The document discusses Bit Interleaved Coded Modulation (BICM). It introduces BICM, which combines binary encoding, bitwise interleaving, and M-ary modulation to improve performance over fading channels compared to trellis coded modulation. It describes the system model of BICM, including the use of a binary encoder, bitwise interleaver, Gray mapping, and equivalent parallel channel model. It also discusses the information theoretical framework for analyzing BICM, including its capacity and cut-off rate.