相干光WDM系統(tǒng)相位估計(jì)和XPM效應(yīng)的研究
發(fā)布時(shí)間：2019-01-05 02:18
【摘要】：高速相干光通信和大容量波分復(fù)用系統(tǒng)(WDM)是當(dāng)前光纖傳輸領(lǐng)域的主要技術(shù)。在相干光WDM系統(tǒng)中,以交叉相位調(diào)制(XPM)為代表的光纖非線性效應(yīng)是影響系統(tǒng)性能的主要因素。本文針對(duì)相干光WDM系統(tǒng)中相位估計(jì)和XPM效應(yīng),在理論分析、系統(tǒng)建模、算法構(gòu)建和性能仿真等方面對(duì)系統(tǒng)性能優(yōu)化進(jìn)行了全面深入的研究。論文針對(duì)單信道相干光通信系統(tǒng),提出了一種彈性相位估計(jì)(PE)算法。通過(guò)最大似然方法求取權(quán)重系數(shù),從而消除傳統(tǒng)PE接收機(jī)塊長(zhǎng)度效應(yīng)對(duì)系統(tǒng)的影響。通過(guò)理論分析,給出了彈性PE接收機(jī)的相位差方差公式進(jìn)行系統(tǒng)性能的預(yù)測(cè)。其次,論文基于小信號(hào)的分析方法,XPM強(qiáng)度噪聲通過(guò)近似處理可以轉(zhuǎn)化為乘性噪聲的形式,論文提出了一個(gè)整體的XPM效應(yīng)模型以描述XPM強(qiáng)度噪聲和XPM相位噪聲對(duì)系統(tǒng)的影響。理論和仿真顯示XPM強(qiáng)度噪聲主要表現(xiàn)為信噪比(SNR)的損傷。論文針對(duì)QPSK/OOK混合WDM系統(tǒng),基于XPM相位噪聲的自相關(guān)函數(shù),給出了QPSK信道帶有M次冪和DA-ML PE接收機(jī)的相位差方差表達(dá)式,從而進(jìn)行最優(yōu)塊長(zhǎng)度的理論預(yù)測(cè)。在QPSK信道PE接收機(jī)中引入權(quán)重系數(shù),從而消除QPSK/OOK混合WDM系統(tǒng)中的塊長(zhǎng)度效應(yīng)。針對(duì)16-QAM相干光WDM系統(tǒng)中,基于XPM相位噪聲的自相關(guān)函數(shù)和16-QAM信號(hào)功率的統(tǒng)計(jì)特性,給出了傳統(tǒng)PE算法的相位差方差表達(dá)式,從而進(jìn)行最優(yōu)塊長(zhǎng)度的預(yù)測(cè)。為了消除16-QAM WDM系統(tǒng)PE接收機(jī)的塊長(zhǎng)度效應(yīng),權(quán)重系數(shù)被引入到PE接收機(jī)中,理論和仿真顯示彈性PE接收機(jī)在16-QAM相干光WDM系統(tǒng)中不再受到塊長(zhǎng)度效應(yīng)的影響。論文最后針對(duì)OFDM WDM系統(tǒng),提出了一種相鄰信道頻譜搬移減小XPM效應(yīng)的方法。XPM強(qiáng)度噪聲方差隨著中頻頻率(IF)的增加呈現(xiàn)變化的穩(wěn)定性,XPM相位噪聲方差隨著IF的增加呈現(xiàn)單調(diào)下降特性。CO-OFDM信道在XPM效應(yīng)和放大的自發(fā)輻射(ASE)噪聲作用下,給出了誤碼率(BER)表達(dá)式,從而驗(yàn)證頻譜搬移降低XPM效應(yīng)方法的有效性。
[Abstract]:High speed coherent optical communication and large capacity wavelength division multiplexing system (WDM) are the main technologies in the field of optical fiber transmission. In coherent optical WDM systems, the nonlinear effect of cross-phase modulation (XPM) is the main factor affecting the performance of the system. In this paper, phase estimation and XPM effect in coherent optical WDM systems are studied in detail in terms of theoretical analysis, system modeling, algorithm construction and performance simulation. In this paper, an elastic phase estimation (PE) algorithm is proposed for single channel coherent optical communication systems. The weight coefficient is obtained by the maximum likelihood method to eliminate the influence of block length effect of traditional PE receiver on the system. Based on the theoretical analysis, the phase difference variance formula of elastic PE receiver is given to predict the system performance. Secondly, based on the small signal analysis method, XPM intensity noise can be transformed into multiplicative noise by approximate processing. A global XPM effect model is proposed to describe the influence of XPM intensity noise and XPM phase noise on the system. Theoretical and simulation results show that XPM intensity noise is mainly represented by SNR (SNR) damage. In this paper, based on the autocorrelation function of XPM phase noise, the expression of phase difference variance of QPSK channel with M power and DA-ML PE receiver is given for QPSK/OOK hybrid WDM system, and the optimal block length is predicted theoretically. The weight coefficient is introduced into the PE receiver of QPSK channel to eliminate the block length effect in the QPSK/OOK hybrid WDM system. Based on the autocorrelation function of XPM phase noise and the statistical characteristics of 16-QAM signal power in 16-QAM coherent optical WDM system, the expression of phase difference variance of the traditional PE algorithm is given to predict the optimal block length. In order to eliminate block length effect of PE receiver in 16-QAM WDM system, weight coefficient is introduced into PE receiver. Theoretical