Abstract. The increasing demand of achieving high data rates in modern communication systems requires highly efficient bandwidth utilization. For this purpose, multilevel modulation schemes are used in association with forward error correction (FEC) codes in order to approach the channel capacity. However, there is a gap between the capacity of a uniform signal constellation and the Shannon unconstrained capacity. This gap can be reduced by applying constellation shaping. The task of shaping is to modify a uniform distributed signal constellation towards a Gaussian like distribution. In this paper, we investigate different approaches to combine the constellation shaping with a bit interleaved coded modulation with iterative decoding (BICM-ID) system. Simulation results show that this combination can offer a shaping gain up to 0.6 dB.