results: 本文总结了这些非侵入式技术的优点和缺点，并展示了它们在各种应用场景中的应用。Abstract
Research on Brain-Computer Interface (BCI) began in the 1970s and has increased in volume and diversified significantly since then. Today BCI is widely used for applications like assistive devices for physically challenged users, mental state monitoring, input devices for hands-free applications, marketing, education, security, games and entertainment. This article explores the advantages and disadvantages of invasive and non-invasive BCI technologies and focuses on use cases of several non-invasive technologies, namely electroencephalogram (EEG), functional Magnetic Resonance Imaging (fMRI), Near Infrared Spectroscopy (NIRs) and hybrid systems.
摘要
研究Brain-Computer Interface（BCI）始于1970年代，自 then onwards 已经增加了量和多样化了很多。今天，BCI 广泛应用于帮助 físically challenged 用户、监测 mental state、手sfree 应用程序的输入设备、marketing、教育、安全、游戏和娱乐等领域。本文介绍了 BCIs 的优势和缺点，并关注了多种非侵入式技术的应用情况，namely 电энцефаogram（EEG）、功能磁共振成像（fMRI）、近红外 спектроскопи（NIRs）和混合系统。
Performance Evaluation for Subarray-based Reconfigurable Intelligent Surface-Aided Wireless Communication Systems
paper_authors: Xinyi Yang, Weicong Chen, Xiao Li, Shi Jin
for: 提高无线通信系统性能，研究基于减数阵的智能表面协助系统
methods: 使用基于减数阵的协助技术，分析和优化协助系统中的反射率和谱系数
results: 提出基于减数阵的协助系统可以提高系统的均衡 spectral efficiency 和能效率，并且可以同时降低功率消耗和反射率Note: The above results are in Simplified Chinese text.Abstract
Reconfigurable intelligent surfaces (RISs) have received extensive concern to improve the performance of wireless communication systems. In this paper, a subarray-based scheme is investigated in terms of its effects on ergodic spectral efficiency (SE) and energy efficiency (EE) in RIS-assisted systems. In this scheme, the adjacent elements divided into a subarray are controlled by one signal and share the same reflection coefficient. An upper bound of ergodic SE is derived and an optimal phase shift design is proposed for the subarray-based RIS. Based on the upper bound and optimal design, we obtain the maximum of the upper bound. In particular, we analytically evaluate the effect of the subarray-based RIS on EE since it reduces SE and power consumption simultaneously. Numerical results verify the tightness of the upper bound, demonstrate the effectiveness of the optimal phase shift design for the subarray-based RIS, and reveal the effects of the subarray-based scheme on SE and EE.
摘要
改进无线通信系统性能的重 Configurable intelligent surfaces (RISs) 已经引起了广泛关注。本文 investigate 一种基于subarray的方案，包括其对ergodic spectral efficiency (SE) 和能效率 (EE) 的影响。在这种方案中，邻近元素被分成一个subarray，并由一个信号控制，共享相同的反射系数。我们 derive 一个上限 bound 的ergodic SE，并提出了一种优化的相位偏移设计。基于上限 bound 和优化设计，我们获得了最大的上限。具体来说，我们分析了subarray-based RIS 对EE的影响，因为它同时降低了SE和功率消耗。 numerically 结果证明了上限 bound 的紧张性，证明了优化相位偏移设计的效果，并揭示了subarray-based scheme 对SE和EE的影响。
Guaranteed Private Communication with Secret Block Structure
results: 研究表明，在某些特定的频率和传输参数下，伪装者可以尝试从通道输出的四次趋势中提取秘密块结构。然而，计算一个统计下界，表明该提出的四次趋势秘密块估计策略几乎是优化的。此外，研究表明，通过spectral clustering算法，可以定义扩大秘密键的时间长度，以确保通信的安全性。Abstract
A novel private communication framework is proposed where privacy is induced by transmitting over channel instances of linear inverse problems that are identifiable to the legitimate receiver, but unidentifiable to an eavesdropper. The gap in identifiability is created in the framework by leveraging secret knowledge between the transmitter and the legitimate receiver. Specifically, the case where the legitimate receiver harnesses a secret block structure to decode a transmitted block-sparse message from underdetermined linear measurements in conditions where classical compressed sensing would provably fail is examined. The applicability of the proposed scheme to practical multiple access wireless communication systems is discussed. The protocol's privacy is studied under a single transmission, and under multiple transmissions without refreshing the secret block structure. It is shown that, under a specific scaling of the channel dimensions and transmission parameters, the eavesdropper can attempt to overhear the block structure from the fourth-order moments of the channel output. Computation of a statistical lower bound, suggests that the proposed fourth-order moment secret block estimation strategy is near optimal. The performance of a spectral clustering algorithm is studied to that end, defining scaling laws on the lifespan of the secret key before the communication is compromised. Finally, numerical experiments corroborating the theoretical findings are conducted.
