Preface

Wireless communications and networks have been one of the major revolutions of the last three decades. We are witnessing a very fast growth in these technologies where wireless communications and networks have become so ubiquitous in our society and indispensable our daily lives. The demand for new services to support high speed wideband Internet access and advanced high quality real-time video applications push the researchers to investigate new technologies in wireless communications and networks.

Progress in wireless communications and networks continues as this book is being written. Although there have been many journal and conference publications regarding wireless communication, they are often in the context of academic research or theoretical derivations and sometimes omit practical considerations. Although the literature has many conference and journal papers, technical reports, and standard contributions, they are often fragmental engineering works and thus are not easy to follow up. The objective of this book is to accelerate research and development by serving as a forum in which both academia and industry can share experiences and report original studies and works regarding all aspects of wireless communications. In addition, this book has great educational value because it aims to serve as a virtual, but nonetheless effective bridge between academic research in theory and engineering development in practice, and as a messenger between the technical pioneers and the researchers who followed in their footstep.

This book which is titled "Wireless Communications and Networks - Recent Advances", focuses on the current research topics from wide range of wireless communications and networks and provides "on-going" research progress on these issues. During the preparation of this book, I emphasized to the authors to add recent research findings and future works in this area and to cite latest references in the chapter. For this reason, a variety of novel techniques in wireless communications and networks are investigated in this book. 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 XIV Preface

in much greater detail than in previous publications and in the references cited in these chapters.

This book includes twenty two chapters that were authored by the well-known researchers in the world. Each chapter was written in an introductory style beginning with the fundamentals, describing approaches to the hottest issues and concluding with a comprehensive discussion. The content in each chapter is taken from many publications in prestigious journals and conferences and followed by fruitful insights. The chapters in this book also provide many recent references for relevant topics, and interested readers will find these references helpful when they explore these topics further.

This book was divided into seven parts. Part 1 consists of four chapters which are dedicated to wireless communication antennas. Part 2 consists of three chapters which are dedicated to wireless communication hardware. Part 3 consists of three chapters which are dedicated to channel estimation and capacity. Part 4 consists of three chapters which are dedicated to wireless communication performance analysis tools and methods. Part 5 consists of six chapters which are dedicated to next generation wireless communication technologies. Part 6 consists of only one chapter which is dedicated to biological effects of wireless communication technologies. Finally, Part 7 consists of two chapters which are dedicated to wireless sensor networks & Mobile Ad Hoc Networks (MANETs).

Chapter 1 provides a comprehensive discussion on the latest technologies of antenna design for space-limited Multi-Input Multi-Output (MIMO) applications, such as minimized base station, portable access point and mobile terminals. solve the contradiction of system volume and antenna performance, two basic methods are proposed in this chapter to maintain the channel capacity in a reduced system volume. The first method is to reduce the volume each antenna occupied without decreasing the number of antenna elements.Another is to antenna performance in space-limited MIMO system, without increasing the antenna volume.

Chapter 2 introduces Wireless Capsule Endoscopy (WCE) system and antenna specifications. Special consideration of body characteristics for antenna design and state-of-the-art WCE transmitting and receiving antennas are also reviewed in this chapter.

Chapter 3 explains travelling planar wave antenna for wireless communications. This chapter describes the types of travelling planar wave antennas that are Wave Antenna (LWA), Meanderline antenna, taped LWA and taped composite right/left-handed transmission-line LWA. In this chapter, measurements are verified with simulations for all types of LWA.

Chapter 4 explains how to develop a wideband, high gain and high efficient antenna sufficient for 60 GHz communications using superstrate technology. This chapter also explains the importance of different sources on antenna performance in terms of bandwidth, gain and efficiency.

X Preface

these chapters.

further.

chapter.

for all types of LWA.

Hoc Networks (MANETs).

