paper_authors: Omar Barrera, Sinwoo Cho, Kenny Hyunh, Jack Kramer, Michael Liao, Vakhtang Chulukhadze, Lezli Matto, Mark S. Goorsky, Ruochen Lu
for: This paper aims to develop high-performance acoustic filters for millimeter wave (mmWave) bands using transferred single-crystal thin film lithium niobate (LiNbO3).
methods: The paper uses transferred LiNbO3 on top of silicon (Si) and sapphire (Al2O3) substrates with an intermediate amorphous Si (aSi) bonding and sacrificial layer to achieve compact acoustic filters with record-breaking performance beyond 20 GHz.
results: The paper demonstrates low insertion loss (IL) of 1.62 dB and 3-dB fractional bandwidth (FBW) of 19.8% at 22.1 GHz in the LN-aSi-Al2O3 platform, and low IL of 2.38 dB and FBW of 18.2% at 23.5 GHz in the LN-aSi-Si platform, with high crystalline quality of the stacks validated by material analysis.Abstract
This paper reports the first high-performance acoustic filters toward millimeter wave (mmWave) bands using transferred single-crystal thin film lithium niobate (LiNbO3). By transferring LiNbO3 on the top of silicon (Si) and sapphire (Al2O3) substrates with an intermediate amorphous Si (aSi) bonding and sacrificial layer, we demonstrate compact acoustic filters with record-breaking performance beyond 20 GHz. In the LN-aSi-Al2O3 platform, the third-order ladder filter exhibits low insertion loss (IL) of 1.62 dB and 3-dB fractional bandwidth (FBW) of 19.8% at 22.1 GHz, while in the LN-aSi-Si platform, the filter shows low IL of 2.38 dB and FBW of 18.2% at 23.5 GHz. Material analysis validates the great crystalline quality of the stacks. The high-resolution x-ray diffraction (HRXRD) shows full width half maximum (FWHM) of 53 arcsec for Al2O3 and 206 arcsec for Si, both remarkably low compared to piezoelectric thin films of similar thickness. The reported results bring the state-of-the-art (SoA) of compact acoustic filters to much higher frequencies, and highlight transferred LiNbO3 as promising platforms for mmWave filters in future wireless front ends.
摘要
In the LN-aSi-Al2O3 platform, the third-order ladder filter shows low insertion loss (IL) of 1.62 dB and 3-dB fractional bandwidth (FBW) of 19.8% at 22.1 GHz. In the LN-aSi-Si platform, the filter shows low IL of 2.38 dB and FBW of 18.2% at 23.5 GHz. Material analysis validates the great crystalline quality of the stacks, with high-resolution x-ray diffraction (HRXRD) showing full width half maximum (FWHM) of 53 arcsec for Al2O3 and 206 arcsec for Si, both remarkably low compared to piezoelectric thin films of similar thickness.The reported results bring the state-of-the-art (SoA) of compact acoustic filters to much higher frequencies, and highlight transferred LiNbO3 as promising platforms for mmWave filters in future wireless front ends.
Antenna Selection For Receive Spatial Modulation System Empowered By Reconfigurable Intelligent Surface
paper_authors: Burak Ahmet Ozden, Erdogan Aydin for: The paper proposes a new wireless communication system that enhances signal quality and spectral efficiency using a reconfigurable intelligent surface (RIS) and spatial modulation (SM) techniques.methods: The proposed system combines capacity-optimized antenna selection (COAS), antenna correlation antenna selection (ACAS), and Euclidean distance-optimized antenna selection (EDAS) with RIS-empowered receive SM (RIS-RSM) in a single-input multiple-output (SIMO) structure.results: The proposed system achieves high spectral efficiency, high energy efficiency, and low error data transmission. The analytical ABER results and capacity analyses of the proposed system are derived and shown to outperform counterpart wireless communication systems.Abstract
Reconfigurable intelligent surface (RIS) enhances signal quality by adjusting the phase of electromagnetic waves in wireless communication. Spatial modulation (SM), a prominent index modulation (IM) technique, provides high spectral efficiency and low energy consumption. In this article, a new wireless communication system is proposed by combining capacity-optimized antenna selection (COAS), antenna correlation antenna selection (ACAS), and Euclidean distance-optimized antenna selection (EDAS)-supported RIS-empowered receive SM (RIS-RSM) system (AS-RIS-RSM) in a single-input multiple-output (SIMO) structure. The proposed AS-RIS-RSM schemes (COAS-RIS-RSM, ACAS-RIS-RSM, and EDAS-RIS-RSM) have superior features such as high spectral efficiency, high energy efficiency, and low error data transmission. Integrating COAS, ACAS, and EDAS techniques into the system enables the selection of the channel with the best conditions, thus increasing the error performance of the proposed system. Also, using RIS increases the error performance of the system by controlling the transmitted signal to a certain extent. The analytical ABER results of the proposed AS-RIS-RSM systems are derived and shown to overlap with simulation results. For the proposed systems, an optimal maximum likelihood (ML) detector and a sub-optimal low-complexity greedy detector (GD) are offered. Also, capacity analyses of the proposed AS-RIS-RSM systems are derived and it is observed that they have higher capacity compared to RIS-QAM/PSK and RIS-RSM systems. Then, computational complexity analyses of the proposed COAS-RIS-RSM, ACAS-RIS-RSM, and EDAS-RIS-RSM systems are presented. The proposed systems have been compared to counterpart wireless communication systems including RIS-RSM, RIS-QAM, and RIS-PSK under equivalent conditions, demonstrating that the proposed systems achieve better error performance.
