To the Instructor...

... though its OK for the student to listen in.
Telecommunication Breakdown helps the reader build a complete digital radio that includes each part of a typical digital communication system. Chapter by chapter, the reader creates a Matlab realization of the various pieces of the system, exploring the key ideas along the way. In the final chapter, the reader "puts it all together" to build a fully functional receiver, though it will not operate in real time. Telecommunication Breakdown explores telecommunication systems from a very particular point of view: the construction of a workable receiver. This viewpoint provides a sense of continuity to the study of communication systems. The three steps in the creation of a working digital radio are the following:
  1. building the pieces,

  2. assessing the performance of the pieces,

  3. integrating the pieces.
In order to accomplish this in a single semester, we have had to strip away some topics that are commonly covered in an introductory course and emphasize some topics that are often covered only superficially. We have chosen not to present an encyclopedic catalog of every method that can be used to implement each function of the receiver. For example, we focus on frequency division multiplexing rather than time or code division methods, and we concentrate on pulse amplitude modulation rather than quadrature modulation or frequency shift keying. On the other hand, some topics (such as synchronization) loom large in digital receivers, and we have devoted a correspondingly greater space to these. Our belief is that it is better to learn one complete system from start to finish, than to half-learn the properties of many. Our approach to building the components of the digital radio is consistent throughout Telecommunication Breakdown. For many of the tasks, we define a "performance" function and an algorithm that optimizes this function. This approach provides a unified framework for deriving the AGC, clock recovery, carrier recovery, and equalization algorithms. Fortunately, this can be accomplished using only the mathematical tools that an electrical engineer (at the level of a college Junior) is likely to have, and Telecommunication Breakdown requires no more than knowledge of calculus and Fourier transforms. Any of the comprehensive calculus books by Thomas would provide an adequate background along with an understanding of signals and systems such as might be taught using DSP First or any of the fine texts cited for further reading in Section 3.8.Telecommunication Breakdown emphasizes two ways of assessing the behavior of the components of the communication system: by studying the performance functions, and through the use of experiment. The algorithms embodied in the various components can be derived without making assumptions about details of the constituent signals (such as Gaussian noise). The use of probability is limited to naive ideas such as the notion of an average of a collection of numbers, rather than requiring the machinery of stochastic processes. By removing the advanced probability prerequisite from Telecommunication Breakdown, it is possible to place it earlier in the curriculum. The integration phase of the receiver design is accomplished in Chapters 9 and 16. Since any real digital radio operates in a highly complex environment, analytical models cannot hope to approach the "real" situation. Common practice is to build a simulation and to run a series of experiments. Telecommunication Breakdown provides a set of guidelines (in Chapter 16) for a series of tests to verify the operation of the receiver. The final project challenges the digital radio that the student has built by adding noises and imperfections of all kinds: additive noise, multipath disturbances, phase jitter, frequency inaccuracies, clock errors, etc. A successful design can operate even in the presence of such distortions. It should be clear that these choices distinguish Telecommunication Breakdown from other, more encyclopedic texts. We believe that this "hands-on" method makes Telecommunication Breakdown ideal for use as a learning tool, though it is less comprehensive than a reference book. In addition, the instructor may find that the order of presentation of topics is different from that used by other books. Section 1.3 provides an overview of the flow of topics, and our reasons for structuring the course as we have.


Though this is a first edition, the authors have taught from (various versions of) this text for a number of years. We have explored several different ways to fit coverage of digital radio into a "standard" electrical engineering senior elective sequence. Perhaps the simplest way is via a "stand-alone" course, one semester long, in which the student works through the chapters and ends with the final project as outlined in Chapter 16. Students who have graduated tell us that when they get to the workplace, where software-defined digital radio is increasingly important, the preparation of this course has been invaluable. Combined with a rigorous course in probability, other students have reported that they are well prepared for the typical introductory graduate level class in communications offered at research universities. At both Cornell and the University of Wisconsin (the home institutions of the authors), there is a two semester sequence in communications available for advanced undergraduates. We have integrated the text into this curriculum in three ways:
  1. Teach from a traditional text for the first semester and use Telecommunication Breakdown in the second.

  2. Teach from Telecommunication Breakdown in the first semester and use a traditional text in the second.

  3. Teach from Telecommunication Breakdown in the first semester and teach a project oriented extension in the second.
All three work well. When following the first approach, students often comment that by reading Telecommunication Breakdown they "finally understand what they had been doing the previous semester." Because there is no probability prerequisite for Telecommunication Breakdown, the second approach can be moved earlier in the curriculum. Of course, we encourage students to take probability at the same time. In the third approach, the students were asked to create an extension of the basic pulse amplitude modulation (PAM) digital radio to quadrature amplitude modulation (QAM), to use more advanced equalization techniques, etc. Some of these extensions are available on the enclosed CD.

Contextual Readings

We believe that the increasing market penetration of broadband communications is the driving force behind the continuing (re)design of "radios" (wireless communications devices). Digital devices continue to penetrate the market formerly occupied by analog (for instance, digital television is slated to replace analog television in the US in 2006) and the area of digital and software-defined radio is regularly reported in the mass media. Accordingly, it is easy for the instructor to emphasize the social and economic aspects of the "wireless revolution." We provide a list of articles appearing in the popular press (in the year just prior to publication of Telecommunication Breakdown), and this is available on the CD. For example, articles from this list discuss how local municipalities are investing in wireless internet connections in order to attract businesses, governmental interests in the efficient use of the electromagnetic spectrum, consumer demand for braodband access to the internet, wireless infrastructure, etc. The impacts of digital "radios" are vast, and it is an exciting time to get involved. While Telecommunication Breakdown focuses on technological aspects of the radio design, almost all of the mass media articles emphasize the economic, political, and social aspects. We believe that this can also add an important dimension to the student's education.

Some Extras

The CD-ROM included with the book contains extra material of interest, especially to the instructor. First, we have assembled a complete collection of slides (in .pdf format) that may help in lesson planning. The final project is available in two complete forms, one that exploits the block coding of Chapter 15 and one that does not. In addition, there are a large number of "received signals" on the CD which can be used for assignments and for the project. An extra chapter called A Digital Quadrature Amplitude Modulation (QAM) Radio (and a corresponding set of .pdf lecture slides) is on the CD, and this extends the software-defined radio from pulse amplitude modulation to QAM. Finally, all the Matlab code that is presented in the text is available on the CD-ROM. Once these are added to the Matlab path, they can be used for assignments and for further exploration. See the contents.

Mathematical Prerequisites

Telecomunication Breakdown really requires use of Matlab. It does not require any of the sophisticated toolboxes like Simulink or the communications toolbox, but it does require the Signal Processing toolbox for the filter design and analysis commands (freqz, remez, firpl). Fortunately, this is included with most versions of Matlab, though if you find that freqz (or the others) don't work, that's why.

Software Requirements