一种两步频率捕获和跟踪的载波频率恢复方案  

A carrier frequency recovery scheme using two-step frequency acquisition and tracking

作　　者：梅容芳[1] 简鑫[2] 蔡百川[1] MEI Rongfang;JIAN Xin;CAI Baichuan(School of Automotive Studies&Rail Transportation,Yibin Vocational and Technical College,Yibin Sichuan 644000,China;College of Microelectronics and Communication Engineering,Chongqing University,Chongqing 400044,China)

机构地区：[1]宜宾职业技术学院汽车与轨道交通学院,四川宜宾644000 [2]重庆大学微电子与通信工程学院,重庆400044

出　　处：《太赫兹科学与电子信息学报》2021年第3期405-411,共7页Journal of Terahertz Science and Electronic Information Technology

基　　金：国家自然科学基金面上项目资助(61771080);四川省科技厅科研项目资助(2019zyd045)。

摘　　要：针对正交频分复用(OFDM)系统中的载波频率恢复,本文提出了一种两步频率快速捕获和精确跟踪的恢复方案。首先基于半解析方法分析了频率偏移量对接收机性能的影响,然后基于最大似然估计器提出了频率偏移量的估计算法。最后,对于粗略频率捕获,方案利用单个同步序列的已知符号作为数据辅助捕获,一旦捕获结束,电路切换到判决导向跟踪模式来执行精细的频率跟踪,从而实现可靠的数据解调;对捕获算法在锁定频率范围的扩大和正确锁定性能方面进行了评价,同时在稳态频率误差的偏差和方差方面对跟踪性能进行了评价。最后给出了频率控制回路设计的基本原则和在捕获以及跟踪模式下回路参数的选择准则,并通过仿真验证了所提出的频率恢复系统的性能。A two-step frequency fast acquisition and accurate tracking recovery scheme is proposed aiming at carrier frequency recovery in Orthogonal Frequency Division Multiplexing(OFDM)system.Firstly,the influence of frequency offset on receiver performance is analyzed based on semi-analytical method,and then the estimation algorithm of frequency offset based on maximum likelihood estimator is proposed.Finally,for coarse frequency acquisition,the scheme uses the known symbols of a single synchronization sequence as the data-aided acquisition.Once the acquisition is over,the circuit switches to a decision-directed mode to perform fine frequency tracking,so as to achieve reliable data demodulation.The performance of the acquisition algorithm is evaluated in terms of the expansion of the lock-in frequency range and the correct locking performance,while the tracking performance is evaluated in terms of bias and variance of the steady-state frequency error.Finally,the basic principles of frequency control loop design and the selective criteria of loop parameters in acquisition and tracking mode are provided,and the performance of the proposed frequency recovery system is verified by simulation.

关 键 词：正交频分复用 多载波调制 频率偏移 估计误差 误码率 失锁概率 

分 类 号：TN927.23[电子电信—通信与信息系统]