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標題: | 準無色雷射二極體建構長距離光纖毫米波通訊網路 Quasi-color-free Laser Diode based Long-reach MMWoF Network |
作者: | Zu-Kai Weng 翁祖楷 |
指導教授: | 林恭如(Gong-Ru Lin) |
關鍵字: | 準無色雷射二極體,長距離,高密度分波多工,被動光纖網路,色散管理,正交振幅調變,正交分頻多工,通用濾波多載波,光纖通訊,波長控制,光纖毫米波,無載波毫米波,單邊帶濾波,無線通訊系統, quasi-color-free laser diode (QCFLD),long-reach (LR),dense wavelength division multiplexing (DWDM),passive optical network (PON),dispersion management,QAM-OFDM,UFMC,optical fiber communication,wavelength controlling,millimeter-wave over fiber (MMWoF),carrierless,single-sideband,wireless communication system, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 隨著即時多媒體影音、雲端運算和行動通訊網路等最新科技的發展,現今人們對於高傳輸容量的需求直接促使了短距離和長距離(LR)光接取網路的進步。此外,第五世代(5G)行動通訊為高速無線行動網路的未來展望,其將於毫米波(MMW)頻帶實作。在此情況下,光纖與毫米波整合的無線通訊網路(MMWoF)近年來一直是研究的焦點。在本論文中,為了滿足上述要求,我們提出了準無色雷射二極體(QCFLD)作為LR正交分頻多工(OFDM)被動光網路(PON)和MMWoF應用的訊號發送器。
首先進行以QCFLD為訊號發送器的60 Gbit/s色散管理LR OFDM-PON實驗。所使用之QCFLD可以利用注入鎖定和頻譜預失真於背對背(BtB)傳輸條件之下完成60 Gbit/s的最高傳輸容量。於25、50和75 km單模光纖(SMF)傳輸後,QCFLD的最大傳輸容量分別劣化至45、27和21 Gbit/s,這是由於嚴重色散引起的微波功率衰減(RF fading)現象造成。為了消除這種訊號劣化現象,可利用非零色散位移光纖(NZ-DSF)和色散補償光纖(DCF)的各種組合(其色散係數分別為+5.6 ps/nm/km和-5 ps/nm/km)進行色散管理,其中25-km NZ-DSF和25-km DCF的傳輸皆可達到57 Gbit/s的傳輸容量。此外,將25-km NZ-DSF和25-km DCF組合可以實現近零色散的50-km LR傳輸,從而完成51 Gbit/s的LR傳輸容量。再增加另一捆25-km DCF來建構75 km的LR色散管理傳輸,其可以提供48 Gbit/s的高傳輸容量。與純SMF建構之LR OFDM-PON相比,藉由色散管理可提高2倍以上之總傳輸容量。 接下來,為了建構用於5G無線通訊的28-GHz LR MMWoF網路,我們採用了通用濾波多載波(UFMC)處理的OFDM訊號,並且將其直接調變於雙波長注入鎖定的QCFLD。於BtB、25-km和50-km SMF基頻傳輸時,該雙模QCFLD可以支持57、42和24 Gbit/s的傳輸速率。分別經過25或50 km的SMF傳輸後,利用光學外差產生28 GHz的MMW載波和調變的訊號,於6-m和10-m的自由空間距離中,可以分別完成16 Gbit/s和14 Gbit/s的傳輸。之後,由於訊號旁瓣濾波的特性,採用UFMC處理的OFDM有利於5G無線應用,其可以進一步優化訊號品質。在其中,當加長UFMC的濾波長度進行訊號優化時,將詳細討論傳輸品質和真實傳輸速率之間的權衡。在利用3 GHz 32-QAM的UFMC-OFDM於50-km SMF和10-m的無線傳輸條件之下,其傳輸容量可以被提升至15 Gbit/s。最後藉由採用窄頻寬的512-QAM UFMC-OFDM,可以對實際的5G應用進行有限頻寬內的最高傳輸速率研究。 最後的研究中,我們提出了無載波的MMWoF架構,其可以分別藉由破壞性干涉拍頻或單邊帶濾波的OFDM實現。藉由破壞性干涉拍頻,無載波的2 GHz 16-QAM OFDM可以成功傳輸於100-km SMF和10-m自由空間,而藉由濾波後的OFDM優化,其傳輸容量可以被進一步提升至10 Gbit/s。對於單邊帶濾波,同時採用了純電性和光學測試來研究其對於解除微波放大器飽和現象的影響。於光學測試中,傳輸速率為6 Gbit/s的2 GHz 8-QAM單邊帶OFDM成功傳輸於100-km SMF和10-m自由空間,這是由於其強大的MMW載波被過濾掉而使得OFDM訊號能被正常放大。與單邊帶濾波相比,破壞性干涉拍頻可以提供更高的傳輸速率和更好的頻譜利用率;然而,由於其雙邊帶調變的特性造成使用頻寬的浪費。另一方面,儘管單邊帶濾波的OFDM提供之傳輸速率較低、頻譜使用率也較差,但它可以節省一半的使用頻譜。如果分配另一個MMW載波和OFDM訊號於被節省的頻寬範圍,總傳輸速率可以被加倍。 Nowadays, accompanying with the development of the latest technologies such as live-streaming multimedia, cloud computing and mobile network, the demand on high-capacity data has urged the growth of both short- and long-reach (LR) optical access networks (OANs). Besides, the fifth generation (5G) mobile communication has been expected as the solution for high-speed wireless link, which is regarded to implement through the millimeter-wave (MMW) band. In this circumstance, the fusion of fiber-wired and MMW wireless communication links (also called MMW over fiber, MMWoF) has been a research spotlight in recent years. In this thesis, to meet the requirements above, we propose the quasi-color-free laser diode (QCFLD) as the universal transmitter for both the LR orthogonal frequency division multiplexing (OFDM) passive optical network (PON) and MMWoF applications. First of all, a QCFLD based 60-Gbit/s LR OFDM-PON with dispersion management is demonstrated. The QCFLD can achieve an ultimate transmission capacity of 60 Gbit/s through the help of injection-locking and pre-leveling. During the 25-, 50- and 75-km single-mode fiber (SMF) propagation, the maximal transmission capacities of the QCFLD are respectively achieved at 45, 27 and 21 Gbit/s, which