results: 研究结果显示，这个新型数码声带感应器可以实现高精度的血液流速度测量，并且可以实现低功耗和低带宽的处理。在不同的心跳rhythm下，测量结果皆具有误差不超过0.05Hz（3bpm）。此外，实验室设置显示，这个方法可以实现6倍以上的讯号宽度减少，从12.5MHz降至2MHz。Abstract
Ultrasound is a key technology in healthcare, and it is being explored for non-invasive, wearable, continuous monitoring of vital signs. However, its widespread adoption in this scenario is still hindered by the size, complexity, and power consumption of current devices. Moreover, such an application demands adaptability to human anatomy, which is hard to achieve with current transducer technology. This paper presents a novel ultrasound system prototype based on a fully printed, lead-free, and flexible polymer ultrasound transducer, whose bending radius promises good adaptability to the human anatomy. Our application scenario focuses on continuous blood flow monitoring. We implemented a hardware envelope filter to efficiently transpose high-frequency ultrasound signals to a lower-frequency spectrum. This reduces computational and power demands with little to no degradation in the task proposed for this work. We validated our method on a setup that mimics human blood flow by using a flow phantom and a peristaltic pump simulating 3 different heartbeat rhythms: 60, 90 and 120 beats per minute. Our ultrasound setup reconstructs peristaltic pump frequencies with errors of less than 0.05 Hz (3 bpm) from the set pump frequency, both for the raw echo and the enveloped echo. The analog pre-processing showed a promising reduction of signal bandwidth of more than 6x: pulse-echo signals of transducers excited at 12.5 MHz were reduced to about 2 MHz. Thus, allowing consumer MCUs to acquire and elaborate signals within mW-power range in an inexpensive fashion.
摘要
“ultrasound是现代医疗技术中关键的一种，正在探索无侵入、可穿戴、不间断监测生命体指标的应用场景。然而，现有设备的大小、复杂度和功耗仍然阻碍了广泛的应用。此外，这种应用场景需要适应人体解剖结构，这是现有探音器技术很难实现。这篇论文提出了一种新的探音系统原型，基于完全印刷、无铅、 flexible полимер探音器。这种探音器的弯曲半径 promise good适应人体解剖结构。我们的应用场景是无间断血流监测。我们实施了硬件滤波器，以有效地将高频探音信号转换为低频spectrum。这 reduces computational和功耗占用，几乎不会影响我们所提出的任务。我们验证了我们的方法，使用一个模拟人血流的流体phantom和一个模拟心跳的剧热泵。我们的ultrasound设备可以准确地重construct peristaltic pump frequencies， errors of less than 0.05 Hz（3 bpm）from the set pump frequency， both for the raw echo and the enveloped echo。analog pre-processing showed a promising reduction of signal bandwidth of more than 6x：pulse-echo signals of transducers excited at 12.5 MHz were reduced to about 2 MHz。因此，allowing consumer MCUs to acquire and elaborate signals within mW-power range in an inexpensive fashion。”
Secret-Message Transmission by Echoing Encrypted Probes – STEEP
results: 如果恶作剂Eve无法获得Alice在第一阶段发送的准确探测信号，那么STEEP可以在返回频道上保证从Bob到Alice的秘密率大于0，即使恶作剂在探测频道上的频率 stronger than Bob的。 STEEP适用于物理层和Upper层在连接网络中。Abstract
This paper examines the properties of the lower and upper bounds established by Maurer, Ahlswede and Csiszar (MAC) for secret-key capacity in the case of channel probing over single-input and single-output (SISO) channels. Inspired by the insights into MAC's bounds, a scheme called secret-message transmission by echoing encrypted probes (STEEP) is proposed. STEEP consists of two phases: in phase 1, Alice sends random probes over a probing channel to Bob; in phase 2, Bob echoes back an estimated version of the probes, but encrypted by a secret, over a high-quality return channel. Provided that Eve is unable to obtain the exact probes transmitted by Alice in phase 1, STEEP guarantees a positive secrecy rate from Bob to Alice over the return channel even if Eve's channel strength during channel probing is stronger than Bob's. STEEP is applicable to both physical layer and upper layers in connected networks.
