Low-density hybrid-check coded superposition mapping in BICM-OFDM

Superposition mapping (SM) is known to be capacity achieving on the Gaussian channel, but an outer code is necessary because SM is a non-bijective modulation scheme. Towards this goal, the combination of SM with bit-interleaved coded modulation (BICM) has extensively been studied for the Gaussian channel. SM in conjunction with BICM-OFDM has recently been proposed by the authors for frequency-selective fading channels. In this paper, the results are extended by applying the concept of low-density hybrid-check (LDHC) coding. We propose a flexible overall code design taking adaptive bit loads into account. The performance of the system proposal is analyzed, with special focus on the degree allocation of the concatenated code, and the effect of iterations.