Research And Implementation Of High Speed And Low Complexity Parallel Blind Equalization Technology For Wireless Optical Communication

Wireless optical communication can provide high speed transmission rate and has the advantages of abundant spectrum resources,good secrecy and strong anti-interference capability,which has become one of the hot spots in the field of optical communication research.Laser beam transmission in the atmospheric channel is subject to scattering and refraction of atmospheric molecules,resulting in inter-code interference at the receiver side,which reduces the transmission reliability of the communication system and seriously affects the BER performance of the wireless optical communication system.In this paper,we study the channel equalization technique at the receiver end to suppress the inter-code interference and improve the performance of the communication system.The main research of this paper is as follows:1.The thesis investigates the adaptive equalization technique and blind equalization technique,and foucuses on the principle of Constant Modulus Algorithm(CMA).To address the shortcomings of the CMA algorithm with fixed iteration steps and slow convergence,the thesis analyzes the existing improved CMA algorithms: M-CMA algorithm and variable-step CMA algorithm.Then,the thesis combines the original improved CMA algorithm and proposes the variable step size M-CMA algorithm.2.The convergence speed,steady-state residual error and BER performance of different blind equalization algorithms are simulated and verified by Matlab software.The simulation results show that the blind equalization algorithm proposed in this paper outperforms the conventional CMA algorithm and the M-CMA algorithm.3.In this thesis,an FPGA-based blind equalization hardware module is developed,and the corresponding experimental verification is carried out.During the development of the hardware module,the design of parallel filters based on pulsating arrays and the design of low-complexity exponential functions based on Taylor expansions were focused on,enabling the blind equalizer designed in this thesis to meet the requirements of high speed and low complexity.The experimental test results show that the BER of the signal processed by the equalization algorithm of this paper is reduced by two orders of magnitude,which achieves the research objective of this paper and has practical engineering application value.