Optimum signal input distribution design in the presence of random pointing jitter for intersatellite optical communications

Abstract

Channel capacity is widely investigated for free space optical links to approach high-speed data-rate communication. Instead of traditional equiprobable binary symbol input distribution, an optimum input distribution is proposed with respect to channel capacity by maximizing mutual information for intersatellite optical communications in the presence of random pointing jitter. It is shown that the optimum input distribution varies with the variance of pointing jitter σ and laser beam divergence angle w0 and the normalized intensity threshold IT. For traditional normalized intensity threshold IT=0.5, the optimum input distribution ranges from about p(x=0)=0.52 for weak pointing jitter to about p(x=0)=0.24 for strong pointing jitter given the same laser beam divergence angle. The results obtained in this paper will be useful for intersatellite optical communication system design.