• 항공우주기술
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• 제9권1호
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• pp.98-105
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• 2010

고속푸리에변환(Fast Fourier Transform)은 이산푸리에변환(Discrete Fourier Transform)의 주기적으로 반복되는 연산을 생략하여 그 속도를 향상시킨 연산방법이다. Radix-2 FFT는 그 정의에 따라 함수 재귀호출에 의해 구현될 수 있는데 이 방법은 스택복사 과정의 시간소모 때문에 고속동작이 어렵게 된다. 이를 극복하기 위해 신호점을 연산순서에 맞게 미리 재배열하고 배열된 신호점을 나비연산하는 방법으로 고속연산을 구현할 수 있다. 이 논문은 신호점 재배열 방법에 의한 Radix-2 FFT의 고속연산에 착안하여 Radix-3 FFT에 신호점 재배열 방식을 적용해 보고 그 타당성에 관해 고찰하였다.

• ETRI Journal
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• 제44권3호
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• pp.379-388
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• 2022

This study proposes a novel low-complexity algorithm for computing inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT) operations in binary phase shift keying-modulated orthogonal frequency division multiplexing (OFDM) communication systems without requiring any twiddle factor multiplications. The peak-to-average power ratio (PAPR) reduction capacity of an efficient PAPR reduction technique, that is, H-SLM method, is evaluated using the proposed IFFT algorithm without any complex multiplications, and the impact of oversampling factor for the accurate calculation of PAPR is analyzed. The power spectral density of an OFDM signal generated using the proposed multiplierless IFFT algorithm is also examined. Moreover, the bit-error-rate performance of the H-SLM technique with the proposed IFFT/FFT algorithm is compared with the classical methods. Simulation results show that the proposed IFFT/FFT algorithm used in the H-SLM method requires no complex multiplications, thereby minimizing power consumption as well as the area of IFFT/FFT processors used in OFDM communication systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.87-88
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• 2015

본 논문에서는 제주풍력단지에 대한 측정 데이터(measured wind power outputs)를 기반으로 Fast Fourier Transform(FFT)을 실시하고, 이를 이용하여 각 풍력발전단지의 주파수 특성에 대해 분석해보고자 한다.

• ETRI Journal
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• 제45권6호
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• pp.1035-1045
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• 2023

We propose a novel graphics processing unit (GPU) algorithm that can handle a large-scale 3D fast Fourier transform (i.e., 3D-FFT) problem whose data size is larger than the GPU's memory. A 1D FFT-based 3D-FFT computational approach is used to solve the limited device memory issue. Moreover, to reduce the communication overhead between the CPU and GPU, we propose a 3D data-transposition method that converts the target 1D vector into a contiguous memory layout and improves data transfer efficiency. The transposed data are communicated between the host and device memories efficiently through the pinned buffer and multiple streams. We apply our method to various large-scale benchmarks and compare its performance with the state-of-the-art multicore CPU FFT library (i.e., fastest Fourier transform in the West [FFTW]) and a prior GPU-based 3D-FFT algorithm. Our method achieves a higher performance (up to 2.89 times) than FFTW; it yields more performance gaps as the data size increases. The performance of the prior GPU algorithm decreases considerably in massive-scale problems, whereas our method's performance is stable.

• Journal of Communications and Networks
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• 제8권1호
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• pp.38-48
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• 2006

A synchronous multicarrier (MC) code-division multiple access (CDMA) system using inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) for the downlink mobile communication system operating in a frequency selective Rayleigh fading channel is analyzed. Both carrier frequency offset and timing offset are considered in the analysis. Bit error rate performance of the system with both equal gain combining and maximum ratio combining are obtained. The performance is compared to that of the conventional system using correlation receiver. It is shown that when subcarrier number is large, the system using IFFT/FFT has nearly the same performance as the conventional one, while when the sub carrier number is small, the system using IFFT/FFT will suffer slightly worse performance in the presence of carrier frequency offset.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.73-79
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• 1999

Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

• 한국정보통신학회논문지
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• 제8권3호
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• pp.570-576
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• 2004

본 논문에서는 고속 무선 LAN에서 사용하는 IEEE 802.11a OFDM(Orthogonal Frequency Division Multiplexing)에서 주요 구성인 IFFT/FFT(Inverse Fast Fourier Transform/Fast Fourier Transform)에 대한 설계에 대해 비교하였다. 설계된 IFFT/FFT는 무선 LAN의 표준에 맞게 64 point의 FFT로 연산을 수행하며, S/P(Serial-to-Parallel)이나 P/S(Parallel-to-Serial)변환기가 필요 없는 Pipelined FFT의 구조로 설계하였다. 그 중 Radix-2 알고리즘을 이용한 R22SDF(Radix-2 Single-path Delay Feedback) 방식, R2SDF(Radix-2 Single-path Delay Feedback) 방식과 Radix-4 알고리즘을 이용한 R4SDF(Radix-4 Single-path Delay Feedback) 방식, R4SDC(Radix-4 Single-path Delay Commutator) 방식을 사용하여 비교하였다. 하드웨어 구현 시 발생하는 오차를 줄이기 위해 Butterfly 연산 후 일부 소수점을 가지고 계산하는 구조로 설계하였다. R22SDF 방식을 이용할 경우 메모리를 제외한 전체 게이트 수가 44,747 개로 다른 구조에 비해 적은 하드웨어와 낮은 오차율을 가진다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.473-476
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• 2003

We suggest 2 dimensional Fast Fourier Transform using Polynomial Transform and integer Fast Fourier Transform. Unlike conventional 2D-FFT using the direct quantization of twiddle factor, the suggested 2D-FFT adopts implemented by the lifting so that the suggested 2D-FFT is power adaptable and reversible. Since the suggested FFT performg integer-to-integer mapping, the transform can be implemented by only bit shifts and auditions without multiplications. In addition. polynomial transform severely reduces the multiplications of 2D-FFT. While preserving the reversibility, complexity of this algorithm is shown to be much lower than that of any other algorithms in terms of the numbers of additions and shifts.

• Tribology and Lubricants
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• 제16권3호
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• pp.218-222
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• 2000

Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

• 한국통신학회논문지
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• 제26권4B호
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• pp.418-422
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• 2001

4-점 리버스 자켓 변환 (4-Point Reverse Jacket transform)의 장점 중의 하나는 4-점 fast Fourier transform(FFT)시 야기되는 실수 또는 복소수 곱셈을 행렬분해(matrix decomposition)를 이용, 곱셈인자를 모두 대각행렬에만 집중시킨, 매우 간결하고 효율적인 알고리즘이라는 점이다. 본 논문에서는 이를 N 점 FFT에 적용하는 알고리즘을 제안한다. 이 방법은 기존의 다른 변환형태보다 확장하거나 구조를 파악하기에 매우 용이하다.