5G NR下行链路信号同步算法研究

Research on synchronization algorithm of 5G NR downlink signal

针对5G移动通信物理层调制质量测试需求,研究了适用于信号分析仪的5G NR下行链路信号两种同步方法。第1种同步方法为是基于同步广播块的同步方法,该方法通过对同步广播块进行主同步信号、辅同步信号搜索实现同步广播块时频位置确定,然后利用同步广播块解调参考信号通过对半帧号及同步广播块索引参数进行盲检实现该同步广播块帧内序号的确定。基于同步广播块时频位置及其在帧内序号便可以实现帧起始位置的确定。第2种同步方法为利用数据信道循环前缀的同步方法,其首先利用循环前缀实现半子帧起始位置确定,然后通过盲检数据信道解调参考信号参数实现OFDM符号索引及时隙号确定。基于半子帧起始位置、OFDM符号索引及时隙号同样实现了帧起始位置的确定。最后经过采集数据验证了所提算法可有效实现5G NR下行链路信号的同步。

For the demand of 5G mobile communication physical layer modulation quality test,two synchronization methods for 5G NR downlink signals which are suit for signal analyzer are studied.The first method is based on SS/PBCH block.In this method,the time-frequency location of the SS/PBCH block is determined by searching the primary synchronization signal and the secondary synchronization signal in SS/PBCH block.Then,the number of the synchronous broadcast block in a frame is determined by blind detecting the half frame number and the number of the synchronous broadcasting block in a transmit period which are the parameters of demodulation reference signal in SS/PBCH block.The start point of the frame can be determined based on the time-frequency position of SS/PBCH block and its number in this frame.The second synchronization method is based on cyclic prefix of the PDSCH,which uses cyclic prefix to determine the start point of half subframe.Then,the half subframe number,OFDM symbol number and slot number are determined by blind detection of demodulation reference signal in PDSCH.Based on the half subframe start point,OFDM symbol number and slot number,the start point of the frame can be also determined.Finally,the experiment results based on sampled data show that the proposed algorithm in this paper can effectively realize the synchronization of 5G NR downlink signals.