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Sökning: WFRF:(Glazunov Andres Alayon 1969) > (2020-2023)

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1.
  • Bagheri, Alireza, et al. (författare)
  • A 16 × 16 45° Slant-Polarized Gapwaveguide Phased Array With 65-dBm EIRP at 28 GHz
  • 2023
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:2, s. 1319-1329
  • Tidskriftsartikel (refereegranskat)abstract
    • A high equivalent isotropic radiated power (EIRP) active phased array antenna is proposed for fifth-generation (5G) communication systems at 28 GHz. The numerical design, measurements of a fabricated prototype, and performance analysis are presented. The antenna design is based on the gapwaveguide technology and consists of $16 \times 16$ single 45° slant-polarized elements. The proposed design uses a low complexity printed circuit board (PCB) structure with only six layers, i.e., a half of the existing wideband solutions. The array antenna incorporates up/downconverter integrated circuits (UDCs) and $1 \times 4$ transceiver beamformer integrated circuits (BFICs). Moreover, a compact and highly efficient transition at the end of each channel of the BFICs has been designed to interconnect the antenna elements with the PCB. The antenna's front-end loss, which includes the feed line, mismatch, and ohmic losses, is only 1.3 dB. The array covers the scanning range of ±60° in the azimuth plane and ±10° in the elevation plane. The $S_{11} < -10$ dB frequency bandwidth is from 26.5 to 29.5 GHz. The maximum EIRP of the antenna is 65.5 dBm at saturation point. The presented design offers a compact, robust, and low-loss performance solution meeting the high transmission power requirements of 5G applications.
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2.
  • Bagheri, Alireza, et al. (författare)
  • Micro strip to Ridge Gap Waveguide Transition for 28 GHz Steerable Slot Array Antennas
  • 2020
  • Ingår i: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - 2164-3342. - 9788831299008
  • Konferensbidrag (refereegranskat)abstract
    • In this paper three types of contactless vertical transitions from microstrip to double ridge waveguide are presented. The designs are compact in size and robust, with improved isolation by employing a pin structure, making them ideal for SG mmWave phased arrays. All transitions cover the 26.5 - 29.5 GHz band, their dimensions are less than half a wavelength in pitch and have insertion losses less than 0.6 dB. The three designs apply different matching strategies and offer a trade-off between bandwidth and PCB areas. Finally, the behavior within an array configuration is analyzed.
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3.
  • Bagheri, Alireza, et al. (författare)
  • TX Beamforming EVM Performance of a 65 dBm-EIRP Slant-Polarized Gapwaveguide Phased Array at 28 GHz
  • 2023
  • Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
  • Konferensbidrag (refereegranskat)abstract
    • The transmit error vector magnitude (EVM) performance measurements of a slant-polarized 28 GHz gapwaveguide-based phased array is analyzed in this paper. The performance is studied by using a large range of signals, with varied powers, symbol rates, and quadrature amplitude modulation (QAM) orders. The measurements have been conducted for four different scanning angles. A non-standardized over-the-air (OTA) link between the phased array and the receiver in a laboratory environment is used. The results show that the phased array antenna supports a 31 dB effective isotropic radiated power (EIRP) dynamic range at a maximum 2% EVM when transmitting a 64QAM modulated signal with 250 MS/s symbol rate at all scanning directions.
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4.
  • Bärring, Maja, 1988, et al. (författare)
  • Factory Radio Design of a 5G Network in Offline Mode
  • 2021
  • Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 9, s. 23095-23109
  • Tidskriftsartikel (refereegranskat)abstract
    • The manufacturing industry is connecting people and equipment with new digital technologies, enabling a more continuous stream of data to represent processes. With more things connected, the interest in a connectivity solution that can support communication with high reliability and availability will increase. The fifth generation of telecommunication, i.e., 5G has promising features to deliver this, but the factory environment introduces new challenges to ensure reliable radio coverage. This will require efficient ways to plan the Factory Radio Design prior to installation. 3D laser scanning is used at an ever-increasing rate for capturing the spatial geometry in a virtual representation to perform layout planning of factories. This paper presents how to combine 3D laser scanning and physical optics (PO) for planning the Factory Radio Design of a cellular Long-Term Evolution (LTE) network (5G) in a virtual environment. 3D laser scanning is applied to obtain the spatial data of the factory and the virtual representation serves as the environment where PO computation techniques can be performed. The simulation result is validated in this paper by comparison to measurements of the installed network and empirical propagation models. The results of the study show promising opportunities to simulate the radio coverage in a virtual representation of a factory environment.
