以FPGA實作OFDM系統於低速電力線通訊之應用

隨著網際網路應用的普及，智慧型家庭網路已漸漸的受到重視且相關技術也陸續被開發出來。以電力線網路做為智慧型家庭控制及通訊的一環，在近年來都持續不斷的有基礎研究結果及實際商品出現。電力線網路分別在控制及通訊應用上有著不同的應用條件及技術要求。在數位通訊方面，電力線網路應用裝置持續往高傳輸頻寬上發展，目前已可以作為高畫質影音(HDTV)的傳輸媒介。在控制應用上的發展雖然尚牽涉諸多規格整合問題，但可預見電燈、家電等基本家庭電器將會直接透過電力線網路進行控制，以符合管理及節約能源的趨勢。然而受限於電力線網路本質上不利於資料傳輸的通道模型，使得電力線控制及通訊系統的穩定性及傳輸速率仍有著相當大的改進空間。本論文提出一種基於特定調變方式的低頻控制用電力線傳輸方式，並以簡單的處理機搭配FPGA實驗板進行實做。本論文首先對電力線網路的傳輸特性及現有技術做基本介紹，其次分析一種在通訊系統裡面被廣泛使用的多載波調變技術：「正交分頻多工(OFDM)」的原理，以了解此一技術在對抗多路徑效應造成的訊號延遲及衰減部分的優勢。接著將針對OFDM調變方式設計低頻的電力線網路傳輸模組，包括了以FFT/ IFFT實現OFDM訊號的產生，加入QAM及Guard Band對系統BER的影響，數位/類比轉換的調整，以及類比訊號耦合至電力線的方法。在硬體方面，使用89C55單晶片做為系統控制中心，一端連接FPGA實驗板為FFT/IFFT運算單元，另一端則透過RS232協定與個人電腦連線，利用 Visual Basic設計的人機通訊介面，可在兩部電腦之間進行資料的發送與接收；通過這樣的實驗結果，以驗証OFDM 調變技術應用於電力線通訊系統上的傳輸品質。

關鍵字

家庭自動化；電力線網路通訊系統； OFDM調變；快速傅立葉轉換；現場可程式化邏輯閘陣列

並列摘要

As the applications of internet become more popular, Smart Home Networks have received much attention, and gradually relevant technologies have also been developed successfully. Being one of the media to connect Smart Home Networks, power lines have a unique advantage, i.e., there is no need for re-wiring in residential houses. Power line communications have been utilized for control management in household appliances nowadays. However, the performance of power line communications may be restricted by some characteristics of power lines. In this thesis, a design and implementation of an OFDM system for low bit rate power line communication on FPGA experimental board is studied. Due to the multi-path effect and impulsive noise often seen in power lines, quality of power line communication is tested with the OFDM modulation technique, which has the potential to be a good solution to the problem. The design works include implementing the OFDM signals by the ALTERA FFT MegaCore Function on an FPGA board, using microprocessors as the control center to connect FPGA and PC interface, the conversion of digital/analog segments, generation and demodulation of frequency shift keying signals, and implementing coupling circuits. Finally, quality of this OFDM-based power line communication system is examined by experiment results.

並列關鍵字

Home Automation ； Power Line Communication ； OFDM Modulation ； Fast Fourier Transformation ； FPGA

參考文獻

[22] 陳志帆, “高速家用網路之電力線通訊傳輸模型”, 碩士論文, 國立台灣大學電機工程學系, 2004

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國際替代計量

以FPGA實作OFDM系統於低速電力線通訊之應用

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