On the capacity of BICM with QAM constellations (Invited Paper)

Abstract—In this tutorial paper we analyze the capacity of bit-interleaved coded modulation (BICM) with quadrature amplitude modulation (QAM) constellations, and we pay special attention to different bit-to-symbol labeling strategies. The relation between the BICM capacity and the capacity of other more traditional CM schemes such as trellis coded modulation (TCM) and multilevel codes (MLC) is analyzed. Motivated by the fact that for BICM with some particular labelings, the same Eb/N0 maps to more than one BICM capacity value, we study the relation between the capacity and Eb/N0. In particular, we present some analytical results on this relation, and we also give an intuitive explanation for the somehow contradictory behavior of these curves. I