一种适用于QAM信号的数字载波估计算法  

A novel carrier frequency estimating algorithm for QAM signals

作　　者：邵怀宗[1] 黄巍 周莹[1] 杨帆[1] 

机构地区：[1]电子科技大学通信与信息工程学院,四川成都611731 [2]总装备部重庆军事代表局驻成都地区军事代表室,四川成都610036

出　　处：《电波科学学报》2010年第5期888-892,共5页Chinese Journal of Radio Science

摘　　要：由于发射和接收机振荡器的不稳定或/和信道的多普勒效应,使载波同步与补偿成为QAM信号接收的关键环节。针对非协作通信中各类载波同步算法只能校正较小的频率偏移的局限,根据QAM信号的基本特点,利用传输符号的统计独立特性,提出了一种新的数字载波频率估计方法。该算法采用开环方式,不需要导频数据,可以估计较大的频率偏移;没有反馈环路,复杂度低,实现起来比较简单。同时,该算法作适当改进,可以直接用于载波的估计。计算机仿真结果表明:该算法可以较好地对各种QAM信号中存在的较大频率偏移进行估计并做补偿;适当改进后可以直接用于估计载波频率,估计效果良好有效。Carrier frequency recovery and compensation are of the key factors in digital QAM receivers due to transceiver oscillator instabilitiy and/or channel Doppler effects. There are some carrier estimation algorithms for the non-cooperative communication environment, but they are all adopted when carrier frequency offset is small comparing with the symbol rate. In this paper, a carrier estimation algorithm has been proposed, which is non-data-aided and can be implemented in digital form. Because of its open-loop structure, the proposed algorithm is very simple and easy to be implemented. Using the property of the transmitted symbols, its estimation time is independent of the frequency and the estimation range is large, on the order of the symbol rate. The proposed estimator can be improved to adap the estimation of the carrier frequency directly. The simulation results show that the proposed algorithm can estimate the carrier frequency offset, while the a- mending algorithm can also be used to estimate the carrier frequency directly, and the performance is very good for all QAM signals.

关 键 词：QAM信号 载波估计和补偿 开环结构 

分 类 号：TN911[电子电信—通信与信息系统]