摘要
一种新的私人通信框架被提议，其中隐私是通过在通道上传输线性逆问题的实例，这些问题只能被合法接收者识别出来，但不能被侦测者识别出来。在这个框架中，通过 transmitter 和合法接收者之间的秘密知识来创造不可识别的差异。例如，在 transmitter 将块稀疏消息从不充分的线性测量中解码的情况下，合法接收者可以利用秘密块结构来解码消息。本文探讨了这种方案在实际多接入无线通信系统中的可行性，并研究了协议的隐私性。在单次传输和多次传输无需刷新秘密块结构的情况下，分析表明，在某些频率缩放和传输参数的情况下，侦测者可以尝试从通道输出的四次 moments 中找到秘密块结构。计算统计下界，表明该提议的四次 moment 秘密块估计策略是近似优美的。此外，对spectral clustering算法的研究表明，在某些频率缩放和传输参数的情况下，秘密钥的寿命会随着通信的增加而减少。最后，通过实验证明了理论发现的结论。
A Proof of Concept for OTFS Resilience in Doubly-Selective Channels by GPU-Enabled Real-Time SDR
paper_authors: Yi Xien Yap, Neil Bhushan, Onur Dizdar, Ata Sattarzadeh, David Redgate, Venkateswara Battula, Stephen Wang
for: 该论文旨在研究Orthogonal Time Frequency Space (OTFS) 模ulation技术，并在实际的实时Software Defined Radio (SDR) 设置中进行实验研究。
methods: 该论文使用了一个基于 Graphical Processing Unit (GPU) 的信号处理程序，以及 Universal Software Radio Peripheral (USRP) 设备来实现一个低延迟的接收结构，并在不同的Doppler值下调查其性能。
results: 研究结果表明，OTFS 比 OFDM 更高度具有对双选择通道的鲁棒性，并在实际实验中表现出色。Abstract
Orthogonal time frequency space (OTFS) is a modulation technique which is robust against the disruptive effects of doubly-selective channels. In this paper, we perform an experimental study of OTFS by a real-time software defined radio (SDR) setup. Our SDR consists of a Graphical Processing Unit (GPU) for signal processing programmed using Sionna and TensorFlow, and Universal Software Radio Peripheral (USRP) devices for air interface. We implement a low-latency transceiver structure for OTFS and investigate its performance under various Doppler values. By comparing the performance of OTFS with Orthogonal Frequency Division Multiplexing (OFDM), we demonstrate that OTFS is highly robust against the disruptive effects of doubly-selective channels in a real-time experimental setup.
