面向LoRa的联合同步及频偏估计算法  

JOINT SYNCHRONIZATION AND FREQUENCY OFFSET ESTIMATION FOR LORA

作　　者：罗伟铭 唐述 罗雷 Luo Weiming;Tang Shu;Luo Lei(Chongqing University-University of Cincinnati Joint Co-op Institute,Chongqing University,Chongqing 400030,China;College of Computer Science and Technology,Chongqing University of Posts and Telecommunications,Chongqing 400065,China)

机构地区：[1]重庆大学重庆大学-辛辛那提大学联合学院,重庆400030 [2]重庆邮电大学计算机科学与技术学院,重庆400065

出　　处：《计算机应用与软件》2021年第11期109-113,共5页Computer Applications and Software

基　　金：国家自然科学基金项目(61501074);重庆市技术创新与应用发展专项(cstc2019jscx-msxmX0080)。

摘　　要：LoRa是一种用于广域物联网应用的低功耗通信技术,具有远距离、超低功耗等特点。LoRa采用基于Chirp(线性调频)信号的扩频调制技术,通过对Chirp信号进行循环移位得到调制信号,其传输信息由符号起始位置的初始频率偏移所承载。其通信性能极易受定时偏差和频率偏差的影响。提出一种针对LoRa技术的联合同步及频偏估计算法,根据LoRa循环移位的特点,通过推导时偏和频偏的数学模型,联立方程组求解得到精确的估计值,用于准确纠正LoRa技术中的定时偏差及频率偏差。仿真结果验证了该算法对同步和频偏估计的准确性,能够满足实际场景下的通信需求。LoRa is one of the low power wide area network(LPWAN) technology for large area Internet-of-Things(IoT) applications, which has the features of long range, ultra-low power consumption, and so on. LoRa utilizes the chirp spread spectrum modulation technology, and the essence is to circular shift the chirp signal to obtain the modulated signal. The LoRa modulation is very sensitive to timing and frequency offset. This paper proposes a joint synchronization and frequency offset estimation algorithm. Based on the characteristics of the cycling shift of LoRa’s modulation, combining the time synchronization and frequency offset estimation problem as a unified one, and derivating the mathematical model of time and frequency shift, then the exact estimated value that would be used to precisely correct the timing and frequency offset for LoRa was obtained by solving the simultaneous equations. The simulation results show the accuracy of the proposed method.

关 键 词：物联网 低功率广域网 LoRa 线性调频 同步 频偏 

分 类 号：TP3[自动化与计算机技术—计算机科学与技术] TN929.5[电子电信—通信与信息系统]