Article
Engineering, Electrical & Electronic
Baiyang Liu, Yin Li, Amir Khurrum Rashid, Xiaonan Jiang, Sai-Wai Wong, Xiao Zhang, Kam Weng Tam, Qingfeng Zhang
Summary: This article proposes a meta-atom structure that allows for independent control of two orthogonal polarizations, and designs a high-gain broadband millimeter-wave multidimensional metasurface that can independently generate an x-polarized l=0 beam and a y-polarized l=+1 beam. The proposed metasurface exhibits dual polarization, high gain, and wide bandwidth, making it suitable for high-capacity communication systems.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Engineering, Electrical & Electronic
Yuhan Huang, Xiuping Li, Xiaobin Guo, Zihang Qi, Hua Zhu, Qingwen Li
Summary: This study proposes a single-layer reflective metasurface for generating dual-mode dual-polarized high-order Bessel vortex beams in Ka-band. The metasurface consists of two different subwavelength elements and achieves equal divergence angles of different OAM modes by calculating the radii of the inner and outer regions.
IET MICROWAVES ANTENNAS & PROPAGATION
(2022)
Article
Optics
Wenhua He, Saikat Guha, Jeffrey H. Shapiro, Boulat A. Bash
Summary: This paper theoretically analyzes spatial-mode-multiplexed, decoy-state BB84 quantum key distribution systems with transmitter modes being either a collection of phase-tilted, flat-top focused beams (FBs) or Laguerre-Gaussian (LG) modes. Despite the QKD rate penalty suffered by FBs relative to LG modes in vacuum propagation, their potential ease of implementation makes them an attractive alternative. Furthermore, in the presence of turbulence, FB modes may outperform LG modes.
Article
Optics
Han Cao, Yize Liang, Lulu Wang, Zhengsen Ruan, Hongya Wang, Jinwei Zeng, Jian Wang
Summary: In this paper, a quasi-wavelet conformal mapping method is proposed and demonstrated for scalable and efficient dense OAM demultiplexing in optical communications. The method divides the OAM mode into concentric rings and maps them to tilted plane waves, reducing demultiplexing crosstalk. It is compared with other methods and shown to achieve efficient demultiplexing for 15 OAM modes with low crosstalk. The method is also applied to data-carrying OAM-MDM communications with favorable performance.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Alan E. Willner, Xinzhou Su, Huibin Zhou, Amir Minoofar, Zhe Zhao, Runzhou Zhang, Moshe Tur, Andreas F. Molisch, Doohwan Lee, Ahmed Almaiman
Summary: This paper reviews recent experimental demonstrations of OAM-based THz MDM communication systems, and analyzes the system performance with turbulence, divergence, and multipath effects.
Editorial Material
Nanoscience & Nanotechnology
Alan E. Willner, Cong Liu
Summary: Structured light is a promising technology for increasing communication capacity by transmitting multiple orthogonal beams simultaneously. Future challenges lie in utilizing multiple orbital angular momentum modes to enhance system performance.
Article
Optics
Tinkara Troha, Tomas Ostatnicky, Petr Kuzel
Summary: This study proposes a method to improve the security of a terahertz wireless link by utilizing the carrier wave's degrees of freedom and measuring changes when the transmission line is intercepted. The use of vortex beams is shown to provide an even higher level of security compared to Gaussian beams.
Article
Computer Science, Information Systems
Yi Lei, Yang Yang, Yanzhe Wang, Kai Guo, Yubin Gong, Zhongyi Guo
Summary: This experimental letter demonstrates the performance enhancement of 2x2 MIMO communication based on orbital angular momentum (OAM) by utilizing the diversity of different OAM modes. By using a versatile OAM antenna, the throughput of MIMO communication can be improved by up to 30.50% or 6.59% respectively.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2021)
Article
Optics
Chenguang Gu, Rui Yang, Yachao Li
Summary: The study presents a composite meta-surface beam former that generates reconfigurable multiple OAM vortex waves by integrating a polarization conversion meta-mirror with a multi-functional anisotropic meta-lens, allowing for tailored beam numbers, radiation directions, and topological charges. It shows that the anisotropic characteristics of the meta-lens can create different multiple OAM vortex waves when the meta-mirror is rotated or equipped with different polarized illuminations. This design could pave the way for the reconfigurable generation of multiple OAM vortex waves to expand communication capacity further.
