Pub Date : 2022-05-30DOI: 10.3389/frcmn.2022.859809
Sidrah Javed, A. Elzanaty, Osama Amin, Mohamed-Slim Alouini, B. Shihada
The fifth-generation cellular network requires dense installation of radio base stations (BS) to support the ever-increasing demands of high throughput and coverage. The ongoing deployment has triggered some health concerns among the community. To address this uncertainty, we propose an EMF-aware probabilistic shaping design for hardware-distorted communication systems. The proposed scheme aims to minimize human exposure to radio frequency (RF) radiations while achieving the target throughput using probabilistic shaping. The joint optimization of the transmit power and nonuniform symbol probabilities is a non–convex optimization problem. Therefore, we employ alternate optimization and successive convex approximation to solve the subsequent problems. Our findings reveal a significant reduction in the users’ exposure to EMF while achieving the requisite quality of service with the help of probabilistic shaping in a hardware-distorted communication system.
{"title":"EMF-Aware Probabilistic Shaping Design for Hardware-Distorted Communication Systems","authors":"Sidrah Javed, A. Elzanaty, Osama Amin, Mohamed-Slim Alouini, B. Shihada","doi":"10.3389/frcmn.2022.859809","DOIUrl":"https://doi.org/10.3389/frcmn.2022.859809","url":null,"abstract":"The fifth-generation cellular network requires dense installation of radio base stations (BS) to support the ever-increasing demands of high throughput and coverage. The ongoing deployment has triggered some health concerns among the community. To address this uncertainty, we propose an EMF-aware probabilistic shaping design for hardware-distorted communication systems. The proposed scheme aims to minimize human exposure to radio frequency (RF) radiations while achieving the target throughput using probabilistic shaping. The joint optimization of the transmit power and nonuniform symbol probabilities is a non–convex optimization problem. Therefore, we employ alternate optimization and successive convex approximation to solve the subsequent problems. Our findings reveal a significant reduction in the users’ exposure to EMF while achieving the requisite quality of service with the help of probabilistic shaping in a hardware-distorted communication system.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114146590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-20DOI: 10.3389/frcmn.2022.746201
P. Singya, Mohamed-Slim Alouini
In this work, a mixed free-space optics (FSO)/radio-frequency (RF) based multiple serial high altitude platforms (HAPs) assisted multiuser multiantenna terrestrial communication system is considered. For the considered multi-hop system, earth station to HAP and HAP to HAP links are assumed as FSO links, and HAP to terrestrial mobile users (MUs) link is assumed as RF link. At the FSO detector both the heterodyne detection and intensity modulation direct detection techniques are considered. Atmospheric turbulence of the ES to HAP FSO link is modeled with Gamma-Gamma fading along with the pointing error impairments. As HAP situates in the stratosphere, negligible atmospheric turbulence exists at HAP altitude (20 km), hence, only pointing error is considered for the inter HAP links. Further, the HAP consists of multiantenna array to provide high data-rates to the terrestrial users via RF links, considered to be Nakagami-m distributed. The intermediate HAPs perform selective decode-and-forward relaying and opportunistic user scheduling is performed for the best user selection. For the performance analysis, analytical expression of overall outage probability is obtained and the impact of various selection parameters like pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on the outage performance. Asymptotic outage probability is also derived to obtain the diversity order of the considered communication system. Further, considering various modulation schemes, a generalized average bit-error-rate expression is derived and the impact of pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on its performance. Finally, derived results are validated through Monte-Carlo simulations.
