Acquisition Time for Ground-to-Satellite Optical Communication System in Weak Atmospheric Turbulence with Spatial Diversity

Abstract

In this article, various issues involved in a ground-to-satellite optical communication link (i.e., acquisition time, uncertainty area, and channel noise) are discussed. Acquisition time of a free-space optical link is evaluated for coherent (subcarrier BPSK and QPSK) and non-coherent (OOK and M-PPM) modulation schemes over weak turbulent channel with transmit diversity. In the analysis, both uncorrelated and correlated beams are considered. It is seen that an increase in transmit diversity order helps to improve the acquisition time, irrespective of turbulence strength in the atmosphere. At high correlation, a marginal change in acquisition time is observed with the increase in diversity order.