Review
Nanoscience & Nanotechnology
Jian Wang, Jun Liu, Shuhui Li, Yifan Zhao, Jing Du, Long Zhu
Summary: This paper provides an overview of the applications of orbital angular momentum (OAM) and other technologies in optical communications, covering topics such as the fundamentals of OAM, modulation, multiplexing, multicasting, communication in turbulence, structured light communications, as well as discussing the prospects and challenges for the future.
Article
Nanoscience & Nanotechnology
Jingxing Zhang, Zhongzheng Lin, Jie Liu, Junyi Liu, Zhenrui Lin, Shuqi Mo, Shuqing Lin, Lei Shen, Lei Zhang, Yujie Chen, Xiaobo Lan, Siyuan Yu
Summary: Spatial division multiplexed optical transmission over a multi-ring-core orbital angular momentum (OAM) fibre is achieved for the first time, enabling the simultaneous transmission of 56 OAM mode channels with a total capacity of 31.4 Tbit/s and a spectral efficiency of 62.7 bit/s/Hz. The weak coupling between higher-order mode groups and the use of modular signal processing greatly improve signal processing efficiency and spectral utilization.
Article
Engineering, Electrical & Electronic
Ahmed Almradi, Muhammad Ali Babar Abbasi, Michail Matthaiou, Vincent F. Fusco
Summary: Due to the spatial orthogonality of different OAM modes, MDM using OAM has been explored as a new wireless transmission technique. However, the presence of OAM mode offset can lead to inter-mode interference, impacting the spectral efficiency of line-of-sight free-space wireless communication systems. A theoretical analysis and practical communication experiment were conducted to evaluate the impact and propose solutions for improving system efficiency.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2021)
Article
Optics
Yonglei LIu, Zhen Dong, Fei Wang, Yahong Chen, Yangjian Cai
Summary: We propose a protocol to synthesize a class of vector beam array in the far field with periodic higher-order Poincare sphere (HOPS) polarization states by engineering the second-order spatial coherence structure of a partially coherent light source. The polarization state of a single HOPS beam at the source plane can be mapped into a beam array in the far field by engineering the spatial coherence of the beam source to have a lattice-like distribution. The degree of polarization of the generated HOPS beam array can be conveniently controlled by modulating the transverse spatial coherence width of the source. Our method provides an additional way to construct the structured beam array and may find applications, e.g., in multiparticle manipulations.
Article
Physics, Applied
Jianhua Lin, Chang Chen, Jun Ding, Shuo Wang, Weidong Chen
Summary: This study proposes a strategy for generating multiple compact vortex beams with a single-layer reflective metasurface, offering new possibilities in the field of communications. By designing a dual-frequency metasurface, the generation of four compact vortex beams with different OAM modes at 9 and 13 GHz frequencies was successfully achieved.
APPLIED PHYSICS LETTERS
(2021)
Review
Nanoscience & Nanotechnology
Alan E. E. Willner, Xinzhou Su, Hao Song, Huibin Zhou, Kaiheng Zou
Summary: There is a growing interest in using multiple multiplexed orthogonal orbital angular momentum (OAM) beams to increase data capacity in communication systems. This article discusses the use of pixel-array-based metasurfaces as OAM transmitters and receivers for mode division multiplexing (MDM) communications in the near-infrared (NIR) and terahertz (THz) regimes.
Article
Telecommunications
Shuangyang Li, Weijie Yuan, Zhiqiang Wei, Robert Schober, Giuseppe Caire
Summary: This article provides an overview of the state-of-the-art transceiver designs for OTFS systems, focusing on CP design, window design, pulse shaping, channel estimation, and signal detection. It also analyzes the performance of OTFS modulation, including diversity gain and achievable rate, and compares it with coded OFDM systems.
