OFDM系统载波频率偏移估计

Carrier frequency offset estimation for OFDM systems

正交频分复用技术可广泛应用于未来高速多媒体通信,但它对发射机与接收机本振之间存在的载波频率偏移却非常敏感,从而引入了载波间干扰.因此,在正交频分复用通信系统中,接收信号必须进行频率偏移估计和补偿来减小载波间干扰并维持子载波之间的正交性.给出了加入循环前缀和具有虚拟子载波的正交频分复用系统的数学模型,利用DOA-MATR IX方法,提出了一种新的载波频率偏移估计算法.该算法计算量小,容易获得频率偏移量,同时可得到蕴涵信道信息的矩阵估计,有利于接收信号的频率偏移补偿和解调.

The Orthogonal Frequency Division Multiplexing （OFDM） is broadly considered as an effective approach to future high-speed wireless multimedia communications. But it is very sensitive to carrier frequency offset between the transmitter and the receiver local oscillators, which causes intercarrier interference （ ICI ）. Thus, in OFDM communication sytems, carrier frequency offset must be estimated and compensated at the receiver to minimize the effects of intercarrier interference and maintain orthognnality. In this paper, the mathematical model of OFDM systems with cyclic prefix （CP） and virtual subearrier is derived first. We propose a new carrier frequency offset estimation algorithm using the DOA-MATRIX method. After the rough estimation, it can acquire the frequency offset with low computing complexity, and matrix including channel information simultaneously, which are favorable for offset compensation and demodulation of received signals. Numerical simulations can illustrate the performance of this algorithm.