一種無(wú)需導(dǎo)頻的適用于差分OFDM系統(tǒng)的符號(hào)與采樣鐘聯(lián)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: 該文提出了一種適用于OFDM系統(tǒng)的聯(lián)合符號(hào)和采樣鐘同步校正方法，其中同步校正是在數(shù)字域通過改變對(duì)接收過采樣信號(hào)的插值(interpolation)和抽取(decimation)實(shí)現(xiàn)的。這種方法在發(fā)送端相鄰載波間采用差分QPSK調(diào)制，在接收端利用QPSK的差分解調(diào)信號(hào)獲得同步誤差信號(hào)，從而獲得關(guān)于OFDM符號(hào)同步和采樣鐘同步調(diào)整的算法，其特點(diǎn)是無(wú)需專門的同步導(dǎo)頻信號(hào)。所提出算法的同步性能在高斯白噪聲信道和多徑衰落信道均得到驗(yàn)證。
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關(guān)鍵詞:
- OFDM;符號(hào)同步;采樣鐘同步;插值;抽取
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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