Next-generation Communication Systems Research Articles

The Next Generation of Beam Hopping Satellite Systems: Dynamic Beam Illumination With Selective Precoding

Beam Hopping (BH) is a popular technique considered for next-generation multi-beam satellite communication system which allows a satellite focusing its resources on where they are needed by selectively illuminating beams. While beam illumination plan can be adjusted according to its needs, the main limitation of convectional BH is the adjacent beam avoidance requirement needed to maintain acceptable levels of interference. With the recent maturity of precoding technique, a natural way forward is to consider a dynamic beam illumination scheme with selective precoding, where large areas with high-demand can be covered by multiple active precoded beams. In this paper, we mathematically model such beam illumination design problem employing an interference-based penalty function whose goal is to avoid precoding whenever possible subject to beam demand satisfaction constraints. The problem can be written as a binary quadratic programming (BQP). Next, two convexification frameworks are considered namely: (i) A Semi-Definition Programming (SDP) approach particularly targeting BQP type of problems, and (ii) Multiplier Penalty and Majorization-Minimization (MPMM) based method which guarantees to converge to a local optimum. Finally, a greedy algorithm is proposed to alleviate complexity with minimal impact on the final performance. Supporting results based on numerical simulations show that the proposed schemes outperform the relevant benchmarks in terms of demand matching performance while minimizing the use of precoding.

Performance Art Video Action Management Oriented to 6G Wireless Transmission Technology

With the development of 5G communication networks, the development prospects, capability requirements and key technologies of the next-generation communication system 6G have become new hotspots. This article expands the coverage of the communication system through 6G, realizes the wireless transmission technology, builds the ideal of an intelligent mobile society everywhere, and analyzes the development trend of 6G technology, the challenges it faces, and the possible wireless transmission technology. Wireless transmission technology is widely used in various fields of production and life. Its various technical requirements and terminal energy limitations restrict the application and development of communications. This article focuses on the high-efficiency optimization scheme that combines 6G wireless transmission technology to improve the utilization efficiency of network resources. In addition, this thesis also discusses video action management in public performance art. Based on public performance art, the research on video action recognition can be summarized into three levels from simple to complex according to the content of the action, namely mobile vision, action vision and action vision. Video action vision is currently being studied. In the recognition process, most of the action frame information in the video is repetitive or has a low correlation with action recognition, which not only increases the complexity of calculation, but also affects the accuracy of action recognition. In the process of feature selection and understanding, the main methods include characterization fusion and research based on gesture features. Based on the introduction of 6G wireless transmission technology, this article introduces the technological development of 6G network, which promotes the rapid development of public performance art video action management.

Hyperparameter-Free RFF Based Post-Distorter for OTFS VLC System

Visible light communication (VLC) has emerged as an eco-friendly and low-cost technology for the next-generation communication systems. However, for VLC systems, existing works report performance degradation due to light-emitting-diode (LED) non-linearity, multipath and relative mobility between the transmitter and the receiver. Additionally, multipath and user-mobility introduce inter-symbol-interference (ISI) and frequency-domain spreading which degrades the performance of VLC systems. For such scenarios, orthogonal time frequency space (OTFS) modulation is well-known to jointly addresses impairments due to multipath and user-mobility. To mitigate the distortions due to LED non-linearity, recently reproducing kernel Hilbert space (RKHS)-based random Fourier feature (RFF) techniques have emerged which alleviate the dependence on learning a dictionary and, outperforms classical polynomial based techniques. However, performance of these techniques is sensitive to the choice of kernel-width. Thus, for the OTFS systems impaired by LED non-linearity, this manuscript proposes a hyperparameter-free RFF-based post-distorter, under finite-memory budget without the need of explicitly tuning kernel-width for best performance. Analytical bounds for the bit-error-rate (BER) performance of the proposed post-distorter are presented, and validated via simulations over realistic VLC channels. From the results it is verified that the proposed receiver achieves better BER performance over uncompensated scenario and classical baseline polynomial based technique.

