidity ($0.066 \times 10^{-4} N \cdot m^2/m$) and high air permeability ($11.7 cm^3 / cm^2 \cdot s$). Human neck imaging demonstrated the ability of the probe to monitor the pulsation of the common carotid artery and change in the internal jugular vein diameter, which lead to the early detection of health issues such as arteriosclerosis and dehydration.
摘要
每天监测内部组织的可适应和呼吸性超声成像探针（US）是找到疾病的早期发现的有望的方法。在最近的几年中，纺织品substrate被广泛使用于可穿戴设备，因为它们满足了可适应和呼吸性。然而，目前并不可以使用纺织品substrate来制作US探针，因为在纺织品中的空气孔会反射或吸收US波。在本文中，我们制作了可适应和呼吸性的US成像探针，通过将US元素置于两块织物上，其中一块是织物，另一块是印制在织物上的杯状铜电极。空气孔在电极部分被填充铜，使US波能够深入传播。同时，非电极部分保留了空气孔，使探针具有高呼吸性。制作的纺织品基于探针表示了低的柔性($0.066 \times 10^{-4} N \cdot m^2/m$)和高的空气通透性($11.7 cm^3 / cm^2 \cdot s$）。人 neck imaging表明该探针能够监测通过血管的脉动和内 Jugular vein的 Diameter 的变化，从而早期发现健康问题，如arteriosclerosis和肥厚。
results: 比traditional FPA数组和其他参考方案更高的多束发射能量和干扰抑制性能Abstract
Conventional multi-beam forming with fixed-position antenna (FPA) arrays needs to trade-off between maximizing the beamforming gain over desired directions and minimizing the interference power over undesired directions. In this letter, we study the enhanced multi-beam forming with a linear movable-antenna (MA) array by exploiting the new degrees of freedom (DoFs) via antennas' position optimization. Specifically, we jointly optimize the antenna position vector (APV) and antenna weight vector (AWV) to maximize the minimum beamforming gain over multiple desired directions, subject to a given constraint on the maximum interference power over undesired directions. We propose an efficient alternating optimization algorithm to find a suboptimal solution by iteratively optimizing one of the APV and AWV with the other being fixed. Numerical results show that the proposed multi-beam forming design with MA arrays can significantly outperform that with the traditional FPA arrays and other benchmark schemes in terms of both beamforming gain and interference suppression.
摘要
Here's the Simplified Chinese translation:传统的多束发射器（FPA）阵列需要让束发射器的位置取值进行让束，以最大化 DESIRED 方向的束发射器 gain，同时最小化不 DESIRED 方向的干扰电磁辐射强度。在这封信中，我们研究了使用可变位置的天线阵列（MA）来提高多束发射器的性能。我们jointly优化天线位置 вектор（APV）和天线质量 вектор（AWV），以最大化多个 DESIRED 方向的束发射器 gain，同时保证不 DESIRED 方向的干扰电磁辐射强度不超过一定的限制。我们提出了一种高效的交叉优化算法，可以在一个轮循的方式中，iteratively 优化一个 APV 和 AWV，而另一个保持不变。numerical results show that the proposed multi-beam forming design with MA arrays can significantly outperform that with traditional FPA arrays and other benchmark schemes in terms of both beamforming gain and interference suppression.
Classification of Various Types of Damages in Honeycomb Composite Sandwich Structures using Guided Wave Structural Health Monitoring
results: 研究发现，其中两种损害类型对GW信号具有相似的影响。研究提取和评估了多种特征，包括时域和频域的特征，以及基线和无基线的特征。使用了施加了过滤的Pearson相关系数来消除冗余特征。最终，使用最佳的特征集，使用随机森林分类器在封装信号上获得了高精度。在不同的损害大小下，使用 Parametric 研究所获得的模拟数据进行评估，精度为77.89%。 interpretability 研究表明，基于基线信号的特征更有效。Abstract
Classification of damages in honeycomb composite sandwich structure (HCSS) is important to decide remedial actions. However, previous studies have only detected damages using deviations of monitoring signal from healthy (baseline) using a guided wave (GW) based structural health monitoring system. Classification between various types of damages has not been reported for challenging cases. We show that using careful feature engineering and machine learning it is possible to classify between various types of damages such as core crush (CC), high density core (HDC), lost film adhesive (LFA) and teflon release film (TRF). We believe that we are the first to report numerical models for four types of damages in HCSS, which is followed up with experimental validation. We found that two out of four damages affect the GW signal in a particularly similar manner. We extracted and evaluated multiple features from time as well as frequency domains, and also experimented with features relative to as baseline as well as those that were baseline-free. Using Pearson's correlation coefficient based filtering, redundant features were eliminated. Finally, using an optimal feature set determined using feature elimination, high accuracy was achieved with a random forest classifier on held-out signals. For evaluating performance of the proposed method for different damage sizes, we used simulated data obtained from extensive parametric studies and got an accuracy of 77.89%. Interpretability studies to determine importance of various features showed that features computed using the baseline signal prove more effective as compared to baseline-free features.
