For: 这种Integrated Sensing, Positioning, and Communication (ISPAC)框架可以同时为多个通信用户提供服务，并且实现目标探测和定位。* Methods: 该框架使用了一种新的双数组结构，其中一个小规模的协助传输器（AT）附加到了一个大规模的主传输器（MT）以使通信系统具备探测和定位能力。* Results: 研究人员通过提出的框架，首次 derivated了联合角度和距离Cramér-Rao bound（CRB）。然后，CRB是在下降链和上升链ISPAC场景中进行最小化。数值结果表明：1）提出的ISPAC系统可以仅通过单个BS和有限频率来实现目标的探测和定位；2）折衔式混合分析数字ISPAC方法可以与完全数字ISPAC方法匹配或超越其在无需强制通信率要求下的位置准确性。Abstract
A near-field integrated sensing, positioning, and communication (ISPAC) framework is proposed, where a base station (BS) simultaneously serves multiple communication users and carries out target sensing and positioning. A novel double-array structure is proposed to enable the near-field ISPAC at the BS. Specifically, a small-scale assisting transceiver (AT) is attached to the large-scale main transceiver (MT) to empower the communication system with the ability of sensing and positioning. Based on the proposed framework, the joint angle and distance Cram\'er-Rao bound (CRB) is first derived. Then, the CRB is minimized subject to the minimum communication rate requirement in both downlink and uplink ISPAC scenarios: 1) For downlink ISPAC, a downlink target positioning algorithm is proposed and a penalty dual decomposition (PDD)-based double-loop algorithm is developed to tackle the non-convex optimization problem. 2) For uplink ISPAC, an uplink target positioning algorithm is proposed and an efficient alternating optimization algorithm is conceived to solve the non-convex CRB minimization problem with coupled user communication and target probing design. Both proposed optimization algorithms can converge to a stationary point of the CRB minimization problem. Numerical results show that: 1) The proposed ISPAC system can locate the target in both angle and distance domains merely relying on single BS and limited bandwidths; and 2) the positioning performance achieved by the hybrid-analog-and-digital ISPAC approaches that achieved by fully digital ISPAC when the communication rate requirement is not stringent.
摘要
提出一种靠近场 интеGRATED SENSING、定位和通信（ISPAC）框架，其中基站（BS）同时服务多个通信用户，并同时进行目标探测和定位。提议了一种双array结构，以启用靠近场 ISPAC。具体来说，一个小规模协助传输器（AT）附加到大规模主传输器（MT）以允许通信系统具备探测和定位能力。基于该框架，首先 derivation 了共振矩阵（CRB）的最小值。然后，CRB 被最小化，并且需要在下行和上行 ISPAC 场景中保持最低通信率要求。具体来说，对于下行 ISPAC，我们提出了一种下行目标定位算法，并使用 penalty dual decomposition（PDD）-based double-loop algorithm 来解决非对称优化问题。对于上行 ISPAC，我们提出了一种上行目标定位算法，并开发了一种高效的 alternate optimization algorithm 来解决非对称CRB最小化问题。两种提出的优化算法都可以 converge 到CRB最小化问题的站点。数值结果显示，提出的 ISPAC 系统可以通过唯一BS和有限频率来定位目标，并且在角度和距离两个域中都可以进行定位。此外，在 Fully digital ISPAC 方法不可能达到的情况下，我们的 hybrid-analog-and-digital ISPAC 方法可以实现更高的定位性能。
Vertiport Navigation Requirements and Multisensor Architecture Considerations for Urban Air Mobility
paper_authors: Omar Garcia Crespillo, Chen Zhu, Maximilian Simonetti, Daniel Gerbeth, Young-Hee Lee, Wenhan Hao
for: The paper is written for discussing the navigation technologies required for future safe operation of drones in urban environments, specifically for precision approach operations based on vertiport designs.
methods: The paper proposes a possible multisensor navigation architecture solution to support these operations, which includes an overview of the challenges of each subsystem and initial proof of concept based on flight trials.
results: The paper presents initial proof of concept for some navigation sensor subsystems based on flight trials performed during the German Aerospace Center (DLR) project HorizonUAM.Abstract
Communication, Navigation and Surveillance (CNS) technologies are key enablers for future safe operation of drones in urban environments. However, the design of navigation technologies for these new applications is more challenging compared to e.g., civil aviation. On the one hand, the use cases and operations in urban environments are expected to have stringent requirements in terms of accuracy, integrity, continuity and availability. On the other hand, airborne sensors may not be based on high-quality equipment as in civil aviation and solutions need to rely on tighter multisensor solutions, whose safety is difficult to assess. In this work, we first provide some initial navigation requirements related to precision approach operations based on recently proposed vertiport designs. Then, we provide an overview of a possible multisensor navigation architecture solution able to support these types of operations and we comment on the challenges of each of the subsystems. Finally, initial proof of concept for some navigation sensor subsystems is presented based on flight trials performed during the German Aerospace Center (DLR) project HorizonUAM.
