The Research On The Performance Of Asymmetric Clipping Optical OFDM Based On Discrete Hartley Transform

In recent years,with the degree of informatization continuing to grow,information technology,such as Internet,is developing rapidly;mankind has officially come into the age of information.Consequently,people's demand for higher Internet transmission speed is booming,meanwhile,demands for bandwidth of network are also increasing.By virtue of huge capacity,high speed and long transmission distance,optical fiber communication technology has drawn worldwide attention of researchers'.Optical orthogonal frequency division multiplexing(O-OFDM)has characteristics of high bandwidth efficiency,huge system capacity and counter-dispersion ability etc.As a result,OFDM has high value of application.Among many forms of OFDM systems,direct detection(DD)OFDM has advantages of simple implementation structure and low cost,which makes it applicable in many scenarios such as passive optical networks(PON),visible light communication(VLC),and interconnection of data centers.Asymmetric clipping optical OFDM system is one implementation form of IM/DD optical OFDM,which has the superiority of simpler architecture of transmitter and receiver,higher optical power efficiency and lower vulnerability to nonlinearity.Discrete Hartley Transform(DHT)is a means of real trigonometric transform.If DHT is adopted to realize OFDM system,one-dimensional modulation constellations such as BPSK and M-PAM can be utilized;while no Hermitian symmetry is not required.Moreover,DHT has the self-inverse property,which leads to lower system implementation complexity.ACO-OFDM based on DHT integrates the advantages of DHT and ACO-OFDM,which makes it an alternative for IM/DD OFDM bearing characteristics like high power efficiency.The main contents of this paper are the research on the performance of Asymmetric clipping optical OFDM based on Discrete Hartley Transform.After researches on the background and research status,the principle of the system is introduced and improved scheme is proposed.Additionally,via simulation and experiments the performance is researched.The detailed research contents are listed as follows:Main contributions and researches of the thesis are presented as below:1)OFDM systems were summarized and introduced,including system components,modulation and demodulation principle and derivation,and key technologies and components used in OFDM system were introduced;and finally OFDM technology for classification are introduced briefly,discussing its principles,characteristics and application of scenes,etc.Researches on the generation scheme of multi-carrier optical source based on re-circulating frequency shifter are carried out.Improved scheme generation scheme of multi-carrier optical source based on re-circulating frequency shifter is introduced,and principle deviation is also conducted.Experiments are designed to verify the feasibility and usability of the proposed scheme,and stable multi-carrier optical source output is obtained,the flatness fluctuation of which is approximately 3dB.2)The composition architecture and implementation principle of ACO-OFDM are introduced along with the simulation analyses.A brief introduction of IM/DD optical OFDM is included,while two forms of IM/DD optical OFDM,namely DCO-OFDM and ACO-OFDM,are also introduced in principle and simulation.Finally,a comparison between DCO-OFDM and ACO-OFDM is conducted briefly..3)Analyses and researches on the performance of ACO-OFDM based on DHT are introduced,mainly including the application of diversity combining technique in the ACO-OFDM system based on DHT.Moreover,the implementation principle and theory deviation are conducted along with feasibility verification via simulation.Finally,we do experiments to analyze and research on the proposed scheme,which approves that the BER performance has been significantly improved by 1.5dB in 50km transmission experiment.