In this thesis, rate-splitting based interference exploitation has been investigated in order to bridge theory and practice. The results shows that conventional detection-decoding techniques cannot provide desirable results within a reasonable complexity and thereby substantially reduce interference mitigation gains. A multi-layer rate splitting scheme is proposed to deal with this obstacle. This multi-layer rate splitting scheme can approach or achieve the same maximum sum rate as that achieved by joint decoding.
Interference Avoidance Methods for Wireless Systems is an introduction to wireless techniques useful for uncoordinated unlicensed band systems, which use adaptive transmitters and receivers. The book provides a comprehensive theoretical analysis of interference avoidance algorithms in a general signal space framework that applies to a wide range of wireless communication scenarios with multiple users accessing the same communication resources. This book will be of interest to researchers, graduate students, and engineers working in the area of wireless communications as well as to technology policy makers working on radio frequency spectrum allocation. The book can also be used as a supplement text to advanced topics graduate courses in the area of wireless communication systems.
Massive MIMO Networks is the first book on the subject to cover the spatial channel correlation and consider rigorous signal processing design essential for the complete understanding by the students, practicing engineers and researchers working on modern day communication systems.
This textbook takes a unified view of the fundamentals of wireless communication and explains cutting-edge concepts in a simple and intuitive way. An abundant supply of exercises make it ideal for graduate courses in electrical and computer engineering and it will also be of great interest to practising engineers.
Currently, we are witnessing a veritable explosion in the number of mobile devices with network connectivity. This explosion in the number of mobile devices which guzzle data is resulting in bandwidth becoming an increasingly scarce resource. The surge in the demand for data calls for new techniques to understand and improve the capacity (data rates) of wireless networks. In this thesis, I will describe and explore the benefits of interference alignment - a recently discovered technique to manage interference, which is the primary bottleneck of rates of communication in wireless communication networks. A primary object of study of this thesis is a communication network with K wireless transmitter-receiver pairs mutually interfering with each other, also known as the K user interference network. In this thesis, we study a high SNR approximation to its capacity known as the degrees of freedom. A widely held belief that influences design of most, if not all wireless networks is the following: in the K user interference network it is optimal from a network degrees of freedom perspective to divide the spectrum among the users like cutting a cake. This cake cutting view of spectrum access also known as orthogonalization enables each user in the interference network to get a fraction of 1/K degrees of freedom, i.e., 1/K of the spectrum free of interference. In this thesis, we will show that, from a degrees of freedom perspective, the belief in the optimality of the cake cutting view of spectrum access (i.e., orthogonalization) is flawed. We show that if the network is frequency-selective or time-varying, then each of the K users of an interference network can essentially get half the degrees of freedom of a single user (i.e., half the spectrum at high signal-to-noise ratios) simultaneously. In other words, each user can get ``half the cake'' rather than merely a fraction 1/K. The key to achieving this is the powerful interference management strategy of interference alignment. The thesis will study and develop various aspects of interference alignment. First, we develop an asymptotic alignment scheme to achieve ``half the cake'' in frequency-selective/time-varying interference channels. We then extend the idea of interference alignment to channels that are not frequency-selective or time-varying (i.e., channels which are constant) via three approaches: asymmetric complex signaling, a deterministic approach, and a distributed (numerical) alignment algorithm. In each of these cases, we will demonstrate degrees of freedom and capacity benefits of interference alignment in wireless interference networks. We also demonstrate practical benefits of the third approach - distributed alignment - in terms of rates at moderate signal-to-noise ratios and distributed implementations. Finally, we show that the impact of interference alignment extends beyond the context of just wireless systems. In particular, we explore an alternate application of the idea of alignment - erasure codes for distributed storage systems.
The book describes how interference can be managed so that radio systems co-exist, without harmful mutual effects, within a finite amount of spectrum. This is timely in view of the increasing proliferation of wireless systems. It covers both the processes, such as regional or international coordination, as well as the engineering principles. Written by an author with extensive experience in the industry, it describes in detail the main methodologies for calculating or computing the interference between radio systems of the same type, and also between radio systems of different types
The escalating demand for advanced communication, sensing, and scanning systems across various applications as well as the urgency to comprehend the complexities of RF Frontend systems is more pronounced than ever. At the heart of this challenge lies the reconfigurability feature, playing a vital role in shaping the current trajectory of wireless technologies. The book Radar and RF Front End System Designs for Wireless Systems delves straight into this pressing issue and examines the relentless pace of innovation spurred by a myriad of configuration and design architectures. While these advancements hold great promise, they also introduce challenges that warrant thorough examination. Within the pages of this publication, a narrative unfolds that transcends theoretical discourse. The book offers a unique opportunity for academic scholars, researchers, and industry professionals to not only understand the intricacies of RF Frontend systems but also to grapple with the practical challenges posed by their rapid evolution. It becomes a guide in navigating this dynamic landscape, providing a deep exploration of the issues at hand and paving the way for informed solutions and breakthroughs.
