Spatio-temporal delta-sigma modulation for shared wideband transmit arrays

Scholnik, Dan P.; Coleman, J.O.; Bowling, D.R.; Neel, Michael M.

doi:10.1109/nrc.2004.1316400

Cited by 14 publications

(12 citation statements)

References 8 publications

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“…For the particular set of excitations corresponding to scan angle , it follows that , where is a diagonal matrix with entries given by (20). Because of this, the scattering matrix at this scan angle can also be replaced by substituting with such that (21) Since for each scan angle the matrix in (21) is diagonal, it may be decoupled into scalar equations of the form (22) with the scan reflection coefficient for element (at scan angle ) corresponding to the th diagonal entry of .…”

Section: Power Efficiencymentioning

confidence: 99%

“…Because the scan reflection coefficient is a function of , which includes the effects of coupling for all array elements, this reflection is in reality a superposition of both the incident signal at the element as well as the coupled signals from the other elements. As such, (8) can be expressed as the array scan efficiency (23) Using the scalar equivalent for the element impedance in (20), it is possible to match each element such that in the same way one would match a single antenna. However, since this scan impedance is only valid at , when the beam is scanned to any other angle, the change in scan impedance results in a loss of efficiency.…”

Section: Power Efficiencymentioning

confidence: 99%

“…The scan impedances of the unmatched array elements were calculated using (20) for the broadside scan direction of the array, , and an individual matching network consisting of a series reactance and a quarter-wave transmission line was applied at each element to match these impedances to the normalized system impedance . The resulting average matched scan impedances are shown in Fig.…”

Section: Power Efficiencymentioning

confidence: 99%

“…In particular, they apply it to the data itself, whereas in our approach it is applied to the actual sensors/transducers, i.e., the antenna elements. Finally, in [20], a spatio-temporal quantization scheme is developed for transmit antenna arrays. While there are some superficial similarities to the methods we describe in the present paper, the goals are quite different, and how the methodology is exploited diverges sharply.…”

Section: Introductionmentioning

confidence: 99%

“…While there are some superficial similarities to the methods we describe in the present paper, the goals are quite different, and how the methodology is exploited diverges sharply. In particular, whereas the architecture in [20] aims to reduce the temporal oversampling requirements of the time domain waveforms, ours seeks to produce specified antenna beam patterns with simpler structure and hardware.…”

Section: Introductionmentioning

confidence: 99%

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Dense Delta-Sigma Phased Arrays

Krieger

Yeang²,

Wornell

2013

IEEE Trans. Antennas Propagat.

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The high cost of high-resolution phase shifters required to maintain precise control over the array beam pattern in traditional phased arrays preclude their use in a variety of emerging millimeter-wave applications. We develop a phased array architecture that obviates the need for such precise phase shifters, based on the use of sub-half-wavelength array element spacing and novel spatial domain delta-sigma processing. We characterize the performance of this architecture in terms of the array signal-to-quantization-noise ratio (SQNR) and the array power transfer efficiency, and demonstrate a tradeoff between these two metrics. As an illustrative design, we show that when constrained to two-bit phase shifters, a four-fold increase in the array density can provide a roughly 6 dB improvement in SQNR over standard design techniques, with an average efficiency loss of less than 1.5 dB with respect to a perfectly tuned ideal array. In our analysis, we account for the effects of mutual coupling, and describe a simple, practical impedance matching network for this architecture. The resulting framework allows a system designer with a given set of circuit, device, and antenna fabrication and integration technologies to choose from a spectrum of tradeoffs between array density and RF component complexity.

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Section: Power Efficiencymentioning

confidence: 99%

Section: Power Efficiencymentioning

confidence: 99%

Section: Power Efficiencymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dense Delta-Sigma Phased Arrays

Krieger

Yeang²,

Wornell

2013

IEEE Trans. Antennas Propagat.

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Massive MIMO Channel Estimation With Low-Resolution Spatial Sigma-Delta ADCs

et al. 2021

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We consider channel estimation for an uplink massive multiple-input multiple-output (MIMO) system where the base station (BS) uses an array with low-resolution (1-2 bit) analog-to-digital converters and a spatial Sigma-Delta (Σ∆) architecture to shape the quantization noise away from users in some angular sector. We develop a linear minimum mean squared error (LMMSE) channel estimator based on the Bussgang decomposition that reformulates the nonlinear quantizer model using an equivalent linear model plus quantization noise. We also analyze the uplink achievable rate with maximal ratio combining (MRC), zero-forcing (ZF) and LMMSE receivers and provide a lower bound for the achievable rate with the MRC receiver. Numerical results show superior channel estimation and sum spectral efficiency performance using the Σ∆ architecture compared to conventional 1-or 2-bit quantized massive MIMO systems.

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Massive Mimo Channel Estimation with 1-Bit Spatial Sigma-delta ADCS

Rao

Swindlehurst

Pirzadeh

2019

ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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We consider channel estimation for an uplink massive multiple input multiple output (MIMO) system where the base station (BS) uses an array with low-resolution (1-2 bit) analog-to-digital converters and a spatial Sigma-Delta (Σ∆) architecture to shape the quantization noise away from users in some angular sector. We develop a linear minimum mean squared error (LMMSE) channel estimator based on the Bussgang decomposition that reformulates the nonlinear quantizer model using an equivalent linear model plus quantization noise. We also analyze the uplink achievable rate with maximal ratio combining (MRC) and zero-forcing (ZF) receivers and provide a closed-form expression for the achievable rate with the MRC receiver. Numerical results show superior channel estimation and sum spectral efficiency performance using the Σ∆ architecture compared to conventional 1-or 2-bit quantized massive MIMO systems.

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Spatio-temporal delta-sigma modulation for shared wideband transmit arrays

Cited by 14 publications

References 8 publications

Dense Delta-Sigma Phased Arrays

Dense Delta-Sigma Phased Arrays

Massive MIMO Channel Estimation With Low-Resolution Spatial Sigma-Delta ADCs

Massive Mimo Channel Estimation with 1-Bit Spatial Sigma-delta ADCS

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