PN序列分布的空子载波OFDM频偏估计算法研究  

Approach to frequency offset estimation of OFDM based on PN sequences distributed null subcarriers

作　　者：李琦[1] 李宏伟[1] 蔡斌[1] 张建忠[2] 耿耿[3] 吕燕[4] 

机构地区：[1]空军工程大学信息与导航学院 [2]中国人民解放军94159部队52分队 [3]空军装备研究院通信所 [4]中国人民解放军94032部队

出　　处：《信号处理》2013年第1期60-67,共8页Journal of Signal Processing

基　　金：国家自然科学基金项目(No.61172169);航空基金(No.20112096016)资助课题

摘　　要：频偏同步是正交频分复用系统中的一项关键技术。论文提出了一种通过计算PN序列分布的空子载波功率值进行频偏估计的方法,克服了在传统空子载波法中,受信道频域响应的零点影响所导致的频偏估计错误。该方法利用了PN序列良好的相关性,整数倍频偏部分采取子载波位置序列互相关计算,小数倍频偏采用最陡下降法迭代计算。所计算的代价函数不会产生多个最小值,同时不会在全频域内搜索,大幅降低了运算量。仿真实验表明:与基于循环前缀的最大似然估计相比,提高了同步精度和频偏估计范围,验证了所提方法的有效性。Frequency offset synchronization is one of key apartment of orthogonal frequency division multiplexing technology. This paper analyzed the relationship between single channel frequency response zeros and null-subcarriers. A novel frequency offset estimation algorithm was proposed. It is based on null subcarriers distributed as Pseudo Noise （ PN ） sequences and overcomes the error induced by channel frequency response zeros in traditional null-subcarriers methods. This method makes great use of good correlation properties of PN sequences. Integer offset estimation is achieved by subcarriers position sequence cross-correlation calculation; meanwhile fraction offset estimation computation implemented by iterative steepest descent algorithm. Cost function calculated by this method will not produce more than the minimum, not the whole frequency domain search, dramatically reducing the amount of computation. According to the simulation results, this method improved estimation accuracy and estimation scope compared with maximum likelihood estimation algorithms based on cycle prefix, to verify its validity.

关 键 词：正交频分复用 空子载波 频偏同步 伪随机序列 最陡下降法 

分 类 号：TN911.3[电子电信—通信与信息系统]