{"title":"Mixed FSO/RF Based Multiple HAPs Assisted Multiuser Multiantenna Terrestrial Communication","authors":"P. Singya, Mohamed-Slim Alouini","doi":"10.3389/frcmn.2022.746201","DOIUrl":"https://doi.org/10.3389/frcmn.2022.746201","url":null,"abstract":"In this work, a mixed free-space optics (FSO)/radio-frequency (RF) based multiple serial high altitude platforms (HAPs) assisted multiuser multiantenna terrestrial communication system is considered. For the considered multi-hop system, earth station to HAP and HAP to HAP links are assumed as FSO links, and HAP to terrestrial mobile users (MUs) link is assumed as RF link. At the FSO detector both the heterodyne detection and intensity modulation direct detection techniques are considered. Atmospheric turbulence of the ES to HAP FSO link is modeled with Gamma-Gamma fading along with the pointing error impairments. As HAP situates in the stratosphere, negligible atmospheric turbulence exists at HAP altitude (20 km), hence, only pointing error is considered for the inter HAP links. Further, the HAP consists of multiantenna array to provide high data-rates to the terrestrial users via RF links, considered to be Nakagami-m distributed. The intermediate HAPs perform selective decode-and-forward relaying and opportunistic user scheduling is performed for the best user selection. For the performance analysis, analytical expression of overall outage probability is obtained and the impact of various selection parameters like pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on the outage performance. Asymptotic outage probability is also derived to obtain the diversity order of the considered communication system. Further, considering various modulation schemes, a generalized average bit-error-rate expression is derived and the impact of pointing error, FSO detection type, MU selection, number of antennas, and RF fading severity are observed on its performance. Finally, derived results are validated through Monte-Carlo simulations.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133342654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-17DOI: 10.3389/frcmn.2022.850781
Julius Ssimbwa, Byungju Lim, Ju-Hyung Lee, Young-Chai Ko
The unrelenting technological advancement in the generation of wireless networks in recent years has awakened the motion concerning the inclusion of satellites in personal communications. Leveraging their ability to provide wide coverage, uniform services, wide bandwidth, and so forth, Satellite systems will be expected to co-exist with the current state-of-the-art infrastructure of terrestrial networks. Herein, we present a comparative study on the representative digital modulation techniques for use in personal satellite communications. We discuss the advantages and limitations of different modulation techniques, such as phase shift keying, continuous phase modulation, amplitude phase shift keying, and quadrature amplitude modulation. We also perform evaluations based on spectral efficiency, power efficiency, modulation error ratio, error vector magnitude, and peak-to-average power ratio in the presence of high power amplifier nonlinearities and Doppler effects. Comparisons in the form of tables, illustrations, and curves are also presented. In correspondence to the comparisons made basing on the aforementioned metrics, we conclude that continuous phase modulation is the best candidate modulation scheme for personal satellite communications since it outperforms other schemes by compromising the trade-off between power efficiency, bandwidth efficiency, and immunity to errors. We further present open issues that would reinforce personal satellite communications in terms of reliability, throughput and latency, other than power and spectral efficiency, if combined with appropriate modulation schemes.
{"title":"A Survey on Robust Modulation Requirements for the Next Generation Personal Satellite Communications","authors":"Julius Ssimbwa, Byungju Lim, Ju-Hyung Lee, Young-Chai Ko","doi":"10.3389/frcmn.2022.850781","DOIUrl":"https://doi.org/10.3389/frcmn.2022.850781","url":null,"abstract":"The unrelenting technological advancement in the generation of wireless networks in recent years has awakened the motion concerning the inclusion of satellites in personal communications. Leveraging their ability to provide wide coverage, uniform services, wide bandwidth, and so forth, Satellite systems will be expected to co-exist with the current state-of-the-art infrastructure of terrestrial networks. Herein, we present a comparative study on the representative digital modulation techniques for use in personal satellite communications. We discuss the advantages and limitations of different modulation techniques, such as phase shift keying, continuous phase modulation, amplitude phase shift keying, and quadrature amplitude modulation. We also perform evaluations based on spectral efficiency, power efficiency, modulation error ratio, error vector magnitude, and peak-to-average power ratio in the presence of high power amplifier nonlinearities and Doppler effects. Comparisons in the form of tables, illustrations, and curves are also presented. In correspondence to the comparisons made basing on the aforementioned metrics, we conclude that continuous phase modulation is the best candidate modulation scheme for personal satellite communications since it outperforms other schemes by compromising the trade-off between power efficiency, bandwidth efficiency, and immunity to errors. We further present open issues that would reinforce personal satellite communications in terms of reliability, throughput and latency, other than power and spectral efficiency, if combined with appropriate modulation schemes.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133922549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-28DOI: 10.3389/frcmn.2022.824593
Jianyang Shi, Ouhan Huang, Yinaer Ha, Wenqing Niu, Ruizhe Jin, Guojin Qin, Zengyi Xu, N. Chi
As 6G research progresses, both visible light communication (VLC) and artificial intelligence (AI) become important components, which makes them appear to converge. Neural networks (NN) as equalizers are gradually occupying an increasingly important position in the research of the physical layer of VLC, especially in nonlinear compensation. In this paper, we will propose three categories of neural network equalizers, including input data reconfiguration NN, network reconfiguration NN and loss function reconfiguration NN. We give the definitions of these three neural networks and their applications in VLC systems. This work allows the reader to have a clearer understanding and future trends of neural networks in visible light communication, especially in terms of equalizers.
