Editing Channel capacity (section)

{{Short description|Information-theoretical limit on transmission rate in a communication channel}}
{{More citations needed|date=May 2023}}
{{Information theory}}
'''Channel capacity''', in [[electrical engineering]], [[computer science]], and [[information theory]], is the theoretical maximum rate at which [[information]] can be reliably transmitted over a [[communication channel]].

Following the terms of the [[noisy-channel coding theorem]], the channel capacity of a given [[Channel (communications)|channel]] is the highest information rate (in units of [[information entropy|information]] per unit time) that can be achieved with arbitrarily small error probability.<ref>{{cite web |url=http://www.cs.ucl.ac.uk/staff/S.Bhatti/D51-notes/node31.html |author=Saleem Bhatti |title=Channel capacity |work=Lecture notes for M.Sc. Data Communication Networks and Distributed Systems D51 -- Basic Communications and Networks |url-status=dead |archive-url=https://web.archive.org/web/20070821212637/http://www.cs.ucl.ac.uk/staff/S.Bhatti/D51-notes/node31.html |archive-date=2007-08-21 }}</ref><ref>{{cite web | url = http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/iandm/part8/page1.html | title = Signals look like noise! | author = Jim Lesurf | work = Information and Measurement, 2nd ed.}}</ref>

[[Information theory]], developed by [[Claude E. Shannon]] in 1948, defines the notion of channel capacity and provides a mathematical model by which it may be computed. The key result states that the capacity of the channel, as defined above, is given by the maximum of the [[mutual information]] between the input and output of the channel, where the maximization is with respect to the input distribution.<ref>{{cite book| author = Thomas M. Cover, Joy A. Thomas | title = Elements of Information Theory | publisher = John Wiley & Sons, New York |year=2006| isbn = 9781118585771 |url=https://books.google.com/books?id=VWq5GG6ycxMC&q=%22channel+capacity%22}}</ref>

The notion of channel capacity has been central to the development of modern wireline and wireless communication systems, with the advent of novel [[Error correction code|error correction coding]] mechanisms that have resulted in achieving performance very close to the limits promised by channel capacity.