I. Introduction and Preliminary Discussions
Bit-Interleaved coded modulation (BICM) is a simple, well-known method for achieving both power and spectral efficiency [1], [4], [18]. While it was originally proposed for fading channels [18], BICM with Gray mapping has proved to perform very close to the capacity of an additive white Gaussian noise (AWGN) channel as well [1], [4]. Interleaving is required to break down any correlation between the bits which may exist due to the memory of the channel, or for memoryless channels, due to the nonbinary modulation. The existence of an interleaver also allows for the pragmatic, but quite effective, approach of mixing and matching powerful coding schemes with different signal sets, avoiding the joint design of coding and modulation [1].