摘要
<>TRANSLATE_TEXT Classification of damages in honeycomb composite sandwich structures (HCSS) is important to determine remedial actions. However, previous studies have only detected damages using deviations of monitoring signals from healthy (baseline) using a guided wave (GW) based structural health monitoring system. Classification between various types of damages has not been reported for challenging cases. We show that using careful feature engineering and machine learning, it is possible to classify between various types of damages such as core crush (CC), high density core (HDC), lost film adhesive (LFA), and teflon release film (TRF). We believe that we are the first to report numerical models for four types of damages in HCSS, which is followed up with experimental validation. We found that two out of four damages affect the GW signal in a similar manner. We extracted and evaluated multiple features from time and frequency domains, and also experimented with features relative to the baseline as well as those that were baseline-free. Using Pearson's correlation coefficient based filtering, redundant features were eliminated. Finally, using an optimal feature set determined using feature elimination, high accuracy was achieved with a random forest classifier on held-out signals. For evaluating the performance of the proposed method for different damage sizes, we used simulated data obtained from extensive parametric studies and got an accuracy of 77.89%. Interpretability studies to determine the importance of various features showed that features computed using the baseline signal prove more effective compared to baseline-free features.TRANSLATE_TEXT
Beyond Traditional Beamforming: Singular Vector Projection Techniques for MU-MIMO Interference Management
methods: 论文首先提出了一个单位 vectors 搜索（SVBS）算法，其中所有单位 вектор 都会被评估，以选择最有效的扬声报文方案。然后，论文提出了一个数学证明，证明了MU-MIMO扬声报文系统中的交互用户干扰可以从多个互相 projet 的单位 вектор 中fficiently计算。
results: numerical results 表明，SVBS算法比现有的算法更有优势，IOSVB算法可以在保持高效率的情况下提供near-identical SE，而DR-IOSVB算法则可以将性能和计算复杂度平衡。这项研究奠定了MU-MIMO无线通信系统中高性能且低复杂性扬声报文的新 benchamrk。Abstract
This paper introduces low-complexity beamforming algorithms for multi-user multiple-input multiple-output (MU-MIMO) systems to minimize inter-user interference and enhance spectral efficiency (SE). A Singular-Vector Beamspace Search (SVBS) algorithm is initially presented, wherein all the singular vectors are assessed to determine the most effective beamforming scheme. We then establish a mathematical proof demonstrating that the total inter-user interference of a MU-MIMO beamforming system can be efficiently calculated from the mutual projections of orthonormal singular vectors. Capitalizing on this, we present an Interference-optimized Singular Vector Beamforming (IOSVB) algorithm for optimal singular vector selection. For further reducing the computational burden, we propose a Dimensionality-reduced IOSVB (DR-IOSVB) algorithm by integrating the principal component analysis (PCA). The numerical results demonstrate the superiority of the SVBS algorithm over the existing algorithms, with the IOSVB offering near-identical SE and the DR-IOSVB balancing the performance and computational efficiency. This work establishes a new benchmark for high-performance and low-complexity beamforming in MU-MIMO wireless communication systems.
摘要
To further reduce computational complexity, an Interference-optimized Singular Vector Beamforming (IOSVB) algorithm is proposed for optimal singular vector selection. Additionally, a Dimensionality-reduced IOSVB (DR-IOSVB) algorithm is proposed by integrating principal component analysis (PCA) to reduce the dimensionality of the problem.Numerical results show that the SVBS algorithm outperforms existing algorithms, while the IOSVB and DR-IOSVB algorithms offer near-identical SE with reduced computational complexity. This work establishes a new benchmark for high-performance and low-complexity beamforming in MU-MIMO wireless communication systems.
