deinterleaver

A deinterleaver is a device or algorithm used in digital communications and data storage to reconstruct the original order of a sequence that has been interleaved. Interleaving is a process that rearranges symbols as a function of position to spread burst errors over time or frequency, enabling error correction codes to recover data more reliably. A deinterleaver reverses this rearrangement by applying the inverse permutation or mapping, restoring the data to its original sequence prior to transmission or storage.

Deinterleaving requires knowledge of the interleaving pattern and its parameters, such as the depth, block size, or the sequence used to permute the symbols. In many standards the deinterleaver is implemented as a fixed circuit or algorithm that consumes the interleaved stream and outputs the correctly ordered stream. Some systems use time-domain deinterleaving, others use frequency-domain or multi-dimensional schemes; in either case the process is designed to be deterministic and reversible given the parameters.

Common types include block interleavers, which rearrange symbols in a matrix and read them out by rows or columns, and convolutional or shuffle interleavers, which apply a fixed but more complex permutation. The choice affects latency, memory use, and error-correction performance. Misalignment between the transmitter and receiver interleaving parameters can degrade performance or prevent data recovery, so proper synchronization and parameter signaling are essential.

Deinterleavers are used in various applications, including digital broadcasting (such as DVB and ATSC standards), wireless communications (3G/4G/5G systems), optical and data storage read channels, and multimedia streaming. They are typically integrated into modem or receiver pipelines after demodulation and before decoding, ensuring burst errors are distributed and corrected by the forward error correction code.