Reasearch And Application Of The Microwave Photonic Radio Frequency Fronthaul Technology For The B5G Mobile Communication

Under the 5G andBeyond 5G(B5G)mobile communication archetecture,the promotion of 4k,AR,VR based on 5G andB5 G is largely depending on large-capacity and multifunctional fronthaul.On one hand,traditional low spectral efficiency digital fronthaul technology is hard to meet the capacity requirement.So the analog radio over fiber(RoF)fronthaul technology stands out for the advantage of capacity.On the other hand,microwave photonic system boasts some advantages like super large bandwidth,immune to the electromaganetic interference and flexible configuration.These advantages enable the realizing of multifunction,including 5G millimeter-wave communications.Therefore,combination of the microwave photonic system and the RoF system is supposed to further the development of multifunction and large capacity fronthaul.However,there are some shortcomings such as instability,single-function,and large size of traditional microwave photonic system,which limit the commercial use of the system.It is the shortcut of expanding fiber fronthaul system function and realizing large-capacity fronthaul to address the above shortcomings and combine the photonic system with the RoF link.The thesis starts from the basic theory of RoF and the basic components of microwave photonic system.Then the thesis makes further researches on the performance optimization and the usages in analog RoF of the microwave photonic system.Research contents are as in following points:(1)Research on the nonlinear and noise characteristics of the analog RoF system.Based on commercial device parameters,several parameter models of cascaded RoF system are built,including spurious free dynamic range(SFDR)and noise floor.The most frequently used devices in microwave photonic system is researched,i.e.MZM.The researches include the operating principle of MZM,and the bias point control theory of single drive MZM(SD-MZM).The pros and cons of traditional methods are analyzed.Moreover,we propose a novel bias control method based on pilot injection and correlation detection.(2)Research on the operating principle of optical IQ modulator.A novel optical IQ modulator bias control method based on pilot injection correlation detection is proposed.The algorithm of linear bias point and arbitrary bias point control are designed,and a bias control module is designed too.Experiment results show that the accuracy of the control module is ±0.2° and the proposed linear bias point and arbitrary bias point tracking algorithms are effective to resist wild temperature fluctuations.The modulation and transmission of a large bandwidth analog OFDM signal is implemented and a millimeter wave carrier of 29.9GHz is generated by using the proposed control module.The application of optical IQ modulator in the fiber security communication is also discussed based on the research of the modulator and the bias control technique.(3)Study the optical method for full duplex antenna self-interference cancellation(SIC).Two typical optical SIC methods are analyzed,one is pure optical SIC method based on SD-MZMs,the other one is a photo-electric-hybrid SIC method based on dual drive MZM(DD-MZM).A novel optical IQ modulator SIC method based on optimized bias point is proposed and proved.Experiement results show that we realize 35 dB cancellation ratio for the 200 MHz F-OFDM self interference by using this method.The digital domain compensating algorism for the mentioned SIC system is researched.An RLS equalization algorism for compensating the multi-path distortion and an RLS-Volterra equalization algorism for compensating non-linear and multi-path distortion are designed.The experiement results show that this algorism can effectively compensate multi-pass effect and non-linear effect and can produce 42 dB cancellation ratio for the 200MHz-F-OFDM.(4)Based on a DP-IQMZM,a full duplex microwave photonic radio frequency transceiving frontend is realized.The functions of SIC,OEO,microwave photonic mixing,and single side band signal generaton are integrated in this frontend.Bias point and structural optimization are applied to the frontend.An IFo F transmission experiment platform is designed.High stability and low phase noise,LO carrier is generated in the experiment.30.3dB cancellation ratio is realized to 150 MHz self-interference signals respectively by using the platform.Morover,the up-convertion for the input LTE-A signal is realized with the SNR of 31.3dB.