正交频分复用分组传输系统中载波频偏和信道的联合估计  

Combined Carrier Frequency Offset and Channel Estimation for Orthogonal Frequency Division Multiplexing Packet Transmission Systems

作　　者：王绍鹏[1] 朱世华[1] 张国梅[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《西安交通大学学报》2008年第6期739-742,共4页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(60372055)

摘　　要：针对传统接收机将载波频偏和信道状态独立估计带来性能损失的缺点,提出了一种载波频偏和信道的联合估计算法.该算法由两个独立的载波频偏和信道估计单元通过迭代的方法实现,其中信道估计单元利用载波频偏估计单元提供的载波频偏估计信息和最大似然方法估计信道状态信息,而载波频偏估计单元则利用信道估计单元提供的信道估计信息和最大似然方法估计载波频偏.随着载波频偏估计单元与信道估计单元间估计信息的不断交换,载波频偏和信道估计的精度得到逐步提高.由于该算法避免了复杂的多维搜索算法,因此具有较低的计算复杂度.此外,在算法迭代过程中考虑了信道估计噪声的影响,进一步提高了估计的精度.仿真结果表明,当符号能量噪声比大于18 dB时,可以获得接近理想同步的误码性能.To reduce the degradation caused by the methods that estimate the carrier frequency offset （CFO） and channel state information （CSI） respectively in the traditional orthogonal frequency division multiplexing （OFDM） receiver, a combined estimation of CFO and CSI for OFDM packet transmission systems is proposed. Two estimators that estimate the CFO and CSI by iteration are used in the method. The CSI estimation is obtained by the maximum likelihood estimation （MLE） method with the CFO estimation value provided by the CFO estimate unit, and the CFO is obtained by MLE method with the CSI estimation value provided by the CSI estimate unit. With the estimation information exchanged between the CFO estimation unit and the CSI estimation unit, the accuracy of the estimation is gradually improved. Since the multidimensional searching algorithm is avoided, the complexity of the proposed method is reduced. Furthermore, the noise impact on the estimated value is considered in the iteration, and hence the performance of the algorithm is improved. The simulation results show that the proposed method can achieve the same bit error rate as the synchronization systems when symbol energy noise ratio is greater than 18 dB.

关 键 词：载波偏移 正交频分复用 信道估计 最大似然估计 

分 类 号：TN911.22[电子电信—通信与信息系统]