Research And Implementation Of Cell Search And Intra-Frequency Detection Algorithm In 5G NR

Nowadays,entering the era of 5G NR means higher rates,larger capacity and better user experience.On December 21,2017,at the 3GPP TSG RAN plenary meeting in Lisbon,the first 5G NR standard specification was successfully determined,marking the beginning of a new era of 5G in the global communication industry.In the physical layer of 5G NR system,the key to improve system performance are efficient cell search and intra-frequency detection algorithms.The main research contents of this thesis are as follows:(1)The 5G NR cell search and downlink synchronization processes are studied,including the overall cell search process,the primary synchronization signal PSS detection,frequency offset estimation and compensation and the secondary synchronization signal SSS detection.The primary synchronization signal PSS detection algorithm includes three types: direct cross-correlation detection,M-segment cross-correlation detection and improved PSS detection.Its basic principle is using the good auto-correlation and cross-correlation of m-sequence to transform time-domain signal of PSS into frequency-domain signal by FFT and then the correlate signal is segmented.The final PSS synchronization position is determined by setting the PMR threshold.Then this thesis introduces the frequency offset estimation and compensation algorithm.It includes fractional frequency offset estimation and integer frequency offset estimation.Next is the study of the secondary synchronization signal SSS detection algorithm.When the channel environment is bad,the traditional SSS detection algorithm will fail.The improved algorithm proposed in this thesis is to transform the SSS time-domain signal into frequency-domain signal by FFT and then correlate.The final SSS synchronization position is determined by setting the PMR threshold.(2)Based on the intra-frequency single beam detection algorithm,an improved algorithm,that is,intra-frequency multi-beam detection algorithm is proposed.It can not only detect multiple SSB beam of each intra-frequency cell,but also ensure its intra-frequency capability.(3)The downlink cell search and intra-frequency detection link are setting up for simulation by Matlab.The simulation results show that improved algorithm has good performance,which can greatly improve the efficiency and satisfy the demands of larger users.