摘要
通信、导航和监测（CNS）技术是未来无人机在都市环境中安全运行的关键促进者。然而，为了满足这些新应用程序的设计，与民航相比， Navigation technologies 的设计更加具有挑战性。一方面，城市环境下的用例和操作具有高度的准确性、完整性、可用性和一致性要求。另一方面，空中探测仪可能不是民航使用的高质量设备，解决方案需要依赖更紧凑的多感器解决方案，其安全性困难评估。在这种情况下，我们首先提供了一些precision approach操作相关的初始导航要求，然后提供了一种可能的多感器导航架构解决方案，并评估了每个子系统的挑战。最后，对一些导航感知子系统的初步证明是基于德国航空中心（DLR）项目HorizonUAM期间进行的飞行试验。
Near-Field Sparse Channel Estimation for Extremely Large-Scale RIS-Aided Wireless Communications
results: 研究结果表明，该两个阶段Channel estimation方法可以减少频率响应的不确定性，并提高通信系统的性能。Abstract
A significant increase in the number of reconfigurable intelligent surface (RIS) elements results in a spherical wavefront in the near field of extremely large-scale RIS (XL-RIS). Although the channel matrix of the cascaded two-hop link may become sparse in the polar-domain representation, their accurate estimation of these polar-domain parameters cannot be readily guaranteed. To tackle this challenge, we exploit the sparsity inherent in the cascaded channel. To elaborate, we first estimate the significant path-angles and distances corresponding to the common paths between the BS and the XL-RIS. Then, the individual path parameters associated with different users are recovered. This results in a two-stage channel estimation scheme, in which distinct learning-based networks are used for channel training at each stage. More explicitly, in stage I, a denoising convolutional neural network (DnCNN) is employed for treating the grid mismatches as noise to determine the true grid index of the angles and distances. By contrast, an iterative shrinkage thresholding algorithm (ISTA) based network is proposed for adaptively adjusting the column coherence of the dictionary matrix in stage II. Finally, our simulation results demonstrate that the proposed two-stage learning-based channel estimation outperforms the state-of-the-art benchmarks.
摘要
“一个重要的增加在弹性智能表面（RIS）元素数量上，导致在EXTREMELY LARGE-SCALE RIS（XL-RIS）的近场内发射圆锥波front。即使这个通道矩阵在对应的两个统计步骤中可能会受到简化，但它们的精确估计仍然不能得到保证。为了解决这个挑战，我们利用了这个简化的通道矩阵中的组合簇统计特性。具体来说，我们首先估计XL-RIS和BS之间的共同路径角度和距离。然后，对不同的用户而言，个别的路径参数被恢复。这结构成了一个两阶段的通道估计方案，在每个阶段中使用不同的学习型网络进行通道训练。更详细地说，在第一阶段中，我们使用了一个检测网络（DnCNN）来处理网格不一致的问题，以确定真正的网格指标。而在第二阶段中，我们提出了一个调整Column coherence的估计网络（ISTA），以适应不同的用户。最后，我们的实验结果显示，我们的两阶段学习型通道估计方案比STATE-OF-THE-ART的参考模型更高效。”
Time-Frequency Localization Characteristics of the Delay-Doppler Plane Orthogonal Pulse
results: 作者发现，使用这种新的干扰信号模ulation可以利用时间和频率多样性，提高探测精度。此外，作者还提出了一种新的干扰信号设计方法，并通过数值计算证明了这种设计的能量分布在TF域中的步骤增长。Abstract
The orthogonal delay-Doppler (DD) division multiplexing (ODDM) modulation has recently been proposed as a promising solution for ensuring reliable communications in high mobility scenarios. In this work, we investigate the time-frequency (TF) localization characteristics of the DD plane orthogonal pulse (DDOP), which is the prototype pulse of ODDM modulation. The TF localization characteristics examine how concentrated or spread out the energy of a pulse is in the joint TF domain. We first derive the TF localization metric, TF area (TFA), for the DDOP. Based on this result, we provide insights into the energy spread of the DDOP in the joint TF domain. Then, we delve into the potential advantages of the DDOP due to its energy spread, particularly in terms of leveraging both time and frequency diversities, and enabling high-resolution sensing. Furthermore, we determine the TFA for the recently proposed generalized design of the DDOP. Finally, we validate our analysis based on numerical results and show that the energy spread for the generalized design of the DDOP in the joint TF domain exhibits a step-wise increase as the duration of sub-pulses increases.
摘要
高速移动场景中可靠通信的新方案是正交延时Doppler分 multiplexing（ODDM）调制。在这个工作中，我们调查了延时频率（TF）本地化特性的DD平面正交普朗（DDOP）。TF本地化特性检查普朗在TF域的能量集中程度。我们首先 derive TF本地化度量（TFA）的DDOP。基于这个结果，我们提供了DDOP在TF域的能量散布的深入理解。然后，我们探讨了DDOP的能量散布在TF域的优点，尤其是利用时间和频率多样性，并实现高分辨率探测。然后，我们确定了Generalized Design of DDOP的TFA。最后，我们 validate our analysis based on numerical results and show that the energy spread for the generalized design of the DDOP in the joint TF domain exhibits a step-wise increase as the duration of sub-pulses increases.
Cooperative Coherent Multistatic Imaging and Phase Synchronization in Networked Sensing
results: 论文表明，通过合作协同成像技术，可以提高探测脆弱目标的可靠性和分辨率，并通过实验示例表明，两辆车辆之间的合作可以检测到静止人体的脚部，并且需要高度准确的时钟同步和探测器的位势准确性来实现。Abstract
Coherent multistatic radio imaging represents a pivotal opportunity for forthcoming wireless networks, which involves distributed nodes cooperating to achieve accurate sensing resolution and robustness. This paper delves into cooperative coherent imaging for vehicular radar networks. Herein, multiple radar-equipped vehicles cooperate to improve collective sensing capabilities and address the fundamental issue of distinguishing weak targets in close proximity to strong ones, a critical challenge for vulnerable road users protection. We prove the significant benefits of cooperative coherent imaging in the considered automotive scenario in terms of both probability of correct detection, evaluated considering several system parameters, as well as resolution capabilities, showcased by a dedicated experimental campaign wherein the collaboration between two vehicles enables the detection of the legs of a pedestrian close to a parked car. Moreover, as \textit{coherent} processing of several sensors' data requires very tight accuracy on clock synchronization and sensor's positioning -- referred to as \textit{phase synchronization} -- (such that to predict sensor-target distances up to a fraction of the carrier wavelength), we present a general three-step cooperative multistatic phase synchronization procedure, detailing the required information exchange among vehicles in the specific automotive radar context and assessing its feasibility and performance by hybrid Cram\'er-Rao bound.
