Capacity Bounds on Optical Wireless Relay Channels

This paper studies the capacity of optical wireless relay channels under peak- or both peak- and average-intensity constraints. Capacity upper bounds are derived by applying the cutset bounding techniques combined with the maximum entropy argument or the capacity duality expression, and ca-pacity lower bounds by using the decode-and-forward coding scheme and decomposition results of certain random variables. The derived bounds are numerically shown to be fairly close in the high signal-to-noise ratio regime.