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Delay Alignment Modulation with Hybrid Analog/Digital Beamforming for Millimeter Wave and Terahertz Communications

IEEE Transactions on Wireless Communications 2025年

作者： Zhang, Jieni Zeng, Yong Yu, Xiangbin Jin, Shi Yuan, Jinhong Liang, Ying-Chang Zhang, Rui Southeast University National Mobile Communication Research Laboratory Nanjing210096 China Purple Mountain Laboratories Nanjing211111 China Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing210016 China The University of New South Wales School of Electrical Engineering and Telecommunications SydneyNSW2052 Australia Chengdu611731 China The Chinese University of Hong Kong School of Science and Engineering Shenzhen Research Institute of Big Data Guangdong Shenzhen518172 China National University of Singapore Department of Electrical and Computer Engineering 117583 Singapore

For millimeter wave (mmWave) or Terahertz (THz) communications, by leveraging the high spatial resolution offered by large antenna arrays and the multi-path sparsity of mmWave/THz channels, a novel inter-symbol interference (ISI) mitigation technique called delay alignment modulation (DAM) has been recently proposed. The key ideas of DAM are delay pre-compensation and path-based beamforming. However, existing research on DAM is mainly based on fully digital beamforming, which requires the number of radio frequency (RF) chains to be equal to the number of antennas. This paper proposes the hybrid analog/digital beamforming based DAM, including both fully and partially connected structures. The analog and digital beamforming matrices are designed to achieve performance close to DAM based on fully digital beamforming. While DAM was considered for the path-based channel model with integer delays in the previous work, this paper extends DAM to a more general tap-based model that accounts for fractional path delays. To further reduce the cost of channel estimation and improve the performance for wireless channels with fractional delays, DAM with codebook-based beam alignment and DAM-orthogonal frequency division multiplexing (DAM-OFDM) with hybrid beamforming are proposed. The effectiveness of the proposed techniques is verified by extensive simulation results. © 2002-2012 IEEE.

关键词： Beamforming

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Efficient Network Representation Learning via Cluster Similarity 28th

Efficient Network Representation Learning via Cluster Simil...

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28th International Conference on database Systems for Advanced Applications, DASFAA 2023

作者： Fujiwara, Yasuhiro Ida, Yasutoshi Kumagai, Atsutoshi Nakano, Masahiro Kimura, Akisato Ueda, Naonori NTT Communication Science Laboratories Kanagawa Atsugi Japan NTT Computer and Data Science Laboratories Tokyo Musashino Japan

ISBN: (纸本)9783031306747

Network representation learning is a de-facto tool for graph analytics. The mainstream of the previous approaches is to factorize the proximity matrix between nodes. However, if n is the number of nodes, since the size of the proximity matrix is n× n, it needs O(n3) time and O(n2) space to perform network representation learning. The proposed approach computes the representations of the clusters from similarities between clusters and computes the representations of nodes by referring to them. If l is the number of clusters, since l n, we can efficiently obtain the representations of clusters from a small l× l similarity matrix. Experiments show that our approach can perform network representation learning more efficiently and effectively than existing approaches. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Algorithm Efficient Network representation learning

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Moiré Reduction Method for Visually Equivalent Light Field Display Using Special Barrier Aperture Structure 29

Moiré Reduction Method for Visually Equivalent Light Field ...

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29th International Display Workshops, IDW 2022

作者： Date, Munekazu Mitasaki, Tokinobu Matsumoto, Ayumi Kitahara, Masaki NTT Computer and Data Science Laboratories Nippon Telegraph and Telephone Corporation Japan

A visually equivalent light field 3D (VELF3D) display is a parallax-barrier-type autostereoscopic 3D display. Since stripes of the barrier and pixels are in parallel, moiré occurred, when the barrier is placed on the screen. In this paper, we suppressed moiré by only providing unevenness in the aperture shape of the barrier. © 2022 ITE and SID.

关键词： Three dimensional displays

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Joint Optimization of Transmit Power and Trajectory for UAV-Enabled data Collection With Dynamic Constraints

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IEEE Transactions on Communications 2025年

作者： Zhang, Hongyun Li, Bin Rong, Yue Zeng, Yong Zhang, Rui School of Aeronautics and Astronautics Sichuan University Sichuan Chengdu610065 China The School of Electrical Engineering Computing and Mathematical Sciences Curtin University GPO Box U1987 PerthWA6845 Australia National Mobile Communications Research Laboratory Southeast University Jiangsu Nanjing210096 China The Purple Mountain Laboratories Nanjing211111 China School of Science and Engineering Shenzhen Research Institute of Big Data The Chinese University of Hon g Kong Guangdong Shenzhen518172 China The Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore

The unmanned aerial vehicle (UAV)-enabled data collection system with a rotary-wing UAV and multiple ground nodes (GNs) is investigated in this paper. The average transmission data rate is maximized through the coordinated optimization of the GNs’ transmit power and the UAV’s trajectory. In particular, the UAV dynamic constraints and physical constraints are imposed. The UAV dynamics, which are governed by a group of differential equations, are usually ignored in existing works. As a consequence, the planned trajectory cannot be fully tracked by the controller in real world applications, which could lead to severe performance degradation. Thus, a control-based method is devised to address this issue. Specifically, by adopting the state-space model from control theory, the data collection problem is established as a dynamic optimization problem subject to state constraints, in which both of the decision variables and constraints are infinite-dimensional in nature. The key idea of the solution method is to convert the infinite-dimensional dynamic program into a finite-dimensional static nonlinear problem. This is achieved by deriving the required gradients of the dynamic optimization problem based on the control parametrization scheme and an exact penalty function method. The effectiveness and superiority of the proposed design are validated via numerical experiments. © 1972-2012 IEEE.

关键词： State space methods

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Improving Raft Performance with Bulk Transfers 11

Improving Raft Performance with Bulk Transfers

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11th International Symposium on Computing and Networking Workshops, CANDARW 2023

作者： Yamashita, Aoi Tanaka, Masahiro Bessho, Yutaro Fujiwara, Yasuhiro Kawashima, Hideyuki Graduate School of Keio University Japan Ntt Computer and Data Science Laboratories Japan Ntt Communication Science Laboratories Japan Keio University Japan

ISBN: (纸本)9798350306941

Raft is known as a replicating state machine that tolerates crash faults, and its use enables various distributed systems, including distributed transaction processing systems. The original Raft protocol creates an intra-cluster consensus by having the leader generate a log of each incoming client request and replicate it to its followers. When requests arrive frequently, the number of replications increases, increasing the number of communications and possibly leading to performance degradation. To solve this problem, we propose a bulk-transfer protocol that replicates multiple requests at once. We implemented the Raft system to verify the effect of the proposed method. We measured the performance of the implemented system when multiple requests were transferred in bulk and observed an increase in throughput with an increase in the amount of data replicated at a time. The highest throughput of 214 MB/sec was achieved when replicating 12.5 MB at a time. This is 12,066 times higher than the performance when replicating one request (18 B) at a time. Besides, the size of the log is reduced to 5/9 of the conventional method. © 2023 IEEE.

关键词： Distributed computer systems

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A Tutorial on Movable Antennas for Wireless Networks

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IEEE Communications Surveys and Tutorials 2025年

作者： Zhu, Lipeng Ma, Wenyan Mei, Weidong Zeng, Yong Wu, Qingqing Ning, Boyu Xiao, Zhenyu Shao, Xiaodan Zhang, Jun Zhang, Rui National University of Singapore Department of Electrical and Computer Engineering 117583 Singapore National Key Laboratory of Wireless Communications Chengdu611731 China Southeast University National Mobile Communications Research Laboratory Frontiers Science Center for Mobile Information Communication and Security Nanjing210096 China Purple Mountain Laboratories Nanjing211111 China Shanghai Jiao Tong University Department of Electronic Engineering Shanghai200240 China Beihang University School of Electronic and Information Engineering Beijing100191 China University of Waterloo Department of Electrical and Computer Engineering WaterlooONN2L 3G1 Canada Beijing Institute of Technology State Key Laboratory of CNS/ATM Miit Key Laboratory of Complex-field Intelligent Sensing Beijing100081 China The Chinese University of HongKong School of Science and Engineering Shenzhen Research Institute of Big Data Guangdong Shenzhen518172 China

Movable antenna (MA) has been recognized as a promising technology to enhance the performance of wireless communication and sensing by enabling antenna movement. Such a significant paradigm shift from conventional fixed antennas (FAs) to MAs offers tremendous new opportunities towards realizing more versatile, adaptive and efficient next-generation wireless networks such as 6G. In this paper, we provide a comprehensive tutorial on the fundamentals and advancements in the area of MA-empowered wireless networks. First, we overview the historical development and contemporary applications of MA technologies. Next, to characterize the continuous variation in wireless channels with respect to antenna position and/or orientation, we present new field-response channel models tailored for MAs, which are applicable to narrowband and wideband systems as well as far-field and near-field propagation conditions. Subsequently, we review the state-of-the-art architectures for implementing MAs and discuss their practical constraints. A general optimization framework is then formulated to fully exploit the spatial degrees of freedom (DoFs) in antenna movement for performance enhancement in wireless systems. In particular, we delve into two major design issues for MA systems. First, we address the intricate antenna movement optimization problem for various communication and/or sensing systems to maximize the performance gains achievable by MAs. Second, we deal with the challenging channel acquisition issue in MA systems for reconstructing the channel mapping between arbitrary antenna positions inside the transmitter and receiver regions. Moreover, we show existing prototypes developed for MA-aided communication/sensing and the experimental results based on them. Finally, the extension of MA design to other wireless systems and its synergy with other emerging wireless technologies are discussed. We also highlight promising research directions in this area to inspire future investigatio

