paper_authors: Joaquin Ruiz, Hau-tieng Wu, Marcelo A. Colominas
for: 填充时间序列中缺失值，包括受低质量或过滤影响的时间序列，是一个重要的信号处理挑战。
methods: 本文提出了一种新的算法，即幂等级 interpolating（HaLI），用于提高现有的填充算法的性能 для振荡时间序列。 HaLI 利用基于自适应非幂模型的幂分解来提高填充精度。
results: 实验结果表明，HaLI 可以有效地提高现有填充算法的性能，并且可以在实验室和实际数据上进行应用。 Matlab 代码已经公开发布，供其他研究人员使用。Abstract
Dealing with time series with missing values, including those afflicted by low quality or over-saturation, presents a significant signal processing challenge. The task of recovering these missing values, known as imputation, has led to the development of several algorithms. However, we have observed that the efficacy of these algorithms tends to diminish when the time series exhibit non-stationary oscillatory behavior. In this paper, we introduce a novel algorithm, coined Harmonic Level Interpolation (HaLI), which enhances the performance of existing imputation algorithms for oscillatory time series. After running any chosen imputation algorithm, HaLI leverages the harmonic decomposition based on the adaptive nonharmonic model of the initial imputation to improve the imputation accuracy for oscillatory time series. Experimental assessments conducted on synthetic and real signals consistently highlight that HaLI enhances the performance of existing imputation algorithms. The algorithm is made publicly available as a readily employable Matlab code for other researchers to use.
摘要
处理含有欠拟合值的时间序列是一项重要的信号处理挑战。恢复这些欠拟合值，称为填充，已经导致了许多算法的发展。然而，我们观察到了这些算法在时间序列表现非站ARY抖动行为时的效果减退。在这篇论文中，我们介绍了一种新的算法，名为响应级 interpolate（HaLI），可以提高现有填充算法对抖动时间序列的准确性。在任何选择的填充算法后，HaLI利用基于适应非幂模型的响应级分解来提高填充精度。实验评估在synthetic和实际信号上 consistently表明，HaLI可以提高现有填充算法的性能。该算法已经公开提供了可靠地使用MATLAB代码，以便其他研究人员可以使用。
Wi-BFI: Extracting the IEEE 802.11 Beamforming Feedback Information from Commercial Wi-Fi Devices
results: 这篇论文通过开发 Wi-BFI 工具，实现了在空中捕获 BFAs 框架后，提取和重建扫描反馈信息的功能。工具支持实时和离线提取和存储 BFAs 和 BFI，并且在实时模式下还包括一个可视化的渠道状态显示器，可以实时地更新基于收集的数据。Abstract
Recently, researchers have shown that the beamforming feedback angles (BFAs) used for Wi-Fi multiple-input multiple-output (MIMO) operations can be effectively leveraged as a proxy of the channel frequency response (CFR) for different purposes. Examples are passive human activity recognition and device fingerprinting. However, even though the BFAs report frames are sent in clear text, there is not yet a unified open-source tool to extract and decode the BFAs from the frames. To fill this gap, we developed Wi-BFI, the first tool that allows retrieving Wi-Fi BFAs and reconstructing the beamforming feedback information (BFI) - a compressed representation of the CFR - from the BFAs frames captured over the air. The tool supports BFAs extraction within both IEEE 802.11ac and 802.11ax networks operating on radio channels with 160/80/40/20 MHz bandwidth. Both multi-user and single-user MIMO feedback can be decoded through Wi-BFI. The tool supports real-time and offline extraction and storage of BFAs and BFI. The real-time mode also includes a visual representation of the channel state that continuously updates based on the collected data. Wi-BFI code is open source and the tool is also available as a pip package.
摘要
近期，研究人员发现，Wi-Fi多输入多输出（MIMO）操作中的扫描反馈角（BFAs）可以作为通道频率响应（CFR）的代理。例如，悬浮人活动识别和设备打印。although BFAs report frames are sent in clear text, there is no unified open-source tool to extract and decode the BFAs from the frames. To fill this gap, we developed Wi-BFI, the first tool that allows retrieving Wi-Fi BFAs and reconstructing the beamforming feedback information (BFI) - a compressed representation of the CFR - from the BFAs frames captured over the air. The tool supports BFAs extraction within both IEEE 802.11ac and 802.11ax networks operating on radio channels with 160/80/40/20 MHz bandwidth. Both multi-user and single-user MIMO feedback can be decoded through Wi-BFI. The tool supports real-time and offline extraction and storage of BFAs and BFI. The real-time mode also includes a visual representation of the channel state that continuously updates based on the collected data. Wi-BFI code is open source and the tool is also available as a pip package.