摘要
水平时频空间（OTFS）是一种干扰强度较弱的模调技术，可以在双 selektiv通道中具有高Robustness。在这篇论文中，我们通过实验研究了OTFS，使用了一个真实时间定制的Software Defined Radio（SDR）设置。我们的SDR包括一个图形处理器（GPU）用于信号处理，并使用Sionna和TensorFlow编程，以及Universal Software Radio Peripheral（USRP）设备用于空中接口。我们实现了一种低延迟的接收结构，并在不同的Doppler值下调查其性能。通过对OTFS和Orthogonal Frequency Division Multiplexing（OFDM）的比较，我们表明了OTFS在真实时间实验设置中对双 selektiv通道的破坏性影响具有高Robustness。
Multiple Satellites Collaboration for Joint Code-aided CFOs and CPOs Estimation
For: 提高低Earth轨道卫星网络的安全性和可靠性* Methods: 使用合作卫星技术，并提出了一种基于编码的迭代参数估计算法来解决低信号噪比下的参数估计挑战* Results: simulation results show that the proposed algorithm can approach Bit Error Rate (BER) performance bound within 0.4 dB with regards to four-satellite collaboration.Abstract
Low Earth Orbit (LEO) satellites are being extensively researched in the development of secure Internet of Remote Things (IoRT). In scenarios with miniaturized terminals, the limited transmission power and long transmission distance often lead to low Signal-to-Noise Ratio (SNR) at the satellite receiver, which degrades communication performance. A solution to address this issue is the utilization of cooperative satellites, which can combine signals received from multiple satellites, thereby significantly improve SNR. However, in order to maximize the combination gain, the signal coherent combining is necessary, which requires the carrier frequency and phase of each receiving signal to be aligned. Under low SNR circumstances, carrier parameter estimation can be a significant challenge, especially for short burst transmission with no training sequence. In order to tackle it, we propose an iterative code-aided estimation algorithm for joint Carrier Frequency Offset (CFO) and Carrier Phase Offset (CPO). The Cram\'er-Rao Lower Bound (CRLB) is suggested as the limit on the parameter estimation performance. Simulation results demonstrate that the proposed algorithm can approach Bit Error Rate (BER) performance bound within 0.4 dB with regards to four-satellite collaboration.
摘要
低地球轨道（LEO）卫星在网络 remote Things（IoRT）的开发中被广泛研究。在具有小型终端的场景下，由于传输功率和传输距离都很小，因此在卫星接收器上常常出现低信噪比（SNR），这会降低通信性能。为解决这个问题，可以利用合作卫星，即将多个卫星接收器的信号合并，从而显著提高SNR。然而，为了最大化合并增益，需要进行信号干涉合并，这需要每个接收信号的干涉频率和相位相同。在低SNR情况下，干涉参数估计可能是一个 significiant挑战，特别是在短暂的传输中没有训练序列。为解决这个问题，我们提出了一种迭代码帮助估计算法，用于同时估计干涉频率偏移（CFO）和干涉相位偏移（CPO）。对于四个卫星的合作，我们提出的算法可以在0.4dB之内 approaching Bit Error Rate（BER）性能 bound。
Alteration of skeletal muscle energy metabolism assessed by 31P MRS in clinical routine, part 1: Advanced Quality Control pipeline
paper_authors: Antoine Naëgel, Hélène Ratiney, Jabrane Karkouri, Djahid Kennouche, Nicolas Royer, Jill M Slade, Jérôme Morel, Pierre Croisille, Magalie Viallon
for: 本研究目的是提供一种基于Literature current recommendations和临床经验所提出的数据质量控制方法，以帮助在 dynamic 31P-MRS 数据处理中获得可靠的结果。
results: 使用QCS可以快速标识具有数据异常的 subjects，并提供对数据进行修正的指导。总的来说，QCS使得可以自动分类45%的 subjects，其中58名参与者的数据没有规则违反，21名参与者的数据需要拒绝。此外，手动审核还可以Acceptance of full datasets from an additional 80 participants and recovery phase data from an additional 16 subjects。总之，patient数据中出现了更多的异常（35%的dataset），比healthy controls（15%的dataset）更高。Abstract