Design of elliptical photonic crystal fiber (E-PCF) for the transmission of 116 OAM channels across the S, C, L and U bands

Orbital angular momentum (OAM) modes over photonic crystal fibers (PCFs) have shown great capability in unleashing the available data rates in optical communication systems. In this paper, we propose and numerically design a novel elliptical photonic crystal fiber (E-PCF) using assisted Germania-doped silica as a material background and elliptical air holes. Using a systematic scanning methodology, we adjusted the E-PCF key parameters with the aim to explore appropriate designs that support large number of OAM channels featuring low confinement loss (CL). Numerical simulations using finite element method (FEM) show the supports of large number of independent/separate OAM channels (116 OAM with Δneff≥ 10−4). A detailed numerical modal analysis has been carried out over the S + C + L + U communication bands show that the designed E-PCF handles robust OAM modes. This includes low chromatic dispersion (CD = 92 ps/km/nm), low differential group delay (<60 ps/km), high effective mode area (max Aeff = 124 µm2), low nonlinearity coefficient (γ < 2.6 /W/m) and low confinement loss (Max CL = 2.07 × 10−4 dB/m). The obtained results and the comparisons with those recently reported in literature shows that the designed E-PCF could find applications in next-generation optical communication systems that uses OAM modes as data carriers.

Preface

4th National Conference on Communication Systems (NCOCS-2022) December 23rd, 2022 ABOUT THE CONFERENCE National Conference on Communication Systems (NCOCS-2022) is fourth in the series of conferences intended to be held every year at NITPY, aimed to disseminate knowledge on the latest technological developments and cutting-edge research in wireless communication, signal processing, antenna and RF design, optical communication, internet of things and sensor networks & electronics among academicians, researchers, scientists, industry personnel, and entrepreneurs across India. This conference will provide the premier interdisciplinary forum relevant with Electronics and Communication Engineering to discuss the recent technologies, innovations, recent research findings, challenges, solutions, and perspectives of the future directions of Communication Engineering through keynote lectures and paper presentations. Young researchers are encouraged to participate and utilize the opportunity to network with others who seek to develop their research abilities and experience. OBJECTIVE & SCOPE OF THE CONFERENCE The objective of the NCOCS 2022 is to provide a platform to perceive, share, and exchange the recent trends related to various aspects of Communication Engineering. The main aim of this conference is to bring together researchers, young faculties and practitioners working in multi-disciplinary fields to discuss and deliberate on challenges, opportunities and strategies involved for next-generation communication systems. The conference will provide a forum to academic researchers and practitioners to discuss critical issues concerning latest technologies towards 6G and mmWave communications. Conference Chairperson Dr. M. Surendar Assistant Professor, Department of ECE,National Institute of Technology Puducherry, Karaikal – 609 609, IndiaConference Website: https://sites.google.com/view/ncocs-2022/home?authuser=0List of Conference Committee is available in this Pdf.

Effect of the Alumina Particle Filler Structure and Particle Size on the Dielectric Constant and Dielectric Loss in the Millimeter-Wave Band.

The sixth-generation communication system (6G) is the next-generation communication system and is expected to be operational in 2030. The following areas will use 6G: the frequency band employed in 6G is expected to be 100 GHz or higher, necessitating additional reduction of the dielectric constant and dielectric loss in the substrate material. In this study, we examined the effects of compounding various phases of alumina with different shapes and crystal phases on the dielectric constant and dielectric loss of cyclo-olefin polymer (COP) compounds. It was confirmed that the smaller the particle size, the higher the effect on the dielectric loss. The dielectric loss decreased from 1.6 × 10-3 of COP to 1.2 × 10-3 when the smallest filler was added at 30 wt %.

Review of Smart Antenna Approaches in Wireless Systems

Wireless mobile communication is one of the rapidly growing fields of Information and Communication Technologies (ICT). The adoption of smart antennas will also minimize the cost. The success of smart antennas relies on two phases: In first phase, the features of smart antennas should be considered in design phase of next-generation wireless mobile communication systems. In second phase, the performance of smart antennas should be analyzed according to crucial parameters that satisfy the requirements of next-generation wireless mobile communication systems. The proposed research study summarizes the concept and types of smart antennas. Further, the most recent innovations in smart antenna domains such as varying network conditions, coverage &amp; connectivity, Quality of Service (QoS), energy efficiency, routing are discussed.