is due to the serious chromatic dispersion induced RF power fading effect. To relieve such signal deterioration, the dispersion management is proposed through the introduction of different segments of non-zero dispersion shifted fiber (NZ-DSF) and dispersion compensating fiber (DCF) with their dispersion coefficient of +5.6 ps/nm/km and -5 ps/nm/km, respectively. After dispersion management, both the 25-km NZ-DSF and the 25-km DCF transmission support 57-Gbit/s capacities. Furthermore, combining both the fiber spools can implement near-zero dispersion 50-km LR transmission, which boosts the transmission capacity up to 51 Gbit/s. Adding another 25-km DCF to construct the 75-km LR dispersion managed propagation provides 48-Gbit/s capacity. Comparing with the same SMF based LR OFDM-PON, the data rate can be obviously improved through dispersion management. Next, to construct the 28-GHz LR MMWoF link for 5G wireless application, the universal filtered multi-carrier (UFMC) processed OFDM data is employed to encode the dual-wavelength injection-locked QCFLD. For the fiber-wired transmission, the dual-mode QCFLD supports raw data rates of 57, 42 and 24 Gbit/s for the BtB, 25-km and 50-km SMF propagations. 28-GHz MMW carrier with its carried data is optically heterodyned after 25- or 50-km SMF transmission, which give the wireless data rates of 16 Gbit/s over 6-m free-space and 14 Gbit/s over 10-m free-space, respectively. Afterwards, the UFMC processed OFDM data is adopted for favoring the 5G wireless application to further optimize the signal quality by its sidelobe filtering characteristic. When lengthening the filter of the UFMC data for optimization, trade-off between the data quality and the net-data-rate ratio is discussed. Through the 3-GHz 32-QAM UFMC data, the wireless capacity is improved to 15 Gbit/s over 50-km SMF and 10-m free-space transmission. Finally, the 512-QAM UFMC data with narrowed bandwidth is adopted to investigate the ultimate data rate within a limited user bandwidth for practical 5G application. At last, the dual-wavelength controlled QCFLD based 100-km LR carrierless MMWoF link with either destructively interfered beating or single-sideband filtered OFDM data is demonstrated. Through destructively interference beating, the carrierless operated 2-GHz 16-QAM OFDM data is able to transmit over 100-km SMF and 10-m free-space, and the 10-Gbit/s transmission capacity can be further improved through the help of filtered OFDM. For single-sideband filtering, both the electrical and optical testing are employed to investigate the effect of relieving the RF amplifier saturation. During the testing, the 2-GHz 8-QAM single-sideband OFDM data with raw data rate of 6 Gbit/s is successfully transmitted over 100-km SMF and 10-m free-space distance with its powerful MMW being filtered out. Comparing with single-sideband filtering, the destructively interfered beating provides higher data rate of 10 Gbit/s and better spectral usage of 4 bit/s/Hz. However, the double-sideband modulated OFDM data results in a waste of usage bandwidth. Oppositely, despite of the lower data rate of 6 Gbit/s and the worse spectral usage of 3 bit/s/Hz, the single-sideband filtered OFDM data saves another spectral sideband. If allocating another carrier and data to the reduced bandwidth, total available data rate can be doubled. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/77700 |
DOI: | 10.6342/NTU201702578 |
全文授權: | 未授權 |
顯示於系所單位: | 光電工程學研究所 |
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