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1. A New Reconfigurable Antenna MIMO Architecture for mmWave Communication

   https://doi.org/10.1109/ICC.2018.8422414  

   Almasi, Mojtaba Ahmadi ; Mehrpouyan, Hani ; Vakilian, Vida ; Behdad, Nader ; Jafarkhani, Hamid ( May 2018 , 2018 IEEE International Conference on Communications (ICC))

   The large spectrum available in the millimeter- Wave (mmWave) band has emerged as a promising solution for meeting the huge capacity requirements of the 5th generation (5G) wireless networks. However, to fully harness the potential of mmWave communications, obstacles such as severe path loss, channel sparsity and hardware complexity should be overcome. In this paper, we introduce a generalized reconfigurable antenna multiple-input multiple-output (MIMO) architecture that takes advantage of lens-based reconfigurable antennas. The considered antennas can support multiple radiation patterns simultaneously by using a single RF chain. The degrees of freedom provided by the reconfigurable antennas are used to, first, combat channel sparsity in MIMO mmWave systems. Further, to suppress high path loss and shadowing at mmWave frequencies, we use a rate- one space-time block code. Our analysis and simulations show that the proposed reconfigurable MIMO architecture achieves full-diversity gain by using linear receivers and without requiring channel state information at the transmitter. Moreover, simulations show that the proposed architecture outperforms traditional MIMO transmission schemes in mmWave channel settings. 

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2. A New Reconfigurable Antenna MIMO Architecture for mmWave Communication

   M. A. Almasi, H. Mehrpouyan ( May 2018 , IEEE International Conference on Communications (ICC-18))

   The large spectrum available in the millimeter- Wave (mmWave) band has emerged as a promising solution for meeting the huge capacity requirements of the 5th generation (5G) wireless networks. However, to fully harness the potential of mmWave communications, obstacles such as severe path loss, channel sparsity and hardware complexity should be overcome. In this paper, we introduce a generalized reconfigurable antenna multiple-input multiple-output (MIMO) architecture that takes advantage of lens-based reconfigurable antennas. The considered antennas can support multiple radiation patterns simultaneously by using a single RF chain. The degrees of freedom provided by the reconfigurable antennas are used to, first, combat channel sparsity in MIMO mmWave systems. Further, to suppress high path loss and shadowing at mmWave frequencies, we use a rate one space-time block code. Our analysis and simulations show that the proposed reconfigurable MIMO architecture achieves full-diversity gain by using linear receivers and without requiring channel state information at the transmitter. Moreover, simulations show that the proposed architecture outperforms traditional MIMO transmission schemes in mmWave channel settings. 

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3. Massive MIMO in 5G: How Beamforming, Codebooks, and Feedback Enable Larger Arrays

   https://doi.org/10.1109/MCOM.001.2300064  

   Dreifuerst, Ryan M. ; Heath, Robert W. ( December 2023 , IEEE Communications Magazine)

   Massive multiple-input multiple-output (MIMO) is an important technology in fifth generation (5G) cellular networks and beyond. To help design the beamforming at the base station, 5G has introduced new support in the form of flexible feedback and configurable antenna array geometries that allow for arbitrarily massive phys- ical arrays. In this article, we present an overview of MIMO throughout the mobile standards, highlight the new beam-based feedback system in 5G NR, and de- scribe how this feedback system enables massive MIMO through beam management. Finally, we conclude with challenges related to massive MIMO in 5G. 

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4. A Pattern Reconfigurable Conformal mmWave Antenna for 5G Applications

   https://doi.org/10.1109/APS/URSI47566.2021.9704230  

   Stroh, Antonio ; Sigda, Matthew ; Carbone, Kevin ; Baun, Dillon ; Tajin, Md Abu ; Bshara, Oday ; Pano, Vasil ; Dandekar, Kapil R. ( December 2021 , 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI))

   We present a pattern reconfigurable conformal mmWave antenna at 28 GHz for 5G applications. Using a T-junction power divider and PIN diodes, eight 2×2 sub-arrays of microstrip patches are configured to radiate independently creating separate states capable of 360° of discrete coverage. 

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5. Comparative Performance Evaluation of mmWave 5G NR and LTE in a Campus Scenario

   Tehrani-Moayyed, M. ; Restuccia, F. ; Basagni, S. ( October 2020 , Proceedings of IEEE VTC 2020 Fall)

   The extremely high data rates provided by communications in the millimeter-length (mmWave) frequency bands can help address the unprecedented demands of next-generation wireless communications. However, atmospheric attenuation and high propagation loss severely limit the coverage of mmWave networks. To overcome these challenges, multi-input-multi-output (MIMO) provides beamforming capabilities and high-gain steer- able antennas to expand communication coverage at mmWave frequencies. The main contribution of this paper is the per- formance evaluation of mmWave communications on top of the recently released NR standard for 5G cellular networks. Furthermore, we compare the performance of NR with the 4G long-term evolution (LTE) standard on a highly realistic campus environment. We consider physical layer constraints such as transmit power, ambient noise, receiver noise figure, and practical antenna gain in both cases, and examine bitrate and area coverage as the criteria to benchmark the performance. We also show the impact of MIMO technology to improve the performance of the 5G NR cellular network. Our evaluation demonstrates that 5G NR provides on average 6.7 times bitrate improvement without remarkable coverage degradation. 

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