| 摘要: |
| 基于COSTAS环的载波同步环路在对较大相位差的正交方波远距离无线电(Long Range Radio,LoRa)信号进行载波同步时，入锁时间长甚至出现失锁现象。针对这一问题，首先分析了正交方波LoRa物理层原理，指出其本质为具有前导码的正交相移键控信号(Quadrature Phase Shift Keying,QPSK)；然后利用正交方波LoRa的前导码结合同步环路设计了改进算法。仿真结果显示，改进算法适用于有前导码的QPSK信号，相比于传统算法，在相位差大于45°时仍能保持良好的工作性能,在信噪比低于20 dB时具有更小的频率误差。 |
| 关键词: LoRa 载波同步 前导码 正交解调 |
| DOI：10.20079/j.issn.1001-893x.230918003 |
|
| 基金项目:国家自然科学基金资助项目（62090015，62293494） |
|
| Carrier Synchronization of Quadrature Square Wave LoRa：Analysis and Solutions |
| XU Rui,SU Ming,YAN Chuming,LIU Yuanan |
| (Wireless Communication & EMC Laboratory,Beijing University of Posts and Telecommunications,Beijing 100876,China) |
| Abstract: |
| When the feedback structure based on COSTAS loop is used in carrier synchronization of the quadrature square wave long range radio(LoRa) signal with large phase offset,the locking time is so long and even the lock-out phenomenon occurs.To resolve this problem,firstly,the physical layer theory of LoRa is analyzed and its essence is quadrature phase shift keying(QPSK) with preamble codes.Then an improved algorithm is designed based on the preamble code of quadrature square wave LoRa and the feedback structure.Simulation results show that the improved algorithm is suitable for QPSK signals with preamble codes.Compared with the traditional COSTAS loop,the improved algorithm can still maintain good performance when the phase offset is greater than 45°,and has a smaller frequency error when the signal-to-noise ratio is less than 20 dB. |
| Key words: LoRa carrier synchronization preamble code quadrature demodulation |
