Approximations for Performance Analysis in Wireless Communications and Applications to Reconfigurable Intelligent Surfaces

In the last few decades, the field of wireless communications has witnessed significant technological advancements to meet the needs of today’s modern world. The rapidly emerging technologies, however, are becoming increasingly sophisticated, and the process of investigating their performance and assessing their applicability in the real world is becoming more challenging. That has aroused a relatively wide range of solutions in the literature to study the performance of the different communication systems or even draw new results that were difficult to obtain. These solutions include field measurements, computer simulations, and theoretical solutions such as alternative representations, approximations, or bounds of classic functions that commonly appear in performance analyses. Field measurements and computer simulations have significantly improved performance evaluation in communication theory. However, more advanced theoretical solutions can be further developed in order to avoid using the ex- pensive and time-consuming wireless communications measurements, replace the numerical simulations, which can sometimes be unreliable and suffer from failures in numerical evaluation, and achieve analytically simpler results with much higher accuracy levels than the existing theoretical ones. To this end, this thesis firstly focuses on developing new approximations and bounds using unified approaches and algorithms that can efficiently and accurately guide researchers through the design of their adopted wireless systems and facilitate the conducted performance analyses in the various communication systems. Two performance measures are of primary interest in this study, namely the average error probability and the ergodic capacity, due to their valuable role in conducting a better understanding of the systems’ behavior and thus enabling systems engineers to quickly detect and resolve design issues that might arise. In particular, several parametric expressions of different analytical forms are developed to approximate or bound the Gaussian Q-function, which occurs in the error probability analysis. Additionally, any generic function of the Q-function is approximated or bounded using a tractable exponential expression. Moreover, a unified logarithmic expression is proposed to approximate or bound the capacity integrals that occur in the capacity analysis. A novel systematic methodology and a modified version of the classical Remez algorithm are developed to acquire optimal coefficients for the accompanying parametric approximation or bound in the minimax sense. Furthermore, the quasi-Newton algorithm is implemented to acquire optimal coefficients in terms of the total error. The average symbol error probability and ergodic capacity are evaluated for various applications using the developed tools. Secondly, this thesis analyzes a couple of communication systems assisted with reconfigurable intelligent surfaces (RISs). RIS has been gaining significant attention lately due to its ability to control propagation environments. In particular, two communication systems are considered; one with a single RIS and correlated Rayleigh fading channels, and the other with multiple RISs and non-identical generic fading channels. Both systems are analyzed in terms of outage probability, average symbol error probability, and ergodic capacity, which are derived using the proposed tools. These performance measures reveal that better performance is achieved when assisting the communication system with RISs, increasing the number of reflecting elements equipped on the RISs, or locating the RISs nearer to either communication node. In conclusion, the developed approximations and bounds, together with the optimized coefficients, provide more efficient tools than those available in the literature, with richer capabilities reflected by the more robust closed-form performance analysis, significant increase in accuracy levels, and considerable reduction in analytical complexity which in turns can offer more understanding into the systems’ behavior and the effect of the different parameters on their performance. Therefore, they are expected to lay the groundwork for the investigation of the latest communication technologies, such as RIS technology, whose performance has been studied for some system models in this thesis using the developed tools

PDF Comparison based on Various FSO Channel Models under Different Atmospheric Turbulence

Recently, wireless communication environments with high speeds and low complexity have become increasingly essential. Free-space optics (FSO) has emerged as a promising solution for providing direct connections between devices in such high-spectrum wireless setups. However, FSO communications are susceptible to weather-induced signal fluctuations, leading to fading and signal weakness at the receiver. To mitigate the effects of these challenges, several mathematical models have been proposed to describe the transition from weak to strong atmospheric turbulence, including Rayleigh, lognormal, Málaga, Nakagami-m, K-distribution, Weibull, Negative-Exponential, Inverse-Gaussian, G-G, and Fisher-Snedecor F distributions. This paper extensively studies and analyses different probability density functions (PDFs) that govern the FSO channel, considering various channel models. This paper aims to comprehensively understand how FSO channels can be effectively modeled using different PDFs. Accurate modeling is crucial for designing FSO systems that can operate optimally under potential environmental conditions. Selecting the appropriate PDF model plays a crucial role in determining the FSO channel's performance during system design. With a multitude of PDF models available, this study aims to identify the most effective PDF model to be employed in FSO channel modeling.