IEEE COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Zhiqiang Wei, Shuangyang Li, Weijie Yuan, Robert Schober, Giuseppe Caire
Summary: This letter is the first part of a three-part tutorial introducing orthogonal time frequency space (OTFS) modulation, a potential waveform for future wireless networks. Two popular implementations of OTFS modulation, SFFT- and DZT-based architectures, are compared and discussed. The fundamental concepts of OTFS modulation, such as the delay-Doppler (DD) domain and its information multiplexing, as well as the challenges ahead, are explored.
IEEE COMMUNICATIONS LETTERS
(2023)
Article
Telecommunications
Weijie Yuan, Zhiqiang Wei, Shuangyang Li, Robert Schober, Giuseppe Caire
Summary: The first two parts of this tutorial on orthogonal time frequency space (OTFS) modulation have discussed the fundamentals of delay-Doppler (DD) domain communications as well as some advanced technologies for transceiver design. In this letter, we present an OTFS-based integrated sensing and communications (ISAC) system, which is an enabling technology in next generation wireless communications. We describe the sensing and communication models for OTFS-ISAC systems, and show that the sensing parameters can be used to infer the communication channels in time-invariant DD channels, leading to an efficient transmission scheme. We also discuss the promising benefits of OTFS-based ISAC systems and highlight potential applications of OTFS for future wireless networks.
IEEE COMMUNICATIONS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Tianyu Yang, Mahdi Barzegar Khalilsarai, Saeid Haghighatshoar, Giuseppe Caire
Summary: In massive multiuser multiple antenna systems, accurate estimation of the users' channel covariance matrix is crucial but challenging when the number of samples is limited compared to the channel vector dimension. To address this, we propose a method based on a parametric representation of the channel angular scattering function. The proposed methods outperform the state of the art in terms of estimation quality metrics and sample sizes.
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING
(2023)
Article
Engineering, Electrical & Electronic
Tayyebeh Jahani-Nezhad, Mohammad Ali Maddah-Ali, Songze Li, Giuseppe Caire
Summary: We propose SwiftAgg+, a novel secure aggregation protocol that aggregates local models from N × N distributed users in federated learning systems. SwiftAgg+ achieves optimal communication loads and provides information theoretic security guarantees. It also allows for a flexible trade-off between communication loads and the number of active communication links.
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Shuangyang Li, Jinhong Yuan, Paul Fitzpatrick, Taka Sakurai, Giuseppe Caire
Summary: In this paper, we investigate the application of DD domain Tomlinson-Harashima precoding (THP) in downlink multiuser multiple-input and multiple-output OTFS (MU-MIMO-OTFS) transmissions. We propose a simple implementation of THP that takes advantage of the DD domain channel property. Our proposed scheme achieves near optimal performance in high SNR regime and shows logarithmic growth with respect to the number of antennas and linear growth with respect to the number of users. Numerical results demonstrate a significant improvement compared to existing MU-MIMO schemes on OTFS and OFDM.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Fabian Gottsch, Noboru Osawa, Takeo Ohseki, Kosuke Yamazaki, Giuseppe Caire
Summary: In this paper, a channel subspace estimation scheme explicitly designed for cell-free wireless networks is proposed. The scheme utilizes a sounding reference signal (SRS) using latin squares wideband frequency hopping, and a subspace estimation method based on robust Principal Component Analysis (R-PCA). Simulation results show that the proposed scheme achieves almost perfect subspace knowledge, solving the problem of pilot contamination in cell-free user-centric TDD wireless networks.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Zhen Du, Fan Liu, Weijie Yuan, Christos Masouros, Zenghui Zhang, Shuqiang Xia, Giuseppe Caire
Summary: This paper investigates sensing-assisted beamforming for vehicle-to-infrastructure (V2I) communication by exploiting integrated sensing and communications (ISAC) functionalities at the roadside unit (RSU). Two novel schemes are proposed to tackle the problem of the point-target assumption being impractical when using a massive multi-input-multi-output (mMIMO) array at mmWave. The first scheme adjusts the beamwidth in real-time to cover the entire vehicle and tracks the position of the communication receiver (CR) using an extended Kalman filter. The second scheme splits the transmission block into two stages, where the first stage is for ISAC with a wide beam and the second stage is for communication with a pencil-sharp beam.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Mohsen Amidzadeh, Hanan Al-Tous, Giuseppe Caire, Olav Tirkkonen
