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1. RF-CMOS Electronic-Photonic Sensing Elements for Millimeter-wave Front-end Systems-on-Chip: Enabling mm-wave Array Scaling/Disaggregation for Radar and Extreme Massive MIMO

   Singh, Manuj Kumar; Gevorgyan, Hayk; Zhang, Xinchang; Zhang, Bohan; Popović, Miloš; Wang, Ruocheng; Buchbinder, Sidney; Stojanović, Vladimir M (March 2024, GomacTech 2024)

   We demonstrate a path to scalable, wavelength- multiplexed RF/mm-wave-photonic front-end systems-on-chip for radar and extreme massive MIMO arrays, in 300mm-foundry 45nm RF SOI CMOS. We demonstrate mm-wave-to-optical sensing elements comprising low-noise amplifiers (LNAs) mono- lithically integrated with triply-resonant photonic microring- resonator based modulators. The “photonic molecule” modulator concept breaks the conventional ring modulator conversion efficiency-bandwidth tradeoff and provides optimal performance RF-photonic applications, while supporting high bandwidth den- sities. We show a first experiment with projected noise figure of 24dB at 57GHz (30mW/element, -45dBm RF-input, 6dBm laser LO). The elements are tileable at small pitches, enabling photonic disaggregation of large-scale phased arrays. 

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2. Sparse Linear Precoders For Mitigating Nonlinearities In Massive MIMO

   https://doi.org/10.1109/SSP49050.2021.9513791  

   Mezghani, Amine; Plabst, Daniel; Swindlehurst, Lee A.; Fijalkow, Inbar; Nossek, Josef A. (July 2021, IEEE Statistical Signal Processing Workshop (SSP))

   null (Ed.)

   Dealing with nonlinear effects of the radio-frequency (RF) chain is a key issue in the realization of very large-scale multi-antenna (MIMO) systems. Achieving the remarkable gains possible with massive MIMO requires that the signal processing algorithms systematically take into account these effects. Here, we present a computationally-efficient linear precoding method satisfying the requirements for low peak-to-average power ratio (PAPR) and low-resolution D/Aconverters (DACs). The method is based on a sparse regularization of the precoding matrix and offers advantages in terms of precoded signal PAPR as well as processing complexity. Through simulation, we find that the method substantially improves conventional linear precoders. 

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3. Dual-Band, Two-Layer Millimeter-Wave Transceiver for Hybrid MIMO Systems

   https://doi.org/10.1109/JSSC.2021.3110520  

   Mondal, Susnata; Carley, Larry Richard; Paramesh, Jeyanandh (October 2021, IEEE Journal of Solid-State Circuits)

   null (Ed.)

   This paper presents a two-layer RF/analog weighting MIMO transceiver that comprises fully-connected (FC) multi-stream beamforming tiles in the RF-domain first layer, followed by a fully connected analog- or digital-domain baseband layer. The architecture mitigates the complexity versus spectral-efficiency tradeoffs of existing hybrid MIMO architectures and enables MIMO stream/user scalability, superior energy-efficiency, and spatial-processing flexibility. Moreover, multi-layer architectures with FC tiles inherently enable the co-existence of MIMO with carrier-aggregation and full-duplex beamforming. A compact, reconfigurable bidirectional circuit architecture is introduced, including a new Cartesian-combining/splitting beamforming receiver/transmitter, dual-band bidirectional beamforming network, dual-band frequency translation chains, and baseband Cartesian beamforming with an improved programmable gain amplifier design. A 28/37 GHz band, two-layer, eight-element, four-stream (with two FC-tiles) hybrid MIMO transceiver prototype is designed in 65-nm CMOS to demonstrate the above features. The prototype achieves accurate beam/null-steering capability, excellent area/power efficiency, and state-of-the-art TX/RX mode performance in two simultaneous bands while demonstrating multi-antenna (up to eight) multi-stream (up to four) over-the-air spatial multiplexing operation using proposed energy-efficient two-layer hybrid beamforming scheme. 

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4. Fast EVM Tuning of MIMO Wireless Systems Using Collaborative Parallel Testing and Implicit Reward Driven Learning

   https://doi.org/10.1109/ITC44778.2020.9325270  

   Komarraju, Suhasini; Chatterjee, Abhijit (November 2020, International Test Conference)

   null (Ed.)

   Modern 5G and projected 6G wireless systems deploy massive MIMO systems with antenna arrays and novel RF transceiver architectures that admit RF beamforming. Testing and tuning of the underlying transceiver arrays on a per-transceiver basis is expensive and can be expedited through the use of parallel testing and tuning techniques that stimulate the entire array transceiver system concurrently. State of the art parallel testing techniques require frequency separation between the tones applied to individual RF chains due to combining of RF signals before down-conversion in analog beamforming MIMO systems. Test schemes that allow some frequency overlap are limited to testing only third order distortion. In this paper, we first present a parallel testing scheme for testing large MIMO transceiver arrays that is amenable to higher order distortion (upto fifth order) in the RF chains considered. Second, we propose a tuning scheme for the entire MIMO array which implicitly tunes for EVM system specifications without explicit knowledge of the relationship between the system test response, the system tuning knobs and the corresponding EVM and SINR specification values. A cost metric is formulated that allows such a solution using reinforcement (multi-arm bandit) learning driven system tuning. Significant yield improvement using this approach is demonstrated by simulation experiments. 

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5. Dynamic Metasurface Antennas for Energy-Efficient MISO Communications

   https://doi.org/10.1109/GLOBECOM54140.2023.10436779  

   Carlson, Joseph; Castellanos, Miguel R.; Heath, Robert W. (December 2023, IEEE)

   Dynamic metasurface antennas (DMA) have been proposed for massive multiple-input multiple-output (MIMO) and millimeter wave applications due to their ability to cre- ate dense, energy-efficient arrays. In this paper, we integrate DMAs into a realistic wireless environment to compare their performance in spectral and energy efficiency with a conventional phased array. We implement a practical transmitter architecture for the DMA and phased array to account for the power consumption and hardware constraints of the radio frequency (RF) front end. Simulation results for a MISO scenario show that while the DMA performs worse in spectral efficiency than an active phased array, the power consumption savings from the reconfigurable component enable better performance in energy efficiency. Therefore, DMAs can provide an energy-efficient alternative to typical phased arrays. 

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