Multibeam Digital Array Receiver Using a 16-Point Multiplierless DFT Approximation

Coelho, Diego F. G.; Pulipati, Sravan; Cintra, Renato J.; Bayer, Fábio M.; Dimitrov, Vassil S.; Madanayake, Arjuna

doi:10.1109/tap.2018.2882629

Cited by 19 publications

(12 citation statements)

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“…These computations can be efficiently performed using a spatial Fast Fourier transform (FFT), which can be implemented using both analog as well as digital approaches [88] and reduces the brute force computational complexity of the DFT from O(N 2 ) down to O(N log N ). Moreover, approximate versions of the DFT can be computed with even lower complexity than the FFT, as shown by Cintra, Bayer, and their collaborators [89]- [93]. The Cintra-Bayer approach to approximate-DFT computation allows significantly smaller arithmetic complexity over FFT-based approaches (in some cases, reducing the computation burden by an order of magnitude for large N ) at the cost of only ∼2 dB penalty in worst-case sidelobe level [89]- [93].…”

Section: Novel Wideband Multi-beamformers At Low Size Weight Anmentioning

confidence: 99%

“…Moreover, approximate versions of the DFT can be computed with even lower complexity than the FFT, as shown by Cintra, Bayer, and their collaborators [89]- [93]. The Cintra-Bayer approach to approximate-DFT computation allows significantly smaller arithmetic complexity over FFT-based approaches (in some cases, reducing the computation burden by an order of magnitude for large N ) at the cost of only ∼2 dB penalty in worst-case sidelobe level [89]- [93]. Note that while today's mobile devices do not concern themselves with the power savings due to FFT computations (because fidelity of the modulation is vital for bit error rate), the same may not be true for future wireless devices at mm-wave and THz.…”

Section: Novel Wideband Multi-beamformers At Low Size Weight Anmentioning

confidence: 99%

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Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

et al. 2019

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Frequencies from 100 GHz to 3 THz are promising bands for the next generation of wireless communication systems because of the wide swaths of unused and unexplored spectrum. These frequencies also offer the potential for revolutionary applications that will be made possible by new thinking, and advances in devices, circuits, software, signal processing, and systems. This paper describes many of the technical challenges and opportunities for wireless communication and sensing applications above 100 GHz, and presents a number of promising discoveries, novel approaches, and recent results that will aid in the development and implementation of the sixth generation (6G) of wireless networks, and beyond. This paper shows recent regulatory and standard body rulings that are anticipating wireless products and services above 100 GHz and illustrates the viability of wireless cognition, hyper-accurate position location, sensing, and imaging. This paper also presents approaches and results that show how long distance mobile communications will be supported to above 800 GHz since the antenna gains are able to overcome airinduced attenuation, and present methods that reduce the computational complexity and simplify the signal processing used in adaptive antenna arrays, by exploiting the Special Theory of Relativity to create a cone of silence in over-sampled antenna arrays that improve performance for digital phased array antennas. Also, new results that give insights into power efficient beam steering algorithms, and new propagation and partition loss models above 100 GHz are given, and promising imaging, array processing, and position location results are presented. The implementation of spatial consistency at THz frequencies, an important component of channel modeling that considers minute changes and correlations over space, is also discussed. This paper offers the first in-depth look at the vast applications of THz wireless products and applications and provides approaches for how to reduce power and increase performance across several problem domains, giving early evidence that THz techniques are compelling and available for future wireless communications. INDEX TERMS mmWave, millimeter wave, 5G, D-band, 6G, channel sounder, propagation measurements, Terahertz (THz), array processing, imaging, scattering theory, cone of silence, digital phased arrays, digital beamformer, signal processing for THz, position location, channel modeling, THz applications, wireless cognition, network offloading. I. INTRODUCTION The tremendous funding and research efforts invested in millimeter wave (mmWave) wireless communications, and The associate editor coordinating the review of this manuscript and approving it for publication was Thomas Kuerner. the early success of 5G trials and testbeds across the world, ensure that commercial widespread 5G wireless networks will be realized by 2020 [1]. The use of mmWave in 5G wireless communication will solve the spectrum shortage in current 4G cellular communication systems that operate

