Modulation doping for iterative demapping of bit-interleaved coded modulation

In this letter, the problem of the transmitter design for bit-interleaved coded modulation (BICM) with the receiver employing iterative demapping, is addressed. Conventionally, the design is focused on the appropriate choice of the constellation mapping so that the iterative process converges to small values of bit- or block- error rates. Here, instead of a difficult design of a new mapping, we propose to use symbols modulated using two different mappings. Through numerical simulation, our simple design is shown to outperform the conventional approach without increase in the receiver's complexity.