摘要
多 static 无线电影像表示未来无线网络的重要机会，即分布式节点合作以实现精确感知和鲁棒性。本文探讨了自动车radar网络中的合作协同准确影像。在这种情况下，多个 радио设备Equipped with vehicles cooperate to improve collective sensing capabilities and address the fundamental issue of distinguishing weak targets in close proximity to strong ones, a critical challenge for vulnerable road users protection. We prove the significant benefits of cooperative coherent imaging in the considered automotive scenario in terms of both probability of correct detection, evaluated considering several system parameters, as well as resolution capabilities, showcased by a dedicated experimental campaign wherein the collaboration between two vehicles enables the detection of the legs of a pedestrian close to a parked car. Moreover, as coherent processing of several sensors' data requires very tight accuracy on clock synchronization and sensor's positioning -- referred to as phase synchronization -- (such that to predict sensor-target distances up to a fraction of the carrier wavelength), we present a general three-step cooperative multistatic phase synchronization procedure, detailing the required information exchange among vehicles in the specific automotive radar context and assessing its feasibility and performance by hybrid Cramér-Rao bound.
Joint Computation and Communication Resource Optimization for Beyond Diagonal UAV-IRS Empowered MEC Networks
results: 这个论文的结果显示，BD-IRS 可以实现更好的系统延迟和数据率，比传统的 diagonally IRS 系统更好。具体来说，该论文的结果显示，BD-IRS 可以 reduc 系统延迟 by 7.25%，并提高数据率 by 17.77%。Abstract
Intelligent Reconfigurable Surfaces (IRS) are crucial for overcoming challenges in coverage, capacity, and energy efficiency beyond 5G (B5G). The classical IRS architecture, employing a diagonal phase shift matrix, hampers effective passive beamforming manipulation. To unlock its full potential, Beyond Diagonal IRS (BD-IRS or IRS 2.0) emerges as a revolutionary member, transcending limitations of the diagonal IRS. This paper introduces BD-IRS deployed on unmanned aerial vehicles (BD-IRS-UAV) in Mobile Edge Computing (MEC) networks. Here, users offload tasks to the MEC server due to limited resources and finite battery life. The objective is to minimize worst-case system latency by optimizing BD-IRS-UAV deployment, local and edge computational resource allocation, task segmentation, power allocation, and received beamforming vector. The resulting non-convex/non-linear NP-hard optimization problem is intricate, prompting division into two subproblems: 1) BD-IRS-UAV deployment, local and edge computational resources, and task segmentation, and 2) power allocation, received beamforming, and phase shift design. Standard optimization methods efficiently solve each subproblem. Monte Carlo simulations provide numerical results, comparing the proposed BD-IRS-UAV-enabled MEC optimization framework with various benchmarks. Performance evaluations include comparisons with fully-connected and group-connected architectures, single-connected diagonal IRS, and binary offloading, edge computation, fixed computation, and local computation frameworks. Results show a 7.25% lower latency and a 17.77% improvement in data rate with BD-IRS compared to conventional diagonal IRS systems, demonstrating the effectiveness of the proposed optimization framework.
摘要
智能可重新配置表面（IRS）是5G以外的挑战的关键，包括覆盖率、容量和能源效率。传统的IRS架构使用对角相位Matrix，导致有效的被动扫描干扰不优化。为了解锁其潜力，Beyond Diagonal IRS（BD-IRS）在Mobile Edge Computing（MEC）网络中出现，这是一种革命性的IRS成员，超越传统的IRS架构。本文介绍BD-IRS在无人航空器（BD-IRS-UAV）上的部署，用户因有限的资源和电池寿命而将任务下载到MEC服务器。目标是最小化系统延迟，通过BD-IRS-UAV部署、本地和边缘计算资源分配、任务分割、电力分配和接收扫描向量优化。这是一个非对称/非线性NP困难优化问题，我们将其分解为两个子问题：1）BD-IRS-UAV部署、本地和边缘计算资源和任务分割，2）电力分配、接收扫描和相位偏移设计。标准优化方法可以有效解决每个子问题。Monte Carlo仿真实现了数字结果，并与各种参考模型进行比较。性能评价包括与完全连接和分组连接架构、单连接对角IRS、 binary offloading、边缘计算、固定计算和本地计算框架进行比较。结果显示BD-IRS相比传统对角IRS系统，提供了7.25%的延迟和17.77%的数据速率提升，这说明了我们提posed的优化框架的有效性。
CASTER: A Computer-Vision-Assisted Wireless Channel Simulator for Gesture Recognition
paper_authors: Zhenyu Ren, Guoliang Li, Chenqing Ji, Chao Yu, Shuai Wang, Rui Wang
for: solves the problem of training dataset acquisition for wireless hand gesture recognition.
methods: uses computer-vision-assisted simulation method to simulate the training dataset via existing videos, and uses a primitive-based hand model to calculate the channel impulse response of each snapshot.
results: achieves an average classification accuracy of 90.8% in simulation-to-reality inference.Here’s the full text in Simplified Chinese:
results: 实现了90.8%的实验到现实推理精度.Abstract
In this paper, a computer-vision-assisted simulation method is proposed to address the issue of training dataset acquisition for wireless hand gesture recognition. In the existing literature, in order to classify gestures via the wireless channel estimation, massive training samples should be measured in a consistent environment, consuming significant efforts. In the proposed CASTER simulator, however, the training dataset can be simulated via existing videos. Particularly, a gesture is represented by a sequence of snapshots, and the channel impulse response of each snapshot is calculated via tracing the rays scattered off a primitive-based hand model. Moreover, CASTER simulator relies on the existing videos to extract the motion data of gestures. Thus, the massive measurements of wireless channel can be eliminated. The experiments demonstrate a 90.8% average classification accuracy of simulation-to-reality inference.