Background: Implementing a standardized 31P-MRS dynamic acquisition protocol to evaluate skeletal muscle energy metabolism and monitor muscle fatigability1,2, while being compatible with various longitudinal clinical studies on diversified patient cohorts, requires a high level of technicality and expertise. Furthermore, processing data to obtain reliable results also demands a great degree of expertise from the operator. In this two-part article, we present an advanced quality control approach for data acquired using a dynamic 31P-MRS protocol. The aim is to provide decision support to the operator in order to assist in data processing and obtain reliable results based on objective criteria. We present first in part one, an advanced data quality control (QC) approach of a dynamic 31P-MRS protocol. Part two is an impact study demonstrating the added value of the QC approach to explore clinical results derived from two patient populations with significant fatigue: COVID19 and multiple sclerosis (MS). Experimental: 31P-MRS was performed on a 3T clinical MRI in 175 subjects from clinical and healthy control populations conducted in a University Hospital. An advanced data QC Score (QCS) was developed using multiple objective criteria. The criteria were based on current recommendations from the literature enriched by new proposals based on clinical experience. The QCS was designed to indicate valid and corrupt data and guide necessary objective data editing to extract as much valid physiological data as possible. Dynamic acquisitions using an MR-compatible ergometer ran over a rest(40s), exercise(2min), and a recovery phase(6min). Results: Using QCS enabled rapid identification of subjects with data anomalies allowing the user to correct the data series or reject them partially or entirely as well as identify fully valid datasets. Overall, the use of the QCS resulted in the automatic classification of 45% of the subjects including 58 participants that had data with no criterion violation and 21 participants with violations that resulted in the rejection of all dynamic data. The remaining datasets were inspected manually with guidance allowing acceptance of full datasets from an additional 80 participants and recovery phase data from an additional 16 subjects. Overall, more anomalies occurred with patient data (35% of datasets) compared to healthy controls (15% of datasets). Conclusion: This paper describes typical difficulties encountered during the dynamic acquisition of 31P-MRS. Based on these observations, a standardized data quality control pipeline was created and implemented in both healthy and patient populations. The QC scoring ensures a standardized data rejection procedure and rigorous objective analysis of dynamic 31P-MRS data obtained from patients. The contribution of this methodology contributes to efforts made to standardize the practices of the 31P-MRS that has been underway for a decade, with the ultimate goal of making it an empowered tool for clinical research.
摘要
Background: 实施标准化31P-MRS动态获取协议，以评估骨骼肌能量代谢和监测肌肉疲劳性，需要高水平的技术性和专业知识。此外，从操作员处理数据以获得可靠结果也需要很高的专业度。在这两篇文章中，我们提出了一种高级数据质控方法，以帮助操作员在数据处理中做出客观的决策。在第一篇文章中，我们介绍了一种高级数据质控方法，以帮助操作员在数据处理中做出客观的决策。第二篇文章是一项影响研究，探讨了这种质控方法在 COVID-19 和多发性骨骼炎（MS）两种疲劳性疾病中的价值。Experimental: 31P-MRS在3T临床MRI上进行了175名临床和健康控制群体的测试。我们开发了一种多重目的 criterion 基于当前文献的建议，以及我们的临床经验所提出的新建议。这种 QCS 是用来指示有效和假数据，并帮助操作员对数据进行客观编辑，以提取最多可靠生物学数据。动态获取使用 MR 兼容的自行车在休息（40s）、运动（2分）和恢复阶段（6分）。结果：通过 QCS，可以快速标识具有数据异常的主体，并让用户对数据系列进行修正或者部分或全部拒绝。总的来说，使用 QCS 导致了自动将45%的主体分类为有效数据，其中有58名参与者没有任何 criterion 违反，而有21名参与者因违反 criterion 而拒绝了所有动态数据。剩下的数据被手动检查，以确定是否acceptable。总的来说， patient 数据中出现了更多的异常（35%的数据），compared to healthy controls（15%的数据）。结论：这篇文章描述了在动态获取31P-MRS数据时常见的困难。基于这些观察，我们创建了一个标准化的数据质控管道，并在健康和疾病人群中实施。 QCS scoring 确保了一个标准化的数据拒绝程序，并且对动态31P-MRS数据从病人中得到的结果进行了严格的客观分析。本质控方法的贡献是为标准化31P-MRS实践做出了贡献，这一实践已经在过去十年中进行了不断的标准化努力，以使其成为严格的研究工具。
Multi-objective Optimization of Space-Air-Ground Integrated Network Slicing Relying on a Pair of Central and Distributed Learning Algorithms
methods: 本文提出了一种基于多智能agent的 deep deterministic policy gradient（CDMADDPG）算法，用于同时优化三种类型的RAN slice的吞吐量、延迟和覆盖面积。
