On The Performance Of Wireless Optical Communcation System Over Exponentiated Weibull Fading Channels

Wireless optical communication(WOC),also known as free space optical communication(FSO),has attracted extensive attention from researchers due to its advantages such as rich frequency resources,high security and strong ability of resisting electromagnetic interference.However,due to the variation of atmospheric conditions,when the laser beam transmitted in the atmosphere environment,atmospheric turbulence(AT)will lead to the fluctuations in both intensity and phase of the received optical signal,which could seriously deteriorate the performance of FSO links.In addition,the installation platforms of the transmitter and receiver may appear random jitter due to earthquake,building thermal expansion and other reasons.This phenomenon is called pointing errors(PE)which will also seriously limit the system performance.Therefore,it is very meaningfull to explore how to improve the performance of FSO system,and how to apply the FSO system in the practical scenarios.In recent years,relay-assisted techniques,aperture averaging,and partially coherent beam(PCB)have been proposed to mitigate the turbulence-induced scintillations and PEs.In this work,the performance of dual-hop mixed radio frequency / free-space optical(RF/FSO)communication system in urban area over exponentiated Weibull(EW)fading channels with pointing errors is studied.Moreover,the average capacity of the PCB communication system based on EW fading channels is also explored in detail.The specific work is as follows:1.The end-to-end transmission performance of the DF based dual-hop mixed RF/FSO urban wireless communication systems is studied.Firstly,the average bit error rate(ABER)of RF and FSO links are derived with the binary phase shift keying(BPSK)data format,where the RF link is characterized by Nakagami-8)and FSO link follows EW distribution.In addition,three scenarios are considered,including FSO links without PE,with zero boresight PE and with none-zero boresight PE.Then the end-to-end ABER expressions are achieved via the combination of ABER results of RF and FSO links.To confirm the correctness of the obtained analytical ABER models,Monte Carlo(MC)simulation is given.Finally,the effect of RF channel parameter?AT?PE and received aperture size on the performance of the mixed RF/FSO is analyzed.Besides,the influence of RF and FSO links on system's ABER peformance is discussed in detail.2.On the basis of EW fading model,PE model and atmospheric loss model,the average channel capacity performance of FSO system with PCB technology is discussed.Firstly,the average channel capacity of the FSO system are deduced which takeing into account the combined channel fading model and the condition of the known and unknown channel state information at the receiver.Then,the channel capacity in two cases are calculated by Monte Carlo Integration in MATLAB.Finally,the average channel capacity of PCB communication system with aperture averaging is analyzed and compared under different weather conditions,different transmission distances,different turbulence and different PE.This thesis can offer some references for the design of FSO communication system and performance research.