paper_authors: Hyeon Seok Rou, Giuseppe Thadeu Freitas de Abreu, Saravanan Nagesh, Andreas Bathelt, David González G., Osvaldo Gonsa, Hans-Ludwig Bloecher
methods: 本文使用了多种简度 robust signal processing技术，如简度 reconstruction和指标模式（IM）来应对 sparse codesign 中的挑战。
results: 该文提出了一种新的SCCR frameworks，并采用了简度 robust signal processing技术来应对 sparse codesign 中的挑战。Abstract
In the envisioned beyond-fifth-generation (B5G) and sixth-generation (6G) scenarios which expect massive multiple-input multiple-output (mMIMO) and high frequency communications in the millimeter-wave (mmWave) and Terahertz (THz) bands, efficiency in both energy and spectrum is of increasing significance. To that extent, a novel ISAC framework called "sparse codesigned communication and radar (SCCR)" systems is described, which codesigns both communication and radar signals by a sparsification of the resource domain and the waveform spectrum domain. This improves the spectral and energy efficiency, but at the inherent cost of missing radar spectrum and irregular beampattern, and decreased throughput and diversity. Such challenges can however be corroborated, by leveraging various sparsity-robust signal processing techniques such as sparse radar reconstruction and index modulation (IM). In light of the above, the white paper aims to outlined the proposed article which provide an overview and a novel classification of the relevant state-of-the-art (SotA) methods and the implications of the challenges in the sparse codesign of the system, followed by a variety of novel SCCR frameworks.
摘要
在预期的 beyond-fifth-generation (B5G) 和 sixth-generation (6G) enario中，massive multiple-input multiple-output (mMIMO) 和高频通信在毫米波 (mmWave) 和teraHz (THz) 频率带中的效率在不断增长。为此，一种新的ISAC frameworkscalled "sparse codesigned communication and radar (SCCR)"系统被描述，该系统在资源领域和波形频谱领域进行了简化，从而提高了spectral和能量效率，但是附加了缺失 radar 频谱和不规则扫描 patrern，以及 Throughput 和多样性的减少。这些挑战可以通过不同的简单性robust signal processing技术，如简单 radar 重建和索引修饰 (IM)，进行整合。以上所述，这份白皮书的目的是提供一份概述和state-of-the-art (SotA) 方法的新分类，以及相关挑战的implications，然后提出一些新的SCCR frameworks。
Design of a Single-User RIS-Aided MISO System Based on Statistical Channel Knowledge
paper_authors: Sadaf Syed, Dominik Semmler, Donia Ben Amor, Michael Joham, Wolfgang Utschick
for: 提高5G网络的spectral和能量效率，降低成本
methods: 利用第二 Statistics of channels，降低培训过程的复杂性
results: 不需要CSI估计和RIS重新配置，提高系统的实用性Abstract
Reconfigurable intelligent surface (RIS) is considered a prospective technology for beyond fifth-generation (5G) networks to improve the spectral and energy efficiency at a low cost. Prior works on the RIS mainly rely on perfect channel state information (CSI), which imposes a huge computational complexity. This work considers a single-user RIS-assisted communication system, where the second-order statistical knowledge of the channels is exploited to reduce the training overhead. We present algorithms that do not require estimation of the CSI and reconfiguration of the RIS in every channel coherence interval, which constitutes one of the most critical practical issues in an RIS-aided system.
摘要
可重配置智能表面技术（RIS）被视为 fifth-generation（5G）网络以上的可能技术，以提高频率和能量效率，而且低成本。先前的RIS研究主要基于完美的通道状态信息（CSI），这会带来巨大的计算复杂度。本工作考虑了单用户RIS协助通信系统，利用通道的第二阶统计知识来减少培训负担。我们提出了不需要CSI估计和RIS重配置每个通道幂etime的算法，这是RIS协助系统中一个最重要的实践问题。
On the performance of an integrated communication and localization system: an analytical framework
results: 实验结果验证了分析模型，并显示在具有较少的antenna数和较大的UE与gNB之间距离的场景中，频域资源分配是更有优势的，而在具有较多的antenna数和较小的UE与gNB之间距离的场景中，时域资源分配是更有优势。Abstract
Quantifying the performance bound of an integrated localization and communication (ILAC) system and the trade-off between communication and localization performance is critical. In this letter, we consider an ILAC system that can perform communication and localization via time-domain or frequency-domain resource allocation. We develop an analytical framework to derive the closed-form expression of the capacity loss versus localization Cramer-Rao lower bound (CRB) loss via time-domain and frequency-domain resource allocation. Simulation results validate the analytical model and demonstrate that frequency-domain resource allocation is preferable in scenarios with a smaller number of antennas at the next generation nodeB (gNB) and a larger distance between user equipment (UE) and gNB, while time-domain resource allocation is preferable in scenarios with a larger number of antennas and smaller distance between UE and the gNB.
