Convolutional code: Difference between revisions

Revision as of 03:13, 15 November 2019

Revision as of 19:21, 5 December 2019

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[[File:Soft34.png|thumb|right|300px|Convolutional codes with 1/2 and 3/4 code rates (and constraint length 7, Soft decision, 4-QAM / QPSK / OQPSK).<ref>[https://ch.mathworks.com/help/comm/ug/punctured-convolutional-coding-1.html Punctured Convolutional Coding (MathWorks)]</ref>]]

Convolutional code with any code rate can be designed based on polynom selection<ref>https://www.mathworks.com/help/comm/ref/poly2trellis.html</ref>, however, in practice, puncturing procedure is used to achiveachieve the required code rate. [[Puncturing]] is a technique used to make a ''m''/''n'' rate code from a "basic" low-rate (e.g., 1/''n'') code. It is reached by deletion of some bits in the encoder output. Bits are deleted according to a ''puncturing matrix''. The following puncturing matrices are the most frequently used:

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