MIMO system, without increasing the antenna volume.

in much greater detail than in previous publications and in the references cited in

This book includes twenty two chapters that were authored by the well-known researchers in the world. Each chapter was written in an introductory style beginning with the fundamentals, describing approaches to the hottest issues and concluding with a comprehensive discussion. The content in each chapter is taken from many publications in prestigious journals and conferences and followed by fruitful insights. The chapters in this book also provide many recent references for relevant topics, and interested readers will find these references helpful when they explore these topics

This book was divided into seven parts. Part 1 consists of four chapters which are dedicated to wireless communication antennas. Part 2 consists of three chapters which are dedicated to wireless communication hardware. Part 3 consists of three chapters which are dedicated to channel estimation and capacity. Part 4 consists of three chapters which are dedicated to wireless communication performance analysis tools and methods. Part 5 consists of six chapters which are dedicated to next generation wireless communication technologies. Part 6 consists of only one chapter which is dedicated to biological effects of wireless communication technologies. Finally, Part 7 consists of two chapters which are dedicated to wireless sensor networks & Mobile Ad

Chapter 1 provides a comprehensive discussion on the latest technologies of antenna design for space-limited Multi-Input Multi-Output (MIMO) applications, such as minimized base station, portable access point and mobile terminals. solve the contradiction of system volume and antenna performance, two basic methods are proposed in this chapter to maintain the channel capacity in a reduced system volume. The first method is to reduce the volume each antenna occupied without decreasing the number of antenna elements.Another is to antenna performance in space-limited

Chapter 2 introduces Wireless Capsule Endoscopy (WCE) system and antenna specifications. Special consideration of body characteristics for antenna design and state-of-the-art WCE transmitting and receiving antennas are also reviewed in this

Chapter 3 explains travelling planar wave antenna for wireless communications. This chapter describes the types of travelling planar wave antennas that are Wave Antenna (LWA), Meanderline antenna, taped LWA and taped composite right/left-handed transmission-line LWA. In this chapter, measurements are verified with simulations

Chapter 4 explains how to develop a wideband, high gain and high efficient antenna sufficient for 60 GHz communications using superstrate technology. This chapter also

Chapter 5 explains hardware implementation of wireless communications algorithms with a practical approach. This chapter navigates through the author's encounters with different technologies at different stages in his career and how different applications have been and are currently approached. This chapter also gives a summary of the author's last ten years of working with different tools, methodologies and design flows.

Chapter 6 reviews state-of-the-art research in power amplifiers for wireless communication infrastructure featuring advantages of Gallium Nitride (GaN)-based power devices including large bandwidth capability, high power density and high output impedance. Regarding the issues of power amplifier design, state-of-the-art power amplifier architectures discusses with various prospects. This chapter also discusses widespread techniques for average efficiency enhancement including Doherty power amplifier concept and envelope tracking with state-of-the-art results with examples.

Chapter 7 discusses radio frequency (RF) desensitivity analysis for components and devices on mobile products.To improve the total isotropic sensitivity performance of wireless communication on notebook computer, this chapter investigate the electromagnetic interference noise from the built-in camera display moduleas examples andanalyzedthe impact of various modes on performance with throughput measurement. This chapter discovers throughput and receiving sensitivity of wireless communications and the solutions to improve system performance. Moreover, this chapter describes how to design and implement periodic structures for isolation on the notebook computer to effectively suppress noise source-antenna coupling and improve the receiving sensitivity of wireless communication system.

Chapter 8 explains indoor channel measurement for wireless communications. This chapter firstly gives detailed information about indoor channel measurement for MIMO-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems. Secondly, channel measurement schemes are explained. Finally, channel measurement applications are given in this chapter.

Chapter 9 addresses the problem of estimating the linearly time-varying (LTV) channel of MIMO-OFDM systems using superimposed training (ST). The LTV channel is modeled by truncated discrete Fourier bases. Based on this model, a two-step approach is adopted to estimate the LTV channel over multiple OFDM symbols. This chapter also presents a performance analysis of the channel estimation and derives a closed-form expression for the channel estimation variances. It is shown that the estimation variances, unlike that of the conventional ST-based schemes, approach to a fixed lower-bound as the training length increases, which is directly proportional to

#### XVI Preface

information-pilot power ratios. For wireless communications with a limited transmission power, the authors` try to optimize the ST power allocation by maximizing the lower bound of the average channel capacity. Simulation results show that the proposed approach in this chapter outperforms the frequency-division multiplexed trainings schemes.

