Channel Capacity for Optical Space Communication Systems

In this paper, discrete and continuous channel models of free-space optical channel have been described. The discrete channel model is used to determine the channel capacity with photon counter for single-mode and multimode laser beams. The channel capacities with preamplified PIN photodiode direct detection receiver, heterodyne receiver, homodyne receiver and preamplified threshold detection receiver for m-PPM signalling scheme are determined from the continuous channel model.