Millimeter-Waves to Terahertz SISO and MIMO Continuous Variable Quantum Key Distribution

With the exponentially increased demands for large bandwidth, it is important to think about the best network platform as well as the security and privacy of the information in communication networks. Millimetre (mm)-waves and terahertz (THz) with high carrier frequency are proposed as the enabling technologies to overcome Shannon's channel capacity limit of existing communication systems by providing ultrawide bandwidth signals. Mm-waves and THz are also able to build wireless links compatible with optical communication systems. However, most solid-state components that can operate reasonably efficiently at these frequency ranges (100GHz-10THz), especially sources and detectors, require cryogenic cooling, as is a requirement for most quantum systems. Here, we show that secure mm-waves and THz QKD can be achieved when the sources and detectors operate at cryogenic temperatures down to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> = 4K. We compare single-input single-output (SISO) and multiple-input multiple-output (MIMO) Continuous Variable THz Quantum Key Distribution (CVQKD) schemes and find the positive secret key rate in the frequency ranges between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> =100 GHz and 1 THz. Moreover, we find that the maximum transmission distance could be extended, the secret key rate could be improved in lower temperatures, and achieve a maximum secrete communication distance of more than 5km at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> =100GHz and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> =4K by using 1024×1024 antennas. Our results for the first time show the possibility of mm-waves and THz MIMO CVQKD with the system operating at temperatures below <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> = 50K, which may contribute to the efforts to develop next-generation secure wireless communication systems and quantum internet for applications from inter-satellite and deep space to indoor and short-distance communications.

Physical Layer Security for Visible Light Communication in Reflected Indoor Environments With Inter-Symbol Interference

Visible light communication (VLC) is a promising technology for next-generation indoor wireless broadband communication systems. Physical layer security (PLS) is one proposed method to ensure data security for VLC in public areas. However, most PLS studies in the literature neglect the reflections in the VLC channel and do not consider inter-symbol interference (ISI). This paper investigates the ISI effects on the secrecy rate in multiple-input single-output VLC systems where the reflections are not neglected for the cases of perfect and imperfect knowledge of the eavesdropper’s channel state information. We aim to compensate for the ISI effects by designing zero-forcing (ZF) and artificial noise (AN) beamformers. In addition, we formulate optimization problems to maximize the secrecy rate resulting in non-convex and NP-hard problems. Thus, we utilize the particle swarm optimization algorithm for solutions and also convert non-convex optimization problems into easily solvable linear problems. Furthermore, robust ZF and AN beamformers for the worst-case scenario are considered for the cases of ISI and no ISI. The results reveal that ISI severely degrades the secrecy rate; however, well-designed beamformers can reverse the ISI effects.

Channel Estimation for Reconfigurable Intelligent Surface Assisted High-Mobility Wireless Systems

Next-generation communication systems aim for providing pervasive services, including the high-mobility scenarios routinely encountered in mission-critical applications. Hence we harness the recently-developed reconfigurable intelligent surfaces (RIS) to assist the high-mobility cell-edge users. However, in the face of high Doppler frequencies, the existing RIS channel estimation techniques that assume block fading generally result in irreducible error floors. In order to mitigate this problem, we propose a new RIS channel estimation technique, which is the first one that performs minimum mean square error (MMSE) based interpolation for the sake of taking into account the time-varying nature of fading even within the coherence time. The RIS modelling invokes only passive elements without relying on RF chains, where both the direct link and RIS-reflected links as well as both the line-of-sight (LoS) and non-LoS (NLoS) paths are taken into account. As a result, the cascaded base station (BS)-RIS-user links involve the multiplicative concatenation of the channel coefficients in the LoS and NLoS paths across the two segments of the BS-RIS and RIS-user links. Against this background, we model the multiplicative RIS fading correlation functions for the first time in the literature, which facilitates MMSE interpolation for estimating the high-dimensional and high-Doppler RIS-reflected fading channels. Our simulation results demonstrate that for a vehicle travelling at a speed as high as 90 mph, employing a low-complexity RIS at the cell-edge using as few as 16 RIS elements is sufficient for achieving substantial power-effieincy gains, where the Doppler-induced error floor is mitigated by the proposed channel estimation technique.

Deep Learning Based Beam Training for Extremely Large-Scale Massive MIMO in Near-Field Domain

Extremely large-scale massive multiple-input-multiple-output (XL-MIMO) is regarded as a promising technology for next-generation communication systems. In order to enhance the beamforming gains, codebook-based beam training is widely adopted in XL-MIMO systems. However, in XL-MIMO systems, the near-field domain expands, and near-field codebook should be adopted for beam training, which significantly increases the pilot overhead. To tackle this problem, we propose a deep learning-based beam training scheme where the near-field channel model and the near-field codebook are considered. To be specific, we first utilize the received signals corresponding to the far-field wide beams to estimate the optimal near-field beam. Two training schemes are proposed, namely the original and the improved schemes. The original scheme estimates the optimal near-field codeword directly based on the output of the neural networks. By contrast, the improved scheme performs additional beam testing, which can significantly improve the performance of beam training. Finally, the simulation results show that our proposed schemes can significantly reduce the training overhead in the near-field domain and achieve beamforming gains.

