Wireless Communications Systems

An Introduction

Randy L. Haupt

• Éditeur: Wiley-IEEE Press
• Année: 2019
• ISBN:
  9781119419167
• Édition: 1
• Sujet: Technik & Maschinenbau
• Sous-sujet: Mobile & drahtlose Kommunikation

A comprehensive introduction to the fundamentals of design and applications of wireless communications

Wireless Communications Systems starts by explaining the fundamentals needed to understand, design, and deploy wireless communications systems. The author, a noted expert on the topic, explores the basic concepts of signals, modulation, antennas, and propagation with a MATLAB emphasis. The book emphasizes practical applications and concepts needed by wireless engineers.

The author introduces applications of wireless communications and includes information on satellite communications, radio frequency identification, and offers an overview with practical insights into the topic of multiple input multiple output (MIMO). The book also explains the security and health effects of wireless systems concerns on users and designers. Designed as a practical resource, the text contains a range of examples and pictures that illustrate many different aspects of wireless technology. The book relies on MATLAB for most of the computations and graphics. This important text:

• Reviews the basic information needed to understand and design wireless communications systems
• Covers topics such as MIMO systems, adaptive antennas, direction finding, wireless security, internet of things (IoT), radio frequency identification (RFID), and software defined radio (SDR)
• Provides examples with a MATLAB emphasis to aid comprehension
• Includes an online solutions manual and video lectures on selected topics

Written for students of engineering and physics and practicing engineers and scientists, Wireless Communications Systems covers the fundamentals of wireless engineering in a clear and concise manner and contains many illustrative examples.

1
Introduction

At the end of the nineteenth century, “wireless” meant “wireless telegraphy” which eventually became known as radio. Ham radio kept the term “wireless” alive, but obscure, until cell phones resurrected it toward the end of the twentieth century. Most wireless technologies use radio frequencies (RF), but infrared (IR), magnetic, optical, and acoustic systems also enable wireless communication. Wireless systems include a wide range of fixed, mobile, and portable applications. Designing a wireless system involves all the same challenges as a wired system plus the antennas and propagation channel. This chapter begins with a brief history of wireless communications then explains some basic concepts needed for proceeding through the rest of this book. The second half of this book (Chapters 6–12) is devoted to practical applications.

1.1 Historical Development of Wireless Communications

Long distance communications seem easy now, but that was not the case throughout history. In 490 BC, legend says that Philippides ran from Marathon to Athens and announced that the Greeks defeated the Persians in the Battle of Marathon (according to Google Maps about a 44.4 km drive), then dropped dead [1]. That long run became the standard for today's marathon. Current wireless networks deliver that same message in a blink of the eye. People wanted a faster way to communicate over long distances than using a messenger. Several ingenious, low data rate innovations emerged. Figure 1.1 shows four early wireless communication systems that replaced face‐to‐face delivery of the message: smoke signals, heliographs (mirrors), semaphore (flags), and drums. Weather and limited line of sight hindered most wireless communications. In addition, messages had to be simple and were prone to misinterpretation at the receiver.

The first quantum leap in fast long distance communication occurred in the 1800s with the introduction of electrical circuits that send signals over wires. In the 1830s, Cooke and Wheatstone demonstrated a telegraph system with five magnetic needles that an electric current forced to point at letters and numbers that form a message. Britain adopted this invention for railroad signaling [2]. At the same time, Samuel Morse independently developed the electric telegraph. He collaborated with Gale and Vail to build a telegraph that transmitted an electric signal by pushing an operator key that connects a battery to a wire and sends the electric signal down a wire to a receiver [2]. This simple system required a switch and battery at both ends of a wire. The length of wire and the loss of the signal strength over that wire limited communication distance. Wired communications forced users to established nodes, but significantly increased the data rate as well as made communications independent of weather and line of sight.

Figure 1.1 Early forms of wireless communications. (a) Smoke signals, (b) semaphore, (c) heliograph, (d) drums..

Source: (a) https://commons.wikimedia.org/wiki/File:Frederic_Remington_smoke_signal.webp. Public domain; (b) Author originated; (c) www.photolib.noaa.gov/historic/c&gs/theb1633.htm. Courtesy of NOAA; (d) https://www.flickr.com/photos/58034970@N00/178631090. ...