Cellular wireless data traffic is now growing at about 80% compound annual growth rate (CAGR), and hence creating a corresponding demand for additional capacity. This traffic growth in the developed world comes mainly from the increasing use of video file transfers or viewings. In the emerging countries, the increasing smart-phone penetration is an additional factor. The demand for capacity can be met by more spectrum, higher spectrum efficiency, and a greater number of cells. However, increasing spectrum and spectrum efficiency has proved to be slow because of both regulatory and technological barriers. Therefore, increasing the number of cells is an effective way to add capacity. Because of the diverse types of mobile data, the use of different tiers of cells has become necessary: high-power and high-capacity large macro cells to serve vehicle based users, medium-power and medium-capacity small pico cells for outdoor pedestrian users, and very low-power and low-capacity femto cells for indoor users. These cells often work together and are known as a heterogeneous network. The cells in a heterogeneous network often share the limited spectrum available to the operator. They reuse the spectrum across tiers as well as within the same tier. This inter-tier reuse creates interference, e.g., femto to macro interference. In addition, intra-tier interference arises from frequency reuse within a tier, e.g., femto to femto interference. Managing interference in heterogeneous networks is hence complex compared to the interference management of earlier single-tier macro cell networks, which is well understood. The research presented in this dissertation studied two interference management problems: inter-tier interference management between a macro cell and a femto cell, and intra-tier interference among femto cells. Chapter 2 presents the downlink femto-macro inter-tier interference management problem. This chapter proposes a cost criteria of maximizing the minimum (worst-case) rate of femto users while constraining the worst-case performance degradation of macro cell users caused by interference from the femto base station. Analysis shows that a combination of frequency (resource-block) allocation for femto users and power control of each resource block can lead to good results. Because the general joint resource block-allocation and power-control problem is very complex (NP-hard), a suboptimal method is developed using a decoupled resource allocation and power control. All these solutions were also verified by simulations. An analytical solution for the single femto user case also appears. Chapter 3 presents the management of downlink intra-tier interference in an enterprise femto network with multiple femto base stations. This chapter discusses admission of users to receive service, allocation of users to femto base stations, and the downlink power control to maximize the service rate while maintaining the QoS criteria, which specifies the worst-case 95th percentile download time of a file. The analysis demonstrates the effectiveness of the proposed algorithm by simulation and also discusses naive (baseline) scheduling, which does not manage intra-tier interference, that leads to poor throughput as the density of femto cells increase. Last, this chapter explores a flexible user-base station association approach wherein the base station associated with a given user can be dynamically changed during a download period at network events. Such flexibility adds a significant performance improvement. Chapter 4 concludes the thesis by summarizing the results, discussing the limitations of the work presented, and making suggestions for future research.
WIRELESS COMMUNICATION SIGNALS A practical guide to wireless communication systems and concepts Wireless technologies and services have evolved significantly over the last couple of decades, and Wireless Communication Signals offers an important guide to the most recent advances in wireless communication systems and concepts grounded in a practical and laboratory perspective. Written by a noted expert on the topic, the book provides the information needed to model, simulate, test, and analyze wireless system and wireless circuits using modern instrumentation and computer aided design software. Designed as a practical resource, the book provides a clear understanding of the basic theory, software simulation, hardware test, and modeling, system component testing, software and hardware interactions and co-simulations. This important book: Provides organic and harmonized coverage of wireless communication systems Covers a range of systems from radio hardware to digital baseband signal processing Presents information on testing and measurement of wireless communication systems and subsystems Includes MATLAB file codes Written for professionals in the communications industry, technical managers, and researchers in both academia and industry. Wireless Communication Signals introduces wireless communication systems and concepts from both a practical and laboratory perspective.
This book investigates energy management approaches for energy efficient or energy-centric system design and architecture and presents end-to-end energy management in the recent heterogeneous-type wireless network medium. It also considers energy management in wireless sensor and mesh networks by exploiting energy efficient transmission techniques and protocols. and explores energy management in emerging applications, services and engineering to be facilitated with 5G networks such as WBANs, VANETS and Cognitive networks. A special focus of the book is on the examination of the energy management practices in emerging wireless cellular and ad hoc networks. Considering the broad scope of energy management in wireless cellular and ad hoc networks, this book is organized into six sections covering range of Energy efficient systems and architectures; Energy efficient transmission and techniques; Energy efficient applications and services.