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5.
  • Dang, Wen, et al. (författare)
  • Ultra-wideband, Wide Scanning Phased Array for SATCOM Ground Station
  • 2022
  • Ingår i: 2022 International Symposium on Antennas and Propagation, ISAP 2022. ; , s. 57-58
  • Konferensbidrag (refereegranskat)abstract
    • We present the unit cell of a linearly polarised, ultra-wideband (UWB), wide scanning array antenna based on the tightly-coupled dipole antenna (TCDA) concept for cost-effective Ku/Ka-band SATCOM ground station applications. The TCDA unit cell is fed by a coaxial structure and several vias are used to broaden the bandwidth. In addition, a superstrate, functioning as a wide angle impedance matching (WAIM) layer, is employed to achieve together with an E-wall to reduce surface-waves. The simulated results show that the proposed TCDA provide a large bandwidth from 10.6-27.8 GHz at VSWR ≤ 2.0 at broadside radiation. Scanning angles up to 65° and 75° at the E- and H-plane, respectively, are maintained over the desired frequency of 12-1S GHz at VSWR ≤ 2.5.
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6.
  • Glazunov, Andres Alayon, 1969, et al. (författare)
  • Emulating Rician distributed channels in a hybrid chamber for OTA measurements
  • 2021
  • Ingår i: 2020 International Symposium on Antennas and Propagation, ISAP 2020. ; , s. 549-550
  • Konferensbidrag (refereegranskat)abstract
    • It has been shown by means of simulations that the rich isotropic multipath and the random line-of-sight channels and other Rician channels in-between can be successfully generated in the same over-the-air hybrid measurement chamber without the use of additional static or moving scatterers.
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7.
  • Glazunov, Andres Alayon, 1969 (författare)
  • Impact of Test Zone Polarization-Imbalance on MIMO efficiency in a Random-LOS OTA Setup
  • 2022
  • Ingår i: 2022 International Symposium on Antennas and Propagation, ISAP 2022. ; , s. 521-522
  • Konferensbidrag (refereegranskat)abstract
    • Presented is an evaluation of the impact of the power imbalance between the vertical and horizontal polarization in the test zone of a random line-of-sight over-the-air characterization system on multiple-input multiple-output efficiency.
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8.
  • Glazunov, Andres Alayon, 1969, et al. (författare)
  • Impact of User Spread on the Input Power Spread in DL Massive MIMO in Random LOS Channels
  • 2020
  • Ingår i: 2020 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), USNC/URSI 2020 - Proceedings. ; , s. 67-68
  • Konferensbidrag (refereegranskat)abstract
    • Presented are the spread of the amplifier output power and the sum rate capacity loss of a narrowband massive MIMO antenna system in a Random-LOS channel due to cell-sector narrowing. Coupling effects between the array elements have been neglected. A large power spread of the output power of the amplifiers is observed when users are spread over narrow sectors and ZF-precoding is used. The capacity is considerably reduced for both MF- and ZF-precoding, especially for the latter.
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9.
  • Glazunov, Andres Alayon, 1969, et al. (författare)
  • Multipath Rician Channel Simulation in the Test Zone of a Hybrid OTA Chamber
  • 2021
  • Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021.
  • Konferensbidrag (refereegranskat)abstract
    • Multipath fields with ascribed Rician distribution parameters have been simulated in a novel hybrid chamber for over the air characterization of antenna systems and wireless devices. Simulations are based on waveguide mode summations representing a combination of the half-space rich isotropic multipath component and the on-axis line-of-sight component. It has been shown that the Rician distributed channels can be emulated without the use of additional static or moving scatterers.
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10.
