自适应调制光正交频分复用系统的可变长保护间隔研究

Adaptively Modulated Optical Orthogonal Frequency Division Multiplexing System with Variable Guard Interval

利用保护间隔消除由色散引起的符号间干扰(ISI)对于光正交频分复用(OOFMD)系统是必不可少的。延时在不同的传输距离和传输环境下是不同的,采用固定保护长度的方式会硬响系统的功率和频谱利用率。提出了一种先进的自适应循环前缀(ACP)方法。对于多模光纤信道,循环前缀可以根据差分模延时(DMD)与传输距离确定其取值下限来消除ISI的影响。仿真实验验证,采取合适的保护间隔,在多模光纤传输10 Gb/s达1 km时,可达到与采用定长循环前缀时相同的传输性能。

It is indispensable to make use of guard interval to overcome intersymbol interference （ISI） caused by chromatic dispersion for optical orthogonal frequency division multiplexing （OOFMD） . However, the channel delay is not constant in different transmission distances and conditions, fixed guard interval decreases the power and spectrum availabity considerably. A novel adaptive cyclic prefix （ACP） OFDM concept is proposed. The lower limit value of CP, which can be determined by differential mode delay （DMD） and transmission distance, can eliminate influence of ISI. Simulation results demonstrate that the system can transmit a data rate 10 Gb/s about 1 km with reasonable CP without sacrificing the BER performance compared with the conventional non-adaptive CP.