Research On ROF System Based On Optical Frequency Comb And Optical Reuse Technology

The radio over fiber(ROF)system combines the advantages of optical fiber communication and wireless communication,which can effectively solve the problems of high cost of base station construction and high loss of millimeter wave signal transmission.In order to further improve the communication capacity of the ROF system,while reducing the waste of fiber capacity and construction costs,the application of optical multiplexing technology to the ROF system is an important solution for the future optical wireless integrated access network to achieve high speed,large capacity and long distance.The optical frequency comb(OFC)is used as the multi-carrier light source of optical multiplexing technology and the ROF system,which is beneficial to the expansion and reconstruction of the system.This paper focuses on the ROF system based on optical frequency comb and optical multiplexing technology.In the research process of the system,the multi-carrier light source needs high flatness,the appropriate modulation method needs to be selected,and the transmission performance of the system is susceptible to fiber loss,dispersion and nonlinear effects.The specific research contents are as follows:An optical frequency comb generation technique based on cascaded EAM and PM is proposed.Firstly,the working principle of OFC based on cascaded EAM and PM is expounded,and a complete theoretical model is established.The generation scheme of OFC is simulated by using optical communication system simulation design software Optisystem,and the influence of tunable light source center frequency,light source linewidth,EAM working parameters,PM driving signal amplitude and modulator driving signal phase difference on the OFC performance is studied.By optimizing the working parameters of each device,a 21-line OFC with a flatness of 0.93 d B,an average power of-9.56 d Bm,and a frequency separation of 20 GHz is generated.A multi-service layered WDM-ROF system with optional frequency millimeter based on OFC is proposed.The optically suppressed carrier double sideband(OCS)modulation is used in the central station(CS),which has good anti-fiber dispersion performance.The micro-electro-mechanical system technology(MEMS)optical switch matrix is introduced into the secondary central station(SCS)to realize the optional frequency of millimeter wave signals.The layered base station group(BSG)provides multiple service access for each BS.By using wavelength reservation method,BSG uplink transmission without optical source is realized.The optical communication system simulation design software Optisystem is used to simulate the WDM-ROF system.The research results show that 10 kinds of millimeter wave signals with optional frequencies can be realized in the downlink,and the BSG of each channel can transmit multiple services.After 40 km SMF transmission,the receiving sensitivity of the downstream transmission signal is about-10.221 d Bm,and its average power cost is 0.891 d B;the receiving sensitivity of the upstream transmission signal is about-17.948 d Bm,and its average power cost is 0.843 d B;both uplink and downlink transmission eye diagrams are kept open.Therefore,the WDM-ROF system has high-efficiency transmission with low power cost,which is suitable for the application scenarios of multi-service requirements,crowd aggregation and signal instability.A multi-service PDM-WDM-ROF system with optional multi-frequency signal based on OFC is proposed.The introduction of wavelength selective switch(WSS)in SCS not only changes the shortcomings of the same frequency of electrical signals,but also solves the problem that some wavelength devices limit the transmission bandwidth.Using PDM technology and WDM technology,downlink baseband wired signal,intermediate frequency signal and millimeter wave signal are generated by only one optical carrier in BS,and realize wired and wireless access at the same time.By using the wavelength reservation method,the BS uplink transmission without light source is realized.The optical communication system simulation design software Optisystem is used to simulate the PDM-WDM-ROF system.The research results show that five optional multi-frequency signals can be realized in the downlink,and the BS of each channel can transmit multiple services of wired and wireless integration.After 40 km SMF transmission,the receiving sensitivity of the downlink transmission wireless signal is about-12.609 d Bm,and its average power cost is 0.965 d B;the receiving sensitivity of the downlink transmission wired signal is about-17.946 d Bm,and its average power cost is 0.839 d B;the receiving sensitivity of the uplink transmission signal is about-22.017 d Bm,and its average power cost is 0.794 d B;both uplink and downlink transmission eye diagrams are kept open.Therefore,the PDM-WDM-ROF system has a large capacity transmission with wired and wireless integration and low power cost,which is suitable for applications with multiband requirements and simultaneous wired and wireless access.Research on ROF System Based on Optical Frequency Comb and Optical Reuse Technology,the optical frequency comb based on cascaded EAM and PM is selected as the multi-carrier light source of the system,which has the advantages of high flatness,high average power and adjustable frequency interval.The modulation mode of OCS is selected to make the system have better anti-dispersion performance,and the frequency range of the generated optical signal is larger.Optical amplifier,dispersion compensation fiber and other devices are used to reduce the influence of optical fiber on transmission performance.After 40 km SMF transmission,the signal receiving sensitivity is maintained,and the eye diagram remains open and clear.The research of the system effectively solves the problems of high cost,poor scalability and reconfigurability of the laser array used in the traditional system,generating a single electrical signal and adjustable,transmitting a single service per base station,and inflexible user access methods.