Bit-interleaved coded modulation for hybrid IBOC-AM broadcasting

Bit-interleaved coded modulation (BICM) is proposed for hybrid in-band on-channel (IBOC) systems that broadcast digital audio signals simultaneously with analog amplitude modulation (AM) programs in the AM band. Since the additional diversity can be induced by bit-wise interleaving and by using an appropriate soft decision metric as an input to a Viterbi decoder, the performance of the coded modulation for IBOC-AM broadcasting systems can be improved. The paper shows that by using BICM, an IBOC-AM broadcasting system can yield a better coding gain over a Rayleigh fading channel than its original counterpart and BICM scheme with low-rate code performs better than other BICM schemes with the same bandwidth efficiency.