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I was a civil engineering student in Berlin. Berlin is a nice town and there were many opportunities for a student to spend his time in an agreeable manner, for instance with the nice girls. But instead of that we had to perform big and awful calculations.
—Konrad Zuse, 1910
Those of us who have been involved in communications technology for any number of years have witnessed a transformation that truly is revolutionary. The old voice network remained much the same from the late 1800s through the 1960s—Alexander Graham Bell would have recognized it clearly and understood it completely. Around the time of World War II, however, dramatically new technologies started to emerge. Radio systems appeared and the foundation for electronic computer systems was laid. Soon thereafter, serious computer systems emerged and the need to network them soon became obvious. Over time, the networks, themselves, gradually became computerized. During the 1940s, the groundwork also was laid for the development of fiber optics transmission systems, which have the ability to transport huge volumes of information over very long distances and with crystal clarity. Video communications systems began to emerge in the 1960s, although they did not become practical until the last few years.
The rate of development of the underlying system and network technologies gathered speed in the last 20 years to the point that it has become difficult for even the most technically astute to keep pace with the rate of change, much less the depth and breadth of its impact. Copper wires have yielded to glass fibers. Rather than information flowing through networks in continuous streams, it now moves in packets, frames, and cells—sometimes on a connectionless basis. Data rules, but data now includes voice data, video data, image data, and even multimedia data, in addition to data data. The networks not only connect computers, but they also have become networks of computers. Wired networks no longer are supplemented by wireless network technologies, but in many applications are now being challenged by them. Regulation has yielded to deregulation. Monopolistic companies have been torn apart in the interests of increased competition, only to be reformed when the regulators became convinced that the market was the best regulator. Competition has become rife in virtually ever sector of the communications world, bringing with it the inherent advantages of alternative choice, improved performance, greater creativity, enhanced technology, and lower cost. The Internet has been commercialized and now is available in virtually every corner of the world, supplanting more traditional means of communication and even threatening more traditional voice and data networks. Audio, images, animated images, and even video clips are attached to electronic mail, which didn’t even exist a few years ago. Voice network technologies are under development which can translate languages in realtime—as we speak.
This book delivers a comprehensive overview of a wide range of communications systems and networks, including voice, data, video, and multimedia. It provides a plain-English, commonsense basis for understanding system and network technologies, their origins and evolution, and the applications they serve. Further, it discusses the origin, evolution and nature of appropriate standards and standards issues. It also provides a view of the evolution and status of regulation, and examines a number of key regulatory issues that await resolution. From fundamental concepts through network convergence and the Information Superhighway, Communications Systems and Networks offers a single source of information for those who need to understand communications networking. Rather than bogging down in volts, amps, ohms, algorithms and the like, this book weaves a fabric of understanding through a complex set of technologies that underlie meaningful contemporary and future applications. Further, this book is, in effect, a language primer, providing what is in effect a short course in the vocabulary and syntax of the language of telecommunications—having read this book, you will be conversational in telecommunications techno-speak. Finally, you will understand how networks work, and why.
The first several chapters set the stage for understanding the fundamental nature of systems and networks. Chapter 2 offers a set of basic concepts and provides a set of definitions which apply, fairly universally, across all communications and networks. Chapter 3 details, compares, and contrasts traditional transmission systems, both wired and wireless, including twisted-pair, coaxial cable, microwave radio, satellite radio, infrared light, and fiber optics.
Chapter 4 is devoted to a discussion of communications systems that primarily support voice applications, although they increasingly support data and even video communications. It begins with an examination of the several generations of Private Branch Exchanges (PBXs), their capabilities and applications, as well as emerging trends. Chapter 4 also examines Key Telephone Systems (KTSs), Hybrid systems and Centrex, the old standby which has been reborn with something of a vengeance. Automatic Call Distributors (ACDs) are profiled and discussed as well. Chapter 4 concludes with an examination of Computer Telephony Integration (CTI), a recent development that promises to add tremendous value in the processing and management of voice calls.
Chapter 5 is dedicated to electronic messaging technologies and systems, including facsimile, voice processing, and electronic mail. Increasingly, these technologies are viewed as converging into a unified messaging system technology. Indeed, we see the beginnings of such unification in the Internet and the World Wide Web (WWW).
Chapter 6 is the initial treatment of networks, and the final, focused treatment of voice communications. Concentrating on the Public Switched Telephone Network (PSTN), it addresses the origin, evolution and contemporary nature of the traditional voice network. The underlying technologies, regulatory and standards domains, carrier/service provider domains and functional domains all are discussed. This chapter also defines the nature and specifics of signaling and control systems that manage and control the operation of the various network elements in order to ensure that the network functions as a whole. A wide variety of voice network services are defined and illustrated. Chapter 6 concludes with discussion of a number of critical PSTN issues, including numbering plan administration, portability and equal access.
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