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在传统OFDM系统中,OFDM码元在信道特性不佳时可能会超出保护间隔并严重影响相邻码元,从而造成码间干扰和载波间干扰.针对此类干扰,在高速非相干光OFDM通信系统中,提出了一种基于直流偏置光OFDM的帧内信号时域调整方案.该方案运用傅里叶变换的基本性质,通过简单的频域子信道预处理,便可以将直流偏置光OFDM时域信号进行帧内交叉性时序搬移,使信号能量从码元边缘部分集中到中间部分.数值模拟表明,该方案能显著降低因码元超出保护间隔而引起的码间干扰和载波间干扰,从而有效改善系统的误码率性能.对于某些通过减小保护间隔来提高信息传输有效性的光OFDM系统,该方案也具有很大意义.
In the traditional OFDM system, OFDM symbols may exceed the guard interval when the channel characteristics are poor and seriously affect adjacent symbols, resulting in intersymbol interference and inter-carrier interference. For such interference, in a high-speed incoherent optical OFDM communication System, this paper proposes a time-domain signal timing adjustment scheme based on DC-offset optical OFDM.Using the basic properties of Fourier transform, the proposed scheme can pre-process the DC offset light OFDM time-domain signals are cross-frame-timing shifted so that the signal energy is concentrated from the edge of the symbol to the middle part.The numerical simulation shows that this scheme can significantly reduce the intersymbol interference caused by the symbol beyond the guard interval and the inter-carrier interference , So as to effectively improve the BER performance of the system.For some optical OFDM systems that reduce the guard interval to improve the efficiency of information transmission, this scheme is of great significance.