Mismatched Shaping Schemes for Bit-Interleaved Coded Modulation
The authors consider Bit-Interleaved Coded Modulation (BICM) schemes where, instead of the true bit or symbol probabilities and the constellation used at the transmitter, the decoder uses arbitrary probabilities or reference constellations. They study the corresponding low- and high-signal-to-noise-ratio regimes and show that even in the presence of this extra sources of mismatch, BICM has a negligible penalty with respect to coded modulation. In this paper, they take a closer look at shaping and the BICM mismatched decoder. In particular, they consider a generalized BICM decoder where one decodes using arbitrary bit or symbol probabilities and reference constellations instead of the true ones that used at the transmitter.