front_matter - Principles of Digital Communication Robert...

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Principles of Digital Communication Robert G. Gallager January 5, 2008 Cite as: Robert Gallager, course materials for 6.450 Principles of Digital Communications I, Fall 2006. MIT OpenCourseWare (, Massachusetts Institute of Technology. Downloaded on [DD Month YYYY].
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ii Preface: introduction and objectives The digital communication industry is an enormous and rapidly growing industry, roughly com- parable in size to the computer industry. The objective of this text is to study those aspects of digital communication systems that are unique to those systems. That is, rather than focus- ing on hardware and software for these systems, which is much like hardware and software for many other kinds of systems, we focus on the fundamental system aspects of modern digital communication. Digital communication is a field in which theoretical ideas have had an unusually powerful impact on system design and practice. The basis of the theory was developed in 1948 by Claude Shannon, and is called information theory. For the first 25 years or so of its existence, information theory served as a rich source of academic research problems and as a tantalizing suggestion that communication systems could be made more efficient and more reliable by using these approaches. Other than small experiments and a few highly specialized military systems, the theory had little interaction with practice. By the mid 1970’s, however, mainstream systems using information theoretic ideas began to be widely implemented. The first reason for this was the increasing number of engineers who understood both information theory and communication system practice. The second reason was that the low cost and increasing processing power of digital hardware made it possible to implement the sophisticated algorithms suggested by information theory. The third reason was that the increasing complexity of communication systems required the architectural principles of information theory. The theoretical principles here fall roughly into two categories - the first provide analytical tools for determining the performance of particular systems, and the second put fundamental limits on the performance of any system. Much of the first category can be understood by engineering un- dergraduates, while the second category is distinctly graduate in nature. It is not that graduate students know so much more than undergraduates, but rather that undergraduate engineering students are trained to master enormous amounts of detail and to master the equations that deal with that detail. They are not used to the patience and deep thinking required to understand abstract performance limits. This patience comes later with thesis research. My original purpose was to write an undergraduate text on digital communication, but experi-
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This note was uploaded on 02/21/2012 for the course ECON 830 taught by Professor Staff during the Spring '08 term at Michigan State University.

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front_matter - Principles of Digital Communication Robert...

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