  • Glazunov, Andres Alayon, 1969, et al. (författare)
  • Semi-Analytical Model of the Rician K-Factor
  • 2020
  • Ingår i: Radio Science. - 0048-6604 .- 1944-799X. ; 55:11
  • Tidskriftsartikel (refereegranskat)abstract
    • The analysis of the performance of 5G wireless communication systems employing Massive MIMO at millimeter-wave frequencies is of great practical relevance. Of special relevance are the signal fluctuations. In the present paper, we introduce a semi-analytical model for a generic scattering environment by using randomly distributed resonant scatterers to investigate the impact of the size of the scattering environment, the scatterer density, and the number of scatterers on the signal variability in terms of the Rician K-factor as a function of frequency. We further present an investigation of the impact of scattering on the frequency dependence of the signal fading statistics in the 500 MHz–100 GHz band. The simplified model is also verified against full-wave simulation using the Method of Moments (MoM).
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11.
  • Iupikov, Oleg, 1983, et al. (författare)
  • Hybrid OTA Chamber for Multi-Directional Testing of Wireless Devices: Plane Wave Spectrum Generator Design and Experimental Demonstration
  • 2022
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 70:11, s. 10974-10987
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper investigates practical implementation aspects of a novel hybrid chamber concept that has been recently introduced for over-the-air testing of wireless devices. The chamber allows to synthesize a spectrum of plane waves (PWs) incident on a device under test from a wide range of angles-of-arrival (AoAs) through exploiting multiple field scattering inside the overmoded waveguide chamber. An optimal design approach for the plane wave spectrum generator (PWSG) array inside the chamber is presented considering: (i) array antenna impedance matching for the desired test zone (TZ) quality and AoAs range; (ii) an operational frequency bandwidth of the test environment and an instantaneous signal bandwidth; and (iii) the impact of the PWSG excitation errors. A robust linearly constrained minimum variance (LCMV) beamformer is formulated to realize the desired test environment over a wide frequency band, while accounting for the varying number of the waveguide propagating modes as excited by the PWSG array. Numerical simulations and measurements with the first prototype of the hybrid chamber for FR1 frequency band (~3.5 GHz) are presented. This prototype includes a 7 × 7 bowtie antenna element PWSG array, a 1.00 × 1.25 × 1.75 m metal waveguide chamber, an off-line optimal array beamforming setup, and a planar scanner for the TZ characterization.
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12.
  • Iupikov, Oleg, 1983, et al. (författare)
  • The Hybrid Chamber for OTA measurements: Plane Wave Spectrum Quality Vs. Dynamic Range Trade-off
  • 2022
  • Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, the trade-off between the quality of the plane wave spectrum synthesized in the test zone of the hybrid over-the-air (OTA) chamber and factors affecting the dynamic range of this measurement system is investigated. The hybrid chamber performance is compared to a plane wave generator (PWG) in free space. The performance evaluation is focused on the field radiated into the test zone (TZ) while maintaining its quality according to 3GPP specification. It is demonstrated that a good quality can be achieved for the synthesized plane wave spectrum.
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13.
  • Kanters, Noud, et al. (författare)
  • A Supervised Learning Framework for Joint Estimation of Angles-of-Arrival and Number of Sources
  • 2022
  • Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 10, s. 112086-112099
  • Tidskriftsartikel (refereegranskat)abstract
    • Machine learning is a promising technique for angle-of-arrival (AOA) estimation of waves impinging a sensor array. However, the majority of the methods proposed so far only consider a known, fixed number of impinging waves, i.e., a fixed number of sources (NOS). This paper proposes a machine-learning-based estimator designed for the case when the NOS is variable and hence unknown a priori. The proposed estimator comprises a framework of single-label classifiers. Each classifier predicts if waves are present within certain randomly selected segments of the array's field of view (FOV), resulting from discretising the FOV with a certain (FOV) resolution. The classifiers' predictions are combined into a probabilistic angle spectrum, whereupon the NOS and the AOAs are estimated jointly by applying a probability threshold whose optimal level is learned from data. The estimator's performance is assessed using a new performance metric: the joint AOA estimation success rate. Numerical simulations show that for low SNR (-10 dB), a low FOV resolution (2°) yields a higher success rate than a high resolution (1°), whereas the opposite applies for mid (0 dB) and high (10 dB) SNRs. In nearly all simulations, except one at low SNR and a high FOV resolution, the proposed estimator outperforms the MUSIC algorithm if the maximum allowed AOA estimation error is approximately equal to (or larger than) the FOV resolution.
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14.