{"title":"Neural Network Equalizer in Visible Light Communication: State of the Art and Future Trends","authors":"Jianyang Shi, Ouhan Huang, Yinaer Ha, Wenqing Niu, Ruizhe Jin, Guojin Qin, Zengyi Xu, N. Chi","doi":"10.3389/frcmn.2022.824593","DOIUrl":"https://doi.org/10.3389/frcmn.2022.824593","url":null,"abstract":"As 6G research progresses, both visible light communication (VLC) and artificial intelligence (AI) become important components, which makes them appear to converge. Neural networks (NN) as equalizers are gradually occupying an increasingly important position in the research of the physical layer of VLC, especially in nonlinear compensation. In this paper, we will propose three categories of neural network equalizers, including input data reconfiguration NN, network reconfiguration NN and loss function reconfiguration NN. We give the definitions of these three neural networks and their applications in VLC systems. This work allows the reader to have a clearer understanding and future trends of neural networks in visible light communication, especially in terms of equalizers.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114038557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-27DOI: 10.3389/frcmn.2022.867045
Pantea Nadimi Goki, Muhammad Imran, F. Cavaliere, L. Potí
We proposed and investigated a high-performance, energy-efficient, and low-cost self-homodyne coherent detection transmission (SHCDT) system for the 5G access network segment assuring high capacity and light digital signal processing (DSP) at the same time, avoiding the local oscillator for detection. The system implementation is based on a code-based spectral shaping at the transmitter and carrier extractor at the receiver. In the self-homodyne coherent system, a continuous wave carrier is transmitted together with the modulated signal. After transmission, at the receiver, the carrier is extracted and used as a local oscillator (LO) to prevent frequency offset with respect to the transmitted signal and phase noise, resulting in a decrease in the digital signal processing (DSP) complexity. Transmission results indicate that even a low portion of the residual local oscillator (LO) on the transmitted signal at the receiver side can lead to an increase in the signal-to-noise ratio (OSNR) penalty. Consequently, applying a proper technique to separate the unmodulated carrier and the modulated signal is the key to the system’s performance. We evaluated the self-homodyne coherent system performance through numerical analysis and experimental validation. The performance of the proposed self-coherent system, using a narrow bandwidth Fabry–Perot filter for optical carrier extraction, is evaluated experimentally on a 28 Gbaud dual-polarization 16QAM transmission system considering different code block lengths for signal spectral shaping through bit-error-rate (BER) measurements.
