InFocus: A spatial coding technique to mitigate misfocus in near field LoS beamforming

Fuente: arXiv
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Autores principales: Myers, Nitin Jonathan, Heath Jr, Robert W.
Formato: Preprint
Publicado: 2020
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author Myers, Nitin Jonathan
Heath Jr, Robert W.
author_facet Myers, Nitin Jonathan
Heath Jr, Robert W.
contents Phased arrays, commonly used in IEEE 802.11ad and 5G radios, are capable of focusing radio frequency signals in a specific direction or a spatial region. Beamforming achieves such directional or spatial concentration of signals and enables phased array-based radios to achieve high data rates. Designing beams for millimeter wave and terahertz communication using massive phased arrays, however, is challenging due to hardware constraints and the wide bandwidth in these systems. For example, beams which are optimal at the center frequency may perform poor in wideband communication systems where the radio frequencies differ substantially from the center frequency. The poor performance in such systems is due to differences in the optimal beamformers corresponding to distinct radio frequencies within the wide bandwidth. Such a mismatch leads to a misfocus effect in near field systems and the beam squint effect in far field systems. In this paper, we investigate the misfocus effect and propose InFocus, a low complexity technique to construct beams that are well suited for massive wideband phased arrays. The beams are constructed using a carefully designed frequency modulated waveform in the spatial dimension. For the special case of beamforming along the boresight of an array, this waveform is analogous to the frequency modulated continuous wave (FMCW) chirp signal in radar. InFocus mitigates beam misfocus and beam squint when applied to near field and far field systems. Simulation results indicate that InFocus enables massive wideband phased array-based radios to achieve higher data rates than comparable beamforming solutions.
format Preprint
id arxiv_https___arxiv_org_abs_2006_04964
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle InFocus: A spatial coding technique to mitigate misfocus in near field LoS beamforming
Myers, Nitin Jonathan
Heath Jr, Robert W.
Signal Processing
Information Theory
Phased arrays, commonly used in IEEE 802.11ad and 5G radios, are capable of focusing radio frequency signals in a specific direction or a spatial region. Beamforming achieves such directional or spatial concentration of signals and enables phased array-based radios to achieve high data rates. Designing beams for millimeter wave and terahertz communication using massive phased arrays, however, is challenging due to hardware constraints and the wide bandwidth in these systems. For example, beams which are optimal at the center frequency may perform poor in wideband communication systems where the radio frequencies differ substantially from the center frequency. The poor performance in such systems is due to differences in the optimal beamformers corresponding to distinct radio frequencies within the wide bandwidth. Such a mismatch leads to a misfocus effect in near field systems and the beam squint effect in far field systems. In this paper, we investigate the misfocus effect and propose InFocus, a low complexity technique to construct beams that are well suited for massive wideband phased arrays. The beams are constructed using a carefully designed frequency modulated waveform in the spatial dimension. For the special case of beamforming along the boresight of an array, this waveform is analogous to the frequency modulated continuous wave (FMCW) chirp signal in radar. InFocus mitigates beam misfocus and beam squint when applied to near field and far field systems. Simulation results indicate that InFocus enables massive wideband phased array-based radios to achieve higher data rates than comparable beamforming solutions.
title InFocus: A spatial coding technique to mitigate misfocus in near field LoS beamforming
topic Signal Processing
Information Theory
url https://arxiv.org/abs/2006.04964