  • Kanters, Noud, et al. (författare)
  • Channel Estimation Errors and Their Impact on Irregular Array Performance in Massive MIMO
  • 2022
  • Ingår i: 2022 International Symposium on Antennas and Propagation, ISAP 2022. ; , s. 509-510
  • Konferensbidrag (refereegranskat)abstract
    • This paper considers the impact of imperfect channel state information (CSI) on the array antenna layout design in massive multiple-input multiple-output applications. The analysis is based on channel estimation errors resulting from the least squares estimation algorithm in pure line-of-sight channels. We show that signal to interference-plus-noise ratio gains traditionally anticipated with irregular layouts, as compared to regular ones under the assumption of perfect CSI, vanish in case of CSI imperfections for the considered scenario.
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15.
  • Kon, Ryosuke, et al. (författare)
  • Wideband H-slot antenna fed by substrate integrated gap waveguide for mmWave arrays
  • 2021
  • Ingår i: 2020 International Symposium on Antennas and Propagation, ISAP 2020. ; , s. 577-578
  • Konferensbidrag (refereegranskat)abstract
    • This paper proposes a wideband slot antenna design based on the substrate integrated gap waveguide technology for millimetre wave applications. The proposed antenna is realized using the H-shaped slot (H-slot) to improve impedance bandwdith. Simulation results show that the proposed antenna has an impedance bandwidth at S11 ≤-15 dB from 24-29.5 GHz resulting in a 20.5% fractional bandwidth. Hence, the designed slot antenna can potentially be used as the radiating element of an array antenna for fixed-beam point-to-point applications.
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16.
  • Krasov, Pavlo, 1981, et al. (författare)
  • Characterization and Calibration of the Hybrid OTA Chamber Using a Field Scanner
  • 2022
  • Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
  • Konferensbidrag (refereegranskat)abstract
    • This paper investigates the characterization and calibration procedure of the hybrid over-the-air (OTA) measurement chamber. We present a prototype of the hybrid chamber and analyze its capabilities to generate a plane wave spectrum in practice. A planar field scanner is used to acquire the embedded element fields of the chamber array for test zone (TZ) synthesis in post-processing. The repeatability of the field acquisition is evaluated. It is shown that the synthesized TZ meets the 3GPP specifications for TZ field variations for plane wave generators (PWG) in the presence of acquisition imperfections.
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17.
  • Krasov, Pavlo, 1981, et al. (författare)
  • Quiet Zone Quality of a Plane Wave Generator inside an Over-Moded Waveguide Chamber Emulating a Variable Angle of Incidence
  • 2021
  • Ingår i: 15th European Conference on Antennas and Propagation, EuCAP 2021.
  • Konferensbidrag (refereegranskat)abstract
    • We investigate the use of a hybrid over-the-air (OTA) measurement chamber to emulate far-field testing conditions. The focus has been on the generation of a plane wave arriving at an arbitrary angle-of-arrival (AoA) to the device-under-test (DUT) without mechanical steering. The chamber consists of an oversized waveguide (WG) and a planar array antenna with adaptive beamforming. A modified linear constrained minimum variance (LCMV) beamforming algorithm is used to form a quiet zone (QZ) in the DUT region by using the reflections from the WG's metal walls. The LCMV beamformer formulation has been extended to achieve a volumetric QZ with the desired amplitude and phase uniformity. Numerical studies for the QZ size corresponding to an FR1 base station demonstrate promising results with the low levels of amplitude and phase variation. The AoA coverage of this chamber meets 3GPP specification requirements for OTA conformance testing of base stations with active antenna systems.
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18.
  • Krasov, Pavlo, 1981, et al. (författare)
  • Reconfiguration Capabilities of the Anechoic-Reverberation Hybrid Chamber for TRP Measurements of Active Antenna Systems
  • 2023
  • Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
  • Konferensbidrag (refereegranskat)abstract
    • A hybrid, reconfigurable anechoic-reverberation antenna measurement chamber was recently introduced with the vision to enable fast characterization of the active antenna radiated power and directive characteristics in a single measurement environment. The initial studies included its design and analysis in the plane wave spectrum generator scenario. In the present work, we investigate chamber reconfiguration capabilities for performing total radiated power (TRP) measurements. We show how different types of interchangeable hybrid chamber modules allow realizing several possible ways of measuring TRP. Trade-offs in terms of measurement time and implementation complexity are discussed. Finally, one of the methods, using a chamber array antenna module, is selected and demonstrated in simulations. Our initial results indicate TRP measurement error within ±0.5 dB.
