Closed-Form Analysis of the α\alpha-Beaulieu-Xie Shadowed Fading Channel

The presented research proposes the $\alpha$-modification of the Beaulieu-Xie shadowed fading channel for wireless communications. For the assumed model the closed-form analytical description of the basic statistical characteristics is carried out (i.e., probability density function, cumulative distribution function, and their asymptotics). The derived statistical description is exemplified on the problems of the average bit error rate and ergodic capacity calculation, for which the exact analytic and high signal-to-noise ratio asymptotic expressions are derived. The performed extensive numerical analysis demonstrates high correspondence with the analytical work and helps to study the dependence of the channel nonlinearity effects on the bit error probability

Contributions to the modeling, analysis, and simulation of fading channels

Orientador: Michel Daoud YacoubTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de ComputaçãoResumo: Este trabalho provê as seguintes contribuições ao estudo de canais de desvanecimento: (i) aproximações em forma fechada para a função densidade de probabilidade e a função distribuição acumulada de somas de envoltórias independentes sob desvanecimento Nakagami, Rice, Hoyt, Weibull ou lognormal; (ii) expressões gerais para a taxa e duração médias de desvanecimento do combinador de diversidade por seleção pura em canais de desvanecimento arbitrários; (iii) expressões gerais para a taxa e duração médias de desvanecimento dos combinadores de diversidade por seleção pura, ganho igual e razão máxima em canais Ricianos correlacionados e (iv) simulador de envoltória para canais de desvanecimento Nakagami, aplicável a valores arbitrários do parâmetro de desvanecimento e cenários anisotrópicos de propagaçãoAbstract: This work provides the following contributions to the study of fading channels: (i) closed-form approximations to the probability density function and the cumulative distribution function of sums of independent envelopes under Nakagami, Rice, Hoyt, Weibull, or lognormal fading; (ii) general expressions for the average fade rate and the average fade duration of pure selection combining over arbitrary fading channels; (iii) general expressions for the average fade rate and the average fade duration of pure selection, equal-gain, and maximal-ratio combining over correlated Ricean channels, and (iv) envelope simulator for Nakagami fading channels, applicable to arbitrary values of fading parameter and nonisotropic propagation scenariosDoutoradoTelecomunicações e TelemáticaDoutor em Engenharia Elétric

Level crossing rate and average fade duration for the Beaulieu-Xie fading model

Level crossing rate (LCR) and average fade duration (AFD) of a new (Beaulieu-Xie) fading model are analyzed. The characteristic function method is used to derive the LCR for a diversity scheme using maximal ratio combining. The LCR and AFD of the Beaulieu-Xie fading model show improvement beyond the performance levels of the Ricean and Nakagami-m fading models.Applied Science, Faculty ofNon UBCEngineering, School of (Okanagan)ReviewedFacult

Channel prediction in wireless communications

Knowledge of the channel over which signals are sent is of prime importance in modern wireless communications. Inaccurate or incomplete channel information leads to high error rates and wasted bandwidth and energy. Although active channel measurement is commonly used to gain channel knowledge, it can only accurately represent the channel at the time the measurement was taken, makes energy and bandwidth demands, and adds significant complexity to the radio system. Due to the highly time variant nature of wireless channels, active measurements become invalid almost as soon as they are taken, making alternative approaches to predicting future behaviour highly attractive. Such systems would allow maximum advantage to be taken of the limited bandwidth available and make significant power savings. This thesis investigates a number of complementary technologies, leading towards a channel prediction scheme suitable for mobile devices. As a first step towards channel prediction, anomaly detection is investigated within periodic wireless signals to establish when radical changes in the channel occur. In pre- vious experiments, long monotonic sequences had been observed to coincide with certain anomalies but not others when using Kullback-Leibler Divergence (KLD) analysis, possibly allowing the characterisation of anomaly types. An investigation is described to explain the origin of these features in a rigorous mathematical sense. A proof is given for the causes of the monotonic sequences, followed by a discussion of the types of signal anomaly which would underly such a feature and the value of this information. The second part describes a novel channel characterisation method which uses a class of Recurrent Neural Network (RNN) called an Echo State Network (ESN). Using this tool, a channel characterisation system can be constructed without an explicit statistical or mathematical model of the wireless environment, relying instead on observed data. This approach is much more convenient than existing models which require detailed information about the wireless system's parameters and also allows for new channel classifications to be added easily. It is able to achieve double the correct classification rate of a conventional statistical classifier, and is computationally simple to implement, making it ideal for inclusion on low-power mobile devices. Following their successful use in characterisation, ESNs are used in the final part in an investigation into channel prediction in a number of different scenarios. They were however found to be unable to produce useful predictions for all but the most trivial channel models. An alternative method is described for indoor environments using an approach inspired by ray tracing. It is simple and computationally lightweight to implement, again making it suitable for mobile devices. Simulation results show that it can outperform pilot-assisted methods by a significant margin, while not wasting bandwidth on channel measurement