and simulation results show that elastic PE receiver is no longer affected by block length effect in 16-QAM coherent optical WDM system. Finally, for OFDM WDM system, a method of reducing XPM effect by spectrum shift of adjacent channel is proposed. The stability of XPM intensity noise variance changes with the increase of intermediate frequency (IF). The variance of XPM phase noise decreases monotonously with the increase of IF. Under the influence of XPM effect and amplified spontaneous emission (ASE) noise, the expression of BER (BER) is given. The effectiveness of spectrum shift method to reduce XPM effect is verified.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN929.1
，
本文編號(hào)：2401129
[Abstract]:High speed coherent optical communication and large capacity wavelength division multiplexing system (WDM) are the main technologies in the field of optical fiber transmission. In coherent optical WDM systems, the nonlinear effect of cross-phase modulation (XPM) is the main factor affecting the performance of the system. In this paper, phase estimation and XPM effect in coherent optical WDM systems are studied in detail in terms of theoretical analysis, system modeling, algorithm construction and performance simulation. In this paper, an elastic phase estimation (PE) algorithm is proposed for single channel coherent optical communication systems. The weight coefficient is obtained by the maximum likelihood method to eliminate the influence of block length effect of traditional PE receiver on the system. Based on the theoretical analysis, the phase difference variance formula of elastic PE receiver is given to predict the system performance. Secondly, based on the small signal analysis method, XPM intensity noise can be transformed into multiplicative noise by approximate processing. A global XPM effect model is proposed to describe the influence of XPM intensity noise and XPM phase noise on the system. Theoretical and simulation results show that XPM intensity noise is mainly represented by SNR (SNR) damage. In this paper, based on the autocorrelation function of XPM phase noise, the expression of phase difference variance of QPSK channel with M power and DA-ML PE receiver is given for QPSK/OOK hybrid WDM system, and the optimal block length is predicted theoretically. The weight coefficient is introduced into the PE receiver of QPSK channel to eliminate the block length effect in the QPSK/OOK hybrid WDM system. Based on the autocorrelation function of XPM phase noise and the statistical characteristics of 16-QAM signal power in 16-QAM coherent optical WDM system, the expression of phase difference variance of the traditional PE algorithm is given to predict the optimal block length. In order to eliminate block length effect of PE receiver in 16-QAM WDM system, weight coefficient is introduced into PE receiver. Theoretical and simulation results show that elastic PE receiver is no longer affected by block length effect in 16-QAM coherent optical WDM system. Finally, for OFDM WDM system, a method of reducing XPM effect by spectrum shift of adjacent channel is proposed. The stability of XPM intensity noise variance changes with the increase of intermediate frequency (IF). The variance of XPM phase noise decreases monotonously with the increase of IF. Under the influence of XPM effect and amplified spontaneous emission (ASE) noise, the expression of BER (BER) is given. The effectiveness of spectrum shift method to reduce XPM effect is verified.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN929.1
，
本文編號(hào)：2401129
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