page_title: Convolutional code
section_title: Where convolutional codes are used
hierarchical_section_title: Convolutional code / Where convolutional codes are used
caption_attribution_description: English: Stages of channel coding in GSM &#91;1&#93;. Block encoder and Parity check - error detection part. Convolutional encoder and Viterbi decoder - error correction part. Interleaving and Deinterleaving - code words separation increasing in time domain and to avoid bursty distortions.
context_page_description: In telecommunication, a convolutional code is a type of error-correcting code that generates parity symbols via the sliding application of a boolean polynomial function to a data stream. The sliding application represents the 'convolution' of the encoder over the data, which gives rise to the term 'convolutional coding'. The sliding nature of the convolutional codes facilitates trellis decoding using a time-invariant trellis. Time invariant trellis decoding allows convolutional codes to be maximum-likelihood soft-decision decoded with reasonable complexity.
  The ability to perform economical maximum likelihood soft decision decoding is one of the major benefits of convolutional codes. This is in contrast to classic block codes, which are generally represented by a time-variant trellis and therefore are typically hard-decision decoded. Convolutional codes are often characterized by the base code rate and the depth of the encoder. The base code rate is typically given as, where is the input data rate and is the output symbol rate. The depth is often called the "constraint length", where the output is a function of the current input as well as the previous inputs.
context_section_description: Convolutional codes are used extensively to achieve reliable data transfer in numerous applications, such as digital video, radio, mobile communications (e.g., in GSM, GPRS, EDGE and 3G networks (until 3GPP Release 7)) and satellite communications. These codes are often implemented in concatenation with a hard-decision code, particularly Reed–Solomon. Prior to turbo codes such constructions were the most efficient, coming closest to the Shannon limit.
caption: Stages of channel coding in GSM.[2] Block encoder and Parity check - error detection part. Convolutional encoder and Viterbi decoder - error correction part. Interleaving and Deinterleaving - code words separation increasing in time domain and to avoid bursty distortions.
exif: {}