Interleaving

Interleaving is a standard signal processing technique used in a variety of communications systems. An interleaver is a device that takes symbols from a fixed alphabet at the input and produces the identical symbols at the output in a different temporal order. The classical use for interleaving is to “randomize” the locations of errors introduced in transmission, allowing for the use of random error correcting codes at the receiver. Such a situation occurs in (1) burst error channels (e.g., wireless communications channels) and (2) concatenated coding, where the first stage of decoding generates burst errors (e.g., a Viterbi decoder). The more recent application of interleaving is in the parallel concatenated encoders invented by Berrou, Glavieux and Thitimajshima [BGT93].