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3D Printed Terahertz Metalenses for Next-Generation Communication and Imaging Applications
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| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 8) |
| Halaman | : | 1033-1050 |
| Abstrak | : | Three-dimensional (3-D) printing, also known as additive manufacturing, provides a novel and cost-effective approach for implementing microwave devices. With the rapid advancement and improved manufacturing resolution of the 3-D printing technology, additive manufacturing has enabled the design and fabrication of electronic devices in higher terahertz (THz) frequency bands, contributing to bridging the gap between microwaves and photonics. Simultaneously, metalenses have garnered significant attention due to their ability to shape electromagnetic (EM) wavefronts. Metalens technology offers a promising solution for wave focusing, surpassing traditional dielectric lenses with advantages such as reduced weight and low loss, particularly at THz frequencies. In this article, we present an overview of the development of 3-D-printed THz metalenses, ranging from single metalenses to dual-layer and trilayer configurations. The functionality of the metalenses becomes more powerful, from replacing conventional light-focusing dielectric lenses for single-layer metalenses, achieving 2-D beam scanning, holographic imaging, and reconfigurable orbital angular momentum (OAM) for dual-layer metalenses, to enabling 3-D focus scanning for trilayer metalenses. We also discuss practical measurement technologies for THz metalenses and briefly outline the prospective to propel the 3-D-printed metalens technology forward. |
AI-Empowered Multiple Access for 6G: A Survey of Spectrum Sensing, Protocol Designs, and Optimizations
| Pengarang | : | Xuelin Cao |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 9) |
| Halaman | : | 1264-1302 |
| Abstrak | : | With the rapidly increasing number of bandwidth-intensive terminals capable of intelligent computing and communication, such as smart devices equipped with shallow neural network (NN) models, the complexity of multiple access (MA) for these intelligent terminals is increasing due to the dynamic network environment and ubiquitous connectivity in sixth-generation (6G) systems. Traditional MA design and optimization methods are gradually losing ground to artificial intelligence (AI) techniques that have proven their superiority in handling complexity. AI-empowered MA and its optimization strategies aimed at achieving high quality-of-service (QoS) are attracting more attention, especially in the area of latency-sensitive applications in 6G systems. In this work, we aim to: 1) present the development and comparative evaluation of AI-enabled MA; 2) provide a timely survey focusing on spectrum sensing, protocol design, and optimization for AI-empowered MA; and 3) explore the potential use cases of AI-empowered MA in the typical application scenarios within 6G systems. Specifically, we first present a unified framework of AI-empowered MA for 6G systems by incorporating various promising machine learning (ML) techniques in spectrum sensing, resource allocation, MA protocol design, and optimization. We then introduce AI-empowered MA spectrum sensing related to spectrum sharing and spectrum interference management. Next, we discuss the AI-empowered MA protocol designs and implementation methods by reviewing and comparing the state of the art and further explore the optimization algorithms related to dynamic resource management, parameter adjustment, and access scheme switching. Finally, we discuss the current challenges, point out open issues, and outline potential future research directions in this field. |
3D 4D Printed Reconfigurable Metasurfaces for Controlling Electromagnetic Waves
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 8) |
| Halaman | : | 1000-1032 |
| Abstrak | : | A comprehensive review of 3-D/4-D-printed reconfigurable metasurfaces (RMSs) is presented in this article. A metasurface (MS) demonstrates exceptional abilities for electromagnetic (EM) wave molding beyond that offered by conventional planar interfaces, and RMS provides MS with more diverse EM wave-control capabilities. RMSs are categorized by the type of external stimulus used for reconfiguration, such as electrical RMS, fluidic RMS, mechanical RMS, and thermal RMS. To implement these RMSs, it is important to understand the design and fabrication requirements as well as the EM characteristic of each RMS, including its advantages and disadvantages. In particular, except for electrical RMS, RMSs require complex 3-D structures or special materials that are difficult to implement with conventional subtractive manufacturing methods such as printed-circuit-board manufacturing. Recently, advanced 3-D/4-D printing technology has achieved high fabrication freedom and meets the design and fabrication requirements of each type of RMS. In this article, we introduce representative RMSs with the development of 3-D/4-D printing technology and materials. Furthermore, current issues of RMSs based on 3-D/4-D printing technology and future directions are described. |
A Review of Multimaterial Additively Manufactured Electronics and 4-D Printing Origami Shape-Memory Devices: Design, Fabrication, and Implementation
| Pengarang | : | P. SALVKO |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 8) |
| Halaman | : | 954-999 |