摘要
STEEP consists of two phases:1. In phase 1, Alice sends random probes over a probing channel to Bob.2. In phase 2, Bob echoes back an estimated version of the probes, but encrypted by a secret, over a high-quality return channel.Assuming that Eve is unable to obtain the exact probes transmitted by Alice in phase 1, STEEP guarantees a positive secrecy rate from Bob to Alice over the return channel, even if Eve's channel strength during channel probing is stronger than Bob's.STEEP is applicable to both physical layer and upper layers in connected networks.
Heart rate measurement using the built-in triaxial accelerometer from a commercial digital writing device
paper_authors: Julie Payette, Fabrice Vaussenat, Sylvain G. Cloutier
for: 这个研究用于比较智能笔的内置加速度仪和标准ECG仪器中的心率数据是否准确。
methods: 这个研究使用了智能笔equipped with sensors（STABILO的DigiPen）的内置加速度仪和标准ECG仪器来收集数据。数据处理使用了Butterworth滤波器减少噪声。
results: 研究发现，智能笔的内置加速度仪可以准确地预测心率，与标准ECG数据的相关性高于0.99。Abstract
Wearable devices are on the rise. Smart watches and phones, fitness trackers or smart textiles now provide unprecedented access to our own personal data. As such, wearable devices can enable health monitoring without disrupting our daily routines. In clinical settings, electrocardiograms (ECGs) and photoplethysmographies (PPGs) are used to monitor the heart's and respiratory behaviors. In more practical settings, accelerometers can be used to estimate the heartrate when they are attached to the chest. They can also help filter out some noise in ECG signal from movement. In this work, we compare the heart rate data extracted from the built-in accelerometer of a commercial smart pen equipped with sensors (STABILO's DigiPen), with a standard ECG monitor readouts. We demonstrate that it is possible to accurately predict the heart rate from the smart pencil. The data collection is done with eight volunteers, writing the alphabet continuously for five minutes. The signal is processed with a Butterworth filter to cut off noise. We achieve a mean-squared error (MSE) better than 6.685x10$^{-3}$ comparing the DigiPen's computed ${\Delta}$t (time between pulses) with the reference ECG data. The peaks' timestamps for both signals all maintain a correlation higher than 0.99. All computed heart rates from the pen accurately correlate with the reference ECG signals.
摘要
“智能装置在不断增长。智能手表和手机、健身器或智能纺织物现在提供了前所未有的个人数据访问权。因此，智能装置可以不间断地健康监测，不会影响我们的日常生活。在临床设置下，电喷呈（ECG）和光谱呈（PPG）用于监测心脏和呼吸的行为。在更实际的设置下，加速计可以用于估算心率，当它们附加到胸部时。它们还可以帮助滤除一些运动所引起的噪声在ECG信号中。在这个工作中，我们比较了 comercial smart pen 内建的加速计和标准 ECG 监测器的数据。我们示示了可以准确地预测心率从 smart pen 中提取的数据。数据采集使用八名志愿者，在五分钟内连续写字母。信号处理使用Butterworth滤波器剪辑噪声。我们实现了比较于 6.685 x 10$^{-3}$ 的mean-squared error（MSE），比较 commercial smart pen 计算的 $\Delta$t（心脏бит间隔）与参考 ECG 数据。两个信号的峰时间戳都保持了高于 0.99 的相关性。所有从 pen 中计算的心率都准确地与参考 ECG 信号相关。”
Joint RIS Phase Profile Design and Power Allocation for Parameter Estimation in Presence of Eavesdropping
results: 本文通过 alternating 优化和semidefinite relaxation 等方法，解决了RIS级别和发射器级别的优化问题，并通过实验证明了干扰的影响和RIS级别的选择对传输精度的影响。Abstract
We consider secure transmission of a deterministic complex-valued parameter vector from a transmitter to an intended receiver in the presence of an eavesdropper in a reconfigurable intelligent surface (RIS)-integrated environment. We aim to jointly optimize the RIS phase profile and the power allocation matrix at the transmitter to enhance the estimation accuracy at the intended receiver while limiting that at the eavesdropper. We utilize the trace of the Fisher information matrix (FIM), equivalently, the average Fisher information, as the estimation accuracy metric, and obtain its closed form expression for the intended receiver and the eavesdropper. Accordingly, the joint RIS phase profile and power allocation problem is formulated, and it is solved via alternating optimization. When the power allocation matrix is fixed during alternating optimization, the optimal RIS phase profile design problem is formulated as a non-convex problem and it is solved via semidefinite relaxation and rank reduction. When the RIS phase profile is fixed, a linear programming formulation is obtained for optimal power allocation. Via simulations, the effects of RIS phase design and power allocation are illustrated individually and jointly. Moreover, extensions are provided by considering the presence of line of sight paths in the environment and the availability of RIS elements with adjustable magnitudes.