摘要
要量化整合本地化和通信系统（ILAC）的性能上限和通信和定位性能之间的交易是非常重要。在本封信中，我们考虑了一个可以通过时域或频域资源分配进行通信和定位的ILAC系统。我们开发了一个分析框架，以获得通过时域和频域资源分配得到的容量损失与定位Cramer-Rao下限损失的关闭式表达。实验结果证明了分析模型，并示出在具有较少的gNB天线数和较大的UE和gNB之间的距离的场景中，频域资源分配是更佳的选择，而在具有较多的天线数和较小的UE和gNB之间的距离的场景中，时域资源分配是更佳的选择。
Trade-Offs in Decentralized Multi-Antenna Architectures: Sparse Combining Modules for WAX Decomposition
For: This paper focuses on finding decentralized receiver architectures for centralized multi-antenna systems, with the goal of reducing the interconnection bandwidth and processing complexity between the antennas and the central processing unit (CPU).* Methods: The paper proposes using the WAX decomposition, a newly defined matrix decomposition, to achieve information-lossless processing in decentralized architectures. The authors also present several constructions for linear combining modules that can be used in the WAX decomposition, and show how these structures can facilitate decentralized calculation of the WAX decomposition.* Results: The paper obtains an information-lossless trade-off between the level of decentralization and the decentralized processing complexity, and demonstrates the effectiveness of the proposed constructions for linear combining modules in achieving this trade-off. The results show that the proposed methods can be used to efficiently implement information-lossless processing in architectures with an arbitrary level of decentralization.Here is the same information in Simplified Chinese:* For: 这篇论文关注于中心化多天线系统中的分布式接收架构，以减少天线和中央处理器（CPU）之间的连接带宽和处理复杂度。* Methods: 论文提出使用WAX分解，一种新定义的矩阵分解，以实现分布式处理中的信息无损处理。作者们还提出了多种 linear combining module 的构造，并证明这些结构可以在WAX分解中实现分布式计算。* Results: 论文取得了信息无损处理与分布式处理复杂度之间的信息损失融合，并证明了提posed constructions 可以高效地实现分布式处理中的信息无损处理。结果显示，提posed methods 可以在任意水平的分布式化环境中实现信息无损处理。Abstract
With the increase in the number of antennas at base stations (BSs), centralized multi-antenna architectures have encountered scalability problems from excessive interconnection bandwidth to the central processing unit (CPU), as well as increased processing complexity. Thus, research efforts have been directed towards finding decentralized receiver architectures where a part of the processing is performed at the antenna end (or close to it). A recent paper put forth an information-lossless trade-off between level of decentralization (inputs to CPU) and decentralized processing complexity (multiplications per antenna). This trade-off was obtained by studying a newly defined matrix decomposition--the WAX decomposition--which is directly related to the information-lossless processing that should to be applied in a general framework to exploit the trade-off. {The general framework consists of three stages: a set of decentralized filters, a linear combining module, and a processing matrix applied at the CPU; these three stages are linear transformations which can be identified with the three constituent matrices of the WAX decomposition. The previous work was unable to provide explicit constructions for linear combining modules which are valid for WAX decomposition, while it remarked the importance of these modules being sparse with 1s and 0s so they could be efficiently implemented using hardware accelerators.} In this work we present a number of constructions, as well as possible variations of them, for effectively defining linear combining modules which can be used in the WAX decomposition. Furthermore, we show how these structures facilitate decentralized calculation of the WAX decomposition for applying information-lossless processing in architectures with an arbitrary level of decentralization.