摘要
在这篇论文中，一种计算机视觉协助的模拟方法被提出，以解决无线手势识别的训练数据采集问题。现有文献中，为通过无线通道估计识别手势，需要投入巨资，测量大量的适合环境。在提议的 CASTER 模拟器中，然而，训练数据可以通过现有的视频进行模拟。具体来说，每个手势被表示为一个序列的快照，并且每个快照的通道响应被计算通过跟踪一个基于primitive的手模型折射的光线。此外，CASTER 模拟器利用现有的视频提取手势的运动数据，因此可以消除大量的无线通道测量。实验表明，模拟到现实的推断精度达90.8%。
methods: 本文采用了 rate-distortion 理论和源-通道分离定理 (SCT) 来建立 CAS 框架，并对lossy 数据传输中的干扰、编码率和通道容量之间的交互作用进行了全面的理解。
results: 本文提出了两种不同的波形策略：分离的感知通信 (S&C) 波形和双功能波形。其中，分离S&C波形使用了一个简单的一维搜索算法，而双功能波形使用了一种启发式的共声信息优化算法。此外，本文还发现了子空间贸易和水填贸易的存在。最后，通过数字实验 validate 了提议的算法的有效性。Abstract
The exploration of coordination gain achieved through the synergy of sensing and communication (S&C) functions plays a vital role in improving the performance of integrated sensing and communication systems. This paper focuses on the optimal waveform design for communication-assisted sensing (CAS) systems within the context of 6G perceptive networks. In the CAS process, the base station actively senses the targets through device-free wireless sensing and simultaneously transmits the pertinent information to end-users. In our research, we establish a CAS framework grounded in the principles of rate-distortion theory and the source-channel separation theorem (SCT) in lossy data transmission. This framework provides a comprehensive understanding of the interplay between distortion, coding rate, and channel capacity. The purpose of waveform design is to minimize the sensing distortion at the user end while adhering to the SCT and power budget constraints. In the context of target response matrix estimation, we propose two distinct waveform strategies: the separated S&C and dual-functional waveform schemes. In the former strategy, we develop a simple one-dimensional search algorithm, shedding light on a notable power allocation tradeoff between the S&C waveform. In the latter scheme, we conceive a heuristic mutual information optimization algorithm for the general case, alongside a modified gradient projection algorithm tailored for the scenarios with independent sensing sub-channels. Additionally, we identify the presence of both subspace tradeoff and water-filling tradeoff. Finally, we validate the effectiveness of the proposed algorithms through numerical simulations.
摘要
探索协调效益通过感知和通信（S&C）函数的结合可以提高整合感知和通信系统的性能。这篇论文专注于6G感知网络中的通信协助感知（CAS）系统的优化波动设计。在CAS过程中，基站通过无设备无线感知来活动检测目标，并同时将相关信息传递给终端用户。在我们的研究中，我们建立了基于率误差理论和源通道分离定理（SCT）的CAS框架，提供了感知误差、编码率和通道容量之间的全面理解。波动设计的目的是在用户端 minimize 感知误差，同时遵循SCT和功率预算约束。在目标响应矩阵估计中，我们提出了两种不同的波动策略：分离S&C和双功能波动 schemes。在前一种策略中，我们开发了一种简单的一维搜索算法，探讨了S&C波动力度的电力分配负担tradeoff。在后一种策略中，我们提出了一种基于通信协助感知的通用情况下的优化幂息算法，并与独立感知子频道的情况下的修改版 gradient projection algorithm。此外，我们发现了两种质量贸易：子空间贸易和水填贸易。最后，我们通过数值仿真验证了提出的算法的效果。
Performance Analysis of Integrated Data and Energy Transfer Assisted by Fluid Antenna Systems
results: 研究发现，在优化UE数量和TS比例的情况下，FAMA助け的IDET系统可以实现WDT和WET性能的平衡，并且在相同天线大小情况下，FAMA助け的IDET系统比传统MIMO系统表现更好。Abstract
Fluid antenna multiple access (FAMA) is capable of exploiting the high spatial diversity of wireless channels to mitigate multi-user interference via flexible port switching, which achieves a better performance than traditional multi-input-multi-output (MIMO) systems. Moreover, integrated data and energy transfer (IDET) is able to provide both the wireless data transfer (WDT) and wireless energy transfer (WET) services towards low-power devices. In this paper, a FAMA assisted IDET system is studied, where $N$ access points (APs) provide dedicated IDET services towards $N$ user equipments (UEs). Each UE is equipped with a single fluid antenna. The performance of WDT and WET , \textit{i.e.}, the WDT outage probability, the WET outage probability, the reliable throughput and the average energy harvesting amount, are analysed theoretically by using time switching (TS) between WDT and WET. Numerical results validate our theoretical analysis, which reveals that the number of UEs and TS ratio should be optimized to achieve a trade-off between the WDT and WET performance. Moreover, FAMA assisted IDET achieves a better performance in terms of both WDT and WET than traditional MIMO with the same antenna size.
