一种无需导频的适用于差分OFDM系统的符号与采样钟联合同步方法
A Combined Symbol and Sampling Clock Synchronization Method Applied for Differentially Modulated OFDM Systems without Pilot Carriers
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摘要: 该文提出了一种适用于OFDM系统的联合符号和采样钟同步校正方法，其中同步校正是在数字域通过改变对接收过采样信号的插值(interpolation)和抽取(decimation)实现的。这种方法在发送端相邻载波间采用差分QPSK调制，在接收端利用QPSK的差分解调信号获得同步误差信号，从而获得关于OFDM符号同步和采样钟同步调整的算法，其特点是无需专门的同步导频信号。所提出算法的同步性能在高斯白噪声信道和多径衰落信道均得到验证。Abstract: This paper presents a combined symbol and sampling clock synchronization method for OFDM systems. Especially, the timing correction is obtained by interpolation or decimation over sampled signal. This method utilizes the differentially modulated subcarriers in transmitter to obtain the synchronization error signal. The error signal is smoothed by loop filter, then it is used to change the control register of interpolator and decimator: The proposed algorithm can track the frequency shift of sampling clock. The algorithm is simulated in both AWGN and multipath fading channel. Simulation results show that the proposed algorithm is very effective on recovering timing errors of OFDM systems.
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