Turbo Codec with Hybrid Modulation

A novel turbo codec with hybrid modulation is proposed in this paper. Instead of brutal puncturing, we apply different modulation alphabets to the original not-punctured turbo coded bits, where the systematic bits are modulated by a lower order constellation and the parity bits are mapped by a higher order constellation, respectively. Numerical results show that the proposed scheme without puncturing can noticeably improve the bit error rate (BER) and frame error rate (FER) performance of turbo codes in Rayleigh flat fading channels compared with the conventional turbo codes with puncturing and uniform modulation with the same spectral efficiency.