Statističke karakteristike prvog i drugog reda signala u bežičnom telekomunikacionom sistemu sa selekcionim kombinovanjem

In doctoral dissertation, first and second order system performances of wireless communication system in the presence of fading and interference are considered. Theoretically, four cases are taken into consideration, and obtained numerical results are graphically presented and analyzed. Firstly, wireless mobile communication system with the receiver that contains automatic frequency control (AFC) loop operating over fading channel in the presence of single interference is considered. Performance measures, such as average switching rate (ASR) and mean time lose of lock (MTTL), are defined. In this doctoral dissertation, ASR and MTTL, for three different fading channels: Kg, α-μ and k-μ are obtained. In the next chapter, wireless relay communication system with two sections in the presence of multipath fading is considered. Signal envelope at the input of the receiver can be expressed as product of the first section signal envelope and the second section signal envelope. For such system model, average level crossing rate (LCR) for the case when radio relay system of the first section operates over Nakagami-m fading environment and second section operates over k-μ fading environment is obtained. Wireless relay system with two sections in the presence of non-linear α-μ fading channel is than taken into consideration. Moreover, radio relay system with two sections in the presence of multipath fading and interference is also considered. LCR of the ratio of the product of two k-μ random processes and k-μ random process is calculated. Finally, LCR of the ratio of Rician random process and product of two Rician random processes is obtained. Wireless communication system with two inputs SSC diversity receiver operating over correlated multipath η-μ fading in the presence of interference is than considered. Joint probability density function and joint distribution cumulative function of the ratios of signal to interference at inputs of SSC receivers are calculated. By using obtained expressions for probability density function (PDF), average bit error probability (ABER) for different coherent and non-coherent modulation schemes is obtained while by using derived cumulative distribution function (CDF), outage probability (OP) is obtained. At the end of doctoral dissertation, macrodiversity system with macrodiversity SSC receiver and two microdiversity SC receivers operating over Gamma shadowed multipath fading channel is proposed. In one case Nakagami-m multipath fading channel is considered while in the second case k-μ multipath fading is considered. System performances of the proposed system are derived and numerical results are graphically presented and discusse

Performance Analysis of Adaptive Modulation and Mimo Systems Applying Macroscopic Diversity Technologies

School of Electrical and Computer Engineerin

Mechanical failure assessment of Lithium ion battery electrode under electrochemical-mechanical condition

