光纤OFDM系统中的色散补偿技术研究

摘要

In order to reduce the impact of fiber chromatic dispersion on the transmission performance of an orthogonal frequency division multiplexing ( OFDM ) system, a channel estimator was introduced into the system.The influence of fiber chromatic dispersion on OFDM signals transmission in optical fiber was theoretically investigated.And the performance of an OFDM system with a channel estimator based on combined pilots and the least square estimation was demonstrated in the experiment.The amplitude response and phase response for the OFDM system showed that the optical OFDM signal modulated by a direct modulator can transmit 200km in the single-mode dispersion fiber.The bit error rate was less than 10-6 and the power penalty was smaller than 2dB.The results show that fiber chromatic dispersion plays a stronger impact on high frequency subcarrier than low frequency subcarrier.The proposed method can effectively compensate the phase shift and amplitude attenuation caused by fiber chromatic dispersion.%为了减小光纤的色度色散埘光纤正交频分复用(OFDM)系统性能的影响,提出了将无线通信中的信道估计器引入光纤OFDM系统进行信道估计的色散补偿方法.在理论上分析了光纤的色度色散对于传输OFDM信号的影响,并在实验中采用梳状导频的形式,在每个OFDM码元的特定的子载波上插入导频,在接收端通过基于最小平方(LS)原则的LS估计器进行信道估计,得到了OFDM光纤传输的信道幅度响应和相佗响应,通过使用LS估计器,直接调制的光OFDM信号在单模光纤中传输200km,误比特率低于10-6,功率代价小于2dB.结果表明,高频子载波较低频子载波更容易受到色散的影响,在光纤OFDM系统中引入信道估计器进行信道估计能够有效补偿由色度色散带来的相位偏移和幅度衰减.