摘要
随着基站antenna数量的增加，中央多antenna架构遇到了增加与CPU的连接带宽和处理复杂度的挑战。因此，研究者努力找到了分散式接收架构，其中一部分处理在天线端（或近它）进行。一篇最近发表的论文提出了关于分散式处理的信息产生的负担和分散式处理复杂度之间的信息产生负担至关重要的交易。这种交易是通过研究一种新的矩阵分解——WAX分解——来获得的。这个分解直接关系到应用在总体框架中的信息产生处理。在这篇论文中，我们提出了一些可以实现的构造，以及这些构造的可能的变化。此外，我们还证明了这些结构可以帮助实现分散式计算WAX分解，从而应用信息产生处理在不同水平的分散式架构中。
paper_authors: Anatoly Khina, Neri Merhav for: 本研究考虑了在添加白噪声（AWGN）通道上传输参数值的问题，其中助手可以不可预测地观察噪声，并提供有限率($R_\mathrm{h}$)的描述给发送器和接收器。methods: 我们 derive了最佳可能的 $\alpha$-次约束误差的 Achievable bound，并证明它们在小 $\alpha$ 和低 SNR 值下协同存在。上限 bounds 基于最近提出的通道编码方案，可以有效地传输 $R_\mathrm{h}$ 位，并在同一个 AWGN 通道上传输剩下的 rate 无误损失。results: 我们then concentrate on具有发送能量限制的情况，并derive了可行性结果 для多种enario：助手只帮助发送器或接收器，并知道噪声；助手帮助发送器和接收器，并知道噪声和消息。在特定的情况下，我们证明了在通道编码任务中的错误概率会随着幂指数减少。最后，我们将这些结果翻译为关于连续时间的具有限制发送功率的AWGN通道的结果。Abstract
The problem of transmitting a parameter value over an additive white Gaussian noise (AWGN) channel is considered, where, in addition to the transmitter and the receiver, there is a helper that observes the noise non-causally and provides a description of limited rate $R_\mathrm{h}$ to the transmitter and/or the receiver. We derive upper and lower bounds on the optimal achievable $\alpha$-th moment of the estimation error and show that they coincide for small values of $\alpha$ and for low SNR values. The upper bound relies on a recently proposed channel-coding scheme that effectively conveys $R_\mathrm{h}$ bits essentially error-free and the rest of the rate - over the same AWGN channel without help, with the error-free bits allocated to the most significant bits of the quantized parameter. We then concentrate on the setting with a total transmit energy constraint, for which we derive achievability results for both channel coding and parameter modulation for several scenarios: when the helper assists only the transmitter or only the receiver and knows the noise, and when the helper assists the transmitter and/or the receiver and knows both the noise and the message. In particular, for the message-informed helper that assists both the receiver and the transmitter, it is shown that the error probability in the channel-coding task decays doubly exponentially. Finally, we translate these results to those for continuous-time power-limited AWGN channels with unconstrained bandwidth. As a byproduct, we show that the capacity with a message-informed helper that is available only at the transmitter can exceed the capacity of the same scenario when the helper knows only the noise but not the message.
摘要
问题是在加itive white Gaussian noise（AWGN）频道上传输参数值，其中助手可以不 causally 观察噪音并提供有限率 $R_\mathrm{h}$ 的描述给发送器和/或接收器。我们 deriv 最佳可能的 $\alpha$-次幂积分误差的上限和下限，并证明它们在小 $\alpha$ 和低 SNR 值时相同。上限基于最近提出的频道编码方案，可以准确地传输 $R_\mathrm{h}$ 位，并且其余的位量在同一个 AWGN 频道上无助而传输，即使是在静态频道条件下。然后，我们将注意力集中在具有总发送能力限制的情况下，并 deriv 适用于频道编码和参数模式的可行性结果。特别是，当助手协助发送器和接收器，并且知道噪音和消息时，显示了在频道编码任务中的误差概率呈双 exponential 衰减。最后，我们将这些结果翻译到连续时间的功率限制AWGN频道上的结果。作为一个副产品，我们显示了在发送器可以获得助手的情况下，容器的容量可以超过不具备消息助手的情况下的容量。
A Reliable and Resilient Framework for Multi-UAV Mutual Localization
methods: 本文提出的解决方案包括两个关键 ком成分：移动适应梯度下降（MAGD）和时间演化异常探测（TAD）。MAGD适应gradient descent算法 Handle the configuration changes in the mutual localization system， Ensure accurate localization in dynamic scenarios。TAD 与声誉传播（RP）方案合作，探测和缓和可能的攻击，识别有恶待的UAV，提高安全性和抗击力。
results: numerical simulations show that the proposed solution can achieve accurate and reliable mutual localization in multiple UAV systems, even in dynamic scenarios with configuration changes. The MAGD algorithm adapts to the changes and ensures accurate localization, while the TAD and RP schemes detect and mitigate potential attacks, enhancing the security and resilience of the mutual localization.Abstract