摘要
fluid antenna 多元接入 (FAMA) 可以利用无线通信chnnel的高空间多样性来减少多用户干扰，通过flexible port switching实现更好的性能，比traditional 多输入多输出 (MIMO) 系统更好。另外， integral data and energy transfer (IDET) 可以为low-powerdevice提供无线数据传输 (WDT) 和无线能量传输 (WET) 服务。在这篇论文中，我们研究了一种由 N 个Access Points (APs) 提供专门的 IDET 服务，每个用户设备 (UE) 都装备了一个流体天线。我们使用时间switching (TS) 来分析WDT 和 WET 的性能，包括WDT 损失概率、WET 损失概率、可靠传输率和平均能量收集量。我们的理论分析表明，在TS ratio 和用户数量的trade-off下，FAMA 助け的 IDET 系统可以在WDT 和 WET 性能方面达到更好的 equilibria。此外，FAMA 助け的 IDET 系统在相同天线大小情况下比traditional MIMO 系统更好。
Multi-Point Method using Effective Demodulation and Decomposition Techniques allowing Identification of Disturbing Loads in Power Grids
results: 实验和数字 simulate studies表明，提出的方法可以准确地标识干扰负荷的供应点，并且可以在智能计量基础设施中自动地本地化干扰负荷。Abstract
The paper presents an innovative approach to the identification of sources of voltage fluctuations in power networks, also considering the localization understood as the indication of supply points of disturbing loads. The presented approach considers disturbance sources that change their operating state with a frequency higher than the power frequency. Implementation of the proposed solution is also proposed in such a way that its implementation in the smart meter infrastructure allows for automatic localization of disturbance sources without additional expert knowledge. In the proposed approach, the modulation signal is estimated using a carrier signal estimator, which allows for the estimation of modulation signal with a frequency higher than the power frequency. The estimated modulating signal is decomposed into component signals associated with individual disturbing loads by decomposition by approximation using pulse waves. The decomposition process allows for the estimation of selected parameters associated with disturbing loads, on the basis of which the assessment of propagation of voltage fluctuations associated with the impact of individual disturbance sources is performed, which allows for the indication of their supply point. The proposed approach was verified in numerical simulation studies using MATLAB/SIMULINK and in experimental studies carried out in a real low-voltage power grid.
摘要
The method uses a carrier signal estimator to estimate the modulation signal, which is then decomposed into component signals associated with individual disturbing loads using pulse wave decomposition. This allows for the estimation of selected parameters associated with the disturbing loads, enabling the assessment of the propagation of voltage fluctuations and the identification of their supply points.The proposed approach was verified through numerical simulations using MATLAB/SIMULINK and experimental studies in a real low-voltage power grid.
Sum Rate Maximization under AoI Constraints for RIS-Assisted mmWave Communications
results: simulation 结果显示，提出的算法可以有效地提高系统总速率，同时满足所有 UE 的信息新鲜度要求。Abstract
The concept of age of information (AoI) has been proposed to quantify information freshness, which is crucial for time-sensitive applications. However, in millimeter wave (mmWave) communication systems, the link blockage caused by obstacles and the severe path loss greatly impair the freshness of information received by the user equipments (UEs). In this paper, we focus on reconfigurable intelligent surface (RIS)-assisted mmWave communications, where beamforming is performed at transceivers to provide directional beam gain and a RIS is deployed to combat link blockage. We aim to maximize the system sum rate while satisfying the information freshness requirements of UEs by jointly optimizing the beamforming at transceivers, the discrete RIS reflection coefficients, and the UE scheduling strategy. To facilitate a practical solution, we decompose the problem into two subproblems. For the first per-UE data rate maximization problem, we further decompose it into a beamforming optimization subproblem and a RIS reflection coefficient optimization subproblem. Considering the difficulty of channel estimation, we utilize the hierarchical search method for the former and the local search method for the latter, and then adopt the block coordinate descent (BCD) method to alternately solve them. For the second scheduling strategy design problem, a low-complexity heuristic scheduling algorithm is designed. Simulation results show that the proposed algorithm can effectively improve the system sum rate while satisfying the information freshness requirements of all UEs.
摘要
“年龄信息（AoI）概念已经被提出来衡量信息的新鲜度，这对于时间敏感应用非常重要。但是，在 millimeter 波（mmWave）通信系统中，链路堵塞由障碍物和严重的路径损害很大地减少了接收到用户设备（UE）的信息新鲜度。在本文中，我们关注了基于智能表面（RIS）的 mmWave 通信系统，其中在发射器和接收器之间进行方向性射频，并使用 RIS 来抗链路堵塞。我们的目标是通过同时优化发射器的方向性射频、RIS 的反射系数和 UE 的调度策略来最大化系统总吞吐率，同时满足所有 UE 的信息新鲜度要求。为了实现实用解决方案，我们将问题划分为两个互补问题。首先，我们将每个 UE 的数据速率最大化问题划分为发射器的方向性射频优化问题和 RIS 的反射系数优化问题。 compte tenu de la difficulté de l'estimation de canal, nous utilisons la méthode de recherche hiérarchique pour la première et la méthode de recherche locale pour la deuxième, et then we adopt the method of descent coordonné (BCD) pour les résoudre alternativement。其次，我们设计了一种低复杂度的决策算法来解决调度策略设计问题。 simulation results show that the proposed algorithm can effectively improve the system sum rate while satisfying the information freshness requirements of all UEs.”
Secure Wireless Communication via Movable-Antenna Array
for: investigate the MA array-assisted physical-layer security in wireless communication, to maximize the achievable secrecy rate.
methods: jointly design the transmit beamforming and positions of all antennas at Alice using projected gradient ascent (PGA) and alternating optimization methods.
results: the MA array significantly enhances the secrecy rate compared to the conventional fixed-position antenna (FPA) array, due to the additional spatial degree of freedom (DoF) that can be fully exploited.Abstract
Movable antenna (MA) array is a novel technology recently developed where positions of transmit/receive antennas can be flexibly adjusted in the specified region to reconfigure the wireless channel and achieve a higher capacity. In this letter, we, for the first time, investigate the MA array-assisted physical-layer security where the confidential information is transmitted from a MA array-enabled Alice to a single-antenna Bob, in the presence of multiple single-antenna and colluding eavesdroppers. We aim to maximize the achievable secrecy rate by jointly designing the transmit beamforming and positions of all antennas at Alice subject to the transmit power budget and specified regions for positions of all transmit antennas. The resulting problem is highly non-convex, for which the projected gradient ascent (PGA) and the alternating optimization methods are utilized to obtain a high-quality suboptimal solution. Simulation results demonstrate that since the additional spatial degree of freedom (DoF) can be fully exploited, the MA array significantly enhances the secrecy rate compared to the conventional fixed-position antenna (FPA) array.
