Stationary Information Sources

Starting from a non-empty set A, which we refer to as a character set and which may contain at least two and at most a finite number of elements (so-called characters), communication technology often assumes a transmitter who sends a character \(a\in A\) at any time \(t\in\mathbb{Z}\) . At any fixed time \(t_{0}\in\mathbb{Z}\) , the transmitter has already sent an infinite number of characters and will continue to send an infinite number of characters after t0. This unrealistic assumption serves to capture all practically relevant cases in a single mathematical model and not to have to design a separate mathematical model for each special case; we will come back to this.