Performance Analysis Of MPPM Based Wireless Optical Communication System

With the continuous development of the information technology,free space optical(FSO)communication attract people's attention because it has many advantages such as being license-free,high bandwidth,light equipment,conveniently networking,transparency transport protocols,excellent security performance,and so on.FSO uses wireless light as carrier to transmit line-of-sight communication in free space.The performance of FSO links is vulnerable to some impairments,and two of main effects are atmospheric turbulence and pointing errors,which can increase the bit error rate of communication system.Thus,based on multiple pulse position modulation(MPPM),the performances of FSO using optimized decision threshold(ODT)and dynamic decision threshold(DDT)of point-to-point and DDT of relay-aided system over the aggregated EW atmosphere turbulence channels with pointing errors considered are studied in this work.The main contents are shown as follows:(1)Considering the effect of pointing errors,the probability density function(PDF)and the cumulative distribution function(CDF)of the aggregated channel model are derived by using the Meijer-G function over exponentiated Weibull(EW).The closed-form symbol error rate(SER)expressions of communication system with ODT and DDT schemes are obtained on the basis of Gauss–Laguerre quadrature function.Monte Carlo simulation is provided to verify the correctness of the proposed SER expressions.In addition,the influences for ODT and DDT with turbulence strengths,different apertures sizes,jitters and beam width are analyzed in detail.(2)The SER performance of multi-hop parallel FSO system is studied based on the aggregated channels of atmospheric turbulence-induced fading modeled by EW distribution and pointing errors.The CDF of multi-hop parallel FSO system is achieved with choosing the max-min criterion as the best path selection scheme.Then,the SER expression for DDT scheme is derived by using Gauss–Laguerre quadrature function.The SER performances are investigated analyzed systematically under different hop number,turbulence strengths,different apertures sizes and so on.This thesis could provide some theoretical references for designing FSO system.