适用于OFDM-BPSK的载波频偏盲估计算法  

Blind Estimation of Carrier Frequency Offset for OFDM-BPSK Systems

作　　者：赵海龙[1] 马上[2] 张健[1] 周劼[1] 

机构地区：[1]中国工程物理研究院电子工程研究所,四川绵阳621900 [2]电子科技大学通信抗干扰技术国防重点实验室,成都610054

出　　处：《电子科技大学学报》2012年第6期842-846,共5页Journal of University of Electronic Science and Technology of China

基　　金：国家自然科学基金-中国工程物理研究院联合基金(NSAF)(10876103)

摘　　要：提出了两种适合于OFDM-BPSK系统的载波频偏盲估计算法。即通过对两个OFDM符号在时域或频域做互相关运算,利用得到的相位差估计载波频偏和根据OFDM-BPSK符号的共轭对称性估计载波频偏。两种算法均不需要导频符号或训练序列,可以节约带宽资源。仿真结果表明,前一种算法对符号定时不敏感,在高信噪比频率选择性信道下性能要优于基于循环前缀的最大似然(ML)算法。后一种算法对符号定时要求高,在加性白高斯噪声(AWGN)与频率选择性信道下性能均好于基于循环前缀的ML算法,在AWGN信道下,性能趋近于Moose算法。此外,两种算法频偏估计精度都与两个OFDM符号之间间隔的选取有关,间隔选取越大,估计精度越高,但估计范围会相应减小。In this paper, two blind methods are proposed to estimate carrier frequency offset （CFO） for OFT）M-BPSK systems. In the fast method, the CFO estimation is obtained by utilizing phase difference between two OFDM symbols through cross-correlation between them either in time domain or in frequency domain. In the second method, the CFO estimation can be obtained according to the conjugate symmetry properties of OFDM-BPSK symbols. Our novel methods are bandwidth efficient, because they do not need pilot tones or training symbols. Computer simulations are carried out both for these two methods. The first method is not sensitive to symbol timing, and its performance is better than that of maximum likelihood （ML） estimator based on cyclic prefix in a high SNR frequency selective channel. The second method is sensitive to symbol timing, but it has a significantly smaller mean square error （MSE） than the ML estimator both in additive white Gaussian noise （AWGN） and frequency selective channels. Especially, the performance of the second method can approach that of the Moose＇s method in an AWGN channel. Moreover, the CFO estimation precision of the two methods is related to the choices for the space between two OFDM symbols .The larger the OFT）M symbol space is, the more accurate the estimators will be, but the estimation range will decrease accordingly.

关 键 词：盲估计 BPSK 载波频偏 正交频分复用 同步 

分 类 号：TN919.3[电子电信—通信与信息系统]