| Abstrak | : | Emerging additive manufacturing (AM) technologies, specifically additively manufactured electronics (AME), 4-D printing, and origami, are reshaping the design capabilities and functionalities of contemporary electronic devices. Cutting-edge 3-D/4-D printing technologies facilitate the prototyping and realization of complex electronic functions that are challenging to conventional methods. This article provides a comprehensive overview of the evolving techniques in AME, 4-D printing, and origami, employing multimaterials (conductive and dielectric materials) and shape-memory materials (SMMs) to fabricate functional electronic components and devices. Additionally, the overview delves into the state-of-the-art AME and 4-D-printed electronic components across diverse fields, including biomedical electronics, space engineering, and the advancements in the next-generation wireless communications and sensing. |
Resource Allocation Design for Next-Generation Multiple Access: A Tutorial Overview
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 9) |
| Halaman | : | 1230-1263 |
| Abstrak | : | Multiple access is the cornerstone technology for each generation of wireless cellular networks, which fundamentally determines the method of radio resource sharing and significantly influences both the system performance and transceiver complexity. Meanwhile, resource allocation (RA) design plays a crucial role in multiple access, as it can manage both encompassing radio resources and interference, and it is critical for providing high-speed and reliable communication services to multiple users. Given that the RA design is intrinsically scenario-specific and the optimization tools for RA design are typically varied, in this article, we present a comprehensive tutorial overview for junior researchers in this field, aiming to offer a foundational guide for RA design in the context of next-generation multiple access (NGMA). Our discussion spans a broad range of fundamental topics: from typical system models, through intriguing problem formulation in RA design, to the exploration of various potential optimization solution methodologies. Initially, we identify three types of channels in future wireless cellular networks over which NGMA will be implemented, namely, natural channels, reconfigurable channels, and functional channels. Natural channels are traditional uplink and downlink communication channels; reconfigurable channels are defined as channels that can be proactively reshaped via emerging platforms or techniques, such as intelligent reflecting surface (IRS), unmanned aerial vehicle (UAV), and movable/fluid antenna (M/FA); and functional channels support not only communication but also other functionalities simultaneously, with typical examples, including integrated sensing and communication (ISAC) and joint computing and communication (JCAC) channels. Then, we introduce NGMA models applicable to these three types of channels that cover most of the practical communication scenarios of future wireless communications. Subsequently, we articulate the key optimization technical challenges inherent in the RA design for NGMA, categorizing them into rate-, power-, and reliability-oriented RA designs. The corresponding optimization approaches for solving the formulated RA design problems are then presented. Finally, the simulation results are presented and discussed to elucidate the practical implications and insights derived from RA designs in NGMA. |
Unsourced Multiple Access: A Coding Paradigm for Massive Random Access
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 9) |
| Halaman | : | 1214-1229 |
| Abstrak | : | This article is a tutorial introduction to the field of unsourced multiple access (UMAC) protocols. We first provide a historical survey of the evolution of random access protocols, focusing specifically on the case in which uncoordinated users share a wireless broadcasting medium. Next, we highlight the change of perspective originated by the UMAC model, in which the physical and medium access layer’s protocols cooperate, thus reframing random access as a novel coding-theoretic problem. By now, a large variety of UMAC protocols (codes) emerged, necessitating a certain classification that we indeed propose here. Although some random access schemes require a radical change of the physical layer, others can be implemented with minimal changes to existing industry standards. As an example, we discuss a simple modification to the 5G New Radio (5GNR) Release 16 random access channel that builds on the UMAC theory and that dramatically improves energy efficiency for systems with even moderate number of simultaneous users (e.g., 5–10-dB gain for 10–50 users) and also enables handling of high number of users, something completely out of reach of the state of the art. |
Modulation and Coding for NOMA and RSMA
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 9) |
| Halaman | : | 1179-1213 |
