Namespaces
Variants
Actions

Symmetric channel

From Encyclopedia of Mathematics
Revision as of 18:00, 7 February 2011 by 127.0.0.1 (talk) (Importing text file)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

A communication channel whose transition function possesses some kind of symmetry. A homogeneous discrete time memoryless channel with finite alphabets and of input and output letters, respectively, and defined by a matrix of transition probabilities is called a symmetric channel if

(*)

where is the number of elements of , . The most studied example of a memoryless symmetric channel is the binary symmetric channel with matrix of transition probabilities

For symmetric channels, many important information-theoretic characteristics can either be calculated explicitly or their calculation can be substantially simplified in comparison with non-symmetric channels. For example, for a memoryless symmetric channel with matrix of the form (*) the capacity (cf. Transmission rate of a channel) is given by the equation

For references see ,

cited under Communication channel.


Comments

References

[a1] R.C. Gallager, "Information theory and reliable communication" , Wiley (1968)
How to Cite This Entry:
Symmetric channel. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Symmetric_channel&oldid=12571
This article was adapted from an original article by R.L. DobrushinV.V. Prelov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article