Towards a Low-SWaP 1024-Beam Digital Array: A 32-Beam Subsystem at 5.8 GHz

Arjuna Madanayake, Soumyajit Mandal, Theodore S. Rappaport, Viduneth Ariyarathna, Suresh Madishetty, Sravan Pulipati, Renato J. Cintra, Diego Coelho, Raiza Oliviera, Fabio M. Bayer, Leonid Belostotski

Research output: Contribution to journalArticlepeer-review


Millimeter-wave communications require multibeam beamforming to utilize wireless channels that suffer from obstructions, path loss, and multipath 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 radio frequency (RF) beams similar to a discrete Fourier transform (DFT). Arithmetic complexity due to multiplication is reduced from the fast Fourier transform (FFT) complexity of O(N: 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. This article describes the proposed 32-point DFT approximation targeting 1024 beams using a 2-D array and shows the multiplierless approximation and its mapping to a 32-beam subsystem 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 field-programmable gate array (FPGA) at 120 MHz bandwidth per beam. Theoretical beam performance is compared with measured RF patterns from both a fixed-point FFT and the proposed multiplier-free algorithm and is in good agreement.

Original languageEnglish (US)
Article number8826444
Pages (from-to)900-912
Number of pages13
JournalIEEE Transactions on Antennas and Propagation
Issue number2
StatePublished - Feb 2020


  • Approximate beamforming
  • digital arrays
  • multibeams

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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