The Performance Of Free Space Optical Communication Systems Based On The Exponentiated Weibull Fading Channel

Currently, free space optical communication has gained more and more attention around the world. A lot of research has proved that the effect of turbulence atmosphere to the free space optical communication is very significant and is the key restrict factor of performance improvement.In this work, exponentiated Weibull distribution has been used as the fading channel model, the expressions of bit error rate/symbol error rate for BPSK, MPSK, DPSK, and MDPSK modulation of free space optical system have been calculated using generalized Gauss-Laguerre quadrature rule or Gauss-Laguerre quadrature rule. The performance of systems has been studied and system performance improvement brought by the effect of aperture averaging has been quantified. The outage probability of exponentiated Weibull system has been studied. This work may helpful for the system design and performance improvement of the free space optical communication in turbulence atmosphere.The main contents are as follows:1. The exponentiated Weibull distribution has been used to describe the probability density function of the received intensity of free space optical communication systems. The closed forms of the bit error rate for BPSK and MPSK modulation have been obtained using the generalized Guass- Laguerre quadrature rule. Monte Carlo simulation has been used to verify the correctness of the analytical result. The bit error rate(BER) in weak, moderate, and strong turbulence atmosphere is plotted against the signal to noise ratio(SNR), respectively. It can be seen that exponentiated Weibull model is more accurate in describing the received intensity for finite aperture sizes than lognormal model and Gamma-Gamma model in all turbulence strength. Additionally, exponentiated Weibull model still works perfect when aperture averaging takes place.2. The approximate bit error rate of DPSK and symbol error rate of MDPSK of optical communication system based on exponentiated Weibull fading channel have been calculated and have been compared with the exact results. The comparison has confirmed the correctness and effectiveness of the analytical results. Additionally, the outage probability of exponentiated Weibull fading channel has been obtained using the cumulative distribution function. The effect of atmospheric turbulence to the communication system has been analyzed, as the turbulence strength increases, outage probability increases, the system performance get worse. The outage probability using different aperture sizes have been compared, as the aperture size increases, outage probability decreases. Aperture averaging effect can improve the system performance.