This paper presents a robust and secure framework for achieving accurate and reliable mutual localization in multiple unmanned aerial vehicle (UAV) systems. Challenges of accurate localization and security threats are addressed and corresponding solutions are brought forth and accessed in our paper with numerical simulations. The proposed solution incorporates two key components: the Mobility Adaptive Gradient Descent (MAGD) and Time-evolving Anomaly Detectio (TAD). The MAGD adapts the gradient descent algorithm to handle the configuration changes in the mutual localization system, ensuring accurate localization in dynamic scenarios. The TAD cooperates with reputation propagation (RP) scheme to detect and mitigate potential attacks by identifying UAVs with malicious data, enhancing the security and resilience of the mutual localization
摘要
MAGD adapts the gradient descent algorithm to handle configuration changes in the mutual localization system, ensuring accurate localization in dynamic scenarios. TAD cooperates with a reputation propagation (RP) scheme to detect and mitigate potential attacks by identifying UAVs with malicious data, enhancing the security and resilience of the mutual localization.Numerical simulations are used to assess the performance of the proposed solution, demonstrating its effectiveness in achieving accurate and reliable mutual localization in multiple UAV systems. The proposed framework provides a robust and secure solution for a variety of applications, including search and rescue, environmental monitoring, and infrastructure inspection.
D2D-Assisted Mobile Edge Computing: Optimal Scheduling under Uncertain Processing Cycles and Intermittent Communications
methods: 本文首先 derivates a closed-form表达式来表示在设备到设备协助下的MEC系统中任务负载成功率的平均值，然后提出了一个任务负载最大化问题（TOMP），并证明了这个问题是NP困难的。为解决这个问题，如果问题实例具有对称结构，我们提议一种基于动态计划（TSDP）的任务调度算法。对于一般情况，我们通过重新表述问题，提出了一种循环匹配算法（RMA）。
results: 经过性能评估，我们 validate了closed-form表达式的准确性，以及提出的算法的有效性。Abstract
Mobile edge computing (MEC) has been regarded as a promising approach to deal with explosive computation requirements by enabling cloud computing capabilities at the edge of networks. Existing models of MEC impose some strong assumptions on the known processing cycles and unintermittent communications. However, practical MEC systems are constrained by various uncertainties and intermittent communications, rendering these assumptions impractical. In view of this, we investigate how to schedule task offloading in MEC systems with uncertainties. First, we derive a closed-form expression of the average offloading success probability in a device-to-device (D2D) assisted MEC system with uncertain computation processing cycles and intermittent communications. Then, we formulate a task offloading maximization problem (TOMP), and prove that the problem is NP-hard. For problem solving, if the problem instance exhibits a symmetric structure, we propose a task scheduling algorithm based on dynamic programming (TSDP). By solving this problem instance, we derive a bound to benchmark sub-optimal algorithm. For general scenarios, by reformulating the problem, we propose a repeated matching algorithm (RMA). Finally, in performance evaluations, we validate the accuracy of the closed-form expression of the average offloading success probability by Monte Carlo simulations, as well as the effectiveness of the proposed algorithms.
摘要
Mobile edge computing (MEC) 被视为一种有前途的方法，以处理网络边缘的激增计算需求，通过在网络边缘提供云计算功能。现有的 MEC 模型假设了一些强制性的处理周期和不间断的通信，但实际的 MEC 系统受到各种不确定性和间歇性通信的限制，这些假设无法实现。为此，我们研究如何在 MEC 系统中进行任务负载卸载的调度，并对不确定性和间歇性通信进行考虑。首先，我们 deriv 一个关于 MEC 系统中设备间通信助け的 D2D 负载卸载的闭式表达式，该表达式表示设备之间的负载卸载成功率的平均值。然后，我们将任务负载卸载最大化问题（TOMP）进行形式化，并证明该问题是NP困难的。如果问题实例具有对称结构，我们提议一种基于动态编程的任务调度算法（TSDP）。通过解决这个问题实例，我们得到一个 bound 来评估不同算法的性能。对于一般场景，我们通过重新形式化问题，提议一种循环匹配算法（RMA）。最后，我们通过 Monte Carlo 仿真 validate 了关于负载卸载成功率的闭式表达式的准确性，以及我们提议的算法的有效性。
Spatial Modulation with Energy Detection: Diversity Analysis and Experimental Evaluation
paper_authors: Elio Faddoul, Ghassan M. Kraidy, Constantinos Psomas, Symeon Chatzinotas, Ioannis Krikidis
for: This paper proposes a non-coherent energy detection scheme for spatial modulation (SM) systems, which can be implemented with low complexity and is applicable for low-cost low-powered devices.
