Pointing Error Effects on the Average Channel Capacity Performance of AF Relay-Assisted FSO Systems Over Atmospheric Turbulence Channels

Abstract

This paper presents the theoretical analysis of pointing error effects on the average channel capacity performance of amplify-and-forward (AF) relay-assisted free-space optical (FSO) systems employing subcarrier quadrature amplitude modulation (SC-QAM) signal over log-normal distributed atmospheric turbulence channels. The average channel capacity (ACC), which is expressed in terms of average spectral efficiency (ASE) is derived taking into account the atmospheric turbulence effects on the FSO channel, number of relay stations and jitter variable. The jitter variable represents the beam deflection of the system at the receiver, always exist and greatly affect on performance of system. The mathematical formulas of ACC for atmospheric turbulence cases are calculated and quantitatively discuss the influence of turbulence strength, different number of relay stations, jitter variable effects and link distance.