Aperture Averaged BER Performance Analysis of a non-Hermitian coherent optical OFDM FSO system with polarization diversity

Abstract

In this article, we evaluated the amount of improvement in receiver sensitivity fora non-Hermitian OFDM FSO system with polarization diversity due to using aperture averaging, a very effective technique of fading mitigation. Due to the presence of atmospheric turbulence, the transmitted light signal intensity is distorted which degrades the system bit error rate (BER) performance significantly. An analytical study is carried out to find the receiver sensitivity improvement for different receiver aperture diameters. Average BER is obtained by averaging the conditional BER over log-normal distribution and Maxwellian distribution for weak atmospheric turbulence and random misalignment angle due to cross polarization respectively. It is observed that the receiver sensitivity improves by 3.2dß, 4.9dß and 5.8dB for an aperture diameter of 0.5mm, 0.8mm and 1mm, respectively “ith respect to the point receiver for a link distance of 3500m at a BER of 1012. Moreover, 0.48dß, 2.5dß and 5.8dß improvements are obtained fur a link length of 2000m, 3000m and 3500m, respectively for aperture diameter of 1mm at a BER of 1012.