本文關鍵詞： 接入網 OFDM-PON LDPC 峰值平均功率比 SLM　出處：《蘭州交通大學》2016年碩士論文　論文類型：學位論文

【摘要】：隨著未來接入網高速率、大帶寬和寬覆蓋的迅速發(fā)展,正交頻分復用(Orthogonal Frequency Division Multiplexing,OFDM)以其頻譜利用率高,抗窄帶干擾能力強以及能夠克服信道的頻率選擇性衰落等優(yōu)點被通信界認為是解決接入網業(yè)務多元化以及帶寬受限等問題的可靠技術,在各大數(shù)字化通信領域、IEEE802.11無線局域網和4G移動通信系統(tǒng)中已經被廣泛應用。為了滿足光通信中急速增長的用戶信息量以及多元化業(yè)務的要求,尋求下一代光接入網的新型技術也勢在必行。在PON(Passive Optical Network,無源光網絡)系統(tǒng)中加入OFDM技術已成為了光接入網NG-PON2的研究熱點之一。相比于其他PON系統(tǒng),把OFDM技術應用在PON系統(tǒng)中不僅綜合了OFDM技術頻譜效率高的優(yōu)勢,還使得系統(tǒng)帶寬的調度分配方式更加靈活,抗色散能力更強。OFDM-PON系統(tǒng)被認為是解決未來光接入網帶寬“最后一公里”瓶頸的主流方案。論文介紹了OFDM技術和OFDM-PON系統(tǒng)的發(fā)展歷史及研究現(xiàn)狀,以及其基本原理和相關技術,重點圍繞OFDM-PON系統(tǒng)性能的優(yōu)化進行了研究。首先把低密度奇偶校驗(Low-Density Parity-Check,LDPC)碼引入到OFDM-PON系統(tǒng)中,利用LDPC碼的高編碼增益對系統(tǒng)性能進行優(yōu)化。通過仿真對OFDM-PON系統(tǒng)中下行傳輸經未編碼、背靠背未編碼,以及采用LDPC-OFDM編碼調制的性能進行對比,結果顯示在20km的單模光纖上LDPC碼對OFDM-PON系統(tǒng)的性能有了明顯改善。文章中還通過對比研究分析了LDPC碼的不同構造方式和不同譯碼算法對OFDM-PON系統(tǒng)性能的影響。其次論文通過分析OFDM信號產生的高峰值平均功率比(Peak-to-Average Power Ratio,PAPR),研究了光OFDM信號在傳輸過程中產生的高PAPR對光傳輸系統(tǒng)的影響。并在已有的峰均比抑制技術論述分析下,論文提出了一種經LDPC編碼后的改進選擇映射(SLM)法和限幅法聯(lián)合的方法來抑制OFDM信號的高PAPR,達到抑制光OFDM信號峰均比的目的,實現(xiàn)OFDM-PON系統(tǒng)中發(fā)射機的信號的PAPR的抑制,進而通過提高光OFDM信號的質量來改善OFDM-PON系統(tǒng)的性能。通過仿真分析來驗證聯(lián)合改進法的OFDM-PON的下行傳輸性能,仿真結果顯示OFDM-PON系統(tǒng)采用聯(lián)合改進法能夠很好的抑制OFDM信號的峰均比和降低光器件引發(fā)的非線性效應,而且改進后的聯(lián)合法在降低OFDM的高PAPR的基礎上,還降低了普通SLM技術引入的邊帶信息的影響,從而提升系統(tǒng)的性能。
[Abstract]:With the future access network high-speed, large bandwidth and wide coverage of the rapid development of orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) with its high frequency spectrum utilization, anti interference ability and can overcome the advantages of frequency selective fading channel is considered reliable communication technology to solve the access network business diversification and bandwidth the limitation, in the digital communication field, IEEE802.11 wireless LAN and 4G mobile communication system has been widely used. In order to meet the amount of user information in optical communication and the rapid growth of demand diversification, to seek new technologies in the next generation optical access network is imperative. In PON (Passive Optical Network, passive in addition, OFDM optical network) technology has become one of the hot issues in the field of optical access network NG-PON2. Compared with other PON systems, the OFDM Technology Used in the PON system not only integrated OFDM technology has high spectrum efficiency advantages, also makes the allocation of the bandwidth of the system is more flexible, stronger anti dispersion capability of the.OFDM-PON system is considered to be the mainstream of future optical access network bandwidth scheme to solve the "last mile" bottleneck. This paper introduces the OFDM technology and OFDM-PON system development history and research, as well as its basic principle and related technologies were studied to optimize the focus on the performance of the OFDM-PON system. Firstly, the low density parity check (Low-Density Parity-Check LDPC) code into the OFDM-PON system, improve the performance of the system using high gain encoding of LDPC codes. The simulation of downlink OFDM-PON system by transmission without encoding, encoding are compared and not back-to-back, performance using LDPC-OFDM encoding and modulation. The results showed that in the 20km of the single-mode fiber LDPC code on OFDM-PON The performance of the system have been improved. The comparative study analyzes the influence of different construction methods of LDPC codes and different decoding algorithm on OFDM-PON system performance through the article. Secondly, through the analysis of the OFDM signal generated by the high peak to average power ratio (Peak-to-Average Power Ratio, PAPR), PAPR studied the effects of high light signal generated in OFDM in the transmission process of the optical transmission system. And on the base of the paprreduction techniques of discourse analysis, this paper puts forward an improved LDPC encoding after selective mapping (SLM) method combined with the high PAPR method and limiting method to inhibit OFDM signaling, light to suppress the PAPR of OFDM signals to suppress the signal transmitter in OFDM-PON system PAPR, and the performance by improving the quality of optical OFDM signal to improve the OFDM-PON system. Through the simulation analysis to verify the improvement method of OFDM-PON Downlink transmission performance, the simulation results show that the OFDM-PON system with improved method can suppress OFDM signal good PAPR reduction and nonlinear effect of optical devices caused, and combined with the improved method in reducing the OFDM high on the basis of PAPR, but also reduces the influence of introduction of common SLM technology of side information, thus to enhance the performance of the system.

【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TN929.1

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