摘要
智能表面增强信号质量（RIS）可以调整无线通信中电磁波的相位，提高无线通信的质量。空间模ulation（SM）是一种重要的指标模ulation（IM）技术，它可以提供高 spectral efficiency 和低能耗。在这篇文章中，一种新的无线通信系统被提议，该系统通过结合可 configurable antenna selection（COAS）、antenna correlation antenna selection（ACAS）和Euclidean distance-optimized antenna selection（EDAS）支持RIS-empowered receive SM（RIS-RSM）系统，实现高 spectral efficiency、高能耗和低错误数据传输。在SIMO结构中，提议的AS-RIS-RSM方案（COAS-RIS-RSM、ACAS-RIS-RSM和EDAS-RIS-RSM）具有优秀的特点，包括高 spectral efficiency、高能耗和低错误数据传输。将COAS、ACAS和EDAS技术integrated into the system可以选择channel with the best conditions，提高系统的错误性能。同时，使用RIS可以控制传输的信号，从而提高系统的错误性能。文章中提出的analytical ABER结果和实验结果均表明，提议的AS-RIS-RSM系统具有优秀的性能。此外，文章还提出了一个最佳最大可信度（ML）检测器和一个低复杂度的恰好检测器（GD），以及AS-RIS-RSM系统的容量分析。结果表明，提议的AS-RIS-RSM系统具有更高的容量，并且计算复杂度分析表明，提议的系统的计算复杂度较低。最后，文章进行了与其他无线通信系统的比较，结果表明，提议的系统在等效条件下具有更好的错误性能。
Bit Error Rate Performance and Diversity Analysis for Mediumband Wireless Communication
results: 研究发现，通过judicious设计，中频媒体通信系统在非直线视线（NLoS）射频环境中可以 дости到更高的错误率和更高的多普通性顺序。Abstract
Mediumband wireless communication refers to wireless communication through a class of channels known as mediumband that exists on the TmTs-plane. This paper, through statistical analysis and computer simulations, studies the performance limits of this class of channels in terms of uncoded bit error rate (BER) and diversity order. We show that, owing mainly to the effect of the deep fading avoidance, which is unique to the channels in the mediumband region, mediumband wireless systems, if designed judiciously, have the potential to achieve significantly superior error rate and higher order diversity even in non-line-of-sight (NLoS) propagation environments where the achievable diversity order is otherwise low.
摘要
中等频宽无线通信指的是通过称为中等频宽的通道在TmTs平面上进行无线通信。本文通过统计分析和计算模拟，研究中等频宽通道的性能限制，包括未编码比特错误率（BER）和多普逻议级别。我们显示，归因于中等频宽通道特有的深抗减抗效应，中等频宽无线系统，如果judicious设计，在非直线视线（NLoS）媒体环境下可以实现更高的错误率和更高的多普逻议级别。
Learn to Augment Network Simulators Towards Digital Network Twins
for: This paper aims to address the challenge of building digital network twins (DNTs) that can accurately replicate real-world cellular networks, and to improve the generalization, explainability, and transparency of DNTs.
methods: The proposed approach uses a learn-to-bridge algorithm that combines cost-aware Bayesian optimization and Bayesian neural networks (BNN) to bridge the simulation-to-reality (sim-to-real) discrepancy in two stages. The first stage selects states to query performances in real-world networks, and the second stage trains the neural agent to learn the state context and bridge the probabilistic discrepancy.
