111 research outputs found
Reliable indoor optical wireless communication in the presence of fixed and random blockers
The advanced innovation of smartphones has led to the exponential growth of internet users which is expected to reach 71% of the global population by the end of 2027. This in turn has given rise to the demand for wireless data and internet devices that is capable of providing energy-efficient, reliable data transmission and high-speed wireless data services. Light-fidelity (LiFi), known as one of the optical wireless communication (OWC) technology is envisioned as a promising solution to accommodate these demands. However, the indoor LiFi channel is highly environment-dependent which can be influenced by several crucial factors (e.g., presence of people, furniture, random users' device orientation and the limited field of view (FOV) of optical receivers) which may contribute to the blockage of the line-of-sight (LOS) link.
In this thesis, it is investigated whether deep learning (DL) techniques can effectively learn the distinct features of the indoor LiFi environment in order to provide superior performance compared to the conventional channel estimation techniques (e.g., minimum mean square error (MMSE) and least squares (LS)). This performance can be seen particularly when access to real-time channel state information (CSI) is restricted and is achieved with the cost of collecting large and meaningful data to train the DL neural networks and the training time which was conducted offline. Two DL-based schemes are designed for signal detection and resource allocation where it is shown that the proposed methods were able to offer close performance to the optimal conventional schemes and demonstrate substantial gain in terms of bit-error ratio (BER) and throughput especially in a more realistic or complex indoor environment.
Performance analysis of LiFi networks under the influence of fixed and random blockers is essential and efficient solutions capable of diminishing the blockage effect is required. In this thesis, a CSI acquisition technique for a reconfigurable intelligent surface (RIS)-aided LiFi network is proposed to significantly reduce the dimension of the decision variables required for RIS beamforming. Furthermore, it is shown that several RIS attributes such as shape, size, height and distribution play important roles in increasing the network performance. Finally, the performance analysis for an RIS-aided realistic indoor LiFi network are presented. The proposed RIS configuration shows outstanding performances in reducing the network outage probability under the effect of blockages, random device orientation, limited receiver's FOV, furniture and user behavior.
Establishing a LOS link that achieves uninterrupted wireless connectivity in a realistic indoor environment can be challenging. In this thesis, an analysis of link blockage is presented for an indoor LiFi system considering fixed and random blockers. In particular, novel analytical framework of the coverage probability for a single source and multi-source are derived. Using the proposed analytical framework, link blockages of the indoor LiFi network are carefully investigated and it is shown that the incorporation of multiple sources and RIS can significantly reduce the LOS coverage blockage probability in indoor LiFi systems
Modelling, Dimensioning and Optimization of 5G Communication Networks, Resources and Services
This reprint aims to collect state-of-the-art research contributions that address challenges in the emerging 5G networks design, dimensioning and optimization. Designing, dimensioning and optimization of communication networks resources and services have been an inseparable part of telecom network development. The latter must convey a large volume of traffic, providing service to traffic streams with highly differentiated requirements in terms of bit-rate and service time, required quality of service and quality of experience parameters. Such a communication infrastructure presents many important challenges, such as the study of necessary multi-layer cooperation, new protocols, performance evaluation of different network parts, low layer network design, network management and security issues, and new technologies in general, which will be discussed in this book
On the feasibility and applications of in-band full-duplex radios for future wireless networks
Due to the continuous increase of the demands for the wireless network’s capacity, in-band full-duplex (IBFD) has recently become a key research topic due to its potential to double spectral efficiency, reduce latency, enhance emerging applications, etc., by transmitting and receiving simultaneously over the same channel. Meanwhile, many studies in the literature experimentally demonstrated the feasibility of IBFD radios, which leads to the belief that it is possible to introduce IBFD in the standard of the next-generation networks. Therefore, in this thesis, we timely study the feasibility of IBFD and investigate its advantages for emerging applications in future networks.
