5G Downlink Synchronization Technology Research And SDR Verification

The fifth-generation mobile communication system(5G)downlink waveforms follow the Long Term Evolution(LTE)plan,using Orthogonal Frequency Division Multiplexing(OFDM)technology.The synchronization signal,frame structure,channel coding,and application scenarios of the 5G system are different from those of LTE.In scenarios where there is a Doppler frequency offset in high-speed railways and satellite communications,the performance of traditional time-frequency synchronization algorithms is greatly challenged.When traditional channel estimation algorithms are applied to 5G communication system channel estimation,they also have poor anti-noise performance and low estimation accuracy.The research on time-frequency synchronization and channel estimation for 5G systems is of great significance.This paper improves the traditional algorithm based on the 5G frame structure and application scenarios,and improves the robustness of the system in 5G application scenarios.Finally,this paper builds a test platform system based on YunSDR hardware to verify the actual performance of the algorithm proposed in this paper.The specific content is as follows:(1)This article first introduces the OFDM system to illustrate the impact of time-frequency synchronization deviation on the system.Introduce the 5G frame structure and system parameters in detail.Among them,the synchronization signal block(SSB)is an important frame structure of the 5G downlink communication link.This article introduces its time-frequency structure,components and application scenarios in detail.(2)Time-frequency synchronization and signal detection are important modules in cell search applications.The 5G system has a wide range of application scenarios.In scenarios where there is a Doppler frequency offset in high-speed railways,satellite communications,etc.,an improved algorithm is proposed to improve the anti-frequency offset performance of the traditional timing synchronization algorithm for the problem of poor anti-frequency offset performance;Aiming at the problem of low estimation accuracy of classic frequency offset estimation algorithms,a frequency offset estimation algorithm is proposed based on the 5G frame structure to improve the estimation accuracy of the algorithm.(3)This chapter first introduces the sending and receiving process of Physical Broadcast Channel(PBCH).The 5G system has a wide range of application scenarios and complex channel conditions.To solve the problems of poor anti-noise performance and low estimation accuracy when the traditional LS algorithm is applied to 5G communication system channel estimation,a threshold noise reduction LS algorithm is proposed to improve the channel Estimated estimation accuracy.The simulation results show that the algorithm in this paper improves the channel estimation effect in a low signal-to-noise ratio environment.(4)Under the condition that the theory is feasible,this article uses Matlab and YunSDR to build a 5G downlink test platform.Briefly introduce SDR platform and YunSDR equipment software and hardware architecture,and carry out system configuration.This platform is used to test the receiving and sending of 5G signals.During the receiving process,the timing synchronization,frequency offset estimation and channel estimation algorithms proposed in this paper are used.Combined with simulation,it can be seen that the algorithm in this paper can still achieve better results in actual scenarios.