以單載波正交分頻多工直調雙/三模雷射二極體建構毫米波光纖整合第五代無線通訊

Abstract

為了因應大容量於長距離的傳輸，本研究工作在於開發適用於第五代無線通訊並整合長距離毫米波光纖傳輸系統。為了建構毫米波光纖傳輸系統，雙/三模發射器的開發是不可或缺的。另一方面，長距離傳輸所伴隨的色散效應也是無法忽視的。因此本研究透過注入鎖定無色雷射二極體與垂直面射型雷射二極體來開發正交極化之雙/三模發射器用於建構適用於第五代無線通訊之毫米波光纖通訊系統。另外，在有限的頻寬下透過M階正交振幅調變-正交分頻多工(QAM-OFDM)、廣義分頻多工(GFDM)與位元承載(Bit-loading)等技術來提升傳輸位元率並整合於毫米波光纖通訊系統將有助於實現適用於第五代無線通訊之長距離有線整合無線傳輸系統。 在第一部分中，首先透過正交雙模光載波注入鎖定無色雷射二題體來產生正交雙模且單載波調變之雙模光載波來抑制長距離所產生之色散效應並用於建構毫米波光纖有線於無線傳輸系統。在傳統平行即化之雙模載波注入比較下，所產生之四波混頻模態在經過調整雙模間距在0.32 nm下可被抑制致-26與-41 dBm。在經過正交極化與單載波調變的優化下，被調變之64-QAM OFDM且傳輸位元率為24 Gbit/s在經過背對背及25公里單模光纖傳輸下，其各自的誤碼率及錯誤向量分析分別為2.2X10-4/6.48%與2.2X10-4/7.07%。再經過1.6公尺的無線距離後，最大可傳輸16-QAM OFDM且傳輸位元率為8 Gbit/s，對應之誤碼率以及錯誤向量分析分別為3.4X10-3和17.14%。 相較於雙模光載波系統，三模光載波可以產生功率為原本兩倍大之毫米波載波並提升無線傳輸之品質，在第二部分的研究中，透過正交注入鎖定產生正交之三模且單載波調變之光載波用於建構75公里長距離之28-GHz毫米波光纖傳輸系統。透過無色雷射二極體只支持TE極化之注入鎖定成功達到單載波調變。和傳統之平行三模光載波相比，正交三模光載波於75公里單模光纖有線傳輸下最大可傳輸64-QAM OFDM且調變頻寬以及傳輸位元率可高達8.3 GHz與50 Gbit/s，伴隨的訊雜比、誤碼率以及錯誤向量分析分別為21.2 dB、3.5X10-4與8.8%。除此之外，在透過Bit-loading的技術下，透過從64-QAM至1024-QAM其最大傳輸位元率可達88 Gbit/s。經過10公尺之無線傳輸後，透過正交三模光載波且單載波調變最大可傳輸16-QAM OFDM達4.5 GHz (18 Gbit/s)。除此之外，在透過Bit-loading的技術下可提升最大傳輸位元率到29.6 Gbit/s。 在本研究之第三部分中，透過極弱功率注入鎖定垂直面射型雷射二極體來產生正交雙模光載波用於建構無須本地震盪之28-GHz毫米波光纖傳輸系統。另外，為了在有縣頻寬中最大化傳輸位元率，將使用新型QAM-GFDM以及Bit-loading技術整合至傳輸系統中。首先，在經過-26 dBm (2.5 μW)下注入後可產生雙模功率差只有5.43 dB之正交雙模光載波，且經過全光拍頻後可產生28 GHz之毫米波且尖峰功率達-59.8 dBm。另一方面，在經過注入鎖定後，其雷射的相對強度雜訊幾乎沒有改變，除此之外，在模間雜訊的分析下，經過極弱功率注入後期雜訊僅提升2 dBc/Hz。在經過50公里單模光纖有線傳輸後，在調變64-QAM GFDM下最大可傳輸之頻寬為6.75 GHz (40 Gbit/s)。此外，透過Bit-loading技術下，可用調變頻寬可延伸至12.23 GHz，且最大傳輸位元率可達51.9 Gbit/s，此時頻寬使用率可提升至4.24 bit/s/Hz。在經過2公尺無線傳輸且透過功率偵測器達到自我降頻後，透過調變4-QAM GFDM最大可達調變頻寬2 GHz (4 Gbit/s)。另外，透過Bit-loading技術下，最大調變頻寬及傳輸位元率可達4.11 GHz及11.1 Gbit/s，其頻寬使用率為2.69 bit/s/Hz。相較於使用QAM-GFDM，其傳輸容量可提升177.5%。