摘要
移动天线（MA）数组是一种最近发展的新技术，其中传输/接收天线的位置可以在指定区域中flexibly调整，以重新配置无线通道并实现更高的容量。在这封信中，我们第一次调查了MA数组协助物理层安全性，其中秘密信息由MA数组启用的Alice发送给单天线Bob，在多个单天线和合谋伪装者的存在下。我们想要最大化可以实现的机密率，通过对所有发射天线的传输扬射和位置进行joint设计，并且保持传输功率预算和指定的发射天线位置区域。问题非常非 convex，因此我们使用 проекted gradient ascent（PGA）和交互优化方法来获得高质量的不可靠解。实验结果表明，由于可以充分利用额外的空间度量（DoF），MA数组可以明显提高机密率，相比于传统固定位置天线（FPA）数组。
Optimal Configuration of Reconfigurable Intelligent Surfaces with Arbitrary Discrete Phase Shifts
results: 论文表明，在优化配置下，每个RIS元素都是 either turned off or operates at maximum amplitude，并提供了一种复杂度linear with the number of RIS elements的算法来找到最优的反射振荡和阶段。Abstract
We address the reflection optimization problem for a reconfigurable intelligent surface (RIS), where the RIS elements feature a set of non-uniformly spaced discrete phase shifts. This is motivated by the actual behavior of practical RIS elements, where it is shown that a uniform phase shift assumption is not realistic. A problem is formulated to find the optimal refection amplitudes and reflection phase shifts of the RIS elements such that the channel capacity of the target user is maximized. We first prove that in the optimal configuration, each RIS element is either turned off or operates at maximum amplitude. We then develop a method that finds the optimal reflection amplitudes and phases with complexity linear in the number of RIS elements. Some new and interesting insight into the reflection optimization problem is also provided.
摘要
我们处理了对可重配置智能表面（RIS）的反射优化问题，其中RIS元素具有一个非均匀的频率分布的不同阶段阶梯。这是因为实际上的RIS元素行为，其中发现均匀阶梯假设不是现实的。我们形ulated了一个问题，以 Maximize the channel capacity of the target user，找到最佳反射振幅和反射阶梯的解。我们首先证明了，在最佳配置下，每个RIS元素都是 Either turned off or operates at maximum amplitude。然后，我们开发了一种方法，可以在RIS元素数量linear增加的情况下找到最佳反射振幅和阶梯。我们还提供了一些新的和有趣的反射优化问题的思想。
Recursive and non-recursive filters for sequential smoothing and prediction with instantaneous phase and frequency estimation applications
results: simulation 结果表明，IIR 过滤器（使用优化的 lag）可以减少角度旋转错误，特别是对于高频率的信号，从而实现低 SNR 下的准确的时延测量和频率测量。此外，IIR 过滤器的错误卷积达到了 FIR 下界，但需要 significatively lower computational cost。Abstract
A simple procedure for the design of recursive digital filters with an infinite impulse response (IIR) and non-recursive digital filters with a finite impulse response (FIR) is described. The fixed-lag smoothing filters are designed to track an approximately polynomial signal of specified degree without bias at steady state, while minimizing the gain of high-frequency (coloured) noise with a specified power spectral density. For the IIR variant, the procedure determines the optimal lag (i.e. the passband group delay) yielding a recursive low-complexity smoother of low order, with a specified bandwidth, and excellent passband phase linearity. The filters are applied to the problem of instantaneous frequency estimation, e.g. for Doppler-shift measurement, for a complex exponential with polynomial phase progression in additive white noise. For this classical problem, simulations show that the incorporation of a prediction filter (with a one-sample lead) reduces the incidence of (phase or frequency) angle unwrapping errors, particularly for signals with high rates of angle change, which are known to limit the performance of standard FIR estimators at low SNR. This improvement allows the instantaneous phase of low-frequency signals to be estimated, e.g. for time-delay measurement, and/or the instantaneous frequency of frequency-modulated signals, down to a lower SNR. In the absence of unwrapping errors, the error variance of the IIR estimators (with the optimal phase lag) reaches the FIR lower bound, at a significantly lower computational cost. Guidelines for configuring and tuning both FIR and IIR filters are provided.
