Achievable Rate Analysis of Ordered Reliability Bits Guessing Random Additive Noise Decoding (ORBGRAND) for General Bit Channels and Application in Bit-Interleaved Coded Modulation (BICM)

The paper derives the generalized mutual information (GMI) of ordered reliability bits guessing random additive noise decoding (ORBGRAND) for memoryless binary-input channels with general output conditional probability distributions. The analysis provides insights into understanding the gap between the ORBGRAND achievable rate and the channel mutual information. As an application, the paper studies the ORBGRAND achievable rate for bit-interleaved coded modulation (BICM), showing that the gap is typically small, suggesting the feasibility of ORBGRAND for high-order coded modulation schemes.