摘要
我们考虑了一个报文加密传输的幂等复数参数向量从发送器到目标接收器的安全传输，在扩展智能表面（RIS）集成环境中。我们希望同时优化RIS相位特征和发送器的功率分配矩阵，以提高接收器的估计精度，同时限制侦测器的估计精度。我们使用追踪 Fisher信息矩阵（FIM）的跟踪，即平均 Fisher信息，作为估计精度度量，并得到其闭合形式表达。根据此，我们提出了共同优化RIS相位特征和功率分配问题，并通过 alternate 优化解决。当功率分配矩阵在 alternate 优化过程中固定时，则RIS相位特征设计问题变为非对称问题，并通过半definite relaksation和级数减少解决。当RIS相位特征固定时，则发送器的功率分配问题可以转化为线性程序。通过实验，我们证明了RIS相位设计和功率分配在个体和共同优化下的效果。此外，我们还提供了考虑线性路径的存在和RIS元素的调整级别的扩展。
Adaptive Three Layer Hybrid Reconfigurable Intelligent Surface for 6G Wireless Communication: Trade-offs and Performance
results: simulations表明，该三层混合式RIS-assisted配置比单独使用passive或active RIS-assisted技术更有优势。Abstract
A potential candidate technology for the development of future 6G networks has been recognized as Reconfigurable Intelligent Surface (RIS). However, due to the variation in radio link quality, traditional passive RISs only accomplish a minimal signal gain in situations with strong direct links between user equipment (UE) and base station (BS). In order to get over this fundamental restriction of smaller gain, the idea of active RISs might be a suitable solution. In contrast to current passive RIS, which simply reflects and directs signals without any additional amplification, active RISs have the ability to enhance reflected signals by the incorporation of amplifiers inside its elements. However, with additional amplifiers, apart from the relatively complex attributes of RIS-assisted arrangements, the additional energy consumption of such technologies is often disregarded. So, there might be a tradeoff between the additional energy consumption for the RIS technologies and the overall gain acquired by deploying this potential advancement. The objective of this work is to provide a primary idea of a three-layer hybrid RIS-assisted configuration that is responsive to both active and passive RIS, as well as an additional dormant or inactive state. The single RIS structure should be capable of adjusting its overall configuration in response to fluctuations in transmit power and radio link quality. Furthermore, our fabricated passive RIS-assisted structure verifies a portion of the proposed idea, with simulations highlighting its advantages over standalone passive or active RIS-assisted technologies.
摘要
sixth generation 网络（6G）的发展中，一种潜在的技术是可配置智能表面（Reconfigurable Intelligent Surface，RIS）。然而，由于无线链路质量的变化，传统的静止RIS只能实现最小的信号增强，尤其在用户设备（UE）和基站（BS）之间的强直接链路情况下。为了突破这种基本限制，可能适用的解决方案是活动RIS。与现有的静止RIS相比，活动RIS可以通过内置扩增器提高反射信号的强度。然而，随着这些技术的增加，除了RIS-assisted的复杂性外，额外的能源消耗也常被忽视。因此，可能存在一种负担增加和增加的负担之间的权衡。本工作的目标是提供一种三层混合RIS-assisted配置，可以响应活动和静止RIS，以及额外的休眠或不活跃状态。单一RIS结构应该能够根据发射功率和无线链路质量的变化进行调整。此外，我们制造的静止RIS-assisted结构的实验证明了一部分的提案的优势，而且模拟结果表明，与独立的静止或活动RIS-assisted技术相比，这种三层混合配置具有更高的优势。
Single-Antenna Jammers in MIMO-OFDM Can Resemble Multi-Antenna Jammers
results: 研究发现，当干扰器不遵守OFDM协议，它会在多个子帧上引起干扰，而不是单一的一维空间。这意味着在MIMO-OFDM系统中，单天线干扰器可以类比为L天线干扰器。Abstract
In multiple-input multiple-output (MIMO) wireless systems with frequency-flat channels, a single-antenna jammer causes receive interference that is confined to a one-dimensional subspace. Such a jammer can thus be nulled using linear spatial filtering at the cost of one degree of freedom. Frequency-selective channels are often transformed into multiple frequency-flat subcarriers with orthogonal frequency-division multiplexing (OFDM). We show that when a single-antenna jammer violates the OFDM protocol by not sending a cyclic prefix, the interference received on each subcarrier by a multi-antenna receiver is, in general, not confined to a subspace of dimension one (as a single-antenna jammer in a frequency-flat scenario would be), but of dimension L, where L is the jammer's number of channel taps. In MIMO-OFDM systems, a single-antenna jammer can therefore resemble an L-antenna jammer. Simulations corroborate our theoretical results. These findings imply that mitigating jammers with large delay spread through linear spatial filtering is infeasible. We discuss some (im)possibilities for the way forward.
