On the Capacity of FSO Links over Gamma-Gamma Atmospheric Turbulence Channels Using OOK Signaling

Date Added: Mar 2010
Format: PDF

A new upper bound on the capacity of power- and bandwidth-constrained optical wireless links over gamma-gamma atmospheric turbulence channels with intensity modulation and direct detection is derived when On-Off Keying (OOK) formats are used. In this Free-Space Optical (FSO) scenario, unlike previous capacity bounds derived from the classic capacity of the well-known Additive White Gaussian Noise (AWGN) channel with uniform input distribution, a new closed-form upper bound on the capacity is found by bounding the mutual information subject to an average optical power constraint and not only to an average electrical power constraint, showing the fact that the input distribution that maximizes the mutual information varies with the turbulence strength and the Signal-to-Noise Ratio (SNR).