The Basis for Convergence
Click here to read a paper on how Information Theory provides the theoretical basis for telecom convergence. Information Theory and how it relates to convergence are summarized below.
Information Theory
In 1948, Claude Shannon, a Bell Labs researcher, published "A Mathematical Theory of Communication" in the Bell System Technical Journal. This paper presented the definitive theory of communications, which came to be called "Information Theory." Information Theory is a unified and comprehensive view of communications and provides the theroretical basis for telecom convergence.
According to Shannon's theory, communication sources can be characterized by their information rates, which can be considerably lower than their raw data rates, and communication channels can be characterized by their capacities. A communication channel can support applications whose information rates are less than the channel capacity.
The Mathematical Theory of Communication
The Mathematical Theory of Communication by Claude Shannon and Warren Weaver was originally published in 1949. The book contains, with only minor changes, Shannon's 1948 paper on Information Theory and a discussion of Shannon's theory written by Weaver. The book can be obtained from Amazon.com for $17.
There are three levels of the communication problem: the technical problem, involving primarily the accuracy of transmission and reception; the semantic problem, involving the meaning of the symbols that are transmitted; and the effectiveness problem, involving the significance and importance of what is being communicated. Although Shannon's paper addresses only the technical problem, Weaver places Shannon's theory in the perspective off all three problems and claims the theory has a "deep significance" that goes beyond the technical problem. Weaver claims that the three problem levels overlap to a significant degree and that Shannon's theory applies to all three levels.
Weaver's explanation of Shannon's theory makes it understandable to the non-expert. This is important because most of the industry and government people who make decisions that affect communications are not technical experts in the field. Unfortunately, many of these decision makers have been unaware of, or have chosen to ignore, the sound guidance provided by Shannon.
Before The Mathematical Theory of Communication was published, the concepts that united various types of communications were obscure and not widely known. With the publication of Shannon and Weaver's book, the unifying concepts of communications became widely accepted. The case can be made that this was point at which the idea of telecom convergence was born. Below is a convergence statement written by Weaver about Shannon's theory:
"This is a theory so general that one does not need to say what kinds of symbols are being considered - whether written letters or words, or musical notes, or spoken words, or symphonic music, or pictures. The theory is deep enough so that the relationships it reveals indiscriminately apply to all these and to other forms of communication. This means, of course, that the theory is sufficiently imaginatively motivated so that it is dealing with the real inner core of the communication problem - with those basic relationships which hold in general, no matter what special form the actual case may take."