Chapter 10 focuses on more general and nonlinear fading distributions. An analytical study of the *ê*-*ì* fading channel capacity, e.g., under the optimal power and rate adaptation (OPRA), constant power with optimal rate adaptation (ORA), channel inversion with fixed rate (CIFR), and truncated CIFR (TIFR) adaptation policies and maximum ratio combining (MRC) and selection combining diversity techniques are performed. The expressions for the proposed adaptation policies and diversity techniques are derived in this chapter. Capitalizing on them, numerically obtained results are graphically presented, in order to show the effects of various system parameters, such as diversity order and fading severity on observed performances. In a similar manner an analytical study of the Weibull fading channel capacity, under the OPRA, ORA, CIFR and TIFR adaptation policies and MRC diversity technique are performed in this chapter.

Chapter 11 explains generalized approach to signal processing (GASP) in wireless communications with examples. The used technique in this chapter, GASP, allows researchers to extend the well-known boundaries of the potential noise immunity set by classical and modern signal processing theories. Employment of wireless communication systems, the receivers of which are constructed on the basis of GASP, allows the researchers to obtain high detection of signals and high accuracy of signal parameter definition with noise components present compared with that systems, the receivers of which are constructed on the basis of classical and modern signal processing theories.

Chapter 12 emphasizes the importance of conducting an early performance evaluation of the communication protocols and systems, and to suggest an appropriate solution for carrying out such an activity. Performance evaluation activity denotes the actions to evaluate the protocol under development regarding its performance. This process can take place in different phases of the development, and can be based on modelling or measurements. If the designer can control the performance of the product, rather than just manage its functionality, the result will be a much superior creation. This problem is treated in this chapter through a tangible wireless communication protocol example.

Chapter 13 discusses statistical relationships among residual cell dwell time (CDTr), cell dwell time (CDT), and channel holding time (CHT) for new and handoff calls. In particular, under the assumption that unencumbered service time is exponentially distributed and CDT is phase-type distributed, a novel algebraic set of general equations that examine the relationships both between CDT and CDTr and between CDT and channel holding times are obtained. Also, the condition upon which the mean channel holding time for new calls (CHTn) is greater than the mean channel holding time for handoff calls (CHTh) is derived in this chapter. Additionally, novel mathematical expressions for determining the parameters of the resulting CHT distribution as functions of the parameters of the CDT distribution are derived in this chapter for hyper-exponentially or Coxian distributed CDT.

XII Preface

multiplexed trainings schemes.

performed in this chapter.

processing theories.

example.

information-pilot power ratios. For wireless communications with a limited transmission power, the authors` try to optimize the ST power allocation by maximizing the lower bound of the average channel capacity. Simulation results show that the proposed approach in this chapter outperforms the frequency-division

Chapter 10 focuses on more general and nonlinear fading distributions. An analytical study of the *ê*-*ì* fading channel capacity, e.g., under the optimal power and rate adaptation (OPRA), constant power with optimal rate adaptation (ORA), channel inversion with fixed rate (CIFR), and truncated CIFR (TIFR) adaptation policies and maximum ratio combining (MRC) and selection combining diversity techniques are performed. The expressions for the proposed adaptation policies and diversity techniques are derived in this chapter. Capitalizing on them, numerically obtained results are graphically presented, in order to show the effects of various system parameters, such as diversity order and fading severity on observed performances. In a similar manner an analytical study of the Weibull fading channel capacity, under the OPRA, ORA, CIFR and TIFR adaptation policies and MRC diversity technique are

