1. A flow of data characterized by relatively long duration and constant rate. When the rate is known ahead of time then communication resources may be reserved for the stream. For example, stream traffic may be carried using low-overhead synchronous time division multiplexing (TDM), while other traffic on the same channel is carried by higher-overhead asynchronous TDM. This is particularly important in satellite transmission systems, where overhead differences between synchronous and asynchronous traffic are very great. It is also important in applications, such as packet speech, that require a low variation in network delay.
2. A finite or infinite sequence of elements of a nonempty set A indexed by time. If T is a set of time instants, or clock cycles, then the stream can be represented by a function
where
a(
t) is the element in the stream at time
t in
T. Usually, in modelling computing systems, the elements of
A are data or instructions, and time is assumed to be discrete, in which case
T = {0,1,2, …}.