摘要
在多输入多输出（MIMO）无线系统中，频率平坦渠道上的单天线妨碍器会导致接收干扰，这种干扰将被限制在一维空间中。这种妨碍器可以使用线性空间滤波来纠正，但是需要一个自由度。频率选择性渠道通常会被转换为多个平坦频分谱下的多个子帧，使用多载波分多plexing（OFDM）。我们表明，当妨碍器不遵循OFDM协议，并不发送循环前fix，则干扰接收到每个子帧的多天线接收器是，在总体来说，不再局限于一维空间中（如单天线妨碍器在频率平坦场景中会），而是局限于维度L，其中L是妨碍器的通道扩散的数量。在MIMO-OFDM系统中，单天线妨碍器可以类比于L天线妨碍器。实验证明了我们的理论结果。这些发现表明，通过线性空间滤波来mitigate妨碍器的影响是不可能的。我们讨论了一些（不）可能的前进方向。
Beam Squint Assisted User Localization in Near-Field Integrated Sensing and Communications Systems
results: simulations show that the proposed method can effectively reduce the beam sweeping overhead and achieve high accuracy user localization.Abstract
Integrated sensing and communication (ISAC) has been regarded as a key technology for 6G wireless communications, in which large-scale multiple input and multiple output (MIMO) array with higher and wider frequency bands will be adopted. However, recent studies show that the beam squint phenomenon can not be ignored in wideband MIMO system, which generally deteriorates the communications performance. In this paper, we find that with the aid of true-time-delay lines (TTDs), the range and trajectory of the beam squint in near-field communications systems can be freely controlled, and hence it is possible to reversely utilize the beam squint for user localization. We derive the trajectory equation for near-field beam squint points and design a way to control such trajectory. With the proposed design, beamforming from different subcarriers would purposely point to different angles and different distances, such that users from different positions would receive the maximum power at different subcarriers. Hence, one can simply localize multiple users from the beam squint effect in frequency domain, and thus reduce the beam sweeping overhead as compared to the conventional time domain beam search based approach. Furthermore, we utilize the phase difference of the maximum power subcarriers received by the user at different frequencies in several times beam sweeping to obtain a more accurate distance estimation result, ultimately realizing high accuracy and low beam sweeping overhead user localization. Simulation results demonstrate the effectiveness of the proposed schemes.