Summary: This paper considers cellular network caching with network-wide Orthogonal Multipoint Multicast (OMPMC) delivery. A probabilistic model for content placement at the Base Stations (BSs) is applied, and content is delivered with multipoint multicast operating in file-specific orthogonal resources. The outage probability is derived for a network modeled as a Poisson Point Process (PPP). The optimal cache placement and resource allocation are found by solving a joint constrained optimization problem, and a sub-optimal solution is obtained through convex relaxation.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Erfan Khordad, Iain B. Collings, Stephen V. Hanly, Giuseppe Caire
Summary: This paper investigates the implementation of compressive sensing (CS) approaches for beam alignment (BA) in multiuser millimeter wave (mmWave) MIMO systems. The study focuses on wideband time-varying channels in the low SNR regime and compares different time scales for beam-switching and running the CS algorithm. An overarching trial-based protocol and a new deterministic construction for designing the CS sensing matrix (SM) are proposed. The results demonstrate that the proposed SM and trial-based protocol outperform other approaches, while running the CS algorithm every block (CS-EB) has higher complexity and overhead than CS-EE.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Computer Science, Hardware & Architecture
Berksan Serbetci, Eleftherios Lampiris, Thrasyvoulos Spyropoulos, Giuseppe Caire, Petros Elia
Summary: This work presents a new approach to accelerate the impact of transmitter-side data redundancy on receiver-side coded caching by exploiting non-uniform file popularity. It formulates an optimization problem and proposes a search algorithm to optimize the placement of files based on their popularity. The study demonstrates that employing multiple transmitters can fully exploit file popularity and avoid complications arising from altering cache placement based on file popularity.
IEEE-ACM TRANSACTIONS ON NETWORKING
(2023)
Article
Computer Science, Information Systems
Kai Wan, Daniela Tuninetti, Mingyue Ji, Giuseppe Caire
Summary: This paper studies the fundamental limits of the shared-link coded caching problem with correlated files. It presents a tradeoff between cache size and average transmitted load and proposes converse bounds and caching schemes. It also introduces a new delivery scheme based on interference alignment. The results can be extended to worst-case load and have applications in reducing the load of existing schemes for the coded caching problem and achieving optimal transmission load in coded distributed computing.
IEEE TRANSACTIONS ON INFORMATION THEORY
(2023)
Article
Computer Science, Information Systems
Ting Yang, Kai Wan, Minquan Cheng, Robert Caiming Qiu, Giuseppe Caire
Summary: This paper discusses the cache-aided multiple-input single-output (MISO) broadcast channel, where a server with L antennas and K single-antenna users stores N files and each user has a cache of M files. The objective is to design a coded caching scheme that achieves the maximum sum Degree-of-Freedom (sum-DoF) with low subpacketization. The proposed scheme, based on a new combinatorial structure called multiple-antenna placement delivery array (MAPDA) and Latin square, achieves the maximum sum-DoF with reduced subpacketization compared to existing schemes.
IEEE TRANSACTIONS ON INFORMATION THEORY
(2023)
Article
Engineering, Electrical & Electronic
Saeid K. Dehkordi, Lorenzo Gaudio, Mari Kobayashi, Giuseppe Caire, Giulio Colavolpe
Summary: Motivated by automotive applications, this paper investigates the joint radar sensing and data communication in a system operating at millimeter-wave frequency bands. A hybrid digital-analog architecture is proposed to address the hardware complexity and power consumption constraints. A beam-space approach is adopted for radar to perform target detection and parameter estimation. Numerical results demonstrate the effectiveness of the proposed approach in detecting multiple targets and approaching the optimal parameter estimation.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Computer Science, Information Systems
Michail Palaiologos, Mario H. Castaneda Garcia, Richard A. Stirling-Gallacher, Giuseppe Caire
Summary: This paper investigates the optimal design of uniform circular arrays (UCAs) in a 4x4 line-of-sight multiple-input multiple-output (LoS MIMO) system and extends it to the design of elliptical arrays (EAs). The effect of tilting the array at different transmit distances is studied, and it is shown that a tilted array can be optimal in terms of capacity at certain transmit distances.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
