Interleavers for Serial and Parallel Concatenated ( TURBO ) Codes

Abstract Along with convolutional codes, interleavers constitute building blocks of serial and parallel concatenated convolutional (turbo) codes. In this paper, we examine properties of interleavers, in particular, we discuss the “interleaver gain”, that is, the effect of the interleaver length on the bit error probability of the turbo code over an additive white Gaussian noise (AWGN) channel. We review several basic interleaver design approaches, and present some of the most promising interleaver design algorithms in detail together with examples. Although there is significant literature on interleaver design for parallel concatenated convolutional codes, there are only a few results available for serial concatenation. Therefore, while important results on serial concatenation are reviewed, most of the article is devoted for parallel concatenation.