一種新穎光直接偵測正交分頻多工訊號的產生應用二倍頻技術於光載微波訊號系統

Abstract

光載微波訊號系統已經吸引相當大的注意使用在未來的寬頻無線擷取網路裡的潛力。因為可得到的頻寬是有限的，高頻譜效益向量調變格式，例如M-ary相位偏移調變(PSK)，正交振幅調變(QAM)，正交分頻多工(OFDM)，是更好的調變形式。 本論文以實驗的方式展示了一種新穎的直接偵測微波光電向量調變系統應用於光載微波訊號系統上的可行性。不像傳統的雙旁頻帶載波抑制調變只能載送開關鍵移訊號格式，提出的架構不只可以把電的向量訊號編碼在高旁頻帶(USB)也可以在低旁頻帶(LSB)，且有一個很純的次載波在另一個邊帶。因此，相位和振幅資訊在經過直接解調後可以被保存下來。二倍頻技術的使用可以降低光纖通訊系統的費用。我們提出的架構使用載波抑制技術來達到二倍頻效果且成功的傳輸高頻譜效益的正交分頻多工訊號。

Radio-over-fiber (RoF) systems have attracted considerable attention for their potential use in future broadband wireless access networks. Since the available bandwidth is limited, high spectral efficiency vector modulation formats, such as M-ary phase shift keying (PSK), quadrature amplitude modulation (QAM), and Orthogonal frequency-division multiplexing (OFDM), are the preferred modulation schemes. This study experimentally demonstrates the feasibility of a novel direct detection microwave photonic vector modulation scheme for the RoF system. Unlike traditional double-sideband with optical carrier suppression (DSBCS) modulation scheme, which can carry only the on-off keying (OOK) data format, the proposed scheme encodes the electrical vector signal on either the upper sideband (USB) or the lower sideband (LSB) only, and a pure optical subcarrier on the other sideband. Therefore, phase and amplitude information will be preserved after direct detection. A frequency doubling scheme is employed to reduce the cost of RoF systems. The proposed architecture utilizes the carrier suppression technique to achieve frequency doubling and successfully transmits a high spectral efficiency OFDM signal.