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標題: 單/雙倍率管線式FFT/IFFT架構之比較與FPGA實作
Comparison and FPGA Implementation of Single/Double Rate Pipelined FFT/IFFT Architecture
作者: 鄭榮錄
關鍵字: Double-Rate;雙倍率;Pipeline;Fast Fourier Transform;OFDM;802.11a;802.11g;FFT;mapping;管線式;快速傅利葉轉換;正交分頻多工系統;802.11a;802.11g;FFT;調變
出版社: 電機工程學系
過去幾年,無線網路已經在區域網路市場佔有一席之地,應用上涵蓋各種無線系統的研究以及消費性無線區域網路產品的開發,無線網路也因為這種需求而蓬勃發展,是新興或舊有系統打開潛力的關鍵。目前無限網路的主流為802.11 a/g產品,因使用OFDM(正交分頻多工調變系統)技術,使得最高資料存取速度可以到達54Mbps;此外,由於OFDM技術可以有效抵抗多路徑通道造成的頻率衰減,OFDM技術已經被廣泛應用於各種先進數位通訊系統。
本論文主要利用OFDM的訊號處理架構,並運用快速傅立葉/反快速傅立葉(FFT/IFFT)轉換架構中的radix 2和radix 2/4/8演算法,分別設計出單輸入、單輸出以及雙輸入、雙輸出之電路架構,並且將電路實現在FPGA上;在驗證中,我們從802.11a規格書中,複製64筆傳送端和接收端的資料,用自行開發之應用程式將資料作適當移位並轉成16進制,此即為所設計電路之輸入資料,然後經過Post-Place & Route模擬之後,將輸出結果再透過自行開發的應用程式,即可轉為與802.11 a規格相同格式的資料。在模擬功能無誤的情況下,接著實際由邏輯分析儀量測輸出訊號,以驗證實際功能的正確性。

In the past few years, the wireless network had already occupied a significant niche in the local area network market. It is widely adopted in both various wireless systems research and commercial WLAN product development. It is thus the key to open the new or existing systems. Currently, the major new WLAN products are followed by 802.11 a/g standards. Due to the OFDM (Orthogonal Frequency Division Multiplexing) technology, it makes the access rate up to 54Mbps. In addition, the OFDM technology can resist multi-path effects effectively. so, the OFDM technology has already been widely used in various kinds of advancement digital communication system.
This thesis utilizes the signal processing structure of OFDM technology with the radix-2 and radix-2/4/8 algorithms of FFT/IFFT to design the circuits for Single-Input-Single-Output & Dual-Input-Dual-Output, with verification by FPGA. During verification, 64 pieces of data for transmission and receiving from the standard of 802.11a were duplicated using our program to convert to hexadecimal format. These data are the input data streams. After Post-Place & Route simulations, the results were converted to be compared with the 802.11a standard. After the functional verification, the real signals were measured, through LA to verify the functions and speed.
In addition, the areas of 4 circuit structures were compared. For radix-2 algorithm, the double-rate circuit is only 1.2 times to the single-rate circuit in terms of area. Furthermore, since every stage is very similar, it is very easy to be expanded and programmable. The radix-2 circuit structure can be applied to any 2n-point FFT very easily. Even though, radix-2/4/8 utilizes the similar area, but it does not have such flexibility.
Appears in Collections:電機工程學系所

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