Chapter 11 explains generalized approach to signal processing (GASP) in wireless communications with examples. The used technique in this chapter, GASP, allows researchers to extend the well-known boundaries of the potential noise immunity set by classical and modern signal processing theories. Employment of wireless communication systems, the receivers of which are constructed on the basis of GASP, allows the researchers to obtain high detection of signals and high accuracy of signal parameter definition with noise components present compared with that systems, the receivers of which are constructed on the basis of classical and modern signal

Chapter 12 emphasizes the importance of conducting an early performance evaluation of the communication protocols and systems, and to suggest an appropriate solution for carrying out such an activity. Performance evaluation activity denotes the actions to evaluate the protocol under development regarding its performance. This process can take place in different phases of the development, and can be based on modelling or measurements. If the designer can control the performance of the product, rather than just manage its functionality, the result will be a much superior creation. This problem is treated in this chapter through a tangible wireless communication protocol

Chapter 13 discusses statistical relationships among residual cell dwell time (CDTr), cell dwell time (CDT), and channel holding time (CHT) for new and handoff calls. In particular, under the assumption that unencumbered service time is exponentially distributed and CDT is phase-type distributed, a novel algebraic set of general equations that examine the relationships both between CDT and CDTr and between CDT and channel holding times are obtained. Also, the condition upon which the

Chapter 14 highlights the classification of digital quadrature amplitude modulation schemes in wireless adaptive OFDM systems using the likelihood principle. The author particularly focuses on time-division duplex systems in which the channel can be regarded as reciprocal. In contrast to other research work, a lot of new constraints are taken into account. Namely, many parameters are known by the receiver that can be utilized to enhance the classification reliability.

Chapter 15 introduces a user based framework in Worldwide Interoperability for Microwave Access (WiMAX) and explores user based bandwidth allocation algorithms, user based packet classification mechanism and user based call admission control algorithm.

Chapter 16 covers the conceptual description of many representative retransmission schemes under various environments and presented a novel fast packet retransmission scheme intended for effectively transporting delay-sensitive flows in a general cooperative diversity environment.

Chapter 17 highlights the significant role of cooperative (vehicular) communications in future Intelligent Transport Systems. This chapter describes the architecture of cooperative systems, wireless technologies used within the cooperative systems framework and the applications of vehicular networks and their corresponding categories. This chapter also emphasizes on hot research topics concerning cooperative systems such as data fusion, routing, security and privacy.

Chapter 18 describes a specific wireless communications architecture developed taking into account railway communications needs and the restrictions that have to be considered in terms of broadband network features. It is based on standard communication technologies and protocols to establish a bidirectional communication channel between trains and railway control centers. In this chapter, a brief description of the state of art in railway communications, a specific train-to-earth wireless communication architecture, the main challenges concerning with the management of the quality of service in train-to-earth communications, some services that are arising as result of using this connectivity architecture and the way in which they interoperate the future lines of work oriented to improve the proposed communication channel are also explained.

Chapter 19 explains super-broadband wireless access networks. This chapter firstly discusses the evolution of Internet traffic growth in subscribing the internet and wireless network worldwide in diverse domain of services. This chapter secondly presents the solutions for transportation with huge traffic demand, according with the expected growth in interactive video, voice communication and data traffic for providing the cost effective communication services. Finally, it describes the radio over fiber network as a future proof solution for supporting super-broadband services that is a reliable, cost-effective and environmentally friendly technology.

Chapter 20 gives evaluations of more than 30 international expert group reports on the biological effect of wireless communication systems. Evaluated reports in this chapter were published during the 2009-2011 period. The vast majority did not consider that there is a demonstrated health risk of RF exposure from mobile phones and other wireless communication devices.