In the first part, we investigate the interference suppression methods to maximize the IBFD gain by minimizing the effects of self-interference (SI) and co-channel interference (CCI). To this end, we first study a 3-step self-interference cancellation (SIC) scheme. We focus on the time domain-based analog canceller and nonlinear digital canceller, explaining their rationale, demonstrating their effectiveness, and finding the optimal design by minimizing the residual effects. To break the limitation of conventional electrical radio frequency (RF) cancellers, we study the photonic-assisted canceller (PAC) and propose a new design, namely a fiber array-based canceller. We propose a new low-complexity tuning algorithm for the PAC. The effectiveness of the proposed fiber array canceller is demonstrated via simulations. Furthermore, we construct a prototype of the fiber array canceller with two taps and carry out experiments in real-world environments. Results show that the 3-step cancellation scheme can bring the SI close to the receiver's noise floor. Then, we consider the multiple-input multiple-output (MIMO) scenarios, proposing to employ hybrid RF-digital beamforming to reduce the implementation cost and studying its effects on the SIC design. Additionally, we propose a user allocation algorithm to reduce the CCI from the physical layer. A heterogeneous industrial Internet of Things (IIoT) scenario is considered, while the proposed algorithm can be generalized by modifying the parameters to fit any other network.
In the second part, we study the beamforming schemes for IBFD multi-cell multi-user (IBFD-MCMU) networks. The transceiver hardware impairments (HWIs) and channel uncertainty are considered for robustness. We first enhance zero-forcing (ZF) and maximum ratio transmission and combining (MRTC) beamforming to be compatible with IBFD-MCMU networks in the presence of multi-antenna users. Then, we study beamforming for SIC, which is challenging for MCMU networks due to the limited antennas but complex interference. We propose a minimum mean-squared error (MMSE)-based scheme to enhance the SIC performance while minimizing its effects on the sum rate. Furthermore, we investigate a robust joint power allocation and beamforming (JPABF) scheme, which approaches the performance of existing optimal designs with reduced complexity. Their performance is evaluated and compared through 3GPP-based simulations.
In the third part, we investigate the advantages of applying IBFD radios for physical layer security (PLS). We focus on a channel frequency response (CFR)-based secret key generation (SKG) scheme in MIMO systems. We formulate the intrinsic imperfections of IBFD radios (e.g., SIC overheads and noise due to imperfect SIC) and derive their effects on the probing errors. Then we derive closed-form expressions for the secret key capacity (SKC) of the SKG scheme in the presence of a passive eavesdropper. We analyze the asymptotic behavior of the SKC in the high-SNR regime and reveal the fundamental limits for IBFD and half-duplex (HD) radios. Based on the asymptotic SKC, numerical results illustrate that effective analog self-interference cancellation (ASIC) is the basis for IBFD to gain benefits over HD. Additionally, we investigate essential processing for the CFR-based SKG scheme and verify its effectiveness via simulations and the National Institute of Standards and Technology (NIST) test.