关键词： Antenna arrays

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Visually Equivalent Light Field 3-D for Portable Displays

Visually Equivalent Light Field 3-D for Portable Displays

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作者： Date, Munekazu Shimizu, Shinya Yamamoto, Susumu Nippon Telegraph and Telephone Corporation Ntt Computer and Data Science Laboratories Yokosuka239-0847 Japan Ntt Computer and Data Science Laboratories Yokosuka239-0847 Japan Nippon Telegraph and Telephone Corporation Ntt Human Informatics Laboratories Tokyo108-0023 Japan

Highly realistic 3-D displays that can reproduce object images to look like physical objects are utilized for natural and correct remote operation in industrial scenes. Therefore, we developed a visually equivalent light field 3-D (VELF3D) display that can produce highly realistic, accurate images with a high resolution and a smooth, accurate motion parallax. However, the observation distance is slightly long, and users cannot reach the displayed images. Therefore, we aim to develop a tablet-computer-type VELF3D display that enables users to touch the displayed objects. The display viewpoint density has been increased to achieve a shorter observation distance, while maintaining the display depth range. Because higher resolutions are required for a close observation distance and increased display viewpoints, we aimed to improve the effective resolution using almost the same pixel pitch display panel. Therefore, we built a prototype that combines a vertical red, green, blue stripe display panel and a parallax barrier with subpixel width slits. We confirmed effective resolution improvement by tiny subjective tests. This method also helps increase the depth range of the display when it is observed from a normal distance. © 1972-2012 IEEE.

关键词： Three dimensional displays

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Receding-Horizon Trajectory Planning for Under-Actuated Autonomous Vehicles Based on Collaborative Neurodynamic Optimization

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IEEE/CAA Journal of Automatica Sinica 2022年第11期9卷 1909-1923页

作者： Jiasen Wang Jun Wang Qing-Long Han IEEE the Future Network Research Center Purple Mountain LaboratoriesNanjing 211111China the Department of Computer Science the School of Data ScienceCity University of Hong KongHong KongChina the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia

This paper addresses a major issue in planning the trajectories of under-actuated autonomous vehicles based on neurodynamic optimization.A receding-horizon vehicle trajectory planning task is formulated as a sequential global optimization problem with weighted quadratic navigation functions and obstacle avoidance constraints based on given vehicle goal *** feasibility of the formulated optimization problem is guaranteed under derived *** optimization problem is sequentially solved via collaborative neurodynamic optimization in a neurodynamics-driven trajectory planning method/*** results with under-actuated unmanned wheeled vehicles and autonomous surface vehicles are elaborated to substantiate the efficacy of the neurodynamics-driven trajectory planning method.

关键词： Collaborative neurodynamic optimization receding-horizon planning trajectory planning under-actuated vehicles

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Fast Sparse Modeling Technology Opening Up the Future with Ultra-high-dimensional data

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NTT Technical Review 2023年第6期21卷 12-16页

作者： Ida, Yasutoshi NTT Computer and Data Science Laboratories

As one pillar of NTT’s IOWN (Innovative Optical and Wireless Network) vision, Digital Twin Computing aims to construct the world in a digital space. To this end, it is essential that data be obtained from people and things by sensors. However, advances in sensing technologies have created a new issue in which an increase in the number of data dimensions makes processing time longer, which makes it difficult to analyze and use collected data within a realistic period of time. We asked NTT Distinguished Researcher Yasutoshi Ida to tell us about "fast sparse modeling technology" as a means of solving this problem. © 2023 Nippon Telegraph and Telephone Corp.. All rights reserved.

关键词： Deep learning

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Software Digital Twins for Reducing Software Waste and Achieving a Sustainable IT Society

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NTT Technical Review 2024年第2期22卷 6-10页

作者： Saito, Shinobu NTT Computer and Data Science Laboratories Japan

The global information and technology services market for 2022 was reported to be 1.3 trillion U.S. dollars (about 150 trillion yen), and it’s been pointed out that the massive amount of software produced by this market demand, while bringing great value to our daily lives, has also led to a variety of problems. There are expectations that an approach that not only seeks to increase the amount of software (production) but to also reduce that amount (reduction) could help solve those problems. In this interview, we asked NTT Distinguished Researcher Shinobu Saito about his research on "Software Digital Twins." © 2024 Nippon Telegraph and Telephone Corp.. All rights reserved.

关键词： Commerce

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