Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
11,329
result(s) for
"Millimeter waves"
Sort by:
5G mmWave patch antenna array with proximity sensing function for detecting user's hand grip on mobile terminals
We propose a new concept millimetre‐wave patch antenna that integrates the functions of an antenna and a capacitive proximity sensor to detect the hand grip state for 5G mobile terminals and compensate for the hand effect. The proposed antenna has the structure of a proximity‐coupled fed patch and functions as a proximity sensor by using the capacitance change of the patch that occurs when the user's hand approaches the patch. By observing the capacitance change at the centre of the patch operating in the TM01 mode, it is possible to simultaneously perform the functions of antenna and sensor without mutual interference. The proposed antenna is implemented as a 1 × 4 array. The experimental results show that it has a stable gain of 8.3 to 10.1 dBi at 26.5 to 29.5 GHz and can operate as a proximity sensor with a capacitance change of 200 fF according to the proximity of the hand. The authors propose a new concept millimetre‐wave patch antenna that integrates the functions of an antenna and a capacitive proximity sensor to detect the hand grip state for 5G mobile terminals and compensate for the hand effect. The proposed antenna has the structure of a proximity‐coupled fed patch and functions as a proximity sensor by using the capacitance change of the patch that occurs when the user's hand approaches the patch.
Journal Article
Vision Channel Knowledge Map‐Aided mmWave Beam Selection in V2I Communications
Vision‐aided millimetre wave beam selection has gained widespread attention because of its ability to reduce pilot overhead. However, its practical deployment faces challenges due to image transmission latency and high computational overhead. In this letter, we propose a novel environment‐aware communication method called the vision channel knowledge map (VCKM), which minimises redundant image information and improves beam selection performance. To evaluate the method, we use the ViWi colo‐cam scenario dataset, simulation results show that the VCKM‐aided beam selection has better performance than the existing solutions. Vision‐aided millimetre wave beam selection reduces pilot overhead but suffers from high transmission latency and computational costs. To address this, we propose the vision channel knowledge map (VCKM), an environment‐aware framework that eliminates redundant image data to enhance beam selection. Simulation results on the ViWi dataset demonstrate that VCKM outperforms conventional baselines in both efficiency and accuracy.
Journal Article
A survey of millimeter wave communications (mmWave) for 5G: opportunities and challenges
With the explosive growth of mobile data demand, the fifth generation (5G) mobile network would exploit the enormous amount of spectrum in the millimeter wave (mmWave) bands to greatly increase communication capacity. There are fundamental differences between mmWave communications and existing other communication systems, in terms of high propagation loss, directivity, and sensitivity to blockage. These characteristics of mmWave communications pose several challenges to fully exploit the potential of mmWave communications, including integrated circuits and system design, interference management, spatial reuse, anti-blockage, and dynamics control. To address these challenges, we carry out a survey of existing solutions and standards, and propose design guidelines in architectures and protocols for mmWave communications. We also discuss the potential applications of mmWave communications in the 5G network, including the small cell access, the cellular access, and the wireless backhaul. Finally, we discuss relevant open research issues including the new physical layer technology, software-defined network architecture, measurements of network state information, efficient control mechanisms, and heterogeneous networking, which should be further investigated to facilitate the deployment of mmWave communication systems in the future 5G networks.
Journal Article
Acquisition of channel state information for mmWave massive MIMO: traditional and machine learning-based approaches
The accuracy of channel state information (CSI) acquisition directly affects the performance of millimeter wave (mmWave) communications. In this article, we provide an overview on CSI acquisition, including beam training and channel estimation for mmWave massive multiple-input multiple-output systems. The beam training can avoid the estimation of a high-dimension channel matrix, while the channel estimation can flexibly exploit advanced signal processing techniques. In addition to introducing the traditional and machine learning-based approaches in this article, we also compare different approaches in terms of spectral efficiency, computational complexity, and overhead.
Journal Article
Investigating Enols Chemistry in the Interstellar Medium: Rotational Spectroscopy and Interstellar Search of (E)-1-Propenol
Enols represent highly reactive intermediates toward the synthesis of complex organic molecules in the interstellar medium (ISM) and serve as key tracers of nonequilibrium chemistry driven by Galactic cosmic rays. However, only few enols have been identified in the ISM, thus limiting the insights that can be derived from their observations. To expand the inventory of interstellar enols and improve our understanding of their chemistry, we provide the first spectroscopic characterization of 1-propenol, one of the simplest enols potentially observable in the ISM, which is a key step toward enabling its astronomical detection. 1-Propenol was generated through the retro Diels–Alder reaction of 3-methylnorborn-5-en-2-ol using a flash vacuum pyrolysis apparatus, and its rotational spectrum was recorded between 80 and 500 GHz using a millimeter/submillimeter-wave frequency-modulation spectrometer. High-level quantum chemical calculations supported the spectral analysis and provided accurate predictions of spectroscopic parameters. Over 2200 rotational transitions of (E)-1-propenol were successfully assigned and analyzed with the XIAM code, yielding precise rotational and centrifugal distortion constants and the methyl internal rotation barrier. Despite being essentially isoenergetic with the E form, (Z)-1-propenol could not be identified in our spectrum due to the experimental conditions. A targeted astronomical search was also carried out toward the Galactic center molecular cloud G+0.693-0.027 using ultrasensitive millimeter-wave surveys, which, however, did not reveal any hints of emission from (E)-1-propenol. Only an upper limit for its column density could be derived, which is fully consistent with ratios observed for other keto-enol pairs, indicating that more sensitive observations are required.
Journal Article
Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region
Millimeter wave fixed wireless systems in future backhaul and access network applications can be affected by weather conditions. The losses caused by rain attenuation and antenna misalignment due to wind-induced vibrations have greater impacts on the link budget reduction at E-band frequencies and higher. The current International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation has been widely used to estimate rain attenuation, and the recent Asia Pacific Telecommunity (APT) report provides the model to estimate the wind-induced attenuation. This article provides the first experimental study of the combined rain and wind effects in a tropical location using both models at a frequency in the E band (74.625 GHz) and a short distance of 150 m. In addition to using wind speeds for attenuation estimation, the setup also provides direct antenna inclination angle measurements using the accelerometer data. This solves the limitation of relying on the wind speed since the wind-induced loss is dependent on the inclination direction. The results show that the current ITU-R model can be used to estimate the attenuation of a short fixed wireless link under heavy rain, and the addition of wind attenuation via the APT model can estimate the worst-case link budget during high wind speeds.
Journal Article
Compact Quad-Element High-Isolation Wideband MIMO Antenna for mm-Wave Applications
This paper presents a multiple-input multiple-output (MIMO) antenna system for millimeter-wave 5G wireless communication services. The proposed MIMO configuration is composed of four antenna elements, where each antenna possesses an HP-shaped configuration that features simple configuration and excellent performance. The proposed MIMO design can operate at a very wideband of 36.83–40.0 GHz (measured). Furthermore, the proposed MIMO antenna attains a peak gain of 6.5 dB with a maximum element-isolation of −45 dB. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain, and channel capacity (CCL) are analyzed, which demonstrate good characteristics across the operating band. The proposed antenna radiates efficiently with a radiation efficiency of above 80% at the desired frequency band which makes it a potential contender for the upcoming communication applications. The proposed design simulations were performed in the computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one.
Journal Article
Deep Learning Architectures for Accurate Millimeter Wave Positioning in 5G
The introduction of 5G’s millimeter wave transmissions brings a new paradigm to wireless communications. Whereas physical obstacles were mostly associated with signal attenuation, their presence now adds complex, non-linear phenomena, including reflections and scattering. The result is a multipath propagation environment, shaped by the obstacles encountered, indicating a strong presence of hidden spatial information within the received signal. To untangle said information into a mobile device position, this paper proposes the usage of neural networks over beamformed fingerprints, enabling a single-anchor positioning approach. Depending on the mobile device target application, positioning can also be enhanced with tracking techniques, which leverage short-term historical data. The main contributions of this paper are to discuss and evaluate typical neural network architectures suitable to the beamformed fingerprint positioning problem, including convolutional neural networks, hierarchy-based techniques, and sequence learning approaches. Using short sequences with temporal convolutional networks, simulation results show that stable average estimation errors of down to 1.78 m are obtained on realistic outdoor scenarios, containing mostly non-line-of-sight positions. These results establish a new state-of-the-art accuracy value for non-line-of-sight millimeter wave outdoor positioning, making the proposed methods very competitive and promising alternatives in the field.
Journal Article
Laboratory Detection of the Methoxymethyl Radical, CH3OCH2, Using Faraday Rotation and Chirped-pulse Techniques in the (Sub)millimeter Wave Range
Modeling the abundance of interstellar complex organic molecules in space is a major challenge for astrophysicists. The relative roles of gas-phase and grain-surface processes in the formation and destruction of such large molecules remain unclear. Methyl formate (CH3OCHO, MF) and dimethyl ether (CH3OCH3, DME) species have been detected at relatively high abundances in both warm and cold objects of the interstellar medium (ISM), challenging an initial hypothesis favoring grain-surface processes for their formation. In this context, the methoxymethyl radical (CH3OCH2, RDME) has been proposed as a key species linking the abundances of MF and DME in the gas phase. Its detection may provide crucial information to disentangle and quantify the different processes involved in the formation and destruction of MF and DME. To support the search for RDME in space, we present the laboratory detection of its pure rotational spectrum in the vibronic ground state. Special care was taken to measure the frequencies of transitions expected to be intense under cold interstellar conditions. In total, we assigned and fitted 1007 transitions of the RDME with N′ and Ka′ values up to 34 and 5, respectively. A reliable spectral catalog has been generated using the spectroscopic parameters derived from the fit and can be used confidently for future searches of the RDME radical in the ISM.
Journal Article