A Simple Upper Bound on the Channel Capacity of Coherent FSO System for Binary Inputs Over Atmospheric Turbulence Channels

抄録

This letter analyzes the average channel capacity of coherent free-space optical (FSO) systems employing multiple receive aperture for binary inputs and its simple upper bound over atmospheric turbulence-induced channels. The newly derived upper bound is based on the Taylor series and moment generating function, and it significantly reduces computational complexity by involving only a single infinite series, in contrast to the conventional double-integral expression. This analytical simplicity makes it especially appealing for performance evaluation and system design. Through numerical examples, we validate that the proposed upper bound closely approximates the exact average channel capacity across a wide range of receiver configurations and refractive index structure constants.