- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Polydispersed Metal Nanoparticles at the Interface for Improved Optoelectronic Properties in Perovskite Photovoltaics
摘要： This paper considers a multi-cell network with base stations (BSs) equipped with large dual-polarized antenna arrays. We derive closed-form expressions of network performance in terms of user signal-to-interference-and-noise ratio both with perfect channel state information and in the presence of pilot contamination. In general, a dual-polarized system enjoys the reduction in pilot contamination and multiuser interference due to orthogonal polarizations, while the available BS array dimension is reduced in each polarized direction compared with a monopole antenna setup. The derived results, however, reveal that the performance of a dual polarization system can be optimized by properly setting receive antenna polarizations, and fortunately, the optimal performance behaves identically to that of a monopole-antenna one in massive MIMO. We ?nally verify the observations by numerical simulations.
关键词： channel capacity,dual-polarized antenna,multi-cell,Massive MIMO,pilot contamination
更新于2025-09-16 10:30:52
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A Simple Resonant Switched Capacitor LED Driver Employed as a Fast Pulse-Based Transmitter for VLC Applications
摘要： With the rapid development of wireless communication networks, the need of massive Multiple-Input Multiple-Output (MIMO) to offer sufficient network capacity has become evident. As a part of array signal processing, direction-of-arrival (DoA) estimation is of vital importance to obtain directional information of sources and to enable the 3-D beamforming. In this paper, the performance of DoA estimation for massive MIMO systems is analyzed and compared using a low complexity algorithm. To be specific, 2-D unitary estimation of signal parameters via rotational invariance techniques (U-ESPRIT) algorithm is studied to jointly estimate elevation and azimuth information, and uniform rectangular array is selected to represent massive MIMO systems. The simulation results indicate that the U-ESPRIT algorithm works well for the massive MIMO systems. The performance has been evaluated with various types of antenna configuration and source numbers. Finally, the array resolution is adopted to analyze the performance of elevation and azimuth estimation and how to choose the appropriate antenna array configuration.
关键词： array resolution,DoA estimation,massive MIMO,unitary ESPRIT
更新于2025-09-16 10:30:52
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Self-assembled chiral nanoribbons studied by terahertz time-domain spectroscopy and other biological methods
摘要： Massive Multiple Input Multiple Output (MIMO) has been widely considered as one of the most promising technologies for the fifth-generation (5G) wireless communication. In massive MIMO system, the research on channel characteristics is important. In this paper, the characteristics for massive MIMO channels at both 2 GHz and 6 GHz are investigated. Based on the real-world measurements, the channel parameters in the delay and frequency domains are extracted to show the non-stationary phenomenon over the large-scale antenna array. Furthermore, the characteristics of the angular parameters extracted by space-alternating generalized expectation-maximization (SAGE) algorithm are investigated and the fluctuations are modeled. The results for different frequencies are useful for deep understanding of massive MIMO channels in the future.
关键词： Massive MIMO,Channel characteristics,Angular parameter
更新于2025-09-11 14:15:04
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Hybrid Precoding with Partially Connected Structure for mmWave Massive MIMO OFDM: A Parallel Framework and Feasibility Analysis
摘要： Hybrid precoding, a combination of digital and analog precoding, is an alternative to traditional precoding methods in massive MIMO systems with large number of antenna elements and has shown promising results recently. In this work, we implement a parallel framework to make hybrid precoding competitive in fast-fading environments. A low-complexity algorithm which exploits the block diagonal phase only nature of the analog precoder in a partially connected structure is proposed to arrive at a hybrid precoding solution for a multi-carrier single-user system using orthogonal frequency division multiplexing (OFDM). The original problem is broken down into two subproblems of finding the magnitude and the phase components which are solved independently. A per-RF chain power constraint is introduced instead of the sum power constraint over all antennas which is much more practical in real systems. An alternating version of the same algorithm is proposed for increased spectral-efficiency gains. Complexity and run-time analysis demonstrate the advantage of the proposed algorithm over existing hybrid precoding schemes for partially connected structure in an OFDM setting. Simulation results reveal certain insights about the partially connected structure and the trade-offs that have to be made to make it workable in a real wideband system.
关键词： partially connected structure,mmWave,massive MIMO,per-RF chain power constraint,Hybrid precoding,OFDM
更新于2025-09-10 09:29:36
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Beam-Time Block Coding With Joint User Grouping and Beamforming for FDD Massive MIMO Systems
摘要： A downlink (DL) precoding scheme that needs no DL training nor uplink (UL) feedback for massive MIMO systems operated under frequency-division duplex (FDD) is proposed, whereas most of the schemes in the literature were proposed to compress the overhead of training and feedback. Due to the above advantage, the proposed scheme is suitable for extremely low-latency applications. This scheme exploits angle reciprocity of FDD systems to enable the base station to acquire partial DL channel state information through a previous UL signaling. A joint user grouping and beamforming optimization method without DL training and UL feedback is proposed to enhance spectral efficiency and mitigate interference between multiple UEs during DL data transmission. Simulation results suggest that the proposed scheme possesses a comparable performance to a number of previous grouping-based schemes that require DL training and UL feedback.
