Performance analysis of bit-cooperative coded modulation with turbo codes

Bit-cooperative coded modulation (BCCM), known as an improved bit-interleaved coded modulation (BICM) scheme [1], introduces known bits to jointly design the channel coding and modulation. In this paper, we contribute to the theoretical analysis of the turbo-coded BCCM scheme, and specifically, the impact of the known bits on the turbo decoding process. The characteristic of the iteration process is also analyzed for BCCM by the EXIT chart. Furthermore, to describe the fundamental tradeoff between the communication reliability and the data rate, we derive the error exponent for BCCM. Numerical results show that BCCM has a larger exponent than BICM and achieves a considerable gain on AWGN channels.