Average capacity of ground-to-train wireless optical communication links in the non-Kolmogorov and gamma-gamma distribution turbulence with pointing errors

A model of the average capacity of the ground-to-train wireless optical communication (WOC) link is established by using the gamma-gamma distribution of moderate to strong scintillation regions. Our numerical propagations indicate that the average channel capacity increases with the increase of refractive-index structure parameter and turbulence spectral index. For the link operating distance being larger than 100 m, the influences of the change for the normalized beamwidth on the average channel capacity can be ignored. The higher the average SNR results, the higher is the equivalent average channel capacity. The point errors between the transmitter laser and receiver detector are dominant factor to decrease the average capacity of links.