{"title":"Smart Self-Coherent Optical Communication for Short Distances","authors":"Pantea Nadimi Goki, Muhammad Imran, F. Cavaliere, L. Potí","doi":"10.3389/frcmn.2022.867045","DOIUrl":"https://doi.org/10.3389/frcmn.2022.867045","url":null,"abstract":"We proposed and investigated a high-performance, energy-efficient, and low-cost self-homodyne coherent detection transmission (SHCDT) system for the 5G access network segment assuring high capacity and light digital signal processing (DSP) at the same time, avoiding the local oscillator for detection. The system implementation is based on a code-based spectral shaping at the transmitter and carrier extractor at the receiver. In the self-homodyne coherent system, a continuous wave carrier is transmitted together with the modulated signal. After transmission, at the receiver, the carrier is extracted and used as a local oscillator (LO) to prevent frequency offset with respect to the transmitted signal and phase noise, resulting in a decrease in the digital signal processing (DSP) complexity. Transmission results indicate that even a low portion of the residual local oscillator (LO) on the transmitted signal at the receiver side can lead to an increase in the signal-to-noise ratio (OSNR) penalty. Consequently, applying a proper technique to separate the unmodulated carrier and the modulated signal is the key to the system’s performance. We evaluated the self-homodyne coherent system performance through numerical analysis and experimental validation. The performance of the proposed self-coherent system, using a narrow bandwidth Fabry–Perot filter for optical carrier extraction, is evaluated experimentally on a 28 Gbaud dual-polarization 16QAM transmission system considering different code block lengths for signal spectral shaping through bit-error-rate (BER) measurements.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130991776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-04DOI: 10.3389/frcmn.2022.867581
Liang Zhang, Chuanting Zhang, Shuping Dang, B. Shihada
Currently, the sixth-generation (6G) communication research roadmap is being frequently discussed and designed, in which, undoubtedly, aerial telecommunication infrastructures play crucial roles for boosting transmission capacity, enlarging coverage, and democratizing the benefits of information and communications technology (ICT) over the globe. However, the sudden news released in January 2021 that Alphabet is shutting down Project Loon, one of the most important projects enabling communications over aerial infrastructures, surprises the academia of communications science. There is no question that the failure of Project Loon will yield profound impacts on and even shift the current 6G research roadmap design. The latent mismatch between academia and industry in communication science should also raise adequate attention. Therefore, in this article, we analyze the commercial failure of Project Loon by public information from reliable sources and summarize a series of important lessons for the 6G research roadmap design.
{"title":"Lessons From the Commercial Failure of Project Loon for 6G Research Roadmap Design","authors":"Liang Zhang, Chuanting Zhang, Shuping Dang, B. Shihada","doi":"10.3389/frcmn.2022.867581","DOIUrl":"https://doi.org/10.3389/frcmn.2022.867581","url":null,"abstract":"Currently, the sixth-generation (6G) communication research roadmap is being frequently discussed and designed, in which, undoubtedly, aerial telecommunication infrastructures play crucial roles for boosting transmission capacity, enlarging coverage, and democratizing the benefits of information and communications technology (ICT) over the globe. However, the sudden news released in January 2021 that Alphabet is shutting down Project Loon, one of the most important projects enabling communications over aerial infrastructures, surprises the academia of communications science. There is no question that the failure of Project Loon will yield profound impacts on and even shift the current 6G research roadmap design. The latent mismatch between academia and industry in communication science should also raise adequate attention. Therefore, in this article, we analyze the commercial failure of Project Loon by public information from reliable sources and summarize a series of important lessons for the 6G research roadmap design.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124477753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-30DOI: 10.3389/frcmn.2022.827105
Pavlos S. Bouzinis, P. Diamantoulakis, G. Karagiannidis
Federated Learning (FL) is a promising decentralized machine learning technique, which can be efficiently used to reduce the latency and deal with the data privacy in the next 6th generation (6G) of wireless networks. However, the finite computation and communication resources of the wireless devices, is a limiting factor for their very low latency requirements, while users need incentives for spending their constrained resources. In this direction, we propose an incentive mechanism for Wireless FL (WFL), which motivates users to utilize their available radio and computation resources, in order to achieve a fast global convergence of the WFL process. More specifically, we model the interaction among users and the server as a Stackelberg game, where users (followers) aim to maximize their utility/pay-off, while the server (leader) focuses on minimizing the global convergence time of the FL task. We analytically solve the Stackelberg game and derive the optimal strategies for both the server and the user set, corresponding to the Stackelberg equilibrium. Following that, we consider the presence of malicious users, who may attempt to mislead the server with false information throughout the game, aiming to further increase their utility. To alleviate this burden, we propose a deep learning-aided secure mechanism at the servers’ side, which detects malicious users and prevents them from participating into the WFL process. Simulations verify the effectiveness of the proposed method, which result in increased users’ utility and reduced global convergence time, compared with various baseline schemes. Finally, the proposed mechanism for detecting the users’ behavior seems to be very promising in increasing the security of WFL-based networks.