results: The proposed solution substantially outperforms existing methods, with more than 92% reduction in the sim-to-real discrepancy, as demonstrated in a small-scale end-to-end network testbed based on OpenAirInterface RAN and Core with USRP B210 and a smartphone, and replicated in NS-3.Abstract
Digital network twin (DNT) is a promising paradigm to replicate real-world cellular networks toward continual assessment, proactive management, and what-if analysis. Existing discussions have been focusing on using only deep learning techniques to build DNTs, which raises widespread concerns regarding their generalization, explainability, and transparency. In this paper, we explore an alternative approach to augment network simulators with context-aware neural agents. The main challenge lies in the non-trivial simulation-to-reality (sim-to-real) discrepancy between offline simulators and real-world networks. To solve the challenge, we propose a new learn-to-bridge algorithm to cost-efficiently bridge the sim-to-real discrepancy in two alternative stages. In the first stage, we select states to query performances in real-world networks by using newly-designed cost-aware Bayesian optimization. In the second stage, we train the neural agent to learn the state context and bridge the probabilistic discrepancy based on Bayesian neural networks (BNN). In addition, we build a small-scale end-to-end network testbed based on OpenAirInterface RAN and Core with USRP B210 and a smartphone, and replicate the network in NS-3. The evaluation results show that, our proposed solution substantially outperforms existing methods, with more than 92\% reduction in the sim-to-real discrepancy.
摘要
《数字网络双》是一种有前途的思想，可以用于持续评估、积极管理和什么样的分析。现有的讨论都集中在使用深度学习技术来构建数字网络双，但这引发了广泛的担忧，包括其通用性、可解释性和透明度。在这篇论文中，我们尝试了一种不同的方法，即在网络仿真器中添加上下文意识神经网络。主要挑战在于非轻松的仿真到实际（sim-to-real）差异。为解决这个挑战，我们提出了一种新的学习到桥接算法，以cost-efficiently bridging sim-to-real差异。在第一个阶段，我们使用新设计的成本意识搜索选择状态来查询实际网络中的性能。在第二个阶段，我们使用概率神经网络（BNN）训练神经网络学习状态上下文，并bridge probabilistic差异。此外，我们建立了一个小规模的端到端网络测试平台，基于OpenAirInterface RAN和核心，并使用USRP B210和智能手机复制网络。评估结果显示，我们的提案substantially outperforms现有方法，减少了92.3%的sim-to-real差异。
Satellite Swarms for Narrow Beamwidth Applications
results: simulations 结果显示，该方案可以实现非常窄的扩散 Pattern，最大侧LOB level为18.8 dB，最小侧LOB level为14.8 dB。这种方案可以用于高速数据应用或紧急系统。Abstract
Satellite swarms have recently gained attention in the space industry due to their ability to provide extremely narrow beamwidths at a lower cost than single satellite systems. This paper proposes a concept for a satellite swarm using a distributed subarray configuration based on a 2D normal probability distribution. The swarm comprises multiple small satellites acting as subarrays of a big aperture array limited by a radius of 20000 wavelengths working at a central frequency of 19 GHz. The main advantage of this approach is that the distributed subarrays can provide extremely directive beams and beamforming capabilities that are not possible using a conventional antenna and satellite design. The proposed swarm concept is analyzed, and the simulation results show that the radiation pattern achieves a beamwidth as narrow as 0.0015-degrees with a maximum side lobe level of 18.8 dB and a grating lobe level of 14.8 dB. This concept can be used for high data rates applications or emergency systems.
