Interleaver optimization of convolutional turbo code for 802.16 systems

Convolutional turbo code (CTC) has been adopted as an optional channel coding scheme for wireless metropolitan area networks (WMAN) and digital video broadcasting (DVB) owing to its powerful error correction capability and flexibility. In spite of the fact that the internal interleaver of CTC mainly affects the characteristics of the code, interleaving parameters, especially for small and moderate block sizes, have not been fully optimized in terms of performance. In this paper, we investigate structural behavior of interleaving parameters and suggest several optimization methodologies for the CTC interleaver of 802.16 systems. Simulation shows that power gains up to 0.7 dB can be acquired at a target frame error rate of 10^-5 by only substituting the newly optimized parameters for the current ones.