Scrambling-Based Shaping for Turbo Coded Modulation

We propose a multiple-candidate shaping technique for turbo coded modulation systems. Shaping gains are obtained by encoding each message into multiple turbo coded modulation sequences, called candidates, and then selecting the candidate with the lowest energy for transmission. Multiple candidates are generated by adding various scrambling sequences to each message sequence. The proposed shaping technique can also be applied to turbo coded modulation systems equipped with some other shaping methods to obtain additional shaping gains.