Lithium ion battery appears to be the dominant energy source of electric vehicles and most portable electronic devices, due to its high energy density, low self-discharge rate as well as wide temperature range. However, its inherent operation mechanism that, Li-ion reversibly inserts into/extracts from battery electrode, would lead to the repeated swelling and shrinking of the host electrode material and the generation of diffusion-induced stress (DIS). The mechanical failure behaviours under diffusion-induced stress could influence the cyclic performance of electrode and battery. Hence, the structural integrity assessment of battery electrode upon electrochemical condition is vital for the development of this new energy source. This thesis presents the studies of diffusion-induced stress related mechanical failure analyses of Li-ion battery electrode. Firstly, the diffusion driven method and chemical potential driven method are developed and implemented by writing finite element subroutines. These methods make it available to use ABAQUS platform to effectively and efficiently conduct coupled diffusion-stress analysis. Secondly, with using the extended Finite Element Method (XFEM), the complete crack initiation, propagation and fracture process of electrode particle can be investigated, and the critical cracking failure boundaries are innovatively proposed for assessing the different crack status. Thirdly, with using the Linear Matching Method Framework (LMMF), knowledge has been extended on shakedown, reverse plasticity and ratcheting behaviours of battery electrode under electrochemical conditions. Furthermore, a fatigue damage evaluation method is innovatively proposed, which makes it available to assess the continuous mechanical degradation of oxide electrode material. With the proposed assessment method, the fatigue degradation trends of battery electrode configurations under different material levels are modeled. The research works in this thesis offer valuable insights into mechanical failure mechanisms of lithium ion battery electrode under electrochemical loads and provide theoretical information on the optimization of electrode material.Lithium ion battery appears to be the dominant energy source of electric vehicles and most portable electronic devices, due to its high energy density, low self-discharge rate as well as wide temperature range. However, its inherent operation mechanism that, Li-ion reversibly inserts into/extracts from battery electrode, would lead to the repeated swelling and shrinking of the host electrode material and the generation of diffusion-induced stress (DIS). The mechanical failure behaviours under diffusion-induced stress could influence the cyclic performance of electrode and battery. Hence, the structural integrity assessment of battery electrode upon electrochemical condition is vital for the development of this new energy source. This thesis presents the studies of diffusion-induced stress related mechanical failure analyses of Li-ion battery electrode. Firstly, the diffusion driven method and chemical potential driven method are developed and implemented by writing finite element subroutines. These methods make it available to use ABAQUS platform to effectively and efficiently conduct coupled diffusion-stress analysis. Secondly, with using the extended Finite Element Method (XFEM), the complete crack initiation, propagation and fracture process of electrode particle can be investigated, and the critical cracking failure boundaries are innovatively proposed for assessing the different crack status. Thirdly, with using the Linear Matching Method Framework (LMMF), knowledge has been extended on shakedown, reverse plasticity and ratcheting behaviours of battery electrode under electrochemical conditions. Furthermore, a fatigue damage evaluation method is innovatively proposed, which makes it available to assess the continuous mechanical degradation of oxide electrode material. With the proposed assessment method, the fatigue degradation trends of battery electrode configurations under different material levels are modeled. The research works in this thesis offer valuable insights into mechanical failure mechanisms of lithium ion battery electrode under electrochemical loads and provide theoretical information on the optimization of electrode material