Optical Communication

Optical communication is very much useful in telecommunication systems, data processing and networking. It consists of a transmitter that encodes a message into an optical signal, a channel that carries the signal to its desired destination, and a receiver that reproduces the message from the received optical signal. It presents up to date results on communication systems, along with the explanations of their relevance, from leading researchers in this field. The chapters cover general concepts of optical communication, components, systems, networks, signal processing and MIMO systems. In recent years, optical components and other enhanced signal processing functions are also considered in depth for optical communications systems. The researcher has also concentrated on optical devices, networking, signal processing, and MIMO systems and other enhanced functions for optical communication. This book is targeted at research, development and design engineers from the teams in manufacturing industry, academia and telecommunication industries

Theoretical and experimental contributions for modeling wireless channels

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2017.Este trabalho de conclusão de curso visa agregar contribuições teóricas e experimentais para a modelagem de redes sem fio à partir de quatro projetos realizados durante um estágio supervisionado entre a Universidade de Brasília e a escola francesa de engenharia ENSEIRB-MATMECA durante o ano de 2017. Todos os projetos desse trabalho giram em torno do tema "desafios atuais nas comunicações sem fio" e tem como objetivo a apresentação de tais desafios através de uma breve introdução teórica seguida da realização de simulações, análises estatísticas ou medições em campo. O primeiro projeto propõem um estudo teórico e a validação experimental da distribuição de desvanecimento α-μ/Γ generalizada, usada nesse trabalho para caracterizar ambientes realistas que experimentam desvanecimento composto. Ainda no escopo de análises estatísticas, o segundo projeto propõe uma caracterização da qualidade do sinal celular à partir de dados de potência medidos usando um aplicativo Android de analise de qualidade de redes móveis. As análises estatísticas realizadas poderão auxiliar operadoras de telefonia móvel à parametrizar suas redes e contribuir para o melhoramento da cobertura celular no pais. Em seguida, o terceiro projeto desenvolvido nesse trabalho de conclusão de curso propõe estudos práticos e teóricos de interferência entre os sistema LTE 700MHz e TV digital em Brasília na região da Asa Norte, um tema recente de grande importância dada a desconexão da TV analógica no Brasil até 2018. Por fim, o quarto projeto, realizado em parceria com a Agência Nacional de Telecomunicações (ANATEL) propõe contribuições para o desenvolvimento de um simulador de rede IMT para uso em estudos de compartilhamento e compatibilidade proposto para ajudar na identificação de novas faixas de frequência para o IMT-2020. Os projetos propostos nesse trabalho focam na caracterização e modelagem de canais sem fio à partir do levantamento de estatísticas de primeira ordem, na análise de qualidade das redes celulares no país com base nas informações sobre a cobertura celular experimentada pelos usuários de telefonia móvel e na análise da interferência entre sistemas à partir de estudos entre o LTE e a TV digital e da busca de novas possíveis frequências para o 5G. A realização do estágio supervisionado e desse trabalho de conclusão de curso é um requerimento oficial para a obtenção do título de "Engenheiro diplomado do Instituto politécnico de Bordeaux, especialidade Engenharia eletrônica" pela ENSEIRB-MATMECA e para a obtenção do titulo de "Engenheiro de redes de comunicação" pela Universidade de Brasília.This final course assignment aims to add theoretical and experimental contributions to the modeling of wireless networks from four different projects carried out over an supervised internship held between the University of Brasília and the french school of engineering ENSEIRB-MATMECA during the year of 2017. All projects revolve around the central theme "current challenges in wireless communications" and aims to present such challenges through a brief theoretical introduction followed by simulations, statistical analyzes or field measurements. The first project proposes a theoretical study and the experimental investigation of the α-μ/Γ generalized fading distribution, used in this work to characterize realistic environments that experience composite fading. A second project, also based on statistical analysis, proposes a characterization of the mobile phone signal quality from power data measured using an Android application of mobile network quality analysis. Statistical analyzes can help mobile operators to parameterize their network and contribute to the improvement of cellular coverage in the country. Next, the third project developed in the internship proposes practical and theoretical studies of interference between the LTE 700MHz system and digital TV in Brasília in the region of Asa Norte, a recent topic of great importance given the analogue TV disconnection in Brazil until 2018. Finally, the fourth project, carried out in partnership with the National Telecommunications Agency (ANATEL), proposes contributions for the development of an IMT network simulator for use in sharing and compatibility studies to help in the identification of new frequency bands for the IMT-2020. The projects proposed in this work focus on the characterization and modeling of wireless channels from first order statistics, on the analysis of the quality of cellular networks in the country based on the information collected from the App about the network coverage experienced by final users and on the analysis of interference between systems based on studies between LTE and digital TV and on the search for new possible frequencies for 5G. The realization of the supervised internship was an official requirement to obtain the title of "Licensed Engineer of the Polytechnic Institute of Bordeaux, specialized in Electronic Engineering" by ENSEIRB-MATMECA and to obtain the title of "Network Communications Engineer" by the University of Brasília

