| In order to satisfy the strong demands of global market for the performance of mobile communication systems,3GPP initiated the research of the fifth-generation mobile communication system.5G technology which aims to achieve ultra-high wireless transmission rate,ultra-low transmission delay and ultra-high reliability,is widely used in emerging business scenarios such as virtual reality,unmanned driving and Internet of things.At present,the technical specification of radio access network of 5G has been accomplished,and the network architecture and the key technologies have become one of the most hot pots of the communication industry.As an important node in the physical layer of mobile communication system,the synchronization process of cell search and downlink is the key to realize the high performance of 5G wireless access technology.The necessary step in the cell search process is to detect the synchronization signal.Only when the terminal device detects the time-frequency position of the synchronization signal and realizes downlink synchronization can it demodulate the receiving signal and obtain the messages of system and data to establish continuous communication.the physical layer signal processing of 5G is more complex than ever before and 5G occupy higher frequencies.unlike the LTE system,the downlink synchronization signal of 5G NR are bundled together to form SS/PBCH block,SS/PBCH pieces of complicated structure,and sequence length is longer,make sync signal detection complexity increased exponentially,and the hardware implementation is more difficult.However the existing neighborhood search and down link synchronization scheme can’t meet the demand of 5G down link detection,high frequency partial will seriously affect the down link sync signal detection performance,so the need for a lot of research on high frequency partial robustness,and low implementation complexity and high detection performance design,in this paper,the neighborhood search and downlink synchronization scheme is proposed to improve the synchronous signal detection algorithm and reduce the detection complexity implementation scheme,which has very high reference value.In this paper,the synchronization performance of NR was studied based on the primary and secondary synchronization signals of LTE,and the low detection complexity and good anti-frequency deviation performance of NR synchronization signals were verified.At the same time,the structural characteristics of SS/PBCH were studied and its performance was analyzed and verified.In the study of NR cell search and downlink synchronization,in order to improve the overall system performance,a sliding differential correlation algorithm based on the traditional algorithm with high anti-frequency offset performance was proposed to de-tect the main synchronization signal and a blind detection algorithm for the auxiliary synchronization signal,and then the downlink synchronization process was deeply analyzed.Finally,the performance of the traditional algorithm and the improved algorithm is compared and analyzed by MATLAB software,which is equipped with the simulation platform of cell search and downlink synchronization,and the effectiveness of the improved algorithm is verified. |
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