Chapter 21 describes a mechanism for the management of the wireless multimedia sensor nodes. The mechanism, first, clusters nodes according to their scale of similarity in covering the environment; second, selects and schedules members of established clusters to monitor the sensing region which is divided among clusters. The members of each cluster are scheduled with an exclusive frequency based on the number of members in the cluster and the scale of overlapping among fields of view of the cluster members and thus the monitoring efficiency is increased. Moreover, because of the established intra cluster coordination and collaboration, sensing subsystem of multimedia nodes are optimized to avoid redundant and overlapped sensing. Thus, the capability of energy saving is considerably enhanced with respect to ordinary duty-cycling manners of environment monitoring by wireless multimedia sensor networks. On the other hand, optimizing the data sensed by sensing subsystem results in conservation of energy in the transmission and processing subsystems since they meet less amounts of multimedia data to be transmitted and/or processed by the network nodes. Results in this chapter show how this mechanism prolongs the network lifetime along with a better monitoring performance.

Chapter 22 explains wireless communications for over homogeneous and heterogeneous mobile devices. This chapter introduces related background and main concepts of the MANETs, existing wireless mobile network approaches, wireless ad hoc networks, wireless mobile approaches, characteristics of MANETs and types of MANETs. Second, the traffic types in ad hoc networks, ad hoc network routing protocol performance issues and the types of ad hoc protocols are given in this chapter. Third, comparison between proactive versus reactive and clustering versus hierarchical protocols are explained. Finally, mobility, Quality of Service provisioning, multicasting and security issues of MANETs are presented.

Briefly, this book will provide a comprehensive technical guide covering fundamentals, recent advances and open issues in wireless communications and networks to the readers. objective of the book is to serve as a valuable reference for students, educators, scientists, faculty members, researchers, engineers and research strategists in these rapidly evolving fields and to encourage them to actively explore these broad, exciting and rapidly-evolving research areas.

XIV Preface

wireless communication devices.

performance.

presents the solutions for transportation with huge traffic demand, according with the expected growth in interactive video, voice communication and data traffic for providing the cost effective communication services. Finally, it describes the radio over fiber network as a future proof solution for supporting super-broadband services

Chapter 20 gives evaluations of more than 30 international expert group reports on the biological effect of wireless communication systems. Evaluated reports in this chapter were published during the 2009-2011 period. The vast majority did not consider that there is a demonstrated health risk of RF exposure from mobile phones and other

Chapter 21 describes a mechanism for the management of the wireless multimedia sensor nodes. The mechanism, first, clusters nodes according to their scale of similarity in covering the environment; second, selects and schedules members of established clusters to monitor the sensing region which is divided among clusters. The members of each cluster are scheduled with an exclusive frequency based on the number of members in the cluster and the scale of overlapping among fields of view of the cluster members and thus the monitoring efficiency is increased. Moreover, because of the established intra cluster coordination and collaboration, sensing subsystem of multimedia nodes are optimized to avoid redundant and overlapped sensing. Thus, the capability of energy saving is considerably enhanced with respect to ordinary duty-cycling manners of environment monitoring by wireless multimedia sensor networks. On the other hand, optimizing the data sensed by sensing subsystem results in conservation of energy in the transmission and processing subsystems since they meet less amounts of multimedia data to be transmitted and/or processed by the network nodes. Results in this chapter show how this mechanism prolongs the network lifetime along with a better monitoring

Chapter 22 explains wireless communications for over homogeneous and heterogeneous mobile devices. This chapter introduces related background and main concepts of the MANETs, existing wireless mobile network approaches, wireless ad hoc networks, wireless mobile approaches, characteristics of MANETs and types of MANETs. Second, the traffic types in ad hoc networks, ad hoc network routing protocol performance issues and the types of ad hoc protocols are given in this chapter. Third, comparison between proactive versus reactive and clustering versus hierarchical protocols are explained. Finally, mobility, Quality of Service provisioning,

Briefly, this book will provide a comprehensive technical guide covering fundamentals, recent advances and open issues in wireless communications and networks to the readers. objective of the book is to serve as a valuable reference for

multicasting and security issues of MANETs are presented.

that is a reliable, cost-effective and environmentally friendly technology.

**Dr. Ali Ekşim**  Chief Senior Researcher Center of Research for Advanced Technologies of Informatics and Information Security (Tubitak-Bilgem) Turkey