摘要
integrated sensing and communication (ISAC) 被认为是 sixth generation wireless communication (6G) 中的关键技术，其中大规模的多输入多输出 (MIMO) 阵列将在更高频率范围内使用。然而，最近的研究表明，在宽频MIMO系统中，扫描干扰（beam squint）现象无法忽略。在这篇论文中，我们发现，通过使用真实时延线（TTD），在近距离通信系统中扫描干扰的范围和轨迹可以自由控制，因此可以利用扫描干扰进行用户位置localization。我们 derive了近距离扫描干扰点的轨迹方程，并设计了控制这种轨迹的方法。与我们的设计相比，通过时域扫描来实现用户位置的方法可以减少扫描干扰的过程。此外，我们利用不同频率下接收到用户的最大功率Subcarrier的相位差来获取更加准确的距离估计结果，从而实现高精度低扫描干扰的用户位置定位。实验结果表明我们的方案的有效性。
Carrier Aggregation Enabled Integrated Sensing and Communication Signal Design and Processing
results: 实验结果表明，CA技术可以有效提高距离和速度估计的准确性。Abstract
The future mobile communication systems will support intelligent applications such as Internet of Vehicles (IoV) and Extended Reality (XR). Integrated Sensing and Communication (ISAC) is regarded as one of the key technologies satisfying the high data rate communication and highly accurate sensing for these intelligent applications in future mobile communication systems. With the explosive growth of wireless devices and services, the shortage of spectrum resources leads to the fragmentation of available frequency bands for ISAC systems, which degrades sensing performance. Facing the above challenges, this paper proposes a Carrier Aggregation (CA)-based ISAC signal aggregating high and low-frequency bands to improve the sensing performance, where the CA-based ISAC signal can use four different aggregated pilot structures for sensing. Then, an ISAC signal processing algorithm with Compressed Sensing (CS) is proposed and the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) is used to solve the reconfiguration convex optimization problem. Finally, the Cram'er-Rao Lower Bounds (CRLBs) are derived for the CA-based ISAC signal. Simulation results show that CA efficiently improves the accuracy of range and velocity estimation.
摘要
将来的移动通信系统将支持智能应用程序，如网络化交通 (IoV) 和增强现实 (XR)。集成感知通信 (ISAC) 被认为是未来移动通信系统支持高速数据传输和高精度感知的关键技术。随着无线设备和服务的快速增长，可用频率带的缺乏导致 ISAC 系统的分配频率带产生干扰，从而降低感知性能。面对这些挑战，本文提出了基于搅合 (CA) 的 ISAC 信号搅合高频和低频频率带以提高感知性能。然后，一种基于 CS 的 ISAC 信号处理算法和快速融合缩放算法 (FISTA) 被提出，以解决重配置减少问题。最后，CA 基于 ISAC 信号的 Cram'er-Rao Lower Bounds (CRLBs) 被 derivation。实验结果表明，CA 可以有效提高范围和速度估计的准确性。
Near-field Hybrid Beamforming for Terahertz-band Integrated Sensing and Communications
results: 作者通过数值仿真显示了该方法可以在不添加增加硬件Components的情况下实现atisfactory的spectral efficiency表现，并准确地估算near-field beamformers，有效地 mitigate near-field beam-squint。Abstract
Terahertz (THz) band communications and integrated sensing and communications (ISAC) are two main facets of the sixth generation wireless networks. In order to compensate the severe attenuation, the THz wireless systems employ large arrays, wherein the near-field beam-squint severely degrades the beamforming accuracy. Contrary to prior works that examine only either narrowband ISAC beamforming or far-field models, we introduce an alternating optimization technique for hybrid beamforming design in near-field THz-ISAC scenario. We also propose an efficient approach to compensate near-field beam-squint via baseband beamformers. Via numerical simulations, we show that the proposed approach achieves satisfactory spectral efficiency performance while accurately estimating the near-field beamformers and mitigating the beam-squint without additional hardware components.
摘要
六代无线网络中的tera响（THz）频段通信和集成感知通信（ISAC）是两个主要方面。为了抵消严重强化，THz无线系统使用大型阵列，其中靠近场区域的 beam-squint 严重降低了射频形成精度。与先前的工作只研究了窄频段ISAC射频形成或远场模型，我们引入了交替优化技术为混合射频形成设计。我们还提出了一种有效的方法来资料near-field beam-squint via baseband射频former。通过数值仿真，我们表明了我们的方法可以实现满意的spectral efficiency性能，准确地估计near-field射频former和mitigate beam-squint，无需额外硬件组件。
Track-before-detect Algorithm based on Cost-reference Particle Filter Bank for Weak Target Detection
results: 对于非线性频率调制（NLFM）信号检测和跟踪实验， simulate 结果表明，提出的 TBD 算法比现有的 TBD 算法在检测、跟踪和时间效率方面表现更好。Abstract
Detecting weak target is an important and challenging problem in many applications such as radar, sonar etc. However, conventional detection methods are often ineffective in this case because of low signal-to-noise ratio (SNR). This paper presents a track-before-detect (TBD) algorithm based on an improved particle filter, i.e. cost-reference particle filter bank (CRPFB), which turns the problem of target detection to the problem of two-layer hypothesis testing. The first layer is implemented by CRPFB for state estimation of possible target. CRPFB has entirely parallel structure, consisting amounts of cost-reference particle filters with different hypothesized prior information. The second layer is to compare a test metric with a given threshold, which is constructed from the output of the first layer and fits GEV distribution. The performance of our proposed TBD algorithm and the existed TBD algorithms are compared according to the experiments on nonlinear frequency modulated (NLFM) signal detection and tracking. Simulation results show that the proposed TBD algorithm has better performance than the state-of-the-arts in detection, tracking, and time efficiency.
摘要
检测弱目标是许多应用中的一个重要和挑战性问题，如雷达和SONAR等。然而，传统的检测方法经常无法处理这种情况，因为信号噪声比（SNR）过低。这篇论文提出了基于改进的粒子筛算法（cost-reference particle filter bank，CRPFB）的track-before-detect（TBD）算法，将目标检测转化为两层假设测试问题。第一层由CRPFB实现的状态估计可能的目标，CRPFB具有完全平行结构，包括不同假设先验信息的多个成本参照粒子筛。第二层是比较测试指标与给定的阈值，该阈值由第一层的输出和适应GEV分布构建。对于非线性频率模ulation（NLFM）信号检测和跟踪的实验结果显示，提议的TBD算法比现有的TBD算法在检测、跟踪和时间效率方面表现更好。
Online Resource Allocation for Semantic-Aware Edge Computing Systems
results: simulations 显示，提出的算法可以与无 semantics 的分配方法相比，节省至多 41.8% 的能源。Abstract
In this paper, we propose a semantic-aware joint communication and computation resource allocation framework for MEC systems. In the considered system, random tasks arrive at each terminal device (TD), which needs to be computed locally or offloaded to the MEC server. To further release the transmission burden, each TD sends the small-size extracted semantic information of tasks to the server instead of the original large-size raw data. An optimization problem of joint semanticaware division factor, communication and computation resource management is formulated. The problem aims to minimize the energy consumption of the whole system, while satisfying longterm delay and processing rate constraints. To solve this problem, an online low-complexity algorithm is proposed. In particular, Lyapunov optimization is utilized to decompose the original coupled long-term problem into a series of decoupled deterministic problems without requiring the realizations of future task arrivals and channel gains. Then, the block coordinate descent method and successive convex approximation algorithm are adopted to solve the current time slot deterministic problem by observing the current system states. Moreover, the closed-form optimal solution of each optimization variable is provided. Simulation results show that the proposed algorithm yields up to 41.8% energy reduction compared to its counterpart without semantic-aware allocation.
摘要
在这篇论文中，我们提出了一种基于 semantics 的共享计算和通信资源分配框架 для MEC 系统。在考虑的系统中，Random tasks 会随机到each terminal device（TD），需要本地计算或者卸载到 MEC 服务器。为了进一步减轻传输负担，each TD 将送出小型抽象信息（semantic information）到服务器，而不是原始大型原始数据。我们建立了一个优化问题，该问题的目标是最小化整体系统的能耗，同时满足长期延迟和处理率约束。为解决这个问题，我们提出了一种在线低复杂度算法。具体来说，我们利用了 Lyapunov 优化来将原来的 Coupled 长期问题分解成一系列的解耦的决定问题，无需考虑未来任务的到达和通道增益的实现。然后，我们采用了块坐标 descend 方法和Successive Convex Approximation 算法来解决当前时间槽的决定问题，并且提供了每个优化变量的关闭式最优解。实验结果显示，我们的算法可以提供 Up to 41.8% 的能源减少，相比无semantic-aware分配的对照方案。
NoncovANM: Gridless DOA Estimation for LPDF System
results: 提出了一种基于非对称�C-ANM算法的方法，可以快速和高效地优化direction finding表现，并且在实验中比较高效和精度高于比较方法Here’s a more detailed explanation of each point:
for: The paper aims to improve the accuracy and efficiency of low-cost passive direction finding (LPDF) systems.
methods: The proposed method utilizes an intelligent reconfigurable surface (IRS)-aided LPDF system, which only requires one fully functional receiving channel. The method exploits the sparsity of targets in the spatial domain by formulating an atomic norm minimization (ANM) problem to estimate the direction of arrival (DOA). To solve the ANM problem, a novel nonconvex-based ANM (NC-ANM) method is proposed, which uses gradient threshold iteration to avoid falling into saddle points. The theoretical analysis for the convergence of the NC-ANM method is also provided.
results: The proposed method outperforms compared methods in DOA estimation with lower computational complexity in the LPDF system, as shown by simulation results.Abstract
Direction of arrival (DOA) estimation is an important research in the area of array signal processing, and has been studied for decades. High resolution DOA estimation requires large array aperture, which leads to the increase of hardware cost. Besides, high accuracy DOA estimation methods usually have high computational complexity. In this paper, the problem of decreasing the hardware cost and algorithm complexity is addressed. First, considering the ability of flexible controlling the electromagnetic waves and low-cost, an intelligent reconfigurable surface (IRS)-aided low-cost passive direction finding (LPDF) system is developed, where only one fully functional receiving channel is adopted. Then, the sparsity of targets direction in the spatial domain is exploited by formulating an atomic norm minimization (ANM) problem to estimate the DOA. Traditionally, solving ANM problem is complex and cannot be realized efficiently. Hence, a novel nonconvex-based ANM (NC-ANM) method is proposed by gradient threshold iteration, where a perturbation is introduced to avoid falling into saddle points. The theoretical analysis for the convergence of the NC-ANM method is also given. Moreover, the corresponding Cram\'er-Rao lower bound (CRLB) in the LPDF system is derived, and taken as the referred bound of the DOA estimation. Simulation results show that the proposed method outperforms the compared methods in the DOA estimation with lower computational complexity in the LPDF system.
摘要
irection of arrival (DOA) 估计是阵列信号处理领域的重要研究，已经在数十年来被研究。高分辨率DOA估计需要大型阵列尺寸，这会导致硬件成本的增加。此外，高精度DOA估计方法通常具有高计算复杂性。在这篇论文中，解决降低硬件成本和算法复杂性的问题。首先，根据可控电磁波的能力和低成本，一种智能可重配置表面（IRS）帮助的低成本通过探测（LPDF）系统被开发，只有一个完全可用的接收通道。然后，通过利用目标方向在空间领域的稀畴性，提出一个原子范数最小化（ANM）问题来估计DOA。传统上，解决ANM问题是复杂的，无法有效实现。因此，一种新的非对称-基于ANM（NC-ANM）方法被提出，通过梯度阈值迭代来解决。另外，对NC-ANM方法的理论分析也给出。此外，对LPDF系统中DOA估计的Cramér-Rao下界（CRLB）也被 derive，作为DOA估计的参照 bound。实验结果表明，提出的方法在LPDF系统中的DOA估计中具有较低的计算复杂性和更高的精度，并且超过相关比较方法。
DNN-DANM: A High-Accuracy Two-Dimensional DOA Estimation Method Using Practical RIS
results: 该论文通过实验和原型 validate 了该方法在实际 RIS 系统中的性能，并证明了它在两个维度 DOA 估计中具有较低的复杂度和较高的准确率。Abstract
Reconfigurable intelligent surface (RIS) or intelligent reflecting surface (IRS) has been an attractive technology for future wireless communication and sensing systems. However, in the practical RIS, the mutual coupling effect among RIS elements, the reflection phase shift, and amplitude errors will degrade the RIS performance significantly. This paper investigates the two-dimensional direction-of-arrival (DOA) estimation problem in the scenario using a practical RIS. After formulating the system model with the mutual coupling effect and the reflection phase/amplitude errors of the RIS, a novel DNNDANM method is proposed for the DOA estimation by combining the deep neural network (DNN) and the decoupling atomic norm minimization (DANM). The DNN step reconstructs the received signal from the one with RIS impairments, and the DANM step exploits the signal sparsity in the two-dimensional spatial domain. Additionally, a semi-definite programming (SDP) method with low computational complexity is proposed to solve the atomic minimization problem. Finally, both simulation and prototype are carried out to show estimation performance, and the proposed method outperforms the existing methods in the two-dimensional DOA estimation with low complexity in the scenario with practical RIS.