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19.
  • Maaskant, Rob, 1978, et al. (författare)
  • A New Hybrid Chamber for Generating a Spectrum of Oblique Incident Plane Waves at the DUT
  • 2021
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 69:10, s. 6806-6815
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel type of hybrid measurement facility comprising a chamber antenna array (CAA) inside an overmoded waveguide is proposed and analyzed numerically. The reflecting walls of the metal rectangular waveguide (WG) are used in conjunction with a CAA to synthesize obliquely incident plane wave (PW) fields at the device under test (DUT). This enables increased flexibility in emulating almost any PW multipath testing conditions in the WG chamber without the high cost and complexity of classical anechoic measurement systems employing relatively large phase-steered plane wave generators. A modeling framework is proposed that has been used to devise first-order design rules (e.g. the number of independent propagating modes, dimensions of the WG, CAA, and DUT). Afterwards, an optimally beamformed CAA example is presented to numerically validate the quality of the on- and off-axis plane wave fields in the test zone. This study shows design trade-offs between the amplitude ripple in the DUT region, the total power focused in this region, the DUT size and the angle of incidence.
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20.
  • Mahfouz, MHD Zaher, et al. (författare)
  • Impact of Ultra-Narrowband Interference on Wi-Fi Links: An Experimental Study
  • 2021
  • Ingår i: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 20:5, s. 3016-3030
  • Tidskriftsartikel (refereegranskat)abstract
    • We develop a systematic methodology to experimentally investigate the impact of interference from a non-listen-before-talk ultra-narrowband (UNB) signaling technique on Wi-Fi links. The methodology is based on a worst-case interference scenario, and consists of three investigating steps. This methodology is then applied to a measurement setup to practically study the case of 100 bps UNB signals interfering with an IEEE 802.11n transmission in the 2.4GHz band. Five different Wi-Fi devices are tested. The UNB signal is generated in two modulation schemes, the on-off-keying (OOK) and the Gaussian minimum-shift-keying. Both single and multiple simultaneous UNB interferers are considered. An analysis of the measurement results shows that three of the tested Wi-Fi devices cannot coexist with the considered non-listen-before-talk UNB communication system. The throughput performance analysis of the other tested devices shows that the OOK-modulated UNB signal has the least interfering impact, and the Wi-Fi pilot subcarriers are the most vulnerable to UNB interference. However, if a single UNB interferer avoids these subcarriers and employs the OOK-modulation scheme, then wireless coexistence is possible as long as the signal-to-interference ratio of Wi-Fi to UNB is greater than 30 dB, given that a drop to 75% of the maximum Wi-Fi throughput is acceptable.
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21.
  • Mahfouz, MHD Zaher, et al. (författare)
  • Measurement and Estimation Methodology for EMC and OTA Testing in the VIRC
  • 2023
  • Ingår i: IEEE Transactions on Electromagnetic Compatibility. - 0018-9375 .- 1558-187X. ; 65:1, s. 3-16
  • Tidskriftsartikel (refereegranskat)abstract
    • In recent years, promising results have been reported with the vibrating intrinsic reverberation chamber (VIRC) combining performance and cost-efficiency for electromagnetic compatibility (EMC) measurements. This also makes it a potentially attractive solution for over-the-air (OTA) testing, which is yet to be investigated. Therefore, this article proposes the first systematic and thorough methodology to characterize the VIRC for use in EMC and OTA testing of wireless baseband algorithms of narrow-band single-input single-output channels. This methodology has been developed to measure and estimate the channel first- and second-order temporal and spectral characteristics taking into consideration the effect of different carrier frequencies, rotational speeds of VIRC motors, and loading conditions. It is then applied to a channel setup inside a VIRC for a preliminary investigation before the VIRC itself is fully characterized. It is shown that mounting an absorber in a specific location on the hatch significantly improves the rejection rate of the chi-squared goodness-of-fit test for Rician distribution without increasing the K-factor above -10 dB over the frequency range 755-2740 MHz in the VIRC under investigation. However, the proposed methodology has been devised to be universal to any reverberation chamber, and the obtained results can be used to improve EMC testing due to the better understanding of the unique VIRC environment.
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22.
  • Manshari, Saeed, et al. (författare)
  • High-Performance Wideband Horn Antenna for Direction Arrays
  • 2020
  • Ingår i: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - 2164-3342.