关键词： angle reciprocity,no CSI feedback.,frequency-division duplex,Massive MIMO,beam-time block coding
更新于2025-09-10 09:29:36
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Line-Of-Sight Massive MIMO Channel Characteristics in an Indoor Scenario at 94 GHz
摘要： The fading and correlation characteristics of virtual, yet realistic, line-of-sight (LOS) 4 × 2500 millimetric (mmW) massive MIMO channels are investigated at 94 GHz in an indoor office environment for three different Tx–Rx distance scenarios. The capability of the mmW massive MIMO channel to spatially decorrelate the users is evaluated with the computation of the channel correlation and other channel metrics, such as power-to-interference ratio and condition number. In particular, the correlation between channel vectors for a given user and its influence on receiving correlation is discussed. The results clearly demonstrate the capability of mmW massive MIMO systems to reach orthogonal Tx–Rx streams even for a small 7 × 7 antenna array subset with correlation between users <0.2. Moreover, strong phase variations at Tx side at this frequency range are highlighted through channel phase correlation studies and were shown to contribute to the decorrelation at Rx side between close users, paving the way for further massive MIMO system enhancements.
关键词： massive MIMO,Millimeter wave,indoor propagation
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - First Commercial Hybrid Massive MIMO System for Sub-6Hz Bands
摘要： Massive multiple-input and multiple-output (MIMO) has been the subject of interest in both industry and academia for the past few years. Massive MIMO refers to the use of a large number of antennas typically at the base station (BS) to serve multiple user equipment (UE) simultaneously to deliver reliable and high data throughput. Two basic architectures have been considered in the literature. First is a full digital massive MIMO where all the beamforming and precoding is performed digitally in baseband and a radio frequency (RF) chain is required for every antenna element. In the second architecture referred to as hybrid massive MIMO, beamforming and precoding are done in two stages, digital precoding over fewer digital ports followed by analog beamforming across large number of antenna elements. In this paper, we provide a comparison of implementation challenges for each approach. We introduce the High Definition Active Antenna System (HDAAS), a novel scalable architecture to implement a hybrid Massive MIMO system. This design philosophy is used to build BeamCraft500, which we believe is a first commercial hybrid 3D beamforming system operating at 2 GHz. We also present results from one of the field trials in a live LTE network that validate the stability and performance of the system under real world conditions.
关键词： 3D beamforming,HDAAS,Hybrid Massive MIMO,LTE,Massive MIMO,BeamCraft500
更新于2025-09-09 09:28:46
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Optimal Hybrid Beamforming for Multiuser Massive MIMO Systems with Individual SINR Constraints
摘要： In this letter, we consider optimal hybrid beamforming design to minimize the transmission power under individual signal-to-interference-plus-noise ratio (SINR) constraints in a multiuser massive multiple-input-multiple-output (MIMO) system. This results in a challenging non-convex optimization problem. We consider two cases. In the case where the number of users is smaller than or equal to that of radio frequency (RF) chains, we propose a low-complexity method to obtain a globally optimal solution and show that it achieves the same transmission power as an optimal fully-digital beamformer. In the case where the number of users is larger than that of RF chains, we propose a low-complexity globally convergent alternating algorithm to obtain a stationary point.
关键词： power minimization,penalty method,hybrid beamforming,Multiuser massive MIMO
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Millimeter Wave Massive MIMO with Alamouti Code and Imperfect Channel State Information
摘要： Massive MIMO is one of the technologies considered in 5G to provide a much higher capacity without requiring more wireless spectrum. Because of the congestion in the radio frequency spectrum below 6 GHz, the millimeter Wave (mmWave) band has increasingly become more attractive to researchers since it offers a much larger unused bandwidth. However, the higher path loss at mmWave frequencies and the poor scattering nature of the mmWave channel (fewer paths exist) represent a challenge for communications. A hybrid beamforming technique with large antenna arrays and the Alamouti coding scheme are used in this paper to improve the performance of a single-user mmWave massive MIMO system. When perfect Channel State Information (CSI) is not available at the Base Station (BS), computer simulations have shown that a gain of 20 dB or more can be achieved by using the Alamouti code compared to the system with hybrid beamforming only, and more importantly, the error probability does not level off.
关键词： hybrid precoding and combining,mmWave communication,Massive MIMO,Alamouti Code
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE Global Communications Conference (GLOBECOM 2017) - Singapore (2017.12.4-2017.12.8)] GLOBECOM 2017 - 2017 IEEE Global Communications Conference - Polar Decomposition Based Hybrid Beamforming Design for mmWave Massive MIMO Systems
摘要： This paper considers hybrid beamforming (HBF) for the point-to-point (P2P) millimeter wave (mmWave) massive MIMO systems. The optimal hybrid precoding and combining matrices that maximizes the system capacity can be obtained based on the singular value decomposition (SVD) of the channel matrix. Then, the optimal unconstrained hybrid digital and analog precoders (combiners) are designed according to the polar decomposition of the optimal hybrid precoding (combining) matrix. Considering the actual hardware constraints, we propose a joint transmitter and receiver HBF algorithm based upon polar decomposition. In this algorithm, the hybrid analog constrained precoding and combining matrices can be derived without having to incur an excessive computational complexity of an iterative approach. Simulation results show that the proposed algorithm can approach the performance of optimal unconstrained precoding, and is insensitive to the accuracy of the channel state information (CSI).
关键词： spectral efficiency,polar decomposition,massive MIMO,Hybrid beamforming,millimeter wave
更新于2025-09-09 09:28:46