摘要
现代化的智能反射表（RIS）或智能镜面（IRS）技术在未来无线通信和探测系统中具有吸引力。然而，在实际应用中的RIS中，元件之间的共振效应、反射阶段偏移和干扰错误会对RIS性能产生负面影响。本文研究使用实际RIS场景下的两个维度方向来估计（DOA）问题。经过制定系统模型，包括RIS中的共振效应和反射阶段偏移/干扰错误，我们提出了一种基于深度神经网络（DNN）和解决原子范数最小化（DANM）的新的DNNDANM方法。DNN步骤重建接收信号，而DANM步骤利用信号在两个维度空间中的稀疏性。此外，我们还提出了一种具有低计算复杂性的半definiteProgramming（SDP）方法来解决原子最小化问题。最后，我们通过实验和prototype来证明我们的方法在两个维度DOA估计中具有低复杂性和高性能，并且超越了现有的方法。
On the Energy Efficiency of THz-NOMA enhanced UAV Cooperative Network with SWIPT
results: 论文通过分解为两个阶段优化问题，使用替代优化方法，并通过比较基准点来证明提议的资源分配算法的效果。Abstract
This paper considers the energy efficiency (EE) maximization of a simultaneous wireless information and power transfer (SWIPT)-assisted unmanned aerial vehicles (UAV) cooperative network operating at TeraHertz (THz) frequencies. The source performs SWIPT enabling the UAV to receive both power and information while also transmitting the information to a designated destination node. Subsequently, the UAV utilizes the harvested energy to relay the data to the intended destination node effectively. Specifically, we maximize EE by optimizing the non-orthogonal multiple access (NOMA) power allocation coefficients, SWIPT power splitting (PS) ratio, and UAV trajectory. The main problem is broken down into a two-stage optimization problem and solved using an alternating optimization approach. In the first stage, optimization of the PS ratio and trajectory is performed by employing successive convex approximation using a lower bound on the exponential factor in the THz channel model. In the second phase, the NOMA power coefficients are optimized using a quadratic transform approach. Numerical results demonstrate the effectiveness of our proposed resource allocation algorithm compared to the baselines where there is no trajectory optimization or no NOMA power or PS optimization.
摘要
The problem is broken down into a two-stage optimization problem and solved using an alternating optimization approach. In the first stage, the PS ratio and trajectory are optimized using successive convex approximation with a lower bound on the exponential factor in the THz channel model. In the second stage, the NOMA power coefficients are optimized using a quadratic transform approach.Numerical results show that the proposed resource allocation algorithm outperforms baseline scenarios without trajectory optimization or NOMA power or PS optimization.
Study of Robust Adaptive Beamforming Algorithms Based on Power Method Processing and Spatial Spectrum Matching
results: 对比已有方法，提议的方法可以更好地适应covariance矩阵重建错误的情况，并且可以提高RAB的性能。Abstract
Robust adaptive beamforming (RAB) based on interference-plus-noise covariance (INC) matrix reconstruction can experience performance degradation when model mismatch errors exist, particularly when the input signal-to-noise ratio (SNR) is large. In this work, we devise an efficient RAB technique for dealing with covariance matrix reconstruction issues. The proposed method involves INC matrix reconstruction using an idea in which the power and the steering vector of the interferences are estimated based on the power method. Furthermore, spatial match processing is computed to reconstruct the desired signal-plus-noise covariance matrix. Then, the noise components are excluded to retain the desired signal (DS) covariance matrix. A key feature of the proposed technique is to avoid eigenvalue decomposition of the INC matrix to obtain the dominant power of the interference-plus-noise region. Moreover, the INC reconstruction is carried out according to the definition of the theoretical INC matrix. Simulation results are shown and discussed to verify the effectiveness of the proposed method against existing approaches.
摘要
《robust适应 beamforming（RAB）基于干扰＋噪声 covariance（INC）矩阵重建可以遇到性能下降问题，特别是当输入信号响应比（SNR）较大时。在这种工作中，我们设计了一种高效的 RAB 技术来处理 INC 矩阵重建问题。该方法包括使用力量和扫描向量来估算干扰的 INC 矩阵，然后通过空间匹配处理来重建 желатель信号＋噪声 covariance 矩阵。最后，噪声成分被排除，保留 желатель信号 covariance 矩阵。本方法的一个关键特点是不需要对 INC 矩阵进行特征值分解，以获得干扰＋噪声区域的主要功率。此外，INC 重建遵循了理论 INC 矩阵的定义。实验结果表明，提议的方法比既有方法更高效。》Note: Simplified Chinese is also known as "Mandarin" or "Standard Chinese".