results: simulation 结果表明，提出的方法可以尝试到Pareto优化多个RAN slice，并超越参考模型。Abstract
As an attractive enabling technology for next-generation wireless communications, network slicing supports diverse customized services in the global space-air-ground integrated network (SAGIN) with diverse resource constraints. In this paper, we dynamically consider three typical classes of radio access network (RAN) slices, namely high-throughput slices, low-delay slices and wide-coverage slices, under the same underlying physical SAGIN. The throughput, the service delay and the coverage area of these three classes of RAN slices are jointly optimized in a non-scalar form by considering the distinct channel features and service advantages of the terrestrial, aerial and satellite components of SAGINs. A joint central and distributed multi-agent deep deterministic policy gradient (CDMADDPG) algorithm is proposed for solving the above problem to obtain the Pareto optimal solutions. The algorithm first determines the optimal virtual unmanned aerial vehicle (vUAV) positions and the inter-slice sub-channel and power sharing by relying on a centralized unit. Then it optimizes the intra-slice sub-channel and power allocation, and the virtual base station (vBS)/vUAV/virtual low earth orbit (vLEO) satellite deployment in support of three classes of slices by three separate distributed units. Simulation results verify that the proposed method approaches the Pareto-optimal exploitation of multiple RAN slices, and outperforms the benchmarkers.
摘要
作为下一代无线通信技术的吸引人之一，网络剖析支持多种个性化服务在全球空天地 Integrated Network (SAGIN) 中，拥有多种资源限制。在这篇论文中，我们动态考虑了三种常见的无线接入网络 (RAN) slice，namely 高速吞吐 slice, 低延迟 slice 和广泛覆盖 slice，在同一层次的物理 SAGIN 中。这三种 RAN slice 的吞吐率、服务延迟和覆盖区域都是jointly 优化的，而且考虑了不同的通信频率和服务优势，以实现 Pareto 优化解决方案。我们提出了一种基于多代理 deep deterministic policy gradient (CDMADDPG) 算法的 JOINT 中央和分布式算法来解决这个问题。该算法首先确定了最佳虚拟无人机 (vUAV) 位置和间 slice Sub-channel 和功率分配，然后对每种 slice 进行内 slice Sub-channel 和功率分配，以及虚拟基站 (vBS)/vUAV/虚拟低地球 (vLEO) 卫星部署。测试结果表明，提议的方法可以实现 Pareto 优化多个 RAN slice，并超过参考值。
Green Holographic MIMO Communications With A Few Transmit Radio Frequency Chains
results: 分析结果表明，通过增大天线覆盖面积而不增加发射RF束缚数量，可以实现绿色评估多input多output通信系统的高性能。数值结果也验证了我们的分析结论。Abstract
Holographic multiple-input multiple-output (MIMO) communications are widely recognized as a promising candidate for the next-generation air interface. With holographic MIMO surface, the number of the spatial degrees-of-freedom (DoFs) considerably increases and also significantly varies as the user moves. To fully employ the large and varying number of spatial DoFs, the number of equipped RF chains has to be larger than or equal to the largest number of spatial DoFs. However, this causes much waste as radio frequency (RF) chains (especially the transmit RF chains) are costly and power-hungry. To avoid the heavy burden, this paper investigates green holographic MIMO communications with a few transmit RF chains under an electromagnetic-based communication model. We not only look at the fundamental capacity limits but also propose an effective transmission, namely non-uniform holographic pattern modulation (NUHPM), to achieve the capacity limit in the high signal-to-noise (SNR) regime. The analytical result sheds light on the green evaluation of MIMO communications, which can be realized by increasing the size of the antenna aperture without increasing the number of transmit RF chains. Numerical results are provided to verify our analysis and to show the great performance gain by employing the additional spatial DoFs as modulation resources.