A Full Dive Into Realizing the Edge-Enabled Metaverse: Visions, Enabling Technologies, and Challenges

Dubbed “the successor to the mobile Internet,” the concept of the Metaverse has grown in popularity. While there exist lite versions of the Metaverse today, they are still far from realizing the full vision of an immersive, embodied, and interoperable Metaverse. Without addressing the issues of implementation from the communication and networking, as well as computation perspectives, the Metaverse is difficult to succeed the Internet, especially in terms of its accessibility to billions of users today. In this survey, we focus on the edge-enabled Metaverse to realize its ultimate vision. We first provide readers with a succinct tutorial of the Metaverse, an introduction to the architecture, as well as current developments. To enable ubiquitous, seamless, and embodied access to the Metaverse, we discuss the communication and networking challenges and survey cutting-edge solutions and concepts that leverage next-generation communication systems for users to immerse as and interact with embodied avatars in the Metaverse. Moreover, given the high computation costs required, e.g., to render 3D virtual worlds and run data-hungry artificial intelligence-driven avatars, we discuss the computation challenges and cloud-edge-end computation framework-driven solutions to realize the Metaverse on resource-constrained edge devices. Next, we explore how blockchain technologies can aid in the interoperable development of the Metaverse, not just in terms of empowering the economic circulation of virtual user-generated content but also to manage physical edge resources in a decentralized, transparent, and immutable manner. Finally, we discuss the future research directions towards realizing the true vision of the edge-enabled Metaverse.

All-optical AZO-based modulator topped with Si metasurfaces

All-optical communication systems are under continuous development to address different core elements of inconvenience. Here, we numerically investigate an all-optical modulator, realizing a highly efficient modulation depth of 22 dB and a low insertion loss of 0.32 dB. The tunable optical element of the proposed modulator is a layer of Al-doped Zinc Oxide (AZO), also known as an epsilon-near-zero transparent conductive oxide. Sandwiching the AZO layer between a carefully designed distributed Bragg reflector and a dielectric metasurface—i.e., composed of a two-dimensional periodic array of cubic Si—provides a guided-mode resonance at the OFF state of the modulator, preventing the incident signal reflection at λ = 1310 nm. We demonstrate the required pump fluence for switching between the ON/OFF states of the designed modulator is about a few milli-Joules per cm2. The unique properties of the AZO layer, along with the engineered dielectric metasurface above it, change the reflection from 1 to 93%, helping design better experimental configurations for the next-generation all-optical communication systems.

A Methodology to Design Quantized Deep Neural Networks for Automatic Modulation Recognition

Next-generation communication systems will face new challenges related to efficiently managing the available resources, such as the radio spectrum. DL is one of the optimization approaches to address and solve these challenges. However, there is a gap between research and industry. Most AI models that solve communication problems cannot be implemented in current communication devices due to their high computational capacity requirements. New approaches seek to reduce the size of DL models through quantization techniques, changing the traditional method of operations from a 32 (or 64) floating-point representation to a fixed point (usually small) one. However, there is no analytical method to determine the level of quantification that can be used to obtain the best trade-off between the reduction of computational costs and an acceptable accuracy in a specific problem. In this work, we propose an analysis methodology to determine the degree of quantization in a DNN model to solve the problem of AMR in a radio system. We use the Brevitas framework to build and analyze different quantized variants of the DL architecture VGG10 adapted to the AMR problem. The evaluation of the computational cost is performed with the FINN framework of Xilinx Research Labs to obtain the computational inference cost. The proposed design methodology allows us to obtain the combination of quantization bits per layer that provides an optimal trade-off between the model performance (i.e., accuracy) and the model complexity (i.e., size) according to a set of weights associated with each optimization objective. For example, using the proposed methodology, we found a model architecture that reduced 75.8% of the model size compared to the non-quantized baseline model, with a performance degradation of only 0.06%.