methods: The paper derives an energy detection metric for a multi-antenna receiver based on the maximum-likelihood (ML) criterion, and develops an analytical framework for the SM symbol error rate at high signal-to-noise ratios.
results: The paper shows that the proposed scheme outperforms the coherent ML receiver in certain scenarios, particularly when utilizing non-negative constellations, and provides experimental error rate measurements to validate the theoretical contribution.Here’s the same information in Simplified Chinese text:
methods: 论文基于最大 likelihood（ML） criterion derivation 了一种能量检测度量 для多天线接收器，并开发了一个分析性的 SM 符号错误率框架。
results: 论文显示，提案的方案在某些场景下比幂ML接收器更高效，特别是使用非负架构。同时，论文还提供了实验性的错误率测量来验证理论贡献。Abstract
In this paper, we present a non-coherent energy detection scheme for spatial modulation (SM) systems. In particular, the use of SM is motivated by its low-complexity implementation in comparison to multiple-input multiple-output (MIMO) systems, achieved through the activation of a single antenna during transmission. Moreover, energy detection-based communications restrict the channel state information to the magnitude of the fading gains. This consideration makes the design applicable for low-cost low-powered devices since phase estimation and its associated circuitry are avoided. We derive an energy detection metric for a multi-antenna receiver based on the maximum-likelihood (ML) criterion. By considering a biased pulse amplitude modulation, we develop an analytical framework for the SM symbol error rate at high signal-to-noise ratios. Numerical results show that the diversity order is proportional to half the number of receive antennas; this result stems from having partial receiver channel knowledge. In addition, we compare the performance of the proposed scheme with that of the coherent ML receiver and show that the SM energy detector outperforms its coherent counterpart in certain scenarios, particularly when utilizing non-negative constellations. Ultimately, we implement an SM testbed using software-defined radio devices and provide experimental error rate measurements that validate our theoretical contribution.
摘要
在本文中，我们提出了一种非协调能量探测方案 для空间模拟（SM）系统。特别是，使用SM是因为它的实现复杂度较低于多输入多出力（MIMO）系统，通过在传输中活动单个天线来实现。此外，能量探测基于通信 restricts the channel state information to the magnitude of the fading gains，这使得设计适用于低成本低功率设备，因为 phases estimation和相关的电路都被避免。我们 derive an energy detection metric for a multi-antenna receiver based on the maximum-likelihood（ML） criterion。通过考虑偏振普朗 amplitude modulation，我们开发了一个分析框架，用于SM符号错误率的高信号噪声比例。数值结果表明，多antenna接收器的多样性顺序与接收天线数量的一半相关，这是因为它们只有部分接收器通道知识。此外，我们比较了提出的方案与协调ML接收器的性能，并显示SM能量探测器在某些场景下超过其协调对手，特别是使用非负 constellations。最后，我们使用软件定义广播设备实现SM测试床，并提供了实验性错误率测量，以 validate our theoretical contribution。
Double RIS-Assisted MIMO Systems Over Spatially Correlated Rician Fading Channels and Finite Scatterers
methods: 本研究使用了关键性信息驱动的closed form Statistical analysis，以及一种基于 Alternating Direction Method of Multipliers（ADMM）的高效 alternating optimization algorithm（AO）来解决问题。
results: 研究结果表明，通过jointly optimizing active precoding和combining matrices，以及passive beamforming at the double RISs，可以提高通信系统的容量和可靠性。同时，通过使用一种基于 neural network 的 end-to-end learning framework，可以控制transceiver和RISs的相位Shift，以提高符号错误率。Abstract
This paper investigates double RIS-assisted MIMO communication systems over Rician fading channels with finite scatterers, spatial correlation, and the existence of a double-scattering link between the transceiver. First, the statistical information is driven in closed form for the aggregated channels, unveiling various influences of the system and environment on the average channel power gains. Next, we study two active and passive beamforming designs corresponding to two objectives. The first problem maximizes channel capacity by jointly optimizing the active precoding and combining matrices at the transceivers and passive beamforming at the double RISs subject to the transmitting power constraint. In order to tackle the inherently non-convex issue, we propose an efficient alternating optimization algorithm (AO) based on the alternating direction method of multipliers (ADMM). The second problem enhances communication reliability by jointly training the encoder and decoder at the transceivers and the phase shifters at the RISs. Each neural network representing a system entity in an end-to-end learning framework is proposed to minimize the symbol error rate of the detected symbols by controlling the transceiver and the RISs phase shifts. Numerical results verify our analysis and demonstrate the superior improvements of phase shift designs to boost system performance.
