2008 年 8 月 Journal on Communications August 2008
第 29 卷第 8 期 通 信 学 报 Vo l .29
No.8
基于导频的 MC-DS-CDMA 系统载波频偏估计
刘立程
1,2
，戴宪华
1
(1. 中山大学 信息科学与技术学院，广东 广州 510275; 2. 广东工业大学 信息工程学院，广东 广州 510006)
摘 要：针对多载波直扩码分多址(MC-DS-CDMA)系统上行链路提出一种基于导频的多用户载波频偏估计算法：
利用频偏向量的低通特性设计了一种新的梳状导频传输方案，从而在接收端的各用户的导频子载波上近似获得单
用户信号，利用相位角平均法对该信号前后相邻两项的商的幅角取平均值，得到了效果较好的多载波频偏估计值；
并进一步采用了傅立叶变换法来进行多载波频偏估计，提高了算法的抗干扰性能。仿真实验结果表明：相位角平
均法在用户数较少(<3)和信噪比较高 (>15dB)时的频偏估计误差均值能达到 1%以下；而傅立叶变换法在多用户情
形和较低信噪比(<5dB)下对较大归一化频偏范围(−0.5,0.5)内的频偏估计误差均值仍能保持在 0.1%。提出的算法适
合于在频率选择性衰落的慢变信道中对细频偏进行估计。
关键词：OFDM；载波频偏估计；导频；MC-DS-CDMA
中图分类号：TN929.5 文献标识码：A 文章编号：1000-436X(2008)08-0030-08
Pilot-based carrier frequency offset estimation in
MC-DS-CDMA system
LIU Li-cheng
1,2
, DAI Xian-hua
1
(1. School of Information Science & Tech., Sun Yat-sen Univ., Guangzhou 510275,China;
2. School of Information Engineering, Guangdong Univ. of Tech., Guangzhou 510006,China)
Abstract: A pilot-based multiple carrier frequency offset (CFO) estimation algorithm was proposed for the uplink of
multicarrier DS-CDMA (MC-DS-CDMA) system. By exploiting the low-pass property of the CFO vector, a novel comb
pilot transmission scheme was designed to approximately acquire the single user signals on the pilot subcarriers at the re-
ceiver end. With the phase-angle averaging method to deal with the phase-angle of the quotient of two neighboring sam-
ple signals on the pilot subcarriers, the good result of the multiple CFO estimation was achieved. Further, the discrete
Fourier transform (DFT) was employed and consequently improved the algorithm’s robustness to the interference. The
simulation results show that with small number of users (<3) and high signal to noise ratio (SNR) (>15dB), the
phase-angle averaging method may obtain the mean of CFO estimation error below 1%; while under the conditions of
multiple users and low SNR(<5dB), the DFT method can still reach the mean of CFO estimation error equal to 0.1% for
the normalized CFO scale (−0.5,0.5). The proposed algorithm is applicable for the fine CFO estimation through the fre-
quency selective fading slow time-vary channels.
Key words: OFDM; carrier frequency offset estimation; pilot; MC-DS-CDMA
收稿日期：2007-03-21；修回日期：2008-07-22
基金项目：国家自然科学基金资助项目（60772132）；广东省科技计划基金资助项目（207-B010200055）；广东省教育部产学
研基金资助项目（2007A090302116）
Foundation Items: The National Natural Science Foundation of China (60772132); The Science & Technology Project of Guang-
dong Province (2007-B010200055); The Industry Research Project of Guangdong Province (2007A090302116)
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