학술논문
SMUL-FFT: A Streaming Multiplierless Fast Fourier Transform
Document Type
Periodical
Author
Source
IEEE Transactions on Circuits and Systems II: Express Briefs IEEE Trans. Circuits Syst. II Circuits and Systems II: Express Briefs, IEEE Transactions on. 68(5):1715-1719 May, 2021
Subject
Language
ISSN
1549-7747
1558-3791
1558-3791
Abstract
Beamspace processing is an emerging paradigm to reduce hardware complexity in all-digital millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) basestations. This approach exploits sparsity of mmWave channels but requires spatial discrete Fourier transforms (DFTs) across the antenna array, which must be performed at the baseband sampling rate. To mitigate the resulting DFT hardware implementation bottleneck, we propose a fully-unrolled Streaming MUltiplierLess (SMUL) fast Fourier Transform (FFT) engine that performs one transform per clock cycle. The proposed SMUL-FFT architecture avoids hardware multipliers by restricting the twiddle factors to a sum-of-powers-of-two, resulting in substantial power and area savings. Compared to state-of-the-art FFTs, our SMUL-FFT ASIC designs in 65nm CMOS demonstrate more than 45% and 17% improvements in energy-efficiency and area-efficiency, respectively, without noticeably increasing the error-rate in mmWave massive MIMO systems.