| Abstrak | : | The next-generation multiple access (NGMA) serves as an umbrella term encompassing transmission schemes distinct from conventional orthogonal methods. As a prominent candidate of NGMA, nonorthogonal multiple access (NOMA) emerges as a promising solution, enhancing connectivity by allowing multiple users to concurrently share time, frequency, and space. However, NOMA faces challenges in practical implementation, particularly in canceling interuser interference (IUI). In this article, first, we discuss the principles behind NOMA and review the conventional NOMA methods and results. Then, to address the above challenges, we present asynchronous transmission and interference-aware modulation techniques, leading to decoding free from successive interference cancellation (SIC). The goal is to design constellations that dynamically adapt to interference, minimizing bit error rates (BERs) and enhancing user throughput in the presence of IUI, intercarrier interference, and intercell interference (ICI). The traditional linkage between minimizing BER and increasing spectral efficiency is addressed, with the exploration of deep autoencoders (AEs) for end-to-end (E2E) communication as a new concept with significant potential for improving BERs. Interference-aware modulation techniques can revolutionize constellation design and communication over nonorthogonal channels. rate-splitting multiple access (RSMA) is another promising interference management technique in multiuser systems. Beyond addressing existing challenges and misconceptions in finite-alphabet NOMA, this article offers fresh insights into the field and provides an overview of code-domain NOMA (C-NOMA) schemes, trellis-coded NOMA (TC-NOMA), and RSMA as other potential candidates for NGMA. Additionally, we discuss the evolution of channel coding toward low-latency communication and examine the modulation and coding schemes (MCSs) in fifth-generation (5G) cellular networks. Finally, we examine future research avenues and challenges, highlighting the importance of addressing them for the practical realization of NOMA from a theoretical concept to a functional technology. |
Developing Sound Measurement Standards for Early U.S. Radio Loudspeaker Technology A Tale of Two Ears
| Pengarang | : | Shawn Vancour |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 10) |
| Halaman | : | 1632-1643 |
| Abstrak | : | This paper examines the development of radio loudspeaker technologies during US broadcasting’s initial boom period in the 1920s. Loudspeakers were crucial for expanding early radio markets, with manufacturers using them to reposition radio from an experimenter’s device to a domestic entertainment medium. These shifting markets and uses of radio favored tonal fidelity over mere volume and intelligibility, with engineers working to create corresponding standards for measuring tone quality. |
High k Metal Insulator Metal Capacitors for RF and Mixed Signal VLSI Circuits Challenges and Opportunities
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 10) |
| Halaman | : | 1610-1631 |
| Abstrak | : | Metal-insulator–metal (MIM) capacitors are inevitable and critical passive components in analog, mixed-signal, and memory applications. These capacitors occupy nearly 40% of circuit area among other passive and active components of the integrated circuit (IC). Considering this fact, the International Roadmap for Devices and Systems (IRDS) recognized and recommended the miniaturization of MIM capacitors with high permittivity dielectric materials. For future analog and radio frequency (RF) applications, the IRDS has predicted that MIM capacitors should hold a high capacitance density of >10 fF/μm2 , a low voltage linearity of <100 ppm/V2 , and a low leakage current density of <10 nA/cm2 . In this regard, many research works have been carried out over the last few decades with various high-k dielectrics to achieve “low voltage linearity.” However, many of them are facing problems with structural defects, interface traps, and poor polarization process due to limitations of fabrication processes. This article attempts to review the challenges and opportunities involved in the reduction of voltage linearity and leakage of MIM capacitors. Also, this article presents the physical limits and challenges involved in MIM capacitor integration with back end of line (BEOL) process of recent complementary metal-oxide–semiconductor (CMOS) technologies. Using physical modeling, the design formula for low voltage linearity coefficient was derived, which helps IC developers in the design and implementation of highly linear RF-analog and mixed-signal (AMS) systems. |
Next Generation Multiple Access
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 112 (No. 9) |
| Halaman | : | 1149-1178 |
| Abstrak | : | The pressure to develop new network architectures and multiple access technologies is driven by increasing demands on network performance, number of devices, network traffic, and use cases. Recent advances in open radio access networks (RANs) with open interfaces and software-defined network functionalities allow adaptability in terms of medium access control and physical layer, but also flexibility in terms of network architectures. The aim of this tutorial is to provide a comprehensive overview of the current set of network architectures for wireless access together with next-generation multiple access technologies. It starts with the classical models for multiple access channel (MAC), broadcast channel (BC), and interference channel (IC) from network information theory and derives the fundamental results on capacity regions and their coding and signal processing schemes. Extensions to multicarrier, multiantenna, and multicell scenarios are discussed. The evolution from orthogonal to spatial-division multiple access (SDMA), nonorthogonal multiple access (NOMA), and rate splitting multiple access (RSMA) techniques and their performance guarantees are carefully explained. Recent advances toward multiconnectivity, cloud-RAN (C-RAN), and cell-free multiple access (CFMA) are explained. The data rate benefits of an anecdotal open RAN network are developed and the corresponding user data rates are calculated. Massive random and grant-free access schemes are also discussed. The tutorial concludes with a list of open research questions. |