摘要
Translation:卫星群体在空间业务中受到了关注，因为它们可以提供非常窄的扩散角，而且比单卫星系统更加经济。本文提出了基于2D正态分布的卫星群体概念，其中包括多个小卫星 acting as subarrays of a big aperture array，限制Radius of 20000 wavelengths，工作中心频率为19 GHz。主要优点是分布的subarrays可以提供非常导向的扩散和射频能力，这些能力不可能使用传统的天线和卫星设计。提议的卫星群体概念被分析，并且 simulation 结果显示，射频模式可以实现扩散角为0.0015度，最大侧波强度为18.8 dB，镜面强度为14.8 dB。这种概念可以用于高速数据应用或紧急系统。
Empirical Validation of the Impedance-Based RIS Channel Model in an Indoor Scattering Environment
paper_authors: Placido Mursia, Taghrid Mazloum, Frederic Munoz, Vincenzo Sciancalepore, Gabriele Gradoni, Raffaele D Errico, Marco Di Renzo, Xavier Costa-Perez, Antonio Clemente, Geoffroy Lerosey
for: validate a recently-proposed impedance-based RIS channel model
methods: exploit real-life channel measurements and discrete array of loaded dipoles
results: superior performance compared to reference schemesAbstract
Ensuring the precision of channel modeling plays a pivotal role in the development of wireless communication systems, and this requirement remains a persistent challenge within the realm of networks supported by Reconfigurable Intelligent Surfaces (RIS). Achieving a comprehensive and reliable understanding of channel behavior in RIS-aided networks is an ongoing and complex issue that demands further exploration. In this paper, we empirically validate a recently-proposed impedance-based RIS channel model that accounts for the mutual coupling at the antenna array and precisely models the presence of scattering objects within the environment as a discrete array of loaded dipoles. To this end, we exploit real-life channel measurements collected in an office environment to demonstrate the validity of such a model and its applicability in a practical scenario. Finally, we provide numerical results demonstrating that designing the RIS configuration based upon such model leads to superior performance as compared to reference schemes.
摘要
Ensuring the precision of channel modeling plays a crucial role in the development of wireless communication systems, and this requirement remains a persistent challenge within the realm of networks supported by Reconfigurable Intelligent Surfaces (RIS). Achieving a comprehensive and reliable understanding of channel behavior in RIS-aided networks is an ongoing and complex issue that demands further exploration. In this paper, we empirically validate a recently-proposed impedance-based RIS channel model that accounts for the mutual coupling at the antenna array and precisely models the presence of scattering objects within the environment as a discrete array of loaded dipoles. To this end, we exploit real-life channel measurements collected in an office environment to demonstrate the validity of such a model and its applicability in a practical scenario. Finally, we provide numerical results demonstrating that designing the RIS configuration based upon such model leads to superior performance as compared to reference schemes.Here's the translation in Traditional Chinese: Ensuring the precision of channel modeling plays a crucial role in the development of wireless communication systems, and this requirement remains a persistent challenge within the realm of networks supported by Reconfigurable Intelligent Surfaces (RIS). Achieving a comprehensive and reliable understanding of channel behavior in RIS-aided networks is an ongoing and complex issue that demands further exploration. In this paper, we empirically validate a recently-proposed impedance-based RIS channel model that accounts for the mutual coupling at the antenna array and precisely models the presence of scattering objects within the environment as a discrete array of loaded dipoles. To this end, we exploit real-life channel measurements collected in an office environment to demonstrate the validity of such a model and its applicability in a practical scenario. Finally, we provide numerical results demonstrating that designing the RIS configuration based upon such model leads to superior performance as compared to reference schemes.
A Unified Framework for Pulse-Shaping on Delay-Doppler Plane
paper_authors: Mohsen Bayat, Arman Farhang for: This paper aims to classify and analyze the properties of different pulse-shaping techniques used in delay-Doppler multiplexing, and to develop a unified framework for understanding their similarities and distinctions.methods: The paper uses a combination of theoretical analysis and simulation to classify pulse-shaping techniques into two types: circular and linear, and to derive a generalized input-output relationship that captures the influence of pulse-shaping on the effective channel. The authors also propose a unified modem for delay-Doppler plane pulse-shaping and introduce effective techniques to reduce OOB emissions and improve BER performance.results: The paper reveals that the recently emerged waveform ODDM is a linear pulse-shaping technique with an interesting staircase spectral behavior. The proposed modem structures are substantially simpler than existing ones in the literature, and the proposed techniques can reduce OOB emissions and improve BER performance for both circular and linear pulse-shaping techniques. The paper also extensively compares different pulse-shaping techniques using various performance metrics.Here is the answer in Simplified Chinese text:for: 这篇论文的目的是为了分类和分析不同的激光整形技术在延迟-Doppler多路复用中的应用，并发展一个统一的框架，以便更好地理解这些技术之间的相似性和差异。methods: 这篇论文使用了理论分析和 simulating 来分类激光整形技术为两种：圆拱和线性，并 derivate 一个通用的输入-输出关系，以捕捉激光整形对有效通道的影响。作者还提出了一个统一的模式机制，以便在延迟-Doppler平面上进行整形。results: 这篇论文发现，最近提出的波形ODDM是一种线性整形技术，具有一个有趣的楔形频率特性。提出的模式结构比现有的文献中的结构更加简单，并且提出的技术可以降低圆拱整形信号的射频干扰和提高BER性能。论文还对不同的整形技术进行了广泛的比较，使用了多种性能指标。Abstract
