Editing Convolutional code (section)

== Where convolutional codes are used ==
[[File:GSM convol code.png|thumb|right|400px|Stages of channel coding in GSM.<ref>Eberspächer J. et al. GSM-architecture, protocols and services. John Wiley & Sons, 2008. p.97</ref> Block encoder and Parity check – error detection part. Convolutional encoder and Viterbi decoder – error correction part. [[Error correction code#Interleaving|Interleaving]] and Deinterleaving – code words separation increasing in time domain and to avoid bursty distortions.]]

Convolutional codes are used extensively to achieve reliable data transfer in numerous applications, such as [[digital video]], radio, [[Mobile telephony|mobile communications]] (e.g., in GSM, GPRS, EDGE and 3G networks (until 3GPP Release 7)<ref>3rd Generation Partnership Project (September 2012). "3GGP TS45.001: Technical Specification Group GSM/EDGE Radio Access Network; Physical layer on the radio path; General description". Retrieved 2013-07-20.</ref><ref>Halonen, Timo, Javier Romero, and Juan Melero, eds. GSM, GPRS and EDGE performance: evolution towards 3G/UMTS. John Wiley & Sons, 2004. p. 430</ref>) and [[Communications satellite|satellite communications]].<ref>Butman, S. A., L. J. Deutsch, and R. L. Miller. [http://tda.jpl.nasa.gov/progress_report/42-63/63H.PDF "Performance of concatenated codes for deep space missions."] The Telecommunications and Data Acquisition Progress Report 42-63, March–April 1981 (1981): 33-39.</ref> These codes are often implemented in [[Concatenated error correction code|concatenation]] with a hard-decision code, particularly [[Reed–Solomon error correction|Reed–Solomon]]. Prior to [[Turbo code|turbo codes]] such constructions were the most efficient, coming closest to the [[Shannon–Hartley theorem|Shannon limit]].