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Section: Novel Wideband Multi-beamformers At Low Size Weight Anmentioning

confidence: 99%

Section: Novel Wideband Multi-beamformers At Low Size Weight Anmentioning

confidence: 99%

Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

et al. 2019

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“…Our methodology can be directly applied to any DFT for which the block length is a perfect square. Since the current DFT approximations in the literature are restricted to the sizes {8, 16, 32} [8], [35], [48], [50], [51], approximate algorithms can be derived for N ∈ {64, 256, 1024}. In this work, we focused on the 1024-point case.…”

Section: Discussionmentioning

confidence: 99%

“…The required number of multiplications depends on the fast algorithm employed for the particular transform length N in consideration. The computational complexity of the N -point DFT using direct matrix-vector multiplication is O(N 2 ) where O(•) represents the ''big O'' notation for asymptotic complexity [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Fast Radix-32 Approximate DFTs for 1024-Beam Digital RF Beamforming

et al. 2020

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The discrete Fourier transform (DFT) is widely employed for multi-beam digital beamforming. The DFT can be efficiently implemented through the use of fast Fourier transform (FFT) algorithms, thus reducing chip area, power consumption, processing time, and consumption of other hardware resources. This paper proposes three new hybrid DFT 1024-point DFT approximations and their respective fast algorithms. These approximate DFT (ADFT) algorithms have significantly reduced circuit complexity and power consumption compared to traditional FFT approaches while trading off a subtle loss in computational precision which is acceptable for digital beamforming applications in RF antenna implementations. ADFT algorithms have not been introduced for beamforming beyond N = 32, but this paper anticipates the need for massively large adaptive arrays for future 5G and 6G systems. Digital CMOS circuit designs for the ADFTs show the resulting improvements in both circuit complexity and power consumption metrics. Simulation results show similar or lower critical path delay with up to 48.5% lower chip area compared to a standard Cooley-Tukey FFT. The time-area and dynamic power metrics are reduced up to 66.0%. The 1024-point ADFT beamformers produce signal-to-noise ratio (SNR) gains between 29.2-30.1 dB, which is a loss of ≤ 0.9 dB SNR gain compared to exact 1024-point DFT beamformers (worst case) realizable at using an FFT.

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“…The paper [30] presents a spatial DFT-based digital multibeam beamforming implementation scheme for satellite communications. The earlier work of authors in [4] describes a low-complexity algorithm using the spatial DFT based approach for generating 16 simultaneous beams using a ULA. The work in [4] uses a 16-point DFT approximation to generate the simultaneous beams and presents the measured beams of its fully digital implementation targetting 5G MIMO applications.…”

Section: Introductionmentioning

confidence: 99%

Towards a Low-SWaP 1024-beam Digital Array: A 32-beam Sub-system at 5.8 GHz

Madanayake,

Ariyarathna,

Madishetty

et al. 2022

Preprint

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Millimeter wave communications require multibeam beamforming in order to utilize wireless channels that suffer from obstructions, path loss, and multi-path effects. Digital multibeam beamforming has maximum degrees of freedom compared to analog phased arrays. However, circuit complexity and power consumption are important constraints for digital multibeam systems. A low-complexity digital computing architecture is proposed for a multiplication-free 32-point linear transform that approximates multiple simultaneous RF beams similar to a discrete Fourier transform (DFT). Arithmetic complexity due to multiplication is reduced from the FFT complexity of O (N log N) for DFT realizations, down to zero, thus yielding a 46% and 55% reduction in chip area and dynamic power consumption, respectively, for the N = 32 case considered. The paper describes the proposed 32-point DFT approximation targeting a 1024-beams using a 2D array, and shows the multiplierless approximation and its mapping to a 32-beam sub-system consisting of 5.8 GHz antennas that can be used for generating 1024 digital beams without multiplications. Real-time beam computation is achieved using a Xilinx FPGA at 120 MHz bandwidth per beam. Theoretical beam performance is compared with measured RF patterns from both a fixed-point FFT as well as the proposed multiplier-free algorithm and are in good agreement.

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Multibeam Digital Array Receiver Using a 16-Point Multiplierless DFT Approximation

Cited by 19 publications

References 43 publications

Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

Wireless Communications and Applications Above 100 GHz: Opportunities and Challenges for 6G and Beyond

Fast Radix-32 Approximate DFTs for 1024-Beam Digital RF Beamforming

Towards a Low-SWaP 1024-beam Digital Array: A 32-beam Sub-system at 5.8 GHz

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