Analysis and Ad-hoc Networking Solutions for Cooperative Relaying Systems

Users of mobile networks are increasingly demanding higher data rates from their service providers. To cater to this demand, various signal processing and networking algorithms have been proposed. Amongst them the multiple input multiple output (MIMO) scheme of wireless communications is one of the most promising options. However, due to certain physical restrictions, e.g., size, it is not possible for many devices to have multiple antennas on them. Also, most of the devices currently in use are single-antenna devices. Such devices can make use of the MIMO scheme by employing cooperative MIMO methods. This involves nearby nodes utilizing the antennas of each other to form virtual antenna arrays (VAAs). Nodes with limited communication ranges can further employ multi-hopping to be able to communicate with far away nodes. However, an ad-hoc communications scheme with cooperative MIMO multi-hopping can be challenging to implement because of its de-centralized nature and lack of a centralized controling entity such as a base-station. This thesis looks at methods to alleviate the problems faced by such networks.In the first part of this thesis, we look, analytically, at the relaying scheme under consideration and derive closed form expressions for certain performance measures (signal to noise ratio (SNR), symbol error rate (SER), bit error rate (BER), and capacity) for the co-located and cooperative multiple antenna schemes in different relaying configurations (amplify-and-forward and decode-and-forward) and different antenna configurations (single input single output (SISO), single input multiple output (SIMO) and MIMO). These expressions show the importance of reducing the number of hops in multi-hop communications to achieve a better performance. We can also see the impact of different antenna configurations and different transmit powers on the number of hops through these simplified expressions.We also look at the impact of synchronization errors on the cooperative MIMO communications scheme and derive a lower bound of the SINR and an expression for the BER in the high SNR regime. These expressions can help the network designers to ensure that the quality of service (QoS) is satisfied even in the worst-case scenarios. In the second part of the thesis we present some algorithms developed by us to help the set-up and functioning of cluster-based ad-hoc networks that employ cooperative relaying. We present a clustering algorithm that takes into account the battery status of nodes in order to ensure a longer network life-time. We also present a routing mechanism that is tailored for use in cooperative MIMO multi-hop relaying. The benefits of both schemes are shown through simulations.A method to handle data in ad-hoc networks using distributed hash tables (DHTs) is also presented. Moreover, we also present a physical layer security mechanism for multi-hop relaying. We also analyze the physical layer security mechanism for the cooperative MIMO scheme. This analysis shows that the cooperative MIMO scheme is more beneficial than co-located MIMO in terms of the information theoretic limits of the physical layer security.Nutzer mobiler Netzwerke fordern zunehmend höhere Datenraten von ihren Dienstleistern. Um diesem Bedarf gerecht zu werden, wurden verschiedene Signalverarbeitungsalgorithmen entwickelt. Dabei ist das "Multiple input multiple output" (MIMO)-Verfahren für die drahtlose Kommunikation eine der vielversprechendsten Techniken. Jedoch ist aufgrund bestimmter physikalischer Beschränkungen, wie zum Beispiel die Baugröße, die Verwendung von mehreren Antennen für viele Endgeräte nicht möglich. Dennoch können solche Ein-Antennen-Geräte durch den Einsatz kooperativer MIMO-Verfahren von den Vorteilen des MIMO-Prinzips profitieren. Dabei schließen sich naheliegende Knoten zusammen um ein sogenanntes virtuelles Antennen-Array zu bilden. Weiterhin können Knoten mit beschränktem Kommunikationsbereich durch mehrere Hops mit weiter entfernten Knoten kommunizieren. Allerdings stellt der Aufbau eines solchen Ad-hoc-Netzwerks mit kooperativen MIMO-Fähigkeiten aufgrund der dezentralen Natur und das Fehlen einer zentral-steuernden Einheit, wie einer Basisstation, eine große Herausforderung dar. Diese Arbeit befasst sich mit den Problemstellungen dieser Netzwerke und bietet verschiedene Lösungsansätze.Im ersten Teil dieser Arbeit werden analytisch in sich geschlossene Ausdrücke für ein kooperatives Relaying-System bezüglicher verschiedener Metriken, wie das Signal-Rausch-Verhältnis, die Symbolfehlerrate, die Bitfehlerrate und die Kapazität, hergeleitet. Dabei werden die "Amplify-and forward" und "Decode-and-forward" Relaying-Protokolle, sowie unterschiedliche Mehrantennen-Konfigurationen, wie "Single input single output" (SISO), "Single input multiple output" (SIMO) und MIMO betrachtet. Diese Ausdrücke zeigen die Bedeutung der Reduzierung der Hop-Anzahl in Mehr-Hop-Systemen, um eine höhere Leistung zu erzielen. Zudem werden die Auswirkungen verschiedener Antennen-Konfigurationen und Sendeleistungen auf die Anzahl der Hops analysiert.  Weiterhin wird der Einfluss von Synchronisationsfehlern auf das kooperative MIMO-Verfahren herausgestellt und daraus eine untere Grenze für das Signal-zu-Interferenz-und-Rausch-Verhältnis, sowie ein Ausdruck für die Bitfehlerrate bei hohem Signal-Rausch-Verhältnis entwickelt. Diese Zusammenhänge sollen Netzwerk-Designern helfen die Qualität des Services auch in den Worst-Case-Szenarien sicherzustellen. Im zweiten Teil der Arbeit werden einige innovative Algorithmen vorgestellt, die die Einrichtung und die Funktionsweise von Cluster-basierten Ad-hoc-Netzwerken, die kooperative Relays verwenden, erleichtern und verbessern. Darunter befinden sich ein Clustering-Algorithmus, der den Batteriestatus der Knoten berücksichtigt, um eine längere Lebensdauer des Netzwerks zu gewährleisten und ein Routing-Mechanismus, der auf den Einsatz in kooperativen MIMO Mehr-Hop-Systemen zugeschnitten ist. Die Vorteile beider Algorithmen werden durch Simulationen veranschaulicht. Eine Methode, die Daten in Ad-hoc-Netzwerken mit verteilten Hash-Tabellen behandelt wird ebenfalls vorgestellt. Darüber hinaus wird auch ein Sicherheitsmechanismus für die physikalische Schicht in Multi-Hop-Systemen und kooperativen MIMO-Systemen präsentiert. Eine Analyse zeigt, dass das kooperative MIMO-Verfahren deutliche Vorteile gegenüber dem konventionellen MIMO-Verfahren hinsichtlich der informationstheoretischen Grenzen der Sicherheit auf der physikalischen Schicht aufweist

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin