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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • Schottky diodes
  • frequency multipliers
  • submillimeter-wave technology
  • terahertz technology.
  • Submillimeter-wave sources
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • California Institute of Technology
201 条数据
?? 中文（中国） ▾

  • [IEEE 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Sheffield (2018.7.8-2018.7.11)] 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - An Adaptive Sequential Competition Test for Beam Selection in Massive MIMO Systems

    摘要： To solve the problem of beam selection or capturing the highest possible signal power, we propose a sequential test that can adapt to the SNR operating point and speed up the selection procedure in terms of the number of required observations in comparison to a perfectly tuned fixed length test assuming genie knowledge. The speed up gets higher for lower SNR and becomes of particular interest in massive Multiple Input Multiple Output (MIMO) systems using beamforming, where the number of candidate beams is large and exhaustive search can cause intolerable delay due to limited channel coherence time.

    关键词： Generalized Likelihood Ratio Test,Millimeter wave,Sequential Test,Beam Selection,Massive MIMO

    更新于2025-09-23 15:22:29

  • Soft-Output Detection Methods for Sparse Millimeter Wave MIMO Systems with Low-Precision ADCs

    摘要： In this paper, we propose computationally-efficient yet near-optimal soft-output detection methods for coded millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems with low-precision analog-to-digital converters (ADCs). The underlying idea of the proposed methods is to construct an extremely sparse inter-symbol-interference (ISI) channel model by jointly exploiting the delay-domain sparsity in mmWave channels and a high quantization noise caused by low-precision ADCs. Then we harness this sparse channel model to create a trellis diagram with a reduced number of states and a factor graph with very sparse edge connections, which are used for computationally-efficient soft-output detection methods. Using the reduced trellis diagram, we present a soft-output detection method that computes the log-likelihood ratios (LLRs) of coded bits by optimally combining the quantized received signals obtained from multiple receive antennas using a forward-and-backward algorithm. To reduce the computational complexity further, we also present a low-complexity detection method using the sparse factor graph to compute the LLRs in an iterative fashion based on a belief propagation algorithm. Simulations results demonstrate that the proposed soft-output detection methods provide significant frame-error-rates gains compared to the existing frequency-domain equalization techniques in a coded mmWave MIMO system using one or two bit ADCs.

    关键词： soft-output detection,time-domain equalization,low-precision analog-to-digital converter (ADC),multiple-input-multiple-output (MIMO),Millimeter wave communications

    更新于2025-09-23 15:22:29

  • [IEEE 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Boston, MA, USA (2018.7.8-2018.7.13)] 2018 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) - Sub-Diffraction Holographic Imaging with Resonant Scatterers in Proximity of the Objects

    摘要： To overcome the well-known 'diffraction limit' in the resolution of electromagnetic imaging systems, we propose the use of resonant near-field scatterers incorporated in the holographic imaging techniques. These scatterers convert a portion of the evanescent spectrum in the proximity of the object to propagating spectrum which is measurable by the antenna in the far-field.

    关键词： microwave and millimeter wave imaging,sub-diffraction imaging,resonant scatterers

    更新于2025-09-23 15:22:29

  • A Spectrum-Based Saliency Detection Algorithm for Millimeter-Wave InSAR Imaging with Sparse Sensing

    摘要： Object detection in millimeter-wave Interferometric Synthetic Aperture Radiometer (InSAR) imaging is always a crucial task. Facing unpredictable and numerous objects, traditional object detection models running after the InSAR system accomplishing imaging suffer from disadvantages such as complex clutter backgrounds, weak intensity of objects, Gibbs ringing, which makes a general purpose saliency detection system for InSAR necessary. This letter proposes a spectrum-based saliency detection algorithm to extract the salient regions from unknown backgrounds cooperating with sparse sensing InSAR imaging procedure. Directly using the interferometric value and sparse information of scenes in the basis of the Discrete Cosine Transform (DCT) domain adopted by InSAR imaging procedure, the proposed algorithm isolates the support of saliency region and then inversely transforms it back to calculate the saliency map. Comparing with other detecting algorithms which run after accomplishing imaging, the proposed algorithm will not be affected by information-loss accused by imaging procedure. Experimental results prove that it is effective and adaptable for millimeter-wave InSAR imaging.

    关键词： InSAR,saliency,millimeter-wave,sparse

    更新于2025-09-23 15:22:29

  • Spatial-Based Chipless RFID System

    摘要： Conventional techniques in chipless RFID systems are incapable of fully overcoming the key challenges of modern identification applications, including high data capacity, low tag cost and reliable operation. The idea of electromagnetic (EM) imaging in chipless RFID systems is a promising technique that shows many advantages over other conventional approaches. This paper reviews conventional chipless RFID technology and provides a comprehensive analysis of advanced millimeter wave spatial-based (also known as image-based) chipless RFID systems with an optimized MIMO-SAR technique for high-resolution image acquisition and a quick reading process.

    关键词： Multiple-input multiple-output (MIMO),Millimeter wave (mmwave),Chipless radio frequency identification (RFID),EM imaging,Virtual antenna array,Synthetic aperture radar (SAR)

    更新于2025-09-23 15:22:29

  • Improvement of 60 GHz transparent patch antenna array performance through specific double-sided micrometric mesh metal technology

    摘要： This paper presents the performance of optically transparent 4 × 2 microstrip patch antenna arrays operating at 60 GHz and made from double-sided micrometric mesh metal layers. A high level of optical transparency (higher than 80%) over the entire visible light spectrum coupled with a sheet resistance lower than 0.5 Ω/sq of the mesh metal films are achieved. Microwave performance of the transparent antenna arrays has been performed from two different mesh ground plane patterns and compared with those of an opaque antenna array made of double-sided continuous metal films. A gain value equal to 13.6 dBi at 58.0 GHz has been recorded, against 15.6 dBi at 59.7 GHz for the opaque antenna array. The influence of the mesh structure and mesh parameters of the ground plane is investigated and discussed.

    关键词： millimeter wave antenna,Micrometric metal mesh,optically transparent antenna.,microstrip antenna arrays

    更新于2025-09-23 15:22:29

  • [IEEE 2018 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM) - Nagoya (2018.8.29-2018.8.31)] 2018 IEEE International Workshop on Electromagnetics:Applications and Student Innovation Competition (iWEM) - E-Plane Beam-Forming Performance of Rotman-Lens in Multi-Layer Substrate

    摘要： A two-dimensional Rotman-lens feeding circuit was proposed for planar two-dimensional multi-beam antenna using multi-layer substrate integrated waveguide in the millimeter-wave band. In this work, an E-plane Rotman-lens for two-dimensional Rotman-lens was designed and the E-plane beam-forming performance was evaluated by array factors from the simulated S-parameters.

    关键词： multi-beam antenna,feeding circuit,multi-layer substrate,millimeter-wave,Rotman-lens

    更新于2025-09-23 15:22:29

  • [IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - High-Power Photonic Phased Array Antennas

    摘要： We review recent work on a new antenna concept— the high-power photonic phased array. By integrating high-power photodiodes proximal to the transmit aperture’s radiating elements, dense, lightweight, and broadband array designs are realized. Several manifestations of this idea are discussed, emphasizing different application-specific design choices.

    关键词： RF photonics,ultra-wideband (UWB),photonic antenna,phased array antenna,5G,high-power photodiode,millimeter wave (mmW)

    更新于2025-09-23 15:22:29

  • Measurements of Beamswitching Gains and Fade Dynamics for 28 GHz Indoor Static Links in the Presence of Pedestrian Traffic

    摘要： We measured channel dynamics for fixed wireless indoor channels at 28 GHz. We characterize pedestrian-induced fades in open indoor spaces and the effectiveness of beamswitching to mitigate them. We find that fades of the dominant propagation path may be as deep as 9 dB at the 90th percentile and that alternative signal paths are typically not strong enough to provide significant beamswitching gains.

    关键词： Millimeter wave propagation,Rician channels,Channel models,Multipath channels,Fading channels

    更新于2025-09-23 15:22:29

  • Hybrid Beamforming for Millimeter Wave Systems Using the MMSE Criterion

    摘要： Hybrid analog and digital beamforming (HBF) has recently emerged as an attractive technique for millimeter-wave (mmWave) communication systems. It well balances the demand for sufficient beamforming gains to overcome the propagation loss and the desire to reduce the hardware cost and power consumption. In this paper, the mean square error (MSE) is chosen as the performance metric to characterize the transmission reliability. Using the minimum sum-MSE criterion, we investigate the HBF design for broadband mmWave transmissions. To overcome the difficulty of solving the multi-variable design problem, the alternating minimization method is adopted to optimize the hybrid transmit and receive beamformers alternatively. Specifically, a manifold optimization based HBF algorithm is firstly proposed, which directly handles the constant modulus constraint of the analog component. Its convergence is then proved. To reduce the computational complexity, we then propose a low-complexity general eigenvalue decomposition based HBF algorithm in the narrowband scenario and three algorithms via the eigenvalue decomposition and orthogonal matching pursuit methods in the broadband scenario. A particular innovation in our proposed alternating minimization algorithms is a carefully designed initialization method, which leads to faster convergence. Furthermore, we extend the sum-MSE based design to that with weighted sum-MSE, which is then connected to the spectral efficiency based design. Simulation results show that the proposed HBF algorithms achieve significant performance improvement over existing ones, and perform close to full-digital beamforming.

    关键词： Minimum mean square error (MMSE),Alternating optimization,Manifold optimization (MO),Hybrid analog and digital beamforming (HBF),Millimeter-wave (mmWave) communications

    更新于2025-09-23 15:22:29