Apply bit-level interleaver to improve the error rate performance of the double binary turbo code with less decoder complexity

An innovative interleaver design concept is proposed to enhance double binary turbo code which is adopted in IEEE 802.16e and DVB-RCS/RCT. Our concept features bit-level interleaving instead of conventional symbol-level interleaving. In order to prove this concept, we construct a bit-level interblock permutation interleaver. Comparing with IEEE 802.16e CTC, new design outperforms IEEE 802.16e CTC by 0.02-0.3 dB at frame error rate=10^-4 while the associated decoder saves 33% storage extrinsic information. Our concept improves error rate performance and reduces double binary turbo decoder complexity at the same time.