Advanced Trends in Wireless Communications

Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics

Recent Advances in Wireless Communications and Networks

This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

Advanced wireless communications using large numbers of transmit antennas and receive nodes

The concept of deploying a large number of antennas at the base station, often called massive multiple-input multiple-output (MIMO), has drawn considerable interest because of its potential ability to revolutionize current wireless communication systems. Most literature on massive MIMO systems assumes time division duplexing (TDD), although frequency division duplexing (FDD) dominates current cellular systems. Due to the large number of transmit antennas at the base station, currently standardized approaches would require a large percentage of the precious downlink and uplink resources in FDD massive MIMO be used for training signal transmissions and channel state information (CSI) feedback. First, we propose practical open-loop and closed-loop training frameworks to reduce the overhead of the downlink training phase. We then discuss efficient CSI quantization techniques using a trellis search. The proposed CSI quantization techniques can be implemented with a complexity that only grows linearly with the number of transmit antennas while the performance is close to the optimal case. We also analyze distributed reception using a large number of geographically separated nodes, a scenario that may become popular with the emergence of the Internet of Things. For distributed reception, we first propose coded distributed diversity to minimize the symbol error probability at the fusion center when the transmitter is equipped with a single antenna. Then we develop efficient receivers at the fusion center using minimal processing overhead at the receive nodes when the transmitter with multiple transmit antennas sends multiple symbols simultaneously using spatial multiplexing

Mobile and Wireless Communications

Mobile and Wireless Communications have been one of the major revolutions of the late twentieth century. We are witnessing a very fast growth in these technologies where mobile and wireless communications have become so ubiquitous in our society and indispensable for our daily lives. The relentless demand for higher data rates with better quality of services to comply with state-of-the art applications has revolutionized the wireless communication field and led to the emergence of new technologies such as Bluetooth, WiFi, Wimax, Ultra wideband, OFDMA. Moreover, the market tendency confirms that this revolution is not ready to stop in the foreseen future. Mobile and wireless communications applications cover diverse areas including entertainment, industrialist, biomedical, medicine, safety and security, and others, which definitely are improving our daily life. Wireless communication network is a multidisciplinary field addressing different aspects raging from theoretical analysis, system architecture design, and hardware and software implementations. While different new applications are requiring higher data rates and better quality of service and prolonging the mobile battery life, new development and advanced research studies and systems and circuits designs are necessary to keep pace with the market requirements. This book covers the most advanced research and development topics in mobile and wireless communication networks. It is divided into two parts with a total of thirty-four stand-alone chapters covering various areas of wireless communications of special topics including: physical layer and network layer, access methods and scheduling, techniques and technologies, antenna and amplifier design, integrated circuit design, applications and systems. These chapters present advanced novel and cutting-edge results and development related to wireless communication offering the readers the opportunity to enrich their knowledge in specific topics as well as to explore the whole field of rapidly emerging mobile and wireless networks. We hope that this book will be useful for students, researchers and practitioners in their research studies

Advanced DSP Techniques for High-Capacity and Energy-Efficient Optical Fiber Communications

The rapid proliferation of the Internet has been driving communication networks closer and closer to their limits, while available bandwidth is disappearing due to an ever-increasing network load. Over the past decade, optical fiber communication technology has increased per fiber data rate from 10 Tb/s to exceeding 10 Pb/s. The major explosion came after the maturity of coherent detection and advanced digital signal processing (DSP). DSP has played a critical role in accommodating channel impairments mitigation, enabling advanced modulation formats for spectral efficiency transmission and realizing flexible bandwidth. This book aims to explore novel, advanced DSP techniques to enable multi-Tb/s/channel optical transmission to address pressing bandwidth and power-efficiency demands. It provides state-of-the-art advances and future perspectives of DSP as well