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標題: Ofdm Based Receiver Designs for Next Generation Hybrid Optical Fiber Communication Systems
作者: 楊清淵
關鍵字: 應用研究
passive optical network
radio over fiber
optical receiver
base band
optical front end
frequency synthesizer
channel codec
摘要: In this group project, a hybrid optical fiber communication network incorporating bothNext Generation Passive Optical Network (NG-PON) and Radio over Fiber (RoF) will beinvestigated to develop their receiver chip designs. To enhance the spectrum efficiency,orthogonal frequency division multiplexing (OFDM) technique using QAM modulation willbe employed in lieu of the conventional NRZ scheme. The three-year project span will bedivided into two phases. Phase 1 is currently under investigation and is mainly devoted tothe receiver design of NG-PON. The key issues are to reduce the spectrum demand for lowcost optical devices, and to mitigate the chromatic dispersion on fiber communication. Thesystem specs are 1.66GHz in signal bandwidth, 64 QAM modulation, and 12Gbps/8.67Gbpsrespectively for raw and effective data rates. Some preliminary results have been presentedin this proposal. Phase 2 of the project is to explore the 60 Hz RF wireless receiver for theRoF system. Part of the NG-PON receiver module designs will be reused and new endeavorsare put on the 60GHz RF module, high speed ADC, channel decoder, and base band DSPsolutions to mitigate optical and wireless channel impairments simultaneously. Tentativespecs indicate a pass band spectrum usage of 2 GHz, 16 QAM modulation, and8Gps/4.67Gbps respectively for raw and effective data rates. The proposed RoF system alsosupports WDM based MIMO processing, which further raises the data rate up to 9.33GHz in2X2 case.This group project consists of 5 major topics, i.e. base band, front end & RF, PLL &frequency synthesizer, ADC, and channel decoder. The transmitter and the optical networkare software simulated. A high speed 4GSps 6-bit ADC will be investigated. The base banddesign is aimed at combating both the optical and the wireless channel impairments. It alsofeatures a highly parallel architecture to cope with the throughput requirement. The LDPCdecoder supports multi-mode decoding and is expected to yield a coding gain as high as10dB while maintaining the throughput. The RF module contains LNA, mixer and frequencysynthesizer and is able to support 3 different RF frequencies separated by 2GHz each in the60 GHz ISM band. Elaborate test plans are developed in advance before the chip designs sothat all possible testing or interface problems can be ironed out in the first place. The phase 2investigation will first integrate the NG-PON modules developed in phase 2 and develop thekey modules for the RoF system.
本計畫主要是針對能同時支援下世代被動式光纖接取網路(Next GenerationPassive Optical Network, NG-PON)與光載射頻系統(Radio over Fiber, RoF)的混合光纖通訊系統系統(hybrid optical fiber communication network),定義並設計其接收機晶片。而為了增加傳輸訊號的頻譜使用效率,進而提升整體資料傳輸速率,我們將摒棄目前光纖傳輸上常用的 Non-Return-Zero (NRZ) format,而以正交分頻多工(OrthogonalFrequency Division Multiplexing, OFDM)傳送Quadrature Amplitude Modulation (QAM)訊號的方式來實現。計畫分成兩個NG-PON (Phase 1)與RoF (Phase 2)兩個phase 來執行。在已核准執行的Phase 1,NG-PON 接收機設計的重點在以OFDM 方式降低光電元件的成本,並補償光纖傳送的色散問題。NG-PON 設計使用1.66GHz 訊號頻寬,採64QAM 調變方式,預期的raw/effective data rate 可分別達到12Gbps/8.67Gbps。目前已完成部分模組的設計並有初步的成果呈現在本計畫書。Phase 2 則是針對傳送60GHz RF訊號的RoF 系統 wireless receiver 來設計。除了將Reuse NG-PON 的部分OFDM 模組設計外,重點在於60GHz 的RF 模組、高速ADC 及channel decoder 設計以及如何利用base band DSP 來同時解決光纖及無線通道的干擾問題。預計規格是使用約2GHz 的RF 傳輸頻寬,以較保守的16QAM 調變方式,預期的raw/effective data rate 可達到8Gps/4.67Gbps。此外系統也支援WDM(wavelength division multiplexing)方式傳送多組RF 訊號來做MIMO communication。以2X2 SDM 的例子,可將整體的data rate 提升到9.33 Gbps。本群體計畫一共涵蓋了五個子計畫主題,分別是 1)基頻設計 2)前端及射頻電路電路 3)鎖相迴路與頻率合成器 4) 類比數位轉換器,以及5)通道邊解碼器。Transmitter以及RoF 光纖通道的部分將由模擬軟體實現。ADC 之設計為4GHz 6-bit resolution。基頻電路則以一高度平行化的設計來降低其工作頻率。LDPC 通道解碼器可支援多種模式的解碼,並達到10dB 的編碼增益。前端電路,主要是轉阻放大器以及可調式增益放大器等。60GHz RF 模組則涵蓋了高效能的LNA、mixer 以及頻率合成器。為了確保各子計畫的模組能順利的整合,我們從整個系統的效能規範與鍊結預算開始,完整的定義每個模組的功能與界面規格。並且擬定了詳細的測試以及晶片整合規劃。除發展RoFreceiver 的模組外,Phase 2 的計畫也將整合Phase 1 的NG-PON 模組。
其他識別: NSC100-2221-E005-041
Appears in Collections:電機工程學系所



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