| 1. |
- Bressner, Thomas A.H., et al.
(author)
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Cell Partitioning Antenna System Performance in Multi-User Scenarios for mmWave Communications
- 2021
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In: IEEE Access. - 2169-3536 .- 2169-3536. ; 9, s. 127141-127149
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Journal article (peer-reviewed)abstract
- Fixed-beam, high-gain antenna systems can be used for a finer partitioning of the currently used cell-sectoring. This partitioning has the benefit of reducing the number of users seen per antenna beam, which reduces interference. Furthermore, the high antenna gain allows for a high effective isotropic radiated power while keeping the transmit power low. In this paper, we study the performance of such a fixed-beam, high gain antenna system design for millimeter-wave mobile communications. The antenna system is designed to keep the inter-sector interference in a multi-site scenario low. The performance is analyzed for single- and multi-user environments. In single-input single-output mode, the 50th percentile of the signal-to-interference-plus-noise ratio lies between 12.5 dB to 39.7 dB if 3 to 0 interferers are present, respectively. For multiple-input multiple-output transmission using zero-forcing, the signal-to-interference-plus-noise ratio increases and the 50th percentile ranges from 36.1 dB to 43.3 dB if 3 to 0 interferes are present, respectively. By using maximum ratio transmission, the best performance is achieved with no interferers present, while a plunge in performance is observed with interferers. Furthermore, the study revealed that the narrow beam antenna system can also provide a clear signal separation for small spatial separations. In the given example, the signal-to-interference-plus-noise ratio is larger than 32.1 dB with 11 active antenna elements, where 2.8 meters separate the users. Hence, the paper shows that the cell-partitioning antenna systems provide coverage in the desired area while keeping the inter-sector interference low, and the considered transmission techniques can be used for situation optimized mobile communication links.
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| 2. |
- Konstantinou, Dimitrios, et al.
(author)
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5G RAN architecture based on analog radio-over-fiber fronthaul over UDWDM-PON and phased array fed reflector antennas
- 2020
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In: Optics Communications. - : Elsevier BV. - 0030-4018. ; 454
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Journal article (peer-reviewed)abstract
- This manuscript introduces a 5G radio access network architecture concept based on ultra-dense wavelength division multiplexing (UDWDM) and incorporating an optical fronthaul network that uses a novel wireless antenna system for radio frequency transmission and reception. A ring topology is proposed where optical signals travel within the 5G UDWDM passive optical networks and millimeter waves are generated in the optical line terminals by optical heterodyning. The wireless transmission of the millimeter waves is conducted by an innovative phased array fed reflector antenna approach for mobile communications that grants high antenna gain due to highly focused radiation characteristics, as well as multiplexing gain by multiple beam generation. Furthermore, beam steering is provided by a radio frequency analog beamformer network. Finally, implementation options synthesizing the total system are discussed.
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| 3. |
- Aljarosha, Alhassan, 1982, et al.
(author)
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Performance comparison of silicon substrates for IC-waveguide integration based on a contactless transition at mm-wave frequencies
- 2019
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In: 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, APSURSI 2019 - Proceedings. ; July 2019, s. 1081-1082
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Conference paper (peer-reviewed)abstract
- This paper presents a comparison between different silicon (Si) substrates used in Si-based IC technologies at E-Band (71-86 GHz). A unique low-loss and compact contactless transition from a silicon IC (p-doped substrate) to a metal waveguide is used. The proposed transition incorporates a spatial power combiner to enable direct electromagnetic coupling from an array of patches on the IC to a metal waveguide. This design enables a high-power transition from an IC to a waveguide and/or antenna at millimeter-wave (mm-wave) frequencies, where a galvanic contact between the two parts is avoided.
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| 4. |
- Amani, Navid, 1985, et al.
(author)
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Multi-Panel Sparse Base Station Design with Physical Antenna Effects in Massive MU-MIMO
- 2020
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In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 69:6, s. 6500-6510
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Journal article (peer-reviewed)abstract
- A novel base station antenna (BSA) configuration is presented to mitigate degrading physical antenna effects in massive multiple-input multiple-output (MIMO) systems, while minimizing implementation complexities. Instead of using a commonly considered single antenna panel comprising of many elements covering a wide field-of-view (FOV) of 120 degrees, L tilted panels are used employing L times fewer elements and L times smaller FOV per panel. The spatial resolution of each panel is enhanced by employing sparse arrays with suppressed (grating-lobe) radiation outside its corresponding FOV. Therefore, more directive antenna elements can be deployed in each panel to compensate for the effective isotropic radiated power (EIRP) reduction. While sectorisation reduces the antenna gain variation in 120 degrees FOV, cooperation among multiple panels in downlink beamforming is seen to be capable of inter-panel interference suppression for sum-rate enhancement. A network model is used as a multi-user (MU) MIMO simulator incorporating both antenna and channel effects. It is shown that when the number of base station antennas is ten times the number of users, the average downlink sum-rate in pure line-of-sight (LOS), rich and poor multipath environments is increased up to 60.2%, 23% and 11.1%, respectively, by multi-panel sparse arrays applying zero-forcing (ZF) precoding.
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| 5. |
- Farid, N., et al.
(author)
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Exploring Uniformity of Reverberation Chambers: Insights from Antenna Reflection Coefficient
- 2024
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In: 18th European Conference on Antennas and Propagation, EuCAP 2024.
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Conference paper (peer-reviewed)abstract
- Reverberation chambers are widely recognized as a time-efficient testing facility for various applications. The spatial uniformity based on the power transfer function is a critical characteristic of the chamber that affects the measurement uncertainty. To gain more insights into the chamber behavior we introduce a complementary metric: the K-gamma factor. This metric, inspired by the well-established K-factor, quantifies the unstirred contributions of the chamber for each antenna individually and is highly sensitive to the chamber configuration and antenna placement. Analyzing this metric can help identify any undesired effect, such as specular reflections, and, ultimately, improve measurement accuracy. To highlight the usefulness of this metric, two different loading configurations of a reverberation chamber at millimeter-wave frequencies are evaluated as examples.
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| 6. |
- Smolders, Simon, et al.
(author)
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A Titanium(IV)-Based Metal-Organic Framework Featuring Defect-Rich Ti-O Sheets as an Oxidative Desulfurization Catalyst
- 2019
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 58:27, s. 9160-9165
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Journal article (peer-reviewed)abstract
- While titanium-based metal-organic frameworks (MOFs) have been widely studied for their (photo) catalytic potential, only a few Ti-IV MOFs have been reported owing to the high reactivity of the employed titanium precursors. The synthesis of COK-47 is now presented, the first Ti carboxylate MOF based on sheets of (TiO6)-O-IV octahedra, which can be synthesized with a range of different linkers. COK-47 can be synthesized as an inherently defective nanoparticulate material, rendering it a highly efficient catalyst for the oxidation of thiophenes. Its structure was determined by continuous rotation electron diffraction and studied in depth by X-ray total scattering, EXAFS, and solid-state NMR. Furthermore, its photoactivity was investigated by electron paramagnetic resonance and demonstrated by catalytic photodegradation of rhodamine 6G.
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