Editing Convolutional code (section)

== Turbo codes: replacing convolutional codes ==
{{Main article|Turbo code}}

[[File:Turbo codes scheme.png|thumb|350 px| A turbo code with component codes 13, 15.<ref>[http://www.scholarpedia.org/article/Turbo_codes Turbo code]</ref> Turbo codes get their name because the decoder uses feedback, like a turbo engine. Permutation means the same as the interleaving. C1 and C2 are recursive convolutional codes. Recursive and non-recursive convolutional codes are not so much different in BER performance, however, recursive type of is implemented in Turbo convolutional codes due to better interleaving properties.<ref>Benedetto, Sergio, and Guido Montorsi. "[https://web.archive.org/web/20190406181758/https://ieeexplore.ieee.org/abstract/document/390945/ Role of recursive convolutional codes in turbo codes]." Electronics Letters 31.11 (1995): 858-859.</ref>]]

Simple Viterbi-decoded convolutional codes are now giving way to [[turbo code]]s, a new class of iterated short convolutional codes that closely approach the theoretical limits imposed by [[Noisy-channel coding theorem|Shannon's theorem]] with much less decoding complexity than the Viterbi algorithm on the long convolutional codes that would be required for the same performance. [[Concatenated error correction code|Concatenation]] with an outer algebraic code (e.g., [[Reed–Solomon error correction|Reed–Solomon]]) addresses the issue of [[error floor]]s inherent to turbo code designs.