Definition:
The main task of the rate-matching is to extract the exact set of bits to be transmitted within a given TTI. The rate-matching for Turbo coded transport channels is defined for each code block: there are three basic steps composing a rate-matching. Namely, sub-block interleaver, bit collection and bit selection. Finally, after the rate-matching, each individually processed code block has to be concatenated and transferred to a modulation block. The sub-block interleaver is defined for each output stream from Turbo coding. The streams include a systematic bit stream, a parity bit stream and an interleaved parity stream. The bit collection step concatenates the three bit streams together. The bit selection extracts consecutive bits from the circular buffer to the extent that fits into the assigned physical resource.
Further Reading:
Book: The Principles of Product Development Flow by Donald G. Reinertsen