Low-cost, compact, and reconfigurable antennas using complementary split-ring resonator metasurface for next-generation communication systems

AbstractAn innovative and simple method for attaining broadband frequency reconfigurable antenna structure is presented using low-cost materials and a compact design. The frequency reconfigurability is attained by the “OFF” and “ON” mechanisms of three PIN diodes. Many performance observations are carried out such as reflectance coefficient, bandwidth (BW), resonance frequency, electric field, feed position variation, and gain among different configurations. The suitability of the presented work for the different applications lies in the X frequency band. The resonating frequency for all switch OFF modes is achieved at 13.2 GHz and one switch ON mode at 10.7 GHz. The proposed design yields the frequency tunability behavior over the broadband of 2.5 GHz. The design yields the directivity of 5.58 dB, the minimum reflectance coefficient of −17.27 dB, and a total gain of 3.87 dB. This design offers an electric field of 46 558 v/m, a BW of 340 MHz, and a normalized directivity of 87° using low-cost substrates. The results of the presented design were also fabricated and related to simulated results. Performance observation of the proposed work with previously published research work is also included. The presented design provides the solution of the low-cost, compact, reconfigurable antennas, which can be used for next-generation communication systems.

Performance Art Video Action Management Oriented to 6G Wireless Transmission Technology.

With the development of 5G communication networks, the development prospects, capability requirements, and key technologies of the next-generation communication system 6G have become new hotspots. This article expands the coverage of the communication system through 6G, realizes the wireless transmission technology, builds the ideal of an intelligent mobile society everywhere, and analyzes the development trend of 6G technology, the challenges it faces, and the possible wireless transmission technology. Wireless transmission technology is widely used in various fields of production and life. Its various technical requirements and terminal energy limitations restrict the application and development of communications. This article focuses on the high-efficiency optimization scheme that combines 6G wireless transmission technology to improve the utilization efficiency of network resources. In addition, this thesis also discusses video action management in public performance art. Based on public performance art, the research on video action recognition can be summarized into three levels from simple to complex according to the content of the action, namely mobile vision, action vision, and action vision. Video action vision is currently being studied. In the recognition process, most of the action frame information in the video is repetitive or has a low correlation with action recognition, which not only increases the complexity of calculation but also affects the accuracy of action recognition. In the process of feature selection and understanding, the main methods include characterization fusion and research based on gesture features. Based on the introduction of 6G wireless transmission technology, this article introduces the technological development of 6G network, which promotes the rapid development of public performance art video action management.

Guest Editorial Smart Electromagnetic Environment

The exponential growth of mobile data traffic in the last decades is expected to continue in the forthcoming years, and multi-gigabit-per-second connections will soon be experienced by the users at any place and time. Next-generation communication systems will have to sustain a highly immersive and interconnected world (e.g., the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">metaverse</i> ) in which both physical items/persons and their digital twins will have to continuously exchange massive amounts of high-resolution data. Therefore, the wireless infrastructures will have to guarantee unprecedented link performance levels, while minimizing the complexity, the power consumption, and the costs. Towards this end, alternative solutions to the traditional approach “more information and data through more power and more emissions of electromagnetic (EM) waves” will be mandatory because of the current EM congestion.

Guest Editors’ Introduction: Special Section on Smart Management of Future Softwarized Networks

Network softwarization is one of the key enablers of the future Internet evolution, also supporting the road from the fifth generation (5G) to the next-generation communication systems, namely 6G, with their main objective of bringing hyper-connected experience to every corner of society.

MIMO Hybrid Satellite-Terrestrial Cooperative Systems With Spatial Modulation

With the advent of the space industry, hybrid satellite-terrestrial cooperative systems (HSTCSs) have drawn significant attention due to their prominent advantages. Besides, a novel modulation technique called spatial modulation (SM), which uses transmit antenna indices as additional information conveying source, is another technology envisioned to be used for next-generation communication systems. In this article, we propose to use SM in an HSTCS scheme consisting of a satellite, multiple terrestrial relays with multiple-input and multiple-output configuration, and a destination node equipped with multiple antennas on the ground. We derive a union bound for the symbol error probability in a fairly exact form and diversity order to shed light on the significant system parameters on the performance. Our theoretical results are validated through Monte Carlo simulations, and it is shown that using the SM technique provides a better error performance in the considered HSTCS system when compared to vertical Bell Laboratories layered space-time and space-time Alamouti codes.

TCAD simulation of microwave circuits: The Doherty amplifier

Power amplifiers (PAs) for next generation of communication systems are expected to operate at higher frequency and bandwidth to support the growing data rates. The Doherty Power Amplifier (DPA) is one of the most promising circuits for the development of high efficiency PAs: its inherent structure, exploiting two interacting active devices, requires a nonlinear mixed-mode TCAD analysis with multiple devices. In this work we present for the first time a complete TCAD simulation of a DPA, exploiting an improved version of our in-house Harmonic-Balance based drift–diffusion simulator for large-signal mixed-mode analysis. We thus demonstrate that TCAD simulations are mature to assist the design of complex stages requiring multi-device large-signal analysis.