摘要
一种简单的过程用于设计回归数字filters（IIR）和非回归数字 filters（FIR）的设计方法。这些固定滤波器用于跟踪一个指定度的 polynomialsignal在稳态状态下无偏，同时最小化高频（色整）噪声的功率 спектル。对于IIR变体，这种过程确定了最佳的延迟（即极频组延迟），以获得一个低复杂度的回归估计器，并且在指定宽度下实现出色的极频阶线性。这些筛子应用于Doppler偏移测量中的快速频率估计问题，例如复杂的指数几何函数在加itive white noise中的极频偏移测量。对于这个 классиссиical问题，Simulations表明，在包含预测筛（带有一个预测）的情况下，可以减少（相对频率或相对频率）角度弯曲错误的发生，特别是对于高速角度变化的信号，这些信号已知会限制标准FIR估计器的性能在低SNR情况下。这种改进允许估计低频信号的极频幅度，例如时间延迟测量和/或极频信号的极频频率估计，下降到更低的SNR。在缺乏弯曲错误的情况下，IIR估计器（与最佳相位延迟）的错误方差达到FIR下界，但是在显著更低的计算成本下。文章还提供了配置和调整FIR和IIR筛子的指南。
Sensing Mutual Information with Random Signals in Gaussian Channels
results: 通过实验结果，提出的方法可以提高感知性能。Abstract
Sensing performance is typically evaluated by classical metrics, such as Cramer-Rao bound and signal-to-clutter-plus-noise ratio. The recent development of the integrated sensing and communication (ISAC) framework motivated the efforts to unify the metric for sensing and communication, where researchers have proposed to utilize mutual information (MI) to measure the sensing performance with deterministic signals. However, the need to communicate in ISAC systems necessitates the use of random signals for sensing applications and the closed-form evaluation for the sensing mutual information (SMI) with random signals is not yet available in the literature. This paper investigates the achievable performance and precoder design for sensing applications with random signals. For that purpose, we first derive the closed-form expression for the SMI with random signals by utilizing random matrix theory. The result reveals some interesting physical insights regarding the relation between the SMI with deterministic and random signals. The derived SMI is then utilized to optimize the precoder by leveraging a manifold-based optimization approach. The effectiveness of the proposed methods is validated by simulation results.
摘要
感知性能通常通过古典指标评估，如克拉默-瑞托约限和信号噪声比。 reciently，整合感知通信（ISAC）框架的发展激发了研究人员尝试统一感知和通信的度量，其中一些研究人员提议使用共谱（MI）来衡量感知性能。然而，ISAC系统中的通信需求使得感知应用中需要使用随机信号，而关于随机信号的感知共谱（SMI）的关闭形式评估在文献中并没有。这篇论文investigates the achievable performance and precoder design for sensing applications with random signals.为此，我们首先 derivethe closed-form expression for the SMI with random signals by utilizing random matrix theory. The result reveals some interesting physical insights regarding the relation between the SMI with deterministic and random signals. The derived SMI is then utilized to optimize the precoder by leveraging a manifold-based optimization approach. The effectiveness of the proposed methods is validated by simulation results.Note that the translation is in Simplified Chinese, which is the standard form of Chinese used in mainland China and Singapore. If you need Traditional Chinese, please let me know.
Shannon Theory for Wireless Communication in a Resonant Chamber
paper_authors: Amritpal Singh, Thomas Marzetta for: 这个研究探讨了在封闭电磁振兴室（RC）中进行无线通信的可能性。methods: 研究使用了对两个天线的阻抗矩阵的分析，并考虑了对天线的传递和获取。results: 研究发现，当RC壁填充完美导电材料时，通信频率将会受到几何对应的影响，并且随着载重抗的增加，频率将会逐渐趋向真值轴。此外，接收器会受到负iah杂音和内部抗杂变的影响。研究还发现，对于定定力和功率限制，频率和功率的分配可以实现无限制的容量。但是，实际分配不会集中在振兴频率上。Abstract
A closed electromagnetic resonant chamber (RC) is a highly favorable artificial environment for wireless communication. A pair of antennas within the chamber constitutes a two-port network described by an impedance matrix. We analyze communication between the two antennas when the RC has perfectly conducting walls and the impedance matrix is imaginary-valued. The transmit antenna is driven by a current source, and the receive antenna is connected to a load resistor whose voltage is measured by an infinite-impedance amplifier. There are a countably infinite number of poles in the channel, associated with resonance in the RC, which migrate towards the real frequency axis as the load resistance increases. There are two sources of receiver noise: the Johnson noise of the load resistor, and the internal amplifier noise. An application of Shannon theory yields the capacity of the link, subject to bandwidth and power constraints on the transmit current. For a constant transmit power, capacity increases without bound as the load resistance increases. Surprisingly, the capacity-attaining allocation of transmit power versus frequency avoids placing power close to the resonant frequencies.
摘要
闭合电磁振荡室（RC）是一个非常有利的人工环境，用于无线通信。它中的两个天线组成了一个二端网络，可以通过一个阻抗矩阵来描述。我们分析了它们之间的通信，当RC墙为绝对导电的时候，天线之间的阻抗矩阵为虚数值的时候。传输天线由一个电流源驱动，接收天线连接到一个负担抗的抗器，其电压被一个无限大的抗器检测。频率域中有无数多的极点，与RC的振荡相关，随着负担抗增加，极点逐渐移动到实频轴。接收器的噪声有两种来源：加载抗器的约束噪声，以及内部抗器的噪声。根据雪hnen理论，我们可以计算链路容量，受到带宽和功率限制的情况下。对于Constant transmit power，链路容量会无限增长，随着负担抗增加。很奇怪的是，链路容量最佳分配的发射功率与频率的分配不会将功率集中在振荡频率上。
Clifford Algebra-Based Iterated Extended Kalman Filter with Application to Low-Cost INS/GNSS Navigation
results: 数值仿真和实验表明，所有逐步筛选方法均具有快速全球受欢迎性，而逐步Clifford-RQEKF在特别大的IMU偏差情况下表现较好Abstract
The traditional GNSS-aided inertial navigation system (INS) usually exploits the extended Kalman filter (EKF) for state estimation, and the initial attitude accuracy is key to the filtering performance. To spare the reliance on the initial attitude, this work generalizes the previously proposed trident quaternion within the framework of Clifford algebra to represent the extended pose, IMU biases and lever arms on the Lie group. Consequently, a quasi-group-affine system is established for the low-cost INS/GNSS integrated navigation system, and the right-error Clifford algebra-based EKF (Clifford-RQEKF) is accordingly developed. The iterated filtering approach is further applied to significantly improve the performances of the Clifford-RQEKF and the previously proposed trident quaternion-based EKFs. Numerical simulations and experiments show that all iterated filtering approaches fulfill the fast and global convergence without the prior attitude information, whereas the iterated Clifford-RQEKF performs much better than the others under especially large IMU biases.