This thesis aims to implement a fusion of millimeter wave (MMW) 5th generation (5G) mobile wireless and long-reach fiber wired network with high transmission capacity. Dual- and tri-mode transmitter based on orthogonally injection-locking a slave colorless laser diode (CLD) or dual-mode vertical-cavity surface-emitting laser (VCSEL) with extremely weak injection-locking are developed for constructing the long-reach MMWoF system. Besides, using M-quadrature amplitude modulation orthogonal frequency division multiplexing (M-QAM OFDM), generalized frequency division multiplexing (GFDM) and bit-loading scheme, which can improve the usage of modulation bandwidth, can further help for establishing high data rate and long-reach fiber-wireless access links for 5G applications. First of all, a novel MMWoF-OFDM link with chromatic dispersion suppression is demonstrated for wireline and wireless transmission by injection-locking a slave CLD with an orthogonally polarized dual-mode optical carrier. At the parallel polarized dual-wavelength optical carrier injection-locking case, the four-wave mixing (FWM) modes can be suppressed to -26.6 and -41 dBm with the dual-mode spacing of 0.32 nm. After optimization, For the wireline transmission, the bit error rate (BER) of the delivered 24-Gbit/s 64-QAM OFDM modulated on the orthogonally polarized and single-carrier modulated (SCM) coherent dual-mode transmitter can be improved to 2.2X10-4 and 5.9X10-4 after BtB and 25-km single-mode fiber (SMF) with each error vector magnitude (EVM) of 6.48% and 7.07%, respectively. For wireless transmission, the encoded 16-QAM OFDM with 8 Gbit/s is achieved with its BER of 3.4X10-3 and EVM of 17.14% after 25-km SMF and 1.6-m free space. An orthogonally polarized tri-mode transmitter with SCM, which can improve the transmission performance and avoid the dispersion induced fading distortion, is demonstrated for building the 75-km long-reach MMWoF. The SCM optical carrier is obtained by injection-locking the CLD which favors the only TE-mode feedback with the polarized suppression ratio over 40 dB. The maximal modulation bandwidth of the modulated 64-QAM OFDM by the orthogonally polarized SCM tri-mode optical carrier (3λ-⊥-SCM) is 8.3 GHz (50 Gbit/s) with the SNR of 21.2 dB, BER of 3.5X10-3 and EVM of 8.8% after passing 75-km transmission. By employing the bit-loading M-ray OFDM ranged from 64- to 1024-QAM OFDM, the raw data rate can be improved to 88 Gbit/s. For the wireless transmission after 75-km transmission and 10-m wireless transmission, the maximal modulation bandwidth of the delivered 16-QAM OFDM by the orthogonally polarized SCM tri-mode transmitter (3λ-⊥-SCM) is 4.5 GHz (with 18 Gbit/s). Finally, the transmission capacity is optimized to 29.6 Gbit/s by the bit-loading scheme for 5G mobile application. A synthesizer-free 28-GHz 5G MMWoF Link is built based on an orthogonally polarized dual-mode VCSEL and power envelope detection for self-heterodyne down-conversion. After an extremely weak power of only -26 dBm (2.5 μW) injection-controlling at TM-mode polarization, the dual-mode optical carrier with a power difference of only 5.43 dB is achieved and optical heterodyning a 28-GHz MMW carrier with a peak power of -59.8 dBm. Note that the injection-controlled VCSEL is with a similar relative intensity noise (RIN) than the free-running case. Moreover, its mode partition noise (MPN) is just increased less than 2 dBc/Hz. After the long-reach 50-km transmission, the maximal bandwidth and raw data rate of the modulated 64-QAM GFDM are achieved to 6.75 GHz and 40 Gbit/s, respectively. After the bit-loading optimization, the modulation bandwidth is broadened to 12.23 GHz with a total data rate of 51.9 Gbit/s and a ratio of data rate to bandwidth of 4.24 bit/s/Hz. For the wireless transmission with 2-m transmission, the maximal bandwidth and data rate of the received 4-QAM GFDM data are obtained as 2 GHz and 4 Gbit/s, respectively. After bit-loading optimization, the modulation bandwidth is increased to 4.11 GHz with a corresponding total data rate of 11.1 Gbit/s and a ratio of data rate to bandwidth ratio of 2.69 bit/s/Hz. This optimized data rate by using the bit-loading technique is enhanced to 177.5% than that by using the QAM-GFDM modulation.