一种残余频偏算法在OFDM同步跟踪中的应用

Application of Residual Frequency Offset Algorithm in OFDM Synchronization Tracking System

在正交频分复用(OFDM)系统中,定时误差、多普勒效应以及本地振荡器不稳定等因素都会引起估计频率产生偏移,致使子载波星座相位发生旋转,并随着时间而不断累积,最终导致解调失效。为此,提出了用均方误差短时反馈算法来矫正旋转相位的新方法。该方法利用在反馈时间段内计算得出的残余相偏来直接矫正后续接收数据的相位。仿真结果表明,该算法很好地满足实时跟踪的要求,具有运算简单、速度快等特点,同时也提高了系统的性能。

In OFDM systems, the factors such as timing errors, the Doppler effects and the instability of local oscillator can cause estimated offset for the carrier frequency. And with the accumulation of received data, the phase of sub -carrier＇s constellation rotates and the system is failed to demodulate. Therefore, a new algorithm based on the mean square error （MSE）and the short feedback is proposed to correct rotated phase. Residual phase offset calculated during the feedback time is directly used to correct the phase of following received data in this method. The simulation shows that this algorithm is feasible and can satisfy the demand of real time tracking, and its realization is simple. Furthermore, the system performance is also improved.