基于DFT的信道估计算法在CO-OFDM系统中研究

An improved channel estimation based on DFT algorithm for coherent optical OFDM system

信道估计作为相干光OFDM(CO-OFDM)系统的一种关键技术对系统的性能有着十分重要的影响,光纤通信系统通过信道估计,可以将信号经过光纤传输后的影响,如损耗、色散、非线性等,通过在发送端发送已知数据,在接收端利用均衡等恢复出原始信号。本文首先介绍了相干光OFDM系统,并使用optisystem和matlab软件搭建了相干光OFDM系统仿真平台,提出了适用于相干光OFDM系统的基于DFT算法及其进一步的改进算法,并在此平台上进行了仿真试验。结果表明,基于DFT算法及其改进算法能够很好地提高相干光OFDM系统的传输性能,改进的DFT算法与DFT算法在BER的值为10-4的条件下,有1dB的光信噪比增益;与LS算法比较,有3dB的光信噪比增益。

In coherent optical orthogonal frequency division multiplexing(OFDM)communication system,when the transmission rate of a signal reaches 100 Gbit/s or higher,the influence of the channel becomes a major limiting factor affecting system performance.At this time,the system is very sensitive to channel factors,which requires an effective method to accurately track channel changes.Through the channel estimation,the physical effects of optical fiber,such as chromaticity dispersion and nonlinearity,can be obtained at the receiver through the transmitted known data at the transmitter,and then through the equilibrium to restore the original signal.This paper first introduces the coherent optical OFDM system,then builds a coherent optical OFDM system simulation platform.On this platform,a DFT based and improved algorithm is applised to the coherent optical OFDM system for channel estimation.The results show that this algorithm can improve the performance of coherent optical OFDM transmission system,and has 1 dB optical signal-to-noise ratio(OSNR)gain compared with the DFT algorithm at the bit error rate of 10-4,and has 3 dB OSNRgain compared with algorithm.