Recursive Filters as Linear Time-Invariant Systems
results: 这篇论文的结果表明，可以将回卷滤波器视为 LTI 系统，并且可以使用 Fourier 分析来分析它们的性质。Abstract
Recursive filters are treated as linear time-invariant (LTI) systems but they are not: uninitialised, they have an infinite number of outputs for any given input, while if initialised, they are not time-invariant. This short tutorial article explains how and why they can be treated as LTI systems, thereby allowing tools such as Fourier analysis to be applied. It also explains the origin of the z-transform, why the region of convergence is important, and why the z-transform fails to find an infinite number of solutions.
摘要
Linear time-invariant (LTI) 系统是可以使用 Fourier 分析的，但是 Recursive 筛选器并不是 LTI 系统：它们没有初始化，输出为输入的数量是无限的，如果初始化，则不是时间不变的。这篇简短的教程文章解释了如何将 Recursive 筛选器视为 LTI 系统，以便使用 Fourier 分析；它还解释了 z-transform 的起源、区域对称性的重要性，以及 z-transform 为什么无法找到无限多个解。
On the Performance of LoRa Empowered Communication for Wireless Body Area Networks
methods: 该论文使用了closed-form approximate bit error probability（BEP）表达式来描述LoRa系统的性能。
results: 研究结果表明，随着SF的增加和干扰的减少，可以有效地 mitigate shadowing效应。此外，对LoRa基于WBAN的MAC协议进行了比较分析，包括纯ALOHAC、频道分配ALOHAC和载波检测多路访问协议。研究发现，equal-interval-based和equal-area-based的 schemes可以帮助选择合适的SF。Abstract
To remotely monitor the physiological status of the human body, long range (LoRa) communication has been considered as an eminently suitable candidate for wireless body area networks (WBANs). Typically, a Rayleigh-lognormal fading channel is encountered by the LoRa links of the WBAN. In this context, we characterize the performance of the LoRa system in WBAN scenarios with an emphasis on the physical (PHY) layer and medium access control (MAC) layer in the face of Rayleigh-lognormal fading channels and the same spreading factor interference. Specifically, closed-form approximate bit error probability (BEP) expressions are derived for the LoRa system. The results show that increasing the SF and reducing the interference efficiently mitigate the shadowing effects. Moreover, in the quest for the most suitable MAC protocol for LoRa based WBANs, three MAC protocols are critically appraised, namely the pure ALOHA, slotted ALOHA, and carrier-sense multiple access. The coverage probability, energy efficiency, throughput, and system delay of the three MAC protocols are analyzed in Rayleigh-lognormal fading channel. Furthermore, the performance of the equal-interval-based and equal-area-based schemes is analyzed to guide the choice of the SF. Our simulation results confirm the accuracy of the mathematical analysis and provide some useful insights for the future design of LoRa based WBANs.
摘要
为了远程监测人体生理状态，长距离（LoRa）通信被视为适用于无线身体区域网络（WBAN）的非常佳的候选者。通常，LoRa链接会遇到RAYLEIGH-LOGNORMAL折射抑制通道。在这种情况下，我们研究了LoRa系统在WBAN场景中的性能，特别是物理层（PHY）层和媒体访问控制层（MAC）层，面临RAYLEIGH-LOGNORMAL折射通道和同步扩展因子干扰。我们 deriv了LoRa系统的闭形精度 approximate bit error probability（BEP）表达式。结果表明，逐渐提高SF和降低干扰可以有效地 Mitigate the shadowing effects。此外，为了选择LoRa基于WBAN中最佳的MAC协议，我们critically appraised three MAC协议，namely pure ALOHA, slotted ALOHA, and carrier-sense multiple access。我们分析了这三种MAC协议在RAYLEIGH-LOGNORMAL折射通道中的覆盖率、能效率、吞吐量和系统延迟。此外，我们还分析了平衡区 schemes的性能，以便选择SF。我们的 simulate results confirm the accuracy of the mathematical analysis and provide some useful insights for the future design of LoRa based WBANs.