{"title":"Incentive-Based Delay Minimization for 6G-Enabled Wireless Federated Learning","authors":"Pavlos S. Bouzinis, P. Diamantoulakis, G. Karagiannidis","doi":"10.3389/frcmn.2022.827105","DOIUrl":"https://doi.org/10.3389/frcmn.2022.827105","url":null,"abstract":"Federated Learning (FL) is a promising decentralized machine learning technique, which can be efficiently used to reduce the latency and deal with the data privacy in the next 6th generation (6G) of wireless networks. However, the finite computation and communication resources of the wireless devices, is a limiting factor for their very low latency requirements, while users need incentives for spending their constrained resources. In this direction, we propose an incentive mechanism for Wireless FL (WFL), which motivates users to utilize their available radio and computation resources, in order to achieve a fast global convergence of the WFL process. More specifically, we model the interaction among users and the server as a Stackelberg game, where users (followers) aim to maximize their utility/pay-off, while the server (leader) focuses on minimizing the global convergence time of the FL task. We analytically solve the Stackelberg game and derive the optimal strategies for both the server and the user set, corresponding to the Stackelberg equilibrium. Following that, we consider the presence of malicious users, who may attempt to mislead the server with false information throughout the game, aiming to further increase their utility. To alleviate this burden, we propose a deep learning-aided secure mechanism at the servers’ side, which detects malicious users and prevents them from participating into the WFL process. Simulations verify the effectiveness of the proposed method, which result in increased users’ utility and reduced global convergence time, compared with various baseline schemes. Finally, the proposed mechanism for detecting the users’ behavior seems to be very promising in increasing the security of WFL-based networks.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130084181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-24DOI: 10.3389/frcmn.2022.853416
Kai‐Kit Wong, K. Tong, Yuanjun Shen, Yu Chen, Yangyang Zhang
While 5G is tasked to transform our lives for the better over the next 10 years, next-generation mobile communications, a.k.a. 6G, will undoubtedly demand even higher energy and spectral efficiencies capable of providing myriads of new services and experience to users everywhere they go. Although our technologies do evolve from one generation to the next, the root of the ambition in mobile communications has always been to ensure reliable performance from an uncertain, fluctuating medium. The previous generations have already seen numerous technologies such as advanced coding and signal processing, resource allocation, and most famously, multiple-input multiple-output to redeem some stability from the wireless medium. Inevitably, 6G will be built upon further disruptive technologies that enable another cycle of revolution. In this article, we examine one emerging technology, referred to as fluid antenna system that represents any software-controllable fluidic, conductive, or dielectric structure that can alter its shape and position to reconfigure the gain, radiation pattern, operating frequency, and other characteristics. Fluid antenna takes inspiration from Bruce Lee's Jeet Kune Do to innovate mobile communication systems design. In Bruce Lee's philosophy, one can imitate water to adapt combat style, whereas fluid antenna exploits the dynamic nature of fluids or switchable pixels to achieve ultimate flexibility for diversity and multiplexing benefits that have been unseen before in mobile devices, and the implication can be transformative. This article discusses the potential of fluid antenna systems for 6G, and in particular, we introduce six research topics in fluid antenna systems that if solved successfully could revolutionize mobile communications network design and optimization. This article intends to stimulate discussion that will help shape the development of 6G technologies.