In the fourth part, we consider a typical application of IBFD radios: integrated sensing and communication (ISAC). To provide reliable services in high-mobility scenarios, we introduce orthogonal time frequency space (OTFS) modulation and develop a novel framework for OTFS-ISAC. We give the channel representation in different domains and reveal the limitations and disadvantages of existing ISAC frameworks for OTFS waveforms and propose a novel radar sensing method, including a conventional MUSIC algorithm for angle estimation and a delay-time domain-based range and velocity estimator. Additionally, we study the communication design based on the estimated radar sensing parameters. To enable reliable IBFD radios in high-mobility scenarios, a SIC scheme compatible with OTFS and rapidly-changing channels is proposed, which is lacking in the literature. Numerical results demonstrate that the proposed ISAC waveform and associated estimation algorithm can provide both reliable communications and accurate radar sensing with reduced latency, improved spectral efficiency, etc
Systematic Approaches for Telemedicine and Data Coordination for COVID-19 in Baja California, Mexico
Conference proceedings info:
ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologies
Raleigh, HI, United States, March 24-26, 2023
Pages 529-542We provide a model for systematic implementation of telemedicine within a large evaluation center for COVID-19 in the area of Baja California, Mexico. Our model is based on human-centric design factors and cross disciplinary collaborations for scalable data-driven enablement of smartphone, cellular, and video Teleconsul-tation technologies to link hospitals, clinics, and emergency medical services for point-of-care assessments of COVID testing, and for subsequent treatment and quar-antine decisions. A multidisciplinary team was rapidly created, in cooperation with different institutions, including: the Autonomous University of Baja California, the Ministry of Health, the Command, Communication and Computer Control Center
of the Ministry of the State of Baja California (C4), Colleges of Medicine, and the College of Psychologists. Our objective is to provide information to the public and to evaluate COVID-19 in real time and to track, regional, municipal, and state-wide data in real time that informs supply chains and resource allocation with the anticipation of a surge in COVID-19 cases. RESUMEN Proporcionamos un modelo para la implementación sistemática de la telemedicina dentro de un gran centro de evaluación de COVID-19 en el área de Baja California, México. Nuestro modelo se basa en factores de diseño centrados en el ser humano y colaboraciones interdisciplinarias para la habilitación escalable basada en datos de tecnologías de teleconsulta de teléfonos inteligentes, celulares y video para vincular hospitales, clínicas y servicios médicos de emergencia para evaluaciones de COVID en el punto de atención. pruebas, y para el tratamiento posterior y decisiones de cuarentena. Rápidamente se creó un equipo multidisciplinario, en cooperación con diferentes instituciones, entre ellas: la Universidad Autónoma de Baja California, la Secretaría de Salud, el Centro de Comando, Comunicaciones y Control Informático.
de la Secretaría del Estado de Baja California (C4), Facultades de Medicina y Colegio de Psicólogos. Nuestro objetivo es proporcionar información al público y evaluar COVID-19 en tiempo real y rastrear datos regionales, municipales y estatales en tiempo real que informan las cadenas de suministro y la asignación de recursos con la anticipación de un aumento de COVID-19. 19 casos.ICICT 2023: 2023 The 6th International Conference on Information and Computer Technologieshttps://doi.org/10.1007/978-981-99-3236-
Real-Time Waveform Prototyping
Mobile Netzwerke der fünften Generation zeichen sich aus durch vielfältigen Anforderungen und Einsatzszenarien. Drei unterschiedliche Anwendungsfälle sind hierbei besonders relevant: 1) Industrie-Applikationen fordern Echtzeitfunkübertragungen mit besonders niedrigen Ausfallraten. 2) Internet-of-things-Anwendungen erfordern die Anbindung einer Vielzahl von verteilten Sensoren. 3) Die Datenraten für Anwendung wie z.B. der Übermittlung von Videoinhalten sind massiv gestiegen.
Diese zum Teil gegensätzlichen Erwartungen veranlassen Forscher und Ingenieure dazu, neue Konzepte und Technologien für zukünftige drahtlose Kommunikationssysteme in Betracht zu ziehen. Ziel ist es, aus einer Vielzahl neuer Ideen vielversprechende Kandidatentechnologien zu identifizieren und zu entscheiden, welche für die Umsetzung in zukünftige Produkte geeignet sind. Die Herausforderungen, diese Anforderungen zu erreichen, liegen jedoch jenseits der Möglichkeiten, die eine einzelne Verarbeitungsschicht in einem drahtlosen Netzwerk bieten kann. Daher müssen mehrere Forschungsbereiche Forschungsideen gemeinsam nutzen.