摘要
Performance Analysis of OTSM under Hardware Impairments in Millimeter-Wave Vehicular Communication Networks
paper_authors: Abed Doosti-Aref, Sapta Girish Neelam, P. R. Sahu, Xu Zhu, Ertugrul Basar, Sinem Coleri, Huseyin Arslan
for: 本文研究了基于orthogonal time sequency multiplexing（OTSM）的homodyne传输器在硬件障碍（HI）下的性能。
methods: 本文使用了Vector形式的不连续时间基准模型， derivated the system input-output relations in time、delay-time和delay-sequency（DS）domains，并 analyzed the effect of HIs on the system。
results: 研究结果表明，即使在HI下，OTSM仍可以与不做HICompensation（HIC）的SC波形相当，但需要HIC才能在mmWave和更高频率范围内运行。Abstract
Orthogonal time sequency multiplexing (OTSM) has been recently proposed as a single-carrier (SC) waveform offering similar bit error rate (BER) to multi-carrier orthogonal time frequency space (OTFS) modulation in doubly-spread channels under high mobilities; however, with much lower complexity making OTSM a promising candidate for low-power millimeter-wave (mmWave) vehicular communications in 6G wireless networks. In this paper, the performance of OTSM-based homodyne transceiver is explored under hardware impairments (HIs) including in-phase and quadrature imbalance (IQI), direct current offset (DCO), phase noise, power amplifier non-linearity, carrier frequency offset, and synchronization timing offset. First, the discrete-time baseband signal model is obtained in vector form under the mentioned HIs. Then, the system input-output relations are derived in time, delay-time, and delay-sequency (DS) domains in which the parameters of HIs are incorporated. Analytical studies demonstrate that noise stays white Gaussian and effective channel matrix is sparse in the DS domain under HIs. Also, DCO appears as a DC signal at receiver interfering with only the zero sequency over all delay taps in the DS domain; however, IQI redounds to self-conjugated fully-overlapping sequency interference. Simulation results reveal the fact that with no HI compensation (HIC), not only OTSM outperforms plain SC waveform but it performs close to uncompensated OTFS system; however, HIC is essentially needed for OTSM systems operating in mmWave and beyond frequency bands.
摘要
orthogonal time sequence multiplexing (OTSM) 已经被提议作为单载波形（SC）波形，在高速度频率域内提供类似的bit error rate（BER）与多载波形orthogonal time frequency space（OTFS）模ulation，但具有远低的复杂性，使其成为6G无线网络中低功率毫米波通信的有力候选人。在这篇论文中，我们研究了基于OTSM的同步receiver的性能，包括各种硬件障碍（HI）的影响，包括干扰相同和偏置（IQI）、直流偏置（DCO）、频率噪声、功率强度不对称和同步时间偏移。首先，我们获得了基于时分多谱的抽象时间基准信号模型。然后，我们 derive了系统的输入输出关系，包括时域、延迟时域和延迟序列（DS）域，并将HI参数纳入系统。分析研究表明，噪声保持白色高斯性，有效通道矩阵具有DS域中的稀疏性。此外，DCO会出现为接收器中的直流干扰，但IQI会导致自相关的完全重叠序列干扰。实验结果表明，在不进行HI修复（HIC）的情况下，OTSM不仅在干扰下超越普通SC波形，而且在HIC进行修复后，OTSM系统的性能与未修复OTFS系统几乎相同。
Sparse-DFT and WHT Precoding with Iterative Detection for Highly Frequency-Selective Channels
for: 这 paper 的目的是提出一种可以在高度 selecive 频率响应中提高性能和可扩展性的干扰抑制技术。
methods: 这 paper 使用了 Walsh-Hadamard преобразова和 expectation propagation 接收器来解决干扰抑制问题。
results: 研究结果表明，提出的 SWH-Max-Log-MAP 方法在高度 selecive 频率响应中具有更好的性能和可扩展性，但对于更高的 QAM 编码器来说，其复杂性为退化。Abstract
