MU-MIMO-OFDM上行中基于部分频偏预补偿的频偏同步

在MU-MIMO-OFDM上行链路中,载波频偏的估计和补偿均需要信道信息,而利用频域导频信号估计频偏和信道会受到子载波间干扰ICI)的影响.本文提出了一种部分频偏预补偿机制,可以使得快速傅里叶变换(FFT)之后接收信号中的ICI功率最小,从而在不改变频偏和信道估计算法的前提下提高估计精确度.为了求解预补偿频率,文中首先对信号中的ICI建模,接着通过最优化问题明确ICI功率与预补偿频率间的关系,最后得到了近似最优解的闭合表达式.通过仿真验证,使用了部分频偏预补偿机制之后,频偏与信道估计的误差将明显降低.

Carrier frequency synchronization based on pre-compensation of partial frequency offset in MU-MIMO-OFDM uplink

In MU-MIMO-OFDM(Multiple-User Multiple-Input-Multiple-Output-Orthogonal Frequency Division Multiplexing) uplink,the Carrier Frequency Offset(CFO) estimation and compensation need channel estimation results,and the estimations using pilots in frequency domain always suffer from Inter-Carrier Interference(ICI).A partial CFO compensation mechanism is proposed in this paper,which compensates part of CFO of a certain frequency before Fast Fourier Transform(FFT) at each receiving antenna.ICI power in the receiving signal is minimized,needing not to change the algorithms of CFO and channel estimations.In order to decide the frequency of the pre-compensated CFO,the relationship between ICI power and the pre-compensated frequency is analyzed first,and then an optimization problem is built,of which the close-form approximate optimal solution is given.At last,the improvements of the estimation with the partial CFO pre-compensation are verified by simulations.