Diese Arbeit beschreibt daher eine Plattform als Basis für zukünftige experimentelle Erforschung von drahtlosen Netzwerken unter reellen Bedingungen. Es werden folgende drei Aspekte näher vorgestellt:
Zunächst erfolgt ein Überblick über moderne Prototypen und Testbed-Lösungen, die auf großes Interesse, Nachfrage, aber auch Förderungsmöglichkeiten stoßen. Allerdings ist der Entwicklungsaufwand nicht unerheblich und richtet sich stark nach den gewählten Eigenschaften der Plattform. Der Auswahlprozess ist jedoch aufgrund der Menge der verfügbaren Optionen und ihrer jeweiligen (versteckten) Implikationen komplex. Daher wird ein Leitfaden anhand verschiedener Beispiele vorgestellt, mit dem Ziel Erwartungen im Vergleich zu den für den Prototyp erforderlichen Aufwänden zu bewerten.
Zweitens wird ein flexibler, aber echtzeitfähiger Signalprozessor eingeführt, der auf einer software-programmierbaren Funkplattform läuft. Der Prozessor ermöglicht die Rekonfiguration wichtiger Parameter der physikalischen Schicht während der Laufzeit, um eine Vielzahl moderner Wellenformen zu erzeugen. Es werden vier Parametereinstellungen 'LLC', 'WiFi', 'eMBB' und 'IoT' vorgestellt, um die Anforderungen der verschiedenen drahtlosen Anwendungen widerzuspiegeln. Diese werden dann zur Evaluierung der die in dieser Arbeit vorgestellte Implementierung herangezogen.
Drittens wird durch die Einführung einer generischen Testinfrastruktur die Einbeziehung externer Partner aus der Ferne ermöglicht. Das Testfeld kann hier für verschiedenste Experimente flexibel auf die Anforderungen drahtloser Technologien zugeschnitten werden. Mit Hilfe der Testinfrastruktur wird die Leistung des vorgestellten Transceivers hinsichtlich Latenz, erreichbarem Durchsatz und Paketfehlerraten bewertet. Die öffentliche Demonstration eines taktilen Internet-Prototypen, unter Verwendung von Roboterarmen in einer Mehrbenutzerumgebung, konnte erfolgreich durchgeführt und bei mehreren Gelegenheiten präsentiert werden.:List of figures
List of tables
Abbreviations
Notations
1 Introduction
1.1 Wireless applications
1.2 Motivation
1.3 Software-Defined Radio
1.4 State of the art
1.5 Testbed
1.6 Summary
2 Background
2.1 System Model
2.2 PHY Layer Structure
2.3 Generalized Frequency Division Multiplexing
2.4 Wireless Standards
2.4.1 IEEE 802.15.4
2.4.2 802.11 WLAN
2.4.3 LTE
2.4.4 Low Latency Industrial Wireless Communications
2.4.5 Summary
3 Wireless Prototyping
3.1 Testbed Examples
3.1.1 PHY - focused Testbeds
3.1.2 MAC - focused Testbeds
3.1.3 Network - focused testbeds
3.1.4 Generic testbeds
3.2 Considerations
3.3 Use cases and Scenarios
3.4 Requirements
3.5 Methodology
3.6 Hardware Platform
3.6.1 Host
3.6.2 FPGA
3.6.3 Hybrid
3.6.4 ASIC
3.7 Software Platform
3.7.1 Testbed Management Frameworks
3.7.2 Development Frameworks
3.7.3 Software Implementations
3.8 Deployment
3.9 Discussion
3.10 Conclusion
4 Flexible Transceiver
4.1 Signal Processing Modules
4.1.1 MAC interface
4.1.2 Encoding and Mapping
4.1.3 Modem
4.1.4 Post modem processing
4.1.5 Synchronization
4.1.6 Channel Estimation and Equalization
4.1.7 Demapping
4.1.8 Flexible Configuration
4.2 Analysis
4.2.1 Numerical Precision
4.2.2 Spectral analysis
4.2.3 Latency
4.2.4 Resource Consumption
4.3 Discussion
4.3.1 Extension to MIMO
4.4 Summary
5 Testbed
5.1 Infrastructure
5.2 Automation
5.3 Software Defined Radio Platform
5.4 Radio Frequency Front-end
5.4.1 Sub 6 GHz front-end
5.4.2 26 GHz mmWave front-end
5.5 Performance evaluation
5.6 Summary
6 Experiments
6.1 Single Link
6.1.1 Infrastructure
6.1.2 Single Link Experiments
6.1.3 End-to-End
6.2 Multi-User
6.3 26 GHz mmWave experimentation
6.4 Summary
7 Key lessons