Various precoders have been recently studied by the wireless community to combat the channel fading effects. Two prominent precoders are implemented with the discrete Fourier transform (DFT) and Walsh-Hadamard transform (WHT). The WHT precoder is implemented with less complexity since it does not need complex multiplications. Also, spreading can be applied sparsely to decrease the transceiver complexity, leading to sparse DFT (SDFT) and sparse Walsh-Hadamard (SWH). Another relevant topic is the design of iterative receivers that deal with inter-symbol-interference (ISI). In particular, many detectors based on expectation propagation (EP) have been proposed recently for channels with high levels of ISI. An alternative is the maximum a-posterior (MAP) detector, although it leads to unfeasible high complexity in many cases. In this paper, we provide a relatively low-complexity \textcolor{black}{computation} of the MAP detector for the SWH. We also propose two \textcolor{black}{feasible methods} based on the Log-MAP and Max-Log-MAP. Additionally, the DFT, SDFT and SWH precoders are compared using an EP-based receiver with one-tap FD equalization. Lastly, SWH-Max-Log-MAP is compared to the (S)DFT with EP-based receiver in terms of performance and complexity. The results show that the proposed SWH-Max-Log-MAP has a better performance and complexity trade-off for QPSK and 16-QAM under highly selective channels, but has unfeasible complexity for higher QAM orders.
摘要
各种预编码器在无线通信社区中最近被广泛研究，以抗衰变的频率响应。两种最具有优势的预编码器是使用离散傅里叶变换 (DFT) 和华尔什-哈达姆变换 (WHT)。WHT预编码器的实现更加简单，因为它不需要复杂的乘法运算。此外，可以在广播中进行稀疏扩散，从而降低传输器的复杂度，导致SDFT和SWH。另一个相关的话题是对干扰Symbol-Interference (ISI)的设计iterative接收器。特别是，许多基于期望传播 (EP) 的探测器在高度 seleктив 的通道上提出了多种方案。其中一个 altenative是最大 posterior (MAP) 探测器，尽管它在许多情况下会带来不可接受的高复杂度。在这篇文章中，我们提供了一种相对较低的计算复杂性的MAP探测器 для SWH。我们还提出了两种可行的方法，基于Log-MAP和Max-Log-MAP。此外，DFT、SDFT和SWH预编码器被EP基于接收器与一个FD平衡器进行比较。最后，SWH-Max-Log-MAP与(S)DFT和EP基于接收器的性能和复杂度进行比较。结果表明，我们提出的SWH-Max-Log-MAP在高度选择性的通道上有更好的性能和复杂度负担，但对更高的QAM频率来说，其复杂度是不可接受的。
Gabor frames and higher dimensional boundaries in signal analysis on manifolds
for: 该 paper 用于构造 Gabor 框架，用于检测在曲线略微流形上的信号，并且可以检测高维度边界的存在。
methods: 该 paper 使用 Gabor 筛子来检测信号中的高维度边界，并且可以应用于机器人配置空间中的精确约束。
results: 该 paper 提出了一种高维度扩展的 geometric 设置，用于研究信号分析的视觉系统中的应用。Abstract
We provide a construction of Gabor frames that encode local linearizations of a signal detected on a curved smooth manifold of arbitrary dimension, with Gabor filters that can detect the presence of higher-dimensional boundaries in the manifold signal. We describe an application in configuration spaces in robotics with sharp constrains. The construction is a higher-dimensional generalization of the geometric setting developed for the study of signal analysis in the visual cortex.
摘要
我们提供了一种构建卡波框架的方法，该框架可以编码抽象维度的流体信号在抽象维度的满意流体上的本地线性化。我们使用的卡波滤波器可以检测高维度边界的存在在流体信号中。我们描述了一种在机器人配置空间中的应用，具有锐度约束。该构建是高维度扩展的视觉系统中的 геометри Settings的更高维度扩展。Note: Please note that the translation is in Simplified Chinese, which is the standard form of Chinese used in mainland China. If you need Traditional Chinese, please let me know.