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, a structure and design procedure of a novel double ridged horn antenna with a Gaussian amplitude radiation pattern and stable phase center for two-element direction finding arrays is presented. The radiation properties of the structure are improved through appropriate profiling of the ridge taper and utilization of an elliptical aperture. Furthermore, rigorous numerical optimization is employed to adjust the antenna geometry parameter values. The achieved impedance bandwidth (VSWR < 2) is from 1.5 GHz to 12 GHz (8:1). The antenna exhibits 7 dBi to 20 dBi gain, better than 85% aperture efficiency, > 10 dB side lobe level, as well as low phase center variation (< 5 cm over the operating band). The aforementioned features make the proposed antenna suitable for the amplitude and phase hybrid direction finding applications. The design is validated numerically in CST Microwave Studio.
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23.
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24.
  • Poordaraee, Mohammad, et al. (författare)
  • Chamber Array Antenna Layout for Compact OTA Measurements
  • 2020
  • Ingår i: 2020 14TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP 2020). - 2164-3342. - 9788831299008
  • Konferensbidrag (refereegranskat)abstract
    • An optimized irregular planar array antenna layout with uniform excitation of antenna elements is presented for Random-LOS OTA (Random Line-Of-Sight Over-The-Air) characterization setups. A plane wave is synthesized within a cylindrical 3D test zone at 2.7 GHz, which can be scaled to mmWave frequencies. The obtained thinned array achieves a 52% reduction of the number of elements and a 45% aperture size as compared to a uniform fully populated planar array with an inter-element distance of 0.93A, which is the optimum distance through [lambda/2, lambda] based on the presented cost function at this paper. The obtained maximum phase deviation and the maximum field amplitude deviation from the average field distribution in the 3D test zone of the proposed optimized chamber array antenna layout are approximately 6.4 and 3.9 dB, respectively. The numerical computation of the radiation pattern of a 10 x 10 element uniform planar array antenna as AUT (Antenna Under Test) placed within the test zone was performed too. Results show a rather good agreement between the radiation pattern to that obtained assuming far-field conditions.
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25.
  • Qin, C., et al. (författare)
  • Simulation based channel hardening of cell-free massive MIMO in mm-Wave
  • 2021
  • Ingår i: 2021 34th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2021.
  • Konferensbidrag (refereegranskat)abstract
    • In this paper, the spatial distribution of the channel hardening of cell-free massive MIMO array antenna topologies for mm-Wave communications is explored. The simulation of the propagation channels was performed by means of ray tracing computations. The channel hardening is evaluated in two different radio wave propagation channel conditions: first, an indoor office room furnished with desks, chairs and shelters and secondly, the same room without furniture. The spatial distribution of the channel hardening is investigated in both scenarios as a function of the number of antenna elements of the array. The simulation results show that the channel hardening effect is as expected larger in the furnished room as compared with the empty room. Also as expected, the channel hardening increases with the number of antenna elements. An interesting new observation is that the channel hardening is not uniformly distributed within the coverage area. Indeed, for the considered cell-free array antenna topologies and indoor propagation scenarios the channel hardening effect becomes lesser the closer the user gets to the antenna locations and near the walls of the rooms.
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26.
  • Qin, C., et al. (författare)
  • Simulation-based Investigation on Spatial Channel Hardening of Massive MIMO in Different Indoor Scenarios and with Different Array Topologies
  • 2020
  • Ingår i: 2020 33rd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2020.
  • Konferensbidrag (refereegranskat)abstract
    • Spatial channel hardening is one of the key properties of a massive MIMO system. In this paper, we investigate the spatial channel hardening based on ray tracing channel simulations with different array antenna topologies deployed in different radio wave propagation conditions. Investigated are 9 different indoor deployment scenarios of massive MIMO. Considered are the empty room, the rich-furniture room and the room-to-room scenarios, where massive multi-antennas are deployed in the co-located, the split and the cell-free array topologies. The simulation results show that the cell-free topology results in the most-spatially-hardened channel in target area, while the co-located antennas the least-spatially-hardened. It is also found that the convergence of channel spatial variations is consistent with the number of paths estimated in multipath scenarios, i.e., the more multipath components are estimated in a propagation scenario, the smaller the number of antennas is required for the channel to reach the spatially hardened state. In our simulations, the rom-to-room scenario leads to the most-spatially-hardened channel, while for the empty room scenario it is the opposite.