7.1 Limitations Experienced During Development
7.2 Prototyping Future
7.3 Open points
7.4 Workflow
7.5 Summary
8 Conclusions
8.1 Future Work
8.1.1 Prototyping Workflow
8.1.2 Flexible Transceiver Core
8.1.3 Experimental Data-sets
8.1.4 Evolved Access Point Prototype For Industrial Networks
8.1.5 Testbed Standardization
A Additional Resources
A.1 Fourier Transform Blocks
A.2 Resource Consumption
A.3 Channel Sounding using Chirp sequences
A.3.1 SNR Estimation
A.3.2 Channel Estimation
A.4 Hardware part listThe demand to achieve higher data rates for the Enhanced Mobile Broadband scenario and novel fifth generation use cases like Ultra-Reliable Low-Latency and Massive Machine-type Communications drive researchers and engineers to consider new concepts and technologies for future wireless communication systems. The goal is to identify promising candidate technologies
among a vast number of new ideas and to decide, which are suitable for implementation in future products. However, the challenges to achieve those demands are beyond the capabilities a single processing layer in a wireless network can offer. Therefore, several research domains have to collaboratively exploit research ideas.
This thesis presents a platform to provide a base for future applied research on wireless networks. Firstly, by giving an overview of state-of-the-art prototypes and testbed solutions. Secondly by introducing a flexible, yet real-time physical layer signal processor running on a software defined radio platform. The processor enables reconfiguring important parameters of the physical layer during run-time in order to create a multitude of modern waveforms. Thirdly, by introducing a generic test infrastructure, which can be tailored to prototype diverse wireless technology and which is remotely accessible in order to invite new ideas by third parties. Using the test infrastructure, the performance of the flexible transceiver is evaluated regarding latency, achievable throughput and packet error rates.:List of figures
List of tables
Abbreviations
Notations
1 Introduction
1.1 Wireless applications
1.2 Motivation
1.3 Software-Defined Radio
1.4 State of the art
1.5 Testbed
1.6 Summary
2 Background
2.1 System Model
2.2 PHY Layer Structure
2.3 Generalized Frequency Division Multiplexing
2.4 Wireless Standards
2.4.1 IEEE 802.15.4
2.4.2 802.11 WLAN
2.4.3 LTE
2.4.4 Low Latency Industrial Wireless Communications
2.4.5 Summary
3 Wireless Prototyping
3.1 Testbed Examples
3.1.1 PHY - focused Testbeds
3.1.2 MAC - focused Testbeds
3.1.3 Network - focused testbeds
3.1.4 Generic testbeds
3.2 Considerations
3.3 Use cases and Scenarios
3.4 Requirements
3.5 Methodology
3.6 Hardware Platform
3.6.1 Host
3.6.2 FPGA
3.6.3 Hybrid
3.6.4 ASIC
3.7 Software Platform
3.7.1 Testbed Management Frameworks
3.7.2 Development Frameworks
3.7.3 Software Implementations
3.8 Deployment
3.9 Discussion
3.10 Conclusion
4 Flexible Transceiver
4.1 Signal Processing Modules
4.1.1 MAC interface
4.1.2 Encoding and Mapping
4.1.3 Modem
4.1.4 Post modem processing
4.1.5 Synchronization
4.1.6 Channel Estimation and Equalization
4.1.7 Demapping
4.1.8 Flexible Configuration
4.2 Analysis
4.2.1 Numerical Precision
4.2.2 Spectral analysis
4.2.3 Latency
4.2.4 Resource Consumption
4.3 Discussion
4.3.1 Extension to MIMO
4.4 Summary
5 Testbed
5.1 Infrastructure
5.2 Automation
5.3 Software Defined Radio Platform
5.4 Radio Frequency Front-end
5.4.1 Sub 6 GHz front-end
5.4.2 26 GHz mmWave front-end
5.5 Performance evaluation
5.6 Summary
6 Experiments
6.1 Single Link
6.1.1 Infrastructure
6.1.2 Single Link Experiments
6.1.3 End-to-End
6.2 Multi-User
6.3 26 GHz mmWave experimentation
6.4 Summary
7 Key lessons
