On the Sum-Capacity of Two-User Optical Intensity Multiple Access Channels

This paper investigates the sum-capacity of two-user optical intensity multiple access channels with a per-user peak- or average-intensity constraint. By leveraging tools on decomposition of random variables, we derive lower bounds on the sum-capacity. In the high signal-to-noise ratio (SNR) regime, they asymptotically match the sum-capacity. In particular, for the peak-intensity constrained channel, our result closes the high-SNR asymptotic sum-capacity gap in the existing works.