On Multidimensional BICM-ID Constellation Labelling

It is widely recognised that the choice of a specific bit-to-symbol mapping scheme or a beneficial constellation labelling is an influential factor, when designing bit-interleaved coded modulation using iterative decoding (BICM-ID) for the sake of achieving a high iteration gain. Generally, a larger constellation size of a higher-dimensional space renders the bit-to-symbol mapping design more flexible. In this paper, we first define a flexibility measure based on the extrinsic information transfer (EXIT) characteristics of bit-to-symbol mapping schemes. Secondly, we investigate the effect of expanding the constellation to a higher-dimensional space on our proposed EXIT characteristic flexibility index, when transmitting diverse numbers of bits per joint symbol.