7.1 Limitations Experienced During Development
7.2 Prototyping Future
7.3 Open points
7.4 Workflow
7.5 Summary
8 Conclusions
8.1 Future Work
8.1.1 Prototyping Workflow
8.1.2 Flexible Transceiver Core
8.1.3 Experimental Data-sets
8.1.4 Evolved Access Point Prototype For Industrial Networks
8.1.5 Testbed Standardization
A Additional Resources
A.1 Fourier Transform Blocks
A.2 Resource Consumption
A.3 Channel Sounding using Chirp sequences
A.3.1 SNR Estimation
A.3.2 Channel Estimation
A.4 Hardware part lis
Photovoltaics as high-speed optical wireless communication receiver
With an ever-growing network of billions of interconnected smart
devices in the era of the Internet of Things, high-speed communication has
inspired research into the use of low energy and high-speed free-space optical
(FSO) communication systems. In FSO communication, light-emitting diodes
(LEDs) and lasers are used for wireless data transmission in indoor and
outdoor environments and photodiodes are used as data receivers. But these
receivers have two main disadvantages – they require an external power
source to operate, and their small active area makes alignment challenging. A
promising solution to these problems is the use of solar panels as data
receivers. As photovoltaic (PV) panels have a larger active area compared to
that of conventional photodiodes, they relax the strict alignment requirements
and can also simultaneously harvest energy from sunlight.
The current work investigates the use of Si-based off-the-shelf PV
panels as FSO receivers to build an energy-neutral and high-speed FSO
system. As solar panels were never built as optical data communication
receivers, they have a very small communication bandwidth compared to
photodiodes. In this work, a theoretical model of the solar panel is provided
and, using analogue equalization, the usable communication bandwidth of a
solar panel is extended. PV panels were primarily designed to harvest energy
from sunlight. Using the analytical model, simultaneous energy harvesting,
and data communication performances are evaluated. Moreover, the trade-off
between the energy harvesting and data communication capability of the solar
panel is shown. Furthermore, the use of different spectrally efficient
modulation techniques such as direct current optical orthogonal frequency
division multiplexing (DCO-OFDM) and discrete multitone pulse-amplitude
modulation (DMT-PAM) are compared when used with a solar panel as an
optical receiver. It has been found that each modulation scheme is usable
under different applications.
Using the simulated results from the analytical model an FSO prototype
was designed and developed, demonstrating the use of solar panels as the
receivers. A receiver circuit to interface the solar panel with the FSO system
was designed and developed to demonstrate the data communication and
energy harvesting performance. Data rates as high as 75 Mb/s is
demonstrated using DCO-OFDM and offline processing using an off-the-shelf
Si-based solar panel. The PV panel-based FSO system was used to provide
internet access to two residential properties on a remote island in the northern
part of Scotland. The performance of the prototype was carefully studied
under various weather conditions. Furthermore, the maximum user throughput
achieved by the prototype is 28.3 Mb/s with the simultaneous energy
harvesting capability of up to 4.5 W. Lastly, the design of a custom-built solar
panel is proposed which doubles the data rates shown in this work and can be
implemented alongside a small-scale to large-scale solar energy harvesting
infrastructure
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