基于TD-LMS算法的OFDMA上行链路载波频偏补偿

针对OFDMA上行链路的通信系统，各用户存在不同的子载波频偏，导致子载波正交性的破坏，本文提出一种基于最小均方误差(MMSE)的时域自适应算法(TD-LMS)来补偿子载波频偏引起的干扰。该算对OFDMA系统接收端的时域信号进行无偏估计，然后利用估计量来调整频偏值，最后利用TD-LMS算法进行自适应消除。与传统的算法相比，此算法无需获得子载波频偏范围的先验知识。仿真结果表明，该算法对各用户的子载波频偏的估计精度较高，而且补偿的效果更明显。

The TD-LMS Algorithms for Carrier Frequency Offset Compensation in Uplink OFDMA system

In uplink orthogonal frequency division multiple access (OFDMA) system, each user has different carrier frequency offset (CFO), which results in the loss of orthogonality among subcarriers and the interference of the received signals. In this paper, we propose the TD-LMS algorithm to cancel the interference due to the CFO in uplink OFDMA. First, we estimate the CFO of the subcarrier in time domain, and adjust the CFO with the estimator, then adaptively cancel interference with TD-LMS scheme. Simulations are presented to demonstrate that the proposed method is robust to uplink frequency offset cancellation. Compared with the traditional methods, the improvements can be obtained from using the proposed suppression schemes.