Radiation from spectral lines can be absorbed and re- emitted many times in atomic vapours before it reaches the boundaries of the container encasing the vapour. This effect is known as radiation trapping. It plays an important role practically everywhere where atomic vapours occur, e.g. in spectroscopy, in gas lasers, in atomic line filters, in the determination of atomic lifetimes, in measurements of atomic interaction potentials, and in electric discharge lamps. This book for the first time assembles all the information necessary for a treatment of practical problems, emphasizing both physical insights and mathematical methods. After an introduction that reviews resonance radiation and collisional processes in atomic vapours, physical effects and mathematical methods for various types of problems (e.g. with or without saturation, particle diffusion, reflecting cell walls, etc.) are explained in detail. The last part of the book describes the applications of these methods to a variety of practical problems like cross-section measurements or the design of discharge lamps.

This book offers comprehensive, practical guidance on RF propagation channel characterization at mmWave and sub-terahertz frequencies, with an overview of both measurement systems and current and future channel models. It introduces the key concepts required for performing accurate mmWave channel measurements, including channel sounder architectures, calibration methods, channel sounder performance metrics and their relationship to propagation channel characteristics. With a comprehensive introduction to mmWave channel models, the book allows readers to carefully review and select the most appropriate channel model for their application. The book provides fundamental system theory accessible in a step by step way with clear examples throughout. With inter- and multidisciplinary perspectives, the reader will observe the tight interaction between measurements and modeling for these frequency bands and how different disciplines interact. This is an excellent reference for researchers, including graduate students, working on mmWave and sub-THz wireless communications, and for engineers developing communication systems.

An in-depth and comprehensive treatment of wireless communication technology ranging from the fundamentals to the newest research results The expanded and completely revised Third Edition of Wireless Communications delivers an essential text in wireless communication technology that combines mathematical descriptions with intuitive explanations of the physical facts that enable readers to acquire a deep understanding of the subject. This latest edition includes brand-new sections on cutting edge research topics such as massive MIMO, polar codes, heterogeneous networks, non-orthogonal multiple access, as well as 5G cellular standards, WiFi 6, and Bluetooth Low Energy. Together with the re-designed descriptions of fundamentals such as fading, OFDM, and multiple access, it provides a thorough treatment of all the technologies that underlie fifth-generation and beyond systems. A complimentary companion website provides readers with a wealth of old and new material, including instructor resources available upon request. Readers will also find: A thorough introduction to the applications and requirements of modern wireless services, including video streaming, virtual reality, and Internet of Things. Comprehensive explorations of wireless propagation mechanisms and channel models, ranging from Rayleigh fading to advanced models for MIMO communications. Detailed discussions of single-user communications fundamentals, including modern coding techniques, multi-carrier communications, and single-user MIMO. Extensive description of multi-user communications, including packet radio systems, CDMA, scheduling, admission control, cellular and ad-hoc network design, and multi-user MIMO. In-depth examinations of advanced topics in wireless communication, like speech and video coding, cognitive radio, NOMA, network coding, and wireless localization. A comprehensive description of the key wireless standards, including LTE, 5G, WiFi, Bluetooth, and an outlook to Beyond 5G systems. Perfect for advanced undergraduate and graduate students with a basic knowledge of standard communications, Wireless Communications will also earn a place in the libraries of researchers and system designers seeking a one-stop resource on wireless communication technology.