摘要
干扰多输入多输出（MIMO）通信被广泛认为是下一代无线接口的优选候选人。干扰MIMO表面上，空间度量自由（DoF）的数量增加很多，同时也因用户移动而异常变化。要完全利用这些很多和变化很大的空间DoF，需要更多的RF扩展（ especial transmit RF），但这会带来很大的浪费。为了避免这种重荷，本文研究了绿色干扰MIMO通信，使用只有一些发射RF扩展。我们不仅研究基本容量的限制，还提议非均匀干扰模式变换（NUHPM），以实现高信号噪响比（SNR）下的容量限制。分析结果抛光绿色评估MIMO通信，可以通过增加天线覆盖面积而不增加发射RF扩展。数值结果证明我们的分析结果，并显示了采用additional spatial DoF作为模ulation资源时的很大性能提升。
ViT-MDHGR: Cross-day Reliability and Agility in Dynamic Hand Gesture Prediction via HD-sEMG Signal Decoding
results: 研究发现，使用了提案的模型，可以预测11种动作，并且在20名对象中平均精度高于71%，并且在重新训练少于10%的parameters下，可以达到92%的精度。Abstract
Surface electromyography (sEMG) and high-density sEMG (HD-sEMG) biosignals have been extensively investigated for myoelectric control of prosthetic devices, neurorobotics, and more recently human-computer interfaces because of their capability for hand gesture recognition/prediction in a wearable and non-invasive manner. High intraday (same-day) performance has been reported. However, the interday performance (separating training and testing days) is substantially degraded due to the poor generalizability of conventional approaches over time, hindering the application of such techniques in real-life practices. There are limited recent studies on the feasibility of multi-day hand gesture recognition. The existing studies face a major challenge: the need for long sEMG epochs makes the corresponding neural interfaces impractical due to the induced delay in myoelectric control. This paper proposes a compact ViT-based network for multi-day dynamic hand gesture prediction. We tackle the main challenge as the proposed model only relies on very short HD-sEMG signal windows (i.e., 50 ms, accounting for only one-sixth of the convention for real-time myoelectric implementation), boosting agility and responsiveness. Our proposed model can predict 11 dynamic gestures for 20 subjects with an average accuracy of over 71% on the testing day, 3-25 days after training. Moreover, when calibrated on just a small portion of data from the testing day, the proposed model can achieve over 92% accuracy by retraining less than 10% of the parameters for computational efficiency.