Delay-Doppler multiplexing has recently stirred a great deal of attention in research community. While multiple studies have investigated pulse-shaping aspects of this technology, it is challenging to identify the relationships between different pulse-shaping techniques and their properties. Hence, in this paper, we classify these techniques into two types, namely, circular and linear pulse-shaping. This paves the way towards the development of a unified framework that brings deep insights into the properties, similarities, and distinctions of different pulse-shaping techniques. This framework reveals that the recently emerged waveform orthogonal delay-Doppler multiplexing (ODDM) is a linear pulse-shaping technique with an interesting staircase spectral behaviour. Using this framework, we derive a generalized input-output relationship that captures the influence of pulse-shaping on the effective channel. We also introduce a unified modem for delay-Doppler plane pulse-shaping that leads to the proposal of fast convolution based low-complexity structures. Based on our complexity analysis, the proposed modem structures are substantially simpler than the existing ones in the literature. Furthermore, we propose effective techniques that not only reduce the out-of-band (OOB) emissions of circularly pulse-shaped signals but also improve the bit-error-rate (BER) performance of both circular and linear pulse-shaping techniques. Finally, we extensively compare different pulse-shaping techniques using various performance metrics.
摘要
延迟-多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多普勒多
Wearable Technologies for Monitoring Upper Extremity Functions During Daily Life in Neurologically Impaired Individuals
paper_authors: Tommaso Proietti, Andrea Bandini for: This review focuses on wearable technologies to monitor upper extremity (UE) function in neurologically impaired individuals during daily life activities.methods: The review categorizes different sensors, data collection and data processing approaches employed in wearable technologies for UE function monitoring.results: The majority of studies involved stroke survivors, and predominantly employed inertial measurement units and accelerometers to collect kinematics. Most analyses were performed offline, focusing on activity duration and frequency as key metrics. However, an ideal solution that combines non-intrusiveness, lightweight design, detailed hand and finger movement capture, contextual information, extended recording duration, ease of use, and privacy protection remains an elusive goal.Abstract
Neurological disorders, including stroke, spinal cord injuries, multiple sclerosis, and Parkinson's disease, generally lead to diminished upper extremity (UE) function, impacting individuals' independence and quality of life. Traditional assessments predominantly focus on standardized clinical tasks, offering limited insights into real-life UE performance. In this context, this review focuses on wearable technologies as a promising solution to monitor UE function in neurologically impaired individuals during daily life activities. Our primary objective is to categorize the different sensors, data collection and data processing approaches employed. What comes to light is that the majority of studies involved stroke survivors, and predominantly employed inertial measurement units and accelerometers to collect kinematics. Most analyses in these studies were performed offline, focusing on activity duration and frequency as key metrics. Although wearable technology shows potential in monitoring UE function in real-life scenarios, an ideal solution that combines non-intrusiveness, lightweight design, detailed hand and finger movement capture, contextual information, extended recording duration, ease of use, and privacy protection remains an elusive goal. Furthermore, it stands out a growing necessity for a multimodal approach in capturing comprehensive data on UE function during real-life activities to enhance the personalization of rehabilitation strategies and ultimately improve outcomes for these individuals.
摘要
神经系统疾病，包括中风、脊梁损伤、多发性硬化病和 Parkinson 病，通常导致上肢功能减退，影响个体独立和生活质量。传统评估主要集中在标准临床任务上，提供有限的实际生活活动信息。在这种情况下，本文报告着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着着��
A study on Satellite-to-Ground Propagation in Urban Environment
results: 研究发现，在非直线视场情况下，非 Specular反射 debido to surface irregularities emerges as a primary propagation mechanism。此外，K因子在高度角度上显示一个轻微增加趋势，与之前的研究不同。Abstract
Non-Terrestrial Networks are going to play an important role in future 6G wireless networks to enhance global connectivity a performance in cooperation with terrestrial networks. In order to properly design and deploy non-terrestrial networks, the satellite-to-ground channel must be properly characterized, with particular focus on the urban environment. This paper uses a Ray-Tracing simulation tool to analyze the primary propagation mechanisms and the behaviour of the Rician K-factor as a function of satellite position in a reference urban environment. Non-specular reflection due to surface irregularities emerges as a primary propagation mechanism in non-line-of-sight cases. Additionally, the Rician K-factor shows a slightly increasing trend with elevation angle, in contrast to previous studies.
