Improving the convergence of 3D turbo codes

The ever increasing demand for multimedia applications and communication systems with low error rate requirements is a real challenge that needs to be addressed by a powerful code with good distance properties and reasonable decoding complexity. The recently proposed three-dimension turbo codes (3D-TC) have high minimum Hamming distance (dmin) values and therefore a good fit. However, their performances as compared to the classical turbo codes suffer in the waterfall region. This paper proposes a modification to the classical encoding scheme of 3D-TC that allows both good convergence in the waterfall region and reasonably low error floor. Simulation results for rate 1/2, QPSK modulation, AWGN channel, and MPEG-sized packets of 1504 information bits (using max-log a posteriori probability (APP) decoding with scaled extrinsic values and 8 full iterations) show a better convergence compared to the classical 3D-TC and packet error rates (PER) of about 10
^_e
at signal-to-noise ratio (SNR) value of 2.0 dB.