正交频分复用系统中采用离散导频的频偏估计方法

针对采用正交频分复用(OFDM)调制的欧洲数字电视地面广播系统，提出了采用离散导频的载波频偏估计方法。将接收信号中的离散导频与接收机本地生成的离散导频进行相关运算，由相关峰值的偏移量求得整数倍载波频偏，由相关峰值的相位求得每个符号的绝对相位偏转量，再由相邻两个符号的绝对相位偏转量之差求得单个符号时间间隔内的相位偏转，从而得到小数倍载波频偏。仿真结果表明，与传统的采用连续导频的载波频偏估计方法相比，在高斯白噪声信道和慢衰落信道下，采用离散导频的载波频偏估计方法的性能有明显的提高；在快衰落信道中性能则稍差，但仍然保持在系统性能允许的误差范围之内。将离散导频用于载波频偏估计可以提高系统的频谱利用率。

A Novel Method of Frequency-Offset Estimation Using Scattered Pilots for OFDM System

This paper proposed a carrier frequency offset estimation method using scattered pilots for terrestrial digital video broadcasting (DVB-T) systems. Correlating the scattered pilots in received signals with the reproduced version in the receiver, the integer carrier frequency offset is estimated by the position offset of the correlation peak value. By the phase of the peak value, the absolute phase rotation of every symbol is obtained. Using the absolute phase difference between two consecutive symbols, the phase rotation in one symbol interval is acquired. The fractional carrier frequency offset is estimated by dividing the phase difference into the time interval. The simulation results show that, compared with the traditional continual pilots based method, in both AWGN and slow fading channels, the scattered pilots based method has a better performance. Although the latter has a slight worse performance in fast fading channel, the estimator error still remains in the allowed range for the system performance. Using the scattered pilots to estimate frequency-offset will increase the efficiency of spectrum.