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
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
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.
- building the pieces,
- assessing the performance of the pieces,
- integrating the pieces.
How We've Used TELECOMMUNICATION BREAKDOWN
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
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:
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.
- Teach from a traditional text for the first semester and
use Telecommunication Breakdown in the second.
- Teach from Telecommunication Breakdown in the first semester and
use a traditional text in the second.
- Teach from Telecommunication Breakdown in the first semester and teach
a project oriented extension in the second.
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 ExtrasThe 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.
- G.B. Thomas and R.L. Finney, Calculus and Analytic Geometry,
8th edition, Addison-Wesley, 1992.
J. H. McClellan, R. W. Schafer, and M. A. Yoder, DSP First: A
Multimedia Approach Prentice Hall, 1998.
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.