Research On Optical Communication Technology For 5G/B5G Base Station Backhaul Link

The backhaul of 5G/B5 G base station includes ground link and satellite ground link,which is one of the development directions of the next generation ultra wideband earth earth integrated communication system.After the laser signal is disturbed by the atmospheric turbulence,it will cause the spot disturbance at the receiver,signal attenuation and distortion.At the same time,domestic optoelectronic devices with low analog bandwidth will also cause significant channel distortion.Therefore,it is necessary to study adaptive equalization technology to correct symbol distortion and channel encoding and decoding technology to correct communication burst errors.Aiming at the backhaul link scenario of 5G/B5 G base station,this thesis studies the atmospheric turbulence channel model,adaptive equalization algorithm and multi band LDPC decoding algorithm.The main innovations and work contents are as follows:Firstly,according to the requirements of 5G/B5 G backhaul link,this thesis proposes an atmospheric optical channel model that conforms to the light intensity scintillation characteristics of 5G/B5 G backhaul link,simulates a variety of typical atmospheric turbulence channels,and establishes a suitable fading simulation channel for optical communication,which provides a channel basis for the research of digital signal processing algorithms in the 5G/B5 G base station backhaul link.Secondly,in view of the urgent demand for localization of laser communication equipment and breaking through the simulation bandwidth limitation of domestic optoelectronic simulators,this thesis explores the adaptability of LMS,VSSLMS and MVSSLMS equalization algorithms for PAM system to atmospheric turbulence optical channels,effectively improving the user’s available information rate,and conducts simulation and analysis in three typical 5G/B5 G backhaul scenarios to verify the feasibility of the algorithm in the 5G/B5 G backhaul link.Finally,based on the 5G/B5 G backhaul link decoding requirements,this thesis proposes a disordered decoding algorithm to overcome the disadvantage of using too much resources of the m-ary LDPC flood decoding algorithm.At the same time,aiming at the limitation of mutual restriction between the throughput and storage resources of the update bubble detection algorithm of the m-ary LDPC check node,this thesis proposes a FIFO based check node update method,which is implemented through MATLAB simulation and FPGA of the m-ary LDPC decoder,The feasibility and reliability of out of order decoding algorithm and FIFO architecture check node update method proposed in this thesis are verified.