摘要
传统的GNSS协助导航系统（INS）通常利用扩展卡尔曼 Filter（EKF）进行状态估计，初始Orientation的准确性是过滤性能的关键。为了减少对初始Orientation的依赖，这项工作通过在Clifford алгебра中为扩展pose、IMU偏差和杆臂的表示generalize the previously proposed trident quaternion within the framework of Clifford algebra。因此，一个 quasi-group-affine system是建立了低成本INS/GNSS интеegrated navigation system，并对应地开发了Clifford-RQEKF。iterated filtering approach是进一步应用于显著提高Clifford-RQEKF和之前提出的trident quaternion-based EKFs的性能。数字实验和实验显示，所有的iterated filtering approaches可以在不知情IMU偏差的情况下实现快速和全球化的 converges，而iterated Clifford-RQEKF在特别大的IMU偏差情况下表现较好。
Deep Joint Source Channel Coding With Attention Modules Over MIMO Channels
results: 实验结果表明提议的DJSCC结构可以提高图像传输性能，并通过非参数 entropy 估计发现系统通过注意模块来调整发送信息的量，以适应不同通道质量Abstract
In this paper, we propose two deep joint source and channel coding (DJSCC) structures with attention modules for the multi-input multi-output (MIMO) channel, including a serial structure and a parallel structure. With singular value decomposition (SVD)-based precoding scheme, the MIMO channel can be decomposed into various sub-channels, and the feature outputs will experience sub-channels with different channel qualities. In the serial structure, one single network is used at both the transmitter and the receiver to jointly process data streams of all MIMO subchannels, while data steams of different MIMO subchannels are processed independently via multiple sub-networks in the parallel structure. The attention modules in both serial and parallel architectures enable the system to adapt to varying channel qualities and adjust the quantity of information outputs in accordance with the channel qualities. Experimental results demonstrate the proposed DJSCC structures have improved image transmission performance, and reveal the phenomenon via non-parameter entropy estimation that the learned DJSCC transceivers tend to transmit more information over better sub-channels.
摘要
在这篇论文中，我们提出了两种深度结合源码混合编码（DJSCC）结构，包括串行结构和平行结构，以便对多输入多输出（MIMO）通道进行编码。使用基于SVD（特征值分解）的编码方案，MIMO通道可以被分解成多个子通道，并且特征输出将经历不同通道质量的子通道。在串行结构中，发送端和接收端都使用单个网络进行数据流的同时处理，而在平行结构中，不同的MIMO子通道使用多个子网络进行独立的数据流处理。对各个MIMO子通道进行独立处理的注意模块允许系统适应不同的通道质量，并调整发送的信息量以适应通道质量。实验结果表明，我们提出的DJSCC结构可以提高图像传输性能，并通过非参数 entropy 估计来证明系统学习的DJSCC接收器通常将更多的信息发送到更好的子通道。
A Hybrid Joint Source-Channel Coding Scheme for Mobile Multi-hop Networks
results: 经过数字� simulations，这个方案能够超过完全analog和完全数字方案，并且可以避免“峰值效应”和静止噪声的问题。Abstract
We propose a novel hybrid joint source-channel coding (JSCC) scheme for robust image transmission over multi-hop networks. In the considered scenario, a mobile user wants to deliver an image to its destination over a mobile cellular network. We assume a practical setting, where the links between the nodes belonging to the mobile core network are stable and of high quality, while the link between the mobile user and the first node (e.g., the access point) is potentially time-varying with poorer quality. In recent years, neural network based JSCC schemes (called DeepJSCC) have emerged as promising solutions to overcome the limitations of separation-based fully digital schemes. However, relying on analog transmission, DeepJSCC suffers from noise accumulation over multi-hop networks. Moreover, most of the hops within the mobile core network may be high-capacity wireless connections, calling for digital approaches. To this end, we propose a hybrid solution, where DeepJSCC is adopted for the first hop, while the received signal at the first relay is digitally compressed and forwarded through the mobile core network. We show through numerical simulations that the proposed scheme is able to outperform both the fully analog and fully digital schemes. Thanks to DeepJSCC it can avoid the cliff effect over the first hop, while also avoiding noise forwarding over the mobile core network thank to digital transmission. We believe this work paves the way for the practical deployment of DeepJSCC solutions in 6G and future wireless networks.
摘要
我们提出了一种新的混合式 JOINT SOURCE-CHANNEL 编码（JSCC）方案，用于在多个跳代网络上稳定传输图像。在我们考虑的场景中，一个移动用户想要将图像传输到其目标地点，通过移动无线网络。我们假设了一个实际的设定，其中移动用户和首个节点（例如访问点）之间的链路为可能是时间变化的、质量较差的无线链路，而其他节点在移动核心网络中的链路则是稳定的高质量的无线链路。在过去几年中，基于神经网络的JSCC方案（称为深度JSCC）已经 emerged as Promising solutions to overcome the limitations of separation-based fully digital schemes。然而，在Analog transmission中，深度JSCC受到多跳代网络中的噪声积累的限制。此外，大多数内部节点在移动核心网络中的跳代可能是高容量无线连接，需要数字方法。为此，我们提出了一种混合解决方案，其中在首个跳代使用深度JSCC，并将在首个中继器接收的信号数字压缩并传递 через 移动核心网络。我们通过数字实验示例表明，我们的方案能够超越完全数字和完全分析的方案。深度JSCC可以避免首跳效应，同时避免在移动核心网络中传输噪声。我们认为这项工作将在6G和未来的无线网络中实用化深度JSCC解决方案。