Optimizing BICM with convolutional codes for transmission over the AWGN channel

The usual comparison of trellis coded modulation and bit-interleaved coded modulation, both using convolutional codes and Viterbi decoding, leads to the well-known result that for the AWGN channel TCM clearly outperforms BICM. In fading scenarios BICM shows superior results. Based on recent results on optimized bit mappings and bit-interleaver designs for BICM, we demonstrate that the BER of BICM on AWGN channels can be significantly lowered at no additional cost. Depending on the signal constellation size and the constraint length of the convolutional code gains up to 7 dB can be achieved over BICM with random bit interleavers.