本文選題：波分復(fù)用 + 偏振復(fù)用　； 參考：《南京郵電大學(xué)》2017年碩士論文

【摘要】：隨著各種數(shù)據(jù)量的爆炸式增長和帶寬限制,基于光纖放大器和傳統(tǒng)密集波分復(fù)用的光通信系統(tǒng)已漸漸滿足不了快速增長的信息需求。隨著近幾年對偏振復(fù)用技術(shù)的研究,采用兩個(gè)正交偏振態(tài)獨(dú)立傳輸信息,其不需要占用額外帶寬,使得在已有復(fù)用技術(shù)的基礎(chǔ)上增加了傳輸容量,且進(jìn)一步提高了頻譜利用率。與相干檢測技術(shù)相結(jié)合,被廣泛的應(yīng)用在現(xiàn)代高速光通信系統(tǒng)中。在光通信系統(tǒng)中,隨著光纖放大器的應(yīng)用,光纖損耗對通信質(zhì)量的影響可以忽略,所以目前人們把研究重點(diǎn)放在了色散補(bǔ)償上。目前比較成熟的色散補(bǔ)償技術(shù)主要在光域中進(jìn)行的,多針對于直接檢測系統(tǒng),已經(jīng)不能滿足高速相干光通信的要求。本文將針對數(shù)字處理模塊所使用的自適應(yīng)算法進(jìn)行研究,解決算法收斂速度和收斂精度對立的問題,并對高階調(diào)制方式中使用的算法進(jìn)行了深入的研究。文章的具體研究內(nèi)容如下:(1)本文對電域均衡算法做了大量的理論分析,推導(dǎo)出算法收斂速度和收斂時(shí)間對立的問題,并介紹了目前針對這個(gè)問題的兩種優(yōu)化方案,通過對改進(jìn)方案的分析發(fā)現(xiàn)其計(jì)算復(fù)雜要高于固定步長算法。所以本文針對這一問題提出了分段迭代步長的改進(jìn)算法,分段步長中包含固定步長和變步長兩種方式,將這種改進(jìn)方式應(yīng)用于最小二乘法和恒模算法中。通過偏振復(fù)用QPSK調(diào)制系統(tǒng)驗(yàn)證了方案的可行性。結(jié)果表明改進(jìn)的分段步長迭代算法,在收斂速度和精度上要好于一般改進(jìn)算法,且算法的計(jì)算復(fù)雜度較一般改進(jìn)算法低。(2)對于16QAM調(diào)制方式方式,為了保證系統(tǒng)的高頻譜利用率,目前所使用的均衡算法為無需參考序列的恒模算法。但是16QAM調(diào)制方式模值的個(gè)數(shù)不唯一,一般的恒模算法不能直接使用,針對這一問題提出了一種基于虛實(shí)分開計(jì)算的改進(jìn)算法,這種算法可以降低模值個(gè)數(shù),但是不能將模值變?yōu)槲ㄒ?且算法計(jì)算復(fù)雜度較高。所以針對這些問題本文提出了基于判決理論的改進(jìn)恒模算法,這種算法利用接收信號模值唯一的特點(diǎn)實(shí)現(xiàn)恒模算法。通過分析,基于判決理論算法與虛實(shí)處理算法相比,結(jié)構(gòu)更簡單、均衡效果更好,計(jì)算復(fù)雜度更低。
[Abstract]:With the explosive growth of all kinds of data and the limitation of bandwidth, optical communication systems based on fiber amplifiers and traditional dense wavelength division multiplexing (DWDM) have gradually failed to meet the rapidly increasing information demand. With the research of polarization multiplexing technology in recent years, two orthogonal polarization states are adopted to transmit information independently, which does not require extra bandwidth, which makes the transmission capacity increase and the spectrum efficiency further improved on the basis of the existing multiplexing technology. Combined with coherent detection technology, it is widely used in modern high-speed optical communication systems. In optical communication systems, with the application of fiber amplifiers, the influence of optical fiber loss on communication quality can be neglected, so at present, people focus on dispersion compensation. At present, more mature dispersion compensation techniques are mainly carried out in the optical domain, and most of them are aimed at direct detection systems, which can no longer meet the requirements of high-speed coherent optical communication. In this paper, the adaptive algorithm used in the digital processing module is studied to solve the problem of the contradiction between the convergence speed and the convergence accuracy of the algorithm, and the algorithm used in the high-order modulation is deeply studied. The main contents of this paper are as follows: (1) in this paper, we do a lot of theoretical analysis on the electric-domain equalization algorithm, deduce the problem of the contradiction between the convergence speed and the convergence time of the algorithm, and introduce two kinds of optimization schemes for this problem. Through the analysis of the improved scheme, it is found that the computational complexity is higher than that of the fixed-step algorithm. In order to solve this problem, this paper proposes an improved piecewise iterative step size algorithm, which includes fixed step size and variable step size. The improved method is applied to the least square method and constant modulus algorithm. The feasibility of the scheme is verified by polarization multiplexing QPSK modulation system. The results show that the improved piecewise step size iterative algorithm is better than the general improved algorithm in convergence speed and accuracy, and the computational complexity of the algorithm is lower than that of the general improved algorithm.) for the 16QAM modulation mode, in order to ensure the high spectral efficiency of the system, The current equalization algorithm is a constant modulus algorithm without reference sequence. However, the number of modules in 16QAM modulation mode is not unique, and the general constant modulus algorithm can not be used directly. An improved algorithm based on virtual and real separate calculation is proposed to solve this problem. This algorithm can reduce the number of modules. However, the module value can not be changed into a unique value, and the computational complexity of the algorithm is high. Therefore, an improved constant modulus algorithm based on decision theory is proposed in this paper, which utilizes the unique characteristics of the received signal modulus value to realize the constant modulus algorithm. Through analysis, the algorithm based on decision theory has simpler structure, better equalization effect and lower computational complexity than virtual and real algorithm.
【學(xué)位授予單位】：南京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN929.1

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