Research On Adaptive Modulation And Coding Method For High-Speed Long-Distance Transmission Of Millimeter Wave

With the development of communication technology,spectrum resources are increasingly scarce,millimeter wave has abundant spectrum resources and supports higher transmission rates,so it has received extensive attention from scholars.As an important technology of communication,millimeter wave high-speed long-distance adaptive transmission will be affected by Doppler frequency shift under high-speed movement,thereby reducing transmission performance.Therefore,the main research of this thesis is to consider the influence of Doppler frequency shift and other factors on the system on the basis of the traditional adaptive coding modulation method,and optimize the design of the transmitted data frame,which can make the data frame sent by the system change according to the change of channel conditions,thereby reducing the negative impact of Doppler frequency shift and other factors on the communication process,and improving the reliability and transmission performance of the system.Finally,the core module of millimeter-wave high-speed long-distance adaptive transmission baseband system is realized on the hardware platform,and the functional verification is completed.This thesis first introduces the propagation characteristics of millimeter wave,analyzes the Doppler frequency shift caused by high-speed movement on mm Wave signals,and establishes a time-varying channel model of the tap delay line.Then,the introduction of the key technologies of millimeter wave high-speed long-distance adaptive transmission system and the selection of algorithms,including data frame synchronization and channel estimation,are completed,and the relevant performance simulation is carried out.Then,the performance of millimeter wave long-distance adaptive transmission system under fast time-varying channel is studied,and the influence of Doppler shift and noise on system performance is analyzed.Starting from the structure of the transmitted data frame,this thesis proposes a data frame structure suitable for the Doppler frequency shift by adjusting the design of the channel estimation sequence and data block under different channel conditions,and combines it with the traditional adaptive coding modulation method to propose an adaptive coding modulation technology with variable frame structure,and through simulation analysis of its performance,a signal-to-noise ratio threshold lookup table suitable for fast time-varying channels is established,and compared with the traditional adaptive modulation and coding technology,the throughput performance of the system is improved.Finally,this thesis designs the baseband hardware architecture of millimeter-wave high-speed long-distance adaptive transmission system,and implements the core modules such as data frame synchronization,channel estimation,frequency domain equalization,and bitrate-compatible decoder,which verifies the correctness of the functions.In addition,the related modules of the system,the channel estimation module,and the 1024-point Fast Fourier Transform module are improved,and a hardware solution with less resource consumption is proposed and designed.