標題: 下一世代OFDM-based全光封包交換都會網路之技術與實現---光學正交分頻多工微波光電擷取系統支援Quad-play的服務
Optical OFDM Radio-over-Fiber Hybrid Access System Supporting Quad-Play Services
作者: 陳智弘
Chen Jye hong
國立交通大學光電工程學系(所)
關鍵字: 光調制模式;光纖到家;微波光學;radio?over?fiber;modulation format;FTTH;OFDM;microwave photonics
公開日期: 2010
摘要: 由於網際網路的快速發展與網路合併智慧型裝置 (converged devices or smart phone, a single device functions as a phone, camera, personal entertainment console, GPS, PDA, and application platform) 的迅速而普遍的被人們接受並成為生活中不可或缺的一部份。在以資訊為基礎的工業 型態下,每個人都想要隨時隨地的維持信息的更新與取得,因此大量的增加了每個人所需要的 傳輸頻寬。為了因應此發展,最好的解決方法之一就是使用光纖當作傳輸媒介。以光纖為主幹 的通訊系統不但可以有效的舒緩目前無線通訊頻寬不足的窘境,也是目前所知最能滿足未來頻 寬要求的傳輸媒介。因此整合光纖到家 (fiber‐to‐the‐home, FTTH 提供 triple‐play services, voice, video and internet) 以及radio‐over‐fiber (ROF, 提供無線的語音以及網路服務) 的混成光纖擷取 網路架構 (hybrid optical access network) 已經逐漸被大家所認可是最具有經濟效益的網路架構。 混成光纖擷取網路系統可同時傳輸基頻與高頻訊號,提供了一高品質的傳輸媒介 (低損耗、低 干擾) 與多元與豐富的服務內容。如果 FTTH 和 ROF 各自需要鋪設自己的光纖網路,則不但耗 費時間、造成重複資本投資 (capital expenditure, CAPEX),也將大量增加營運與維護的資本支出 (operating expenditure, OPEX)。因此若能整合FTTH 與radio‐over‐fiber 兩個系統,不但能降低成 本、加速網路建置的時效,同時有能有效的降低營運成本、減低支出,進而大大的增加光纖網 路的附加價值。在傳統的基頻 (base‐band, on‐off keying) 光通信中,光是很難攜帶向量信號 (eg. QAM, MPSK),但是在無線通信中為了增加頻帶效率 (spectral efficiency),向量信號是非常重要 的基本要求,因此在傳統的網路中,必須要在基地台將光通信的信號格式轉成無線通信的信號 格式,這不但增加了成本的支出也使的傳輸的效率降低。因此在本計畫中我們將發展以目前無 線通信最受重視的傳輸方式QAM‐OFDM (quadrature amplitude modulation, orthogonal frequency division multiplexing) 將其轉載在光的微波信號頻段來傳輸,以實現提供 quad‐play services (voice, video, internet and wireless) 的目標。我們也將同時發展在 60‐GHz 頻段的戶內超高傳輸 量 (>4 Gb/s) 網路。此一網路的目標就是希望達成在用戶家庭內的高速網路來傳輸HDTV 的信 號。自2001 年美國聯邦通訊委員會 (federal communications commission,FCC) 撤銷從57 到64 GHz 中間7‐GHz 的連續無線通訊頻段,業界和學術界便投入大量心力去研究這具有無限前景的 無線技術。消費電子產業的六大供應商LG、松下、NEC、三星電子、Sony 以及東芝等公司在2006 年底組成的Wireless‐HD 小組來共同制定60‐GHz 無線技術規格 (http://www.wirelesshd.org/)。 60‐GHz 所能使用的頻帶寬高達7‐GHz,直接影響到的資料傳輸率也提升許多。除了具有高的資 料傳輸率外,信號傳輸在60‐GHz 頻帶還有許獨特的特性和益處,如高抗擾力,資料高安全度, 和頻率的重復使用、健康安全性。60‐GHz 的信號在大氣中傳送時絕大部分的能量在傳送1 公里 後就被氧分子吸收掉,所以60‐GHz 頻帶訊號在短距離傳送時具有高度安全性。因此在區域內 可相容許多同頻段的無線訊號傳遞。以接收觀點來看,由於衍射效應的結果,高頻的電磁波比 較低頻的電磁波指向性佳,且60‐GHz 接收端的天線設計較低頻的天線來的小。最後一個比較 值的注意的是對人體健康而言,美國聯邦通訊委員會證實Giga‐link 低功率傳輸時不會穿透人體 表層造成身體的傷害。然而 60‐GHz 的產生在目前仍然非常的昂貴,因此,在這次的計畫中, 我們將開發與驗證我們在已經在理論上完成的4 倍頻光電調變技術來實現60‐GHz 之 radio‐over‐fiber 系統。如此一來,我們只需以低價的元件來產生 60‐GHz 的毫米波信號。然後 在上面承載 4‐Gb/s QAM‐OFDM 的信號,並完成傳輸的驗證。
The convergence of wireless and wireline services on hybrid access networks has great potential to cater multiple services to end users with better choices, better flexibility and lower cost. The basic idea consists of employing the same fiber‐optic backbone to provide both wireline triple‐play (phone, internet and video) service to the home and wireless signal to the base station. This is the so‐called quad‐play services. With the accelerated development of wireless communications, efficient and cost effective methods of generating and transmitting microwaves and millimeter‐waves are of utmost importance. The generation and transmission of microwave or millimeter ‐wave signals over an optical fiber have been intensively investigated for various applications. The advantages of using optical fiber as a millimeter ‐wave signal transmission medium lie in the almost unlimited bandwidth and very low propagation loss. However, the generation of optical millimeter ‐waves at frequencies above 40‐GHz remains a major challenge in various optical fiber‐supported systems. Limited by the frequency response of LiNbO3 Mach‐Zehnder modulator (MZM, typically less than 40‐GHz), and at frequencies over 40‐GHz, the electrical components and equipment, such as amplifiers, mixers, and synthesizers, are very expensive. Therefore, the cost effective generation of millimeter ‐waves beyond 40‐GHz is of great interest for various applications. Numerous optical millimeter ‐wave generation schemes based on frequency multiplication using MZMs or phase modulators (PM) combined with four‐wave mixing have recently been demonstrated. Nonetheless, these proposed systems are either very complex, suffer from low conversion efficiency or need more than one optical filter to remove undesired optical sidebands. The unavoidable optical filtering severely hinders the implementation of wavelength‐division‐multiplexer (WDM) RoF systems. In this project, a novel frequency quadrupling approach that can generate a carrier suppressed optical mm‐wave signal up to 160‐GHz using a single integrated MZM and inexpensive electronic components with a frequency range of 40‐GHz will be demonstrated. The combination of orthogonal frequency‐division multiplexing (OFDM) and radio‐over‐fiber (RoF) systems (OFDM‐RoF) has attracted considerable attention for future broadband wireless communication, especially indoor broadband wireless communication in the millimeter‐wave range. In the second part of this project, a novel method for generating direct‐detection optical 16‐QAM OFDM‐RoF signals employing a new DSBCS double‐sideband with optical carrier suppression (DSBCS) modulation scheme that can carry vector signals will be demonstrated.
官方說明文件#: NSC97-2221-E009-105-MY3
URI: http://hdl.handle.net/11536/100416
https://www.grb.gov.tw/search/planDetail?id=1989532&docId=325181
顯示於類別:研究計畫