Research On Downlink Signal Acquisition Algorithm Of Private Network Communication System Similar To 5G

The 5th Generation Mobile Communication system is developed based on the Long Term Evolution(LTE)system.Compared with LTE system,the technical characteristics of 5G mass connection,low delay and high reliability are very suitable for the construction of private network communication.The private network communication system adopts the physical layer technology similar to 5G.The premise for the terminal to establish communication is to correctly complete the capture of the cell initial synchronization signal transmitted by the base station.Through the acquisition of the primary synchronization signal,the terminal can obtain the initial symbol timing position and determine the ID number within the cell group.After the acquisition of primary synchronization signal(PSS),the coarse synchronization of frequency offset,the acquisition of secondary synchronization signal(SSS)and the fine synchronization of frequency offset are also needed.Orthogonal Frequency Division Multiplexing(OFDM)is one of the key technologies in the physical layer of a wireless private network communication system.OFDM system has many advantages,such as high spectrum efficiency,strong ability to resist fading and inter-symbol interference,but it has high requirements for timing synchronization and carrier synchronization.The key of downlink synchronization is the acquisition of PSS and SSS.The success of synchronization signal acquisition determines the success of downlink synchronization.This thesis will study the downlink signal acquisition algorithm of private network communication system similar to 5G.Firstly,this thesis introduces the development process and basic principle of OFDM technology,which is the key technology of downlink in wireless private network communication system similar to 5G,analyzes the impact of timing offset and frequency offset on signal demodulation,and explains the importance of timing synchronization and frequency synchronization on downlink.The time domain configuration and frequency domain mapping of synchronization signal block are introduced,and the generation mode and correlation characteristics of PSS sequence and SSS sequence are analyzed.Secondly,in the PSS synchronization acquisition,based on the study of the traditional cross-correlation algorithm and segmentation algorithm,a joint segmentation cross-correlation algorithm is proposed according to the time domain configuration characteristics of the private network communication system synchronization signal block.Theoretical analysis and simulation results show that the algorithm has better performance of anti-frequency offset and anti-noise.Finally,the principles of coarse frequency offset estimation algorithm,SSS acquisition algorithm and fine frequency offset synchronization algorithm are studied.Coarse frequency offset estimation is carried out through PSS signals,frequency offset compensation is carried out on receiving signals,then SSS acquisition is carried out by using a frequency domain subsection correlation algorithm,and then PSS and SSS are used for fine frequency offset estimation.The simulation results show that the SSS acquisition success rate can be improved by the coarse frequency offset estimation and compensation,and the demodulation requirements of the physical broadcast channel can be basically met after the coarse frequency offset and fine frequency offset estimation and compensation.