摘要
非地面网络在未来6G无线网络中将扮演重要的角色，以提高全球连接性和性能，并在地面网络的协作下进行设计和部署。为了正确地设计和部署非地面网络，需要准确地 caracterize satellite-to-ground通道，特别是在 urbano环境中。这篇文章使用了射线轨迹模拟工具来分析主要媒体传播机制和射线K-因子在参照城市环境中的行为，发现非 Specular反射因为表面不规则的影响是非线性媒体传播机制的主要作用。此外，射线K-因子与高度角度有一些提升趋势，与前一些研究不同。
Constellation Shaping under Phase Noise Impairment for Sub-THz Communications
results: 本文的实验结果表明，通过使用提出的优化方法，可以实现一种phasenoise和PAPR问题的 numerically robust的SC-FDE波形，并且可以保持低的PAPR值。Abstract
The large untapped spectrum in the sub-THz allows for ultra-high throughput communication to realize many seemingly impossible applications in 6G. One of the challenges in radio communications in sub-THz is the hardware impairments. Specifically, phase noise is one key hardware impairment, which is accentuated as we increase the frequency and bandwidth. Furthermore, the modest output power of the sub-THz power amplifier demands limits on peak to average power ratio (PAPR) signal design. Single carrier frequency domain equalization (SC-FDE) waveform has been identified as a suitable candidate for sub-THz, although some challenges such as phase noise and PAPR still remain to be tackled. In this work, we design a phase noise robust, low PAPR SC-FDE waveform by geometrically shaping the constellation under practical conditions. We formulate the waveform optimization problem in its augmented Lagrangian form and use a back-propagation-inspired technique to obtain a constellation design that is numerically robust to phase noise, while maintaining a low PAPR.
摘要
“对于6G中的几个不可能的应用，让大量未使用的频谱在低频 THz 频段提供了无限高的通信能力。但是，对于射频通信在低频 THz 频段的一个挑战是硬件障碍。具体来说，频率干扰是一个关键的硬件障碍，随着频率和宽度的增加，这个问题会更加突出。此外，低频 THz 发射器的输出功率较低，对于峰值至平均功率比（PAPR）的限制也是一个挑战。单束频率领域均衡（SC-FDE）波形已被识别为低频 THz 的适合选择，但是这些问题仍然需要解决。在这个工作中，我们设计了具有几何对称的、低 PAPR SC-FDE 波形，并通过实际条件下的几何对称形成问题来解决这些问题。我们使用了一种具有调适问题的扩展拉格朗日式问题，并使用一种基于复调的技术来获得一个可 numerically 具有对频率干扰的免疫力，同时维持低 PAPR。”
A Hybrid Frame Structure Design of OTFS for Multi-tasks Communications
results: 我们发现在通道卷积后，这种多元化被打乱，我们提供了实用的算法来 Mitigate ISI между OTFS 和 OFDM，并且数值结果证明了混合帧结构的效果。Abstract
Orthogonal time frequency space (OTFS) is a promising waveform in high mobility scenarios for it fully exploits the time-frequency diversity using a discrete Fourier transform (DFT) based two dimensional spreading. However, it trades off the processing latency for performance and may not fulfill the stringent latency requirements in some services. This fact motivates us to design a hybrid frame structure where the OTFS and Orthogonal Frequency Division Multiplexing (OFDM) are orthogonally multiplexed in the time domain, which can adapt to both diversity-preferred and latency-preferred tasks. As we identify that this orthogonality is disrupted after channel coupling, we provide practical algorithms to mitigate the inter symbol interference between (ISI) the OTFS and OFDM, and the numerical results ensure the effectiveness of the hybrid frame structure.
摘要
高度可移植的时域频率空间（OTFS）是一种有前途的波形，它在高速移动场景中充分利用时域频率多样性，使用基于离散傅里叶变换（DFT）的二维扩散。然而，它需要让处理延迟与性能之间进行权衡，并且可能不符合一些服务的串行时间要求。这种情况驱使我们设计一种混合帧结构，其中OTFS和Orthogonal Frequency Division Multiplexing（OFDM）在时域上相互对抗，以适应多样性和延迟两个任务。然而，我们发现在通道对接后，这种一致性被破坏，因此我们提供了实用的算法来 Mitigate the inter symbol interference（ISI）between OTFS和OFDM，并且数学结果证明了混合帧结构的有效性。