Channel correlation in aperture receiver diversity systems for free-space optical communication

Abstract

In receiver diversity systems, signal replicas will suffer from channel correlations if there are insufficient spacings for component receivers. Knowledge of the channel correlation is important for system performance assessment and improvement. In this paper, we give a theoretical study of the channel correlation in receiver diversity systems. Based on the plane-wave model and the extended Rytov theory for the ABCD ray-matrix formulation, expressions for the channel correlation are derived under general atmospheric conditions. The effects of antenna spacing, turbulence strength, receiver aperture size, and wavelength are examined in detail and the corresponding physical mechanisms for the results are discussed. An approximation for estimating the channel correlation length under strong turbulence conditions is obtained.