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RF-导频(RF-pilot)插入的直接探测光正交频分复用(DDO-OFDM)系统通过调节载信比(CSPR)可以有效对系统传输性能进行优化,是高速短距离局域网传输的备选方案之一。在该系统下,利用导频子载波处信道估计结果,提出一种基于线性插值与时域平均的信道估计方法,用于实现非导频子载波处信道响应的估计。本文方法可以实时跟踪信道变化,有效抑制噪声影响。仿真中,13个导频子载波用于信道估计,采用线性插值与时域平均的方法估计出非导频子载波处的信道响应,传输4-QAM映射的20 Gbit/s信号在光纤中传输400 km。与背靠背相比,在误码率(EBR)为1×10~(-3)时,几乎没有光信噪比(OSNR)损伤。通过原理验证性实验,验证了本文方法在RF-pilot插入DDO-OFDM系统中用于信道估计的可行性。
The RF-pilot inserted direct probe optical Orthogonal Frequency Division Multiplexing (DDO-OFDM) system can effectively optimize the transmission performance of the system by adjusting the carrier-to-signal ratio (CSPR) and is a high-speed short-range local area network One of the options. In this system, a channel estimation method based on linear interpolation and time-domain averaging is proposed to estimate the channel response at a non-pilot subcarrier using the channel estimation results at pilot subcarriers. This method can track the channel changes in real time and effectively restrain the noise impact. In the simulation, 13 pilot sub-carriers are used for channel estimation. The channel response at non-pilot sub-carriers is estimated by linear interpolation and time-domain averaging. The 20 Gbit / s signals transmitted by 4-QAM are transmitted in the fiber 400 km. Compared to the back-to-back, there is almost no OSNR damage at an EBR of 1 × 10 -3. Through the principle verification experiment, this paper verifies the feasibility of this method for channel estimation in the RF-pilot insertion DDO-OFDM system.