摘要
superficiale electromiografia (sEMG) 和高密度 sEMG (HD-sEMG) 生物信号已经广泛研究用于 prosthetic device 控制、neurorobotics 和最近的人机交互，因为它们可以在穿着和非侵入性的方式下识别/预测手势。 高于同一天的性能已经被报道。然而， между天性能（分开训练和测试日）却很差，这限制了这些技术的应用在实际场景中。有限的最近研究表明了多天手势识别的可能性。现有的研究面临主要挑战：需要长时间的 sEMG 时间窗口，使得相关的神经接口不实用，因为引入的myoelectric控制延迟。本文提议了一个快速的 ViT 基于网络，用于多天动手势预测。我们解决了主要的挑战，因为我们的提议模型只需要非常短的 HD-sEMG 信号窗口（即 50 ms，相当于一半的实时 myoelectric 实现），提高了机敏性和响应性。我们的提议模型可以预测 11 种动手势，对 20 名参与者的测试日有效率超过 71%，并且在只使用测试日少量数据进行升级时，可以达到超过 92% 的精度。
results: 提供了一种有效的方法来最小化计算均方差误差，并且数据显示了该方法的明显优势 compared to 基于固定天线的参考系统。Abstract
A novel over-the-air computation (AirComp) framework, empowered by the incorporation of movable antennas (MAs), is proposed to significantly enhance computation accuracy. Within this framework, the joint optimization of transmit power control, antenna positioning, and receive combining is investigated. An efficient method is proposed to tackle the problem of computation mean-squared error (MSE) minimization, capitalizing on the approach of alternating optimization. Numerical results are provided to substantiate the superior MSE performance of the proposed framework, which establish its clear advantage over benchmark systems employing conventional fixed-position antennas (FPAs).
摘要
“一个基于无线电处理（AirComp）框架的新方案，利用可动天线（MA）的增强，以提高计算精度。在这个框架中，联合服务器传输电力控制、天线位置调整和接收结合优化。一种高效的方法是提出来解决计算平均方差误差（MSE）的最小化问题，基于交替优化的方法。实验结果显示了提案的框架具有明显的MSE表现优势，与传统固定天线（FPAs）的系统相比。”Note: 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.
Passive Reflection Codebook Design for IRS-Integrated Access Point
results: 实验结果表明，该设计可以提高总频谱能量平均值，并在单用户和多用户传输中实现显著的性能提升。Abstract
Intelligent reflecting surface (IRS) has emerged as a promising technique to extend the wireless signal coverage of access point (AP) and improve the communication performance cost-effectively. In order to reduce the path-loss of the cascaded user-IRS-AP channels, the IRS-integrated AP architecture has been proposed to deploy the IRSs and the antenna array of the AP within the same antenna radome. To reduce the pilot overhead for estimating all IRS-involved channels, in this paper, we propose a novel codebook-based IRS reflection design for the IRS-integrated AP to enhance the coverage performance in a given area. In particular, the codebook consisting of a small number of codewords is designed offline by employing an efficient sector division strategy based on the azimuth angle. To ensure the performance of each sector, we optimize its corresponding codeword for IRS reflection pattern to maximize the sector-min-average-effective-channel-power (SMAECP) by applying the alternating optimization (AO) and semidefinite relaxation (SDR) methods. With the designed codebook, the AP performs the IRS reflection training by sequentially applying all codewords and selects the one achieving the best communication performance for data transmission. Numerical results show that our proposed codebook design can enhance the average channel power of the whole coverage area, as compared to the system without IRS. Moreover, our proposed codebook-based IRS reflection design is shown to achieve significant performance gain over other benchmark schemes in both single-user and multi-user transmissions.
摘要
智能反射表面（IRS）已经成为一种有前途的技术，以提高无线信号覆盖范围和通信性能，而不需要大量的成本投入。为了减少用户-IRS-AP通道的偏移损耗，我们提议在同一个天线覆盖中部署IRS和AP天线阵列。为了减少估算所需的射频资源，在本文中，我们提出了一种新的codebook-based IRS反射设计，以提高在给定区域的覆盖性能。具体来说，我们采用了一个小型的codeword集合来设计codebook，通过使用高效的扇区策略来基于Azimuth角来设计。为了保证每个扇区的性能，我们对每个扇区的相应codeword进行了最优化，以最大化扇区最小平均有效通道功率（SMAECP）。通过将codebook传递给AP，AP可以通过顺序应用所有codeword来进行IRS反射训练，并选择最佳的通信性能来进行数据传输。numerical results表明，我们的提议的codebook设计可以提高整个覆盖区域的平均通道功率，相比于没有IRS的系统。此外，我们的codebook-based IRS反射设计还被证明可以在单用户和多用户传输中具有显著的性能提升。