{"title":"Bruce Lee-Inspired Fluid Antenna System: Six Research Topics and the Potentials for 6G","authors":"Kai‐Kit Wong, K. Tong, Yuanjun Shen, Yu Chen, Yangyang Zhang","doi":"10.3389/frcmn.2022.853416","DOIUrl":"https://doi.org/10.3389/frcmn.2022.853416","url":null,"abstract":"While 5G is tasked to transform our lives for the better over the next 10 years, next-generation mobile communications, a.k.a. 6G, will undoubtedly demand even higher energy and spectral efficiencies capable of providing myriads of new services and experience to users everywhere they go. Although our technologies do evolve from one generation to the next, the root of the ambition in mobile communications has always been to ensure reliable performance from an uncertain, fluctuating medium. The previous generations have already seen numerous technologies such as advanced coding and signal processing, resource allocation, and most famously, multiple-input multiple-output to redeem some stability from the wireless medium. Inevitably, 6G will be built upon further disruptive technologies that enable another cycle of revolution. In this article, we examine one emerging technology, referred to as fluid antenna system that represents any software-controllable fluidic, conductive, or dielectric structure that can alter its shape and position to reconfigure the gain, radiation pattern, operating frequency, and other characteristics. Fluid antenna takes inspiration from Bruce Lee's Jeet Kune Do to innovate mobile communication systems design. In Bruce Lee's philosophy, one can imitate water to adapt combat style, whereas fluid antenna exploits the dynamic nature of fluids or switchable pixels to achieve ultimate flexibility for diversity and multiplexing benefits that have been unseen before in mobile devices, and the implication can be transformative. This article discusses the potential of fluid antenna systems for 6G, and in particular, we introduce six research topics in fluid antenna systems that if solved successfully could revolutionize mobile communications network design and optimization. This article intends to stimulate discussion that will help shape the development of 6G technologies.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115100844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-22DOI: 10.3389/frcmn.2022.821037
Islam Abu Mahady, E. Bedeer, S. Ikki
This paper studies a two-user downlink non-orthogonal multiple access (NOMA) system that adopts an improper Gaussian signaling (IGS) strategy to compensate for the performance loss due to imperfect successive interference cancellation (SIC). Joint optimization problems are formulated to maximize the overall spectral efficiency and energy efficiency of a two-user NOMA system under minimum user-rate requirements and total power constraints. Sub-optimal solutions of IGS circularity coefficients and power allocation are obtained for the formulated problems. Furthermore, improper constellation diagrams are designed using widely linear transformation with predefined optimized IGS coefficients to study the impact of IGS on throughput and error performance. Simulation results show that the performance of IGS-based NOMA systems, where the IGS strategy is adopted by both users, outperforms that of the proper Gaussian signal (PGS)-based NOMA system under imperfect SIC.
{"title":"Non-Orthogonal Multiple Access: The Case of Improper Gaussian Signaling and Imperfect Successive Interference Cancellation","authors":"Islam Abu Mahady, E. Bedeer, S. Ikki","doi":"10.3389/frcmn.2022.821037","DOIUrl":"https://doi.org/10.3389/frcmn.2022.821037","url":null,"abstract":"This paper studies a two-user downlink non-orthogonal multiple access (NOMA) system that adopts an improper Gaussian signaling (IGS) strategy to compensate for the performance loss due to imperfect successive interference cancellation (SIC). Joint optimization problems are formulated to maximize the overall spectral efficiency and energy efficiency of a two-user NOMA system under minimum user-rate requirements and total power constraints. Sub-optimal solutions of IGS circularity coefficients and power allocation are obtained for the formulated problems. Furthermore, improper constellation diagrams are designed using widely linear transformation with predefined optimized IGS coefficients to study the impact of IGS on throughput and error performance. Simulation results show that the performance of IGS-based NOMA systems, where the IGS strategy is adopted by both users, outperforms that of the proper Gaussian signal (PGS)-based NOMA system under imperfect SIC.","PeriodicalId":106247,"journal":{"name":"Frontiers in Communications and Networks","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122257767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-11DOI: 10.3389/frcmn.2022.836506
Muhammad Usman, Shuja Ansari, Ahmad Taha, A. Zahid, Q. Abbasi, M. Imran
By 2050, experts estimate that the agricultural produce must increase by 60%–70% to meet the needs of the ever increasing population of the world. To this aim, the concept of precision agriculture or smart farming has recently been coined. The idea of precision agriculture is well represented as a smart management system, having the ability to monitor, observe, sense, measure and control the health and water contents in plants at nano-scale and crops at macro-scale. The goal is to maximise the production while preserving the vital resources. The combination of terahertz (THz) based sensing technology to estimate plant health at a cellular level, and wireless sensor networks deployed within crops to monitor different variables while making intelligent decisions is far reaching. The integration and operation of such a macro-nano-sensor system requires a sustainable communication infrastructure that considers the demands of remote and agile agricultural environments. In this paper, an integrated sensing and communication system for plant health monitoring that utilises THz signals, is presented as a 6G use case. The joint architecture is outlined and various challenges including energy harvesting, practical implementation among others, followed by recommendations for future research are presented.
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