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27.
  • Schilliger Kildal, Madeleine, 1987, et al. (författare)
  • Evaluation of a Random Line-of-Sight Over-the-Air Measurement Setup at 28 GHz
  • 2021
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 69:8, s. 5008-5020
  • Tidskriftsartikel (refereegranskat)abstract
    • OTA measurement techniques have, and will continue to have, a key role in evaluating the performance of modern antennas and wireless devices. The new random line-of-sight (random-LOS) measurement setup, offers the evaluation of the OTA performance of different types of devices, for example car antennas and small wireless devices in the random-LOS environment. A plane wave is synthesized in the test zone of the OTA setup, where the far-field of a radio base station can be emulated. We present measurements and simulations of the random-LOS OTA measurement setup employing a reflector antenna, with a dual polarized linear array feed, operating at the 28 GHz band. An analysis of the power and phase field distributions in a cylinder and a circular test zone are presented. The computed standard deviation of the power distribution is approximately 1 dB within a circular test zone, with a diameter of 0.3 m. The standard deviation of the phase, within the same test zone, is less than 15 °. The radiation patterns of a horn antenna have been measured in the random-LOS measurement setup and shown a good agreement with the theoretical values.
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28.
  • Schilliger Kildal, Madeleine, 1987, et al. (författare)
  • Verification of the Random Line-of-Sight Measurement Setup at 1.5-3 GHz including MIMO Throughput Measurements of a Complete Vehicle
  • 2020
  • Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 69:11, s. 13165-13179
  • Tidskriftsartikel (refereegranskat)abstract
    • The performance evaluation of wireless systems is crucial for the development of future systems with more connected devices. It is essential to have an easy and relevant method for ensuring the wireless communication performance of the devices. We have recently developed a new random line-of-sight (random-LOS) measurement system for evaluating the communication performance of wireless devices, e.g., transceivers and antennas installed on a vehicle. In the measurement system, a plane wave is generated in the test zone emulating the far-field wave transmitted from a radio base station. In this paper we present both numerical simulations and actual experimental results of the random-LOS over-the-air (OTA) measurement setup operating in the 1.5-3 GHz band. The measurement accuracy is determined by the field variations within the test zone, where a smaller variation gives better measurement accuracy. In this paper the achieved accuracy expressed in terms of standard deviation (STD) was evaluated to be approximately 1 dB of the power within a cylindrical test zone of height 0.4 m and diameter 2 m. The active multiple-input multiple-output (MIMO) performance of antenna systems installed on an actual vehicle was measured and evaluated using the presented setup. A comparison to a theoretical zero forcing (ZF) receiver is also presented.
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29.
  • van Boeijen, Rutger, et al. (författare)
  • Impact of Manufacturing Tolerances of Waveguide Power Dividers on the Quiet Zone Quality of a Plane Wave Generator
  • 2021
  • Ingår i: 2021 15TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - 2164-3342.
  • Konferensbidrag (refereegranskat)abstract
    • The effects of manufacturing tolerances on the quiet zone quality of a plane wave generator have been investigated. Waveguide power dividers required in the passive power distribution network of a plane wave generator have been designed. Monte Carlo simulations of the S-parameters of the designed power splitters have been performed by varying the power dividers' dimensions within manufacturing tolerances assuming a normal distribution. Furthermore, the splitting ratios resulting from the randomization are assumed to be uniformly distributed as the input for evaluating the quiet zone by means of Monte Carlo simulations. Assuming a 20 by 20 squared cm quiet zone, it has been found that for the considered setup that: (i) the phase deviation in the quiet zone never exceeds +/- 4.79 degrees, and (ii) for the amplitude deviation, never exceeds +/- 0.91 dB within a single simulated quiet zone.
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30.
  • Van De Ven, Coen, et al. (författare)
  • Automotive RADAR Planar Antenna Optimization Based on Conformal Transformation Optics
  • 2023
  • Ingår i: 17th European Conference on Antennas and Propagation, EuCAP 2023.
  • Konferensbidrag (refereegranskat)abstract
    • A novel approach to mitigate diffraction effects from finite ground planes in antenna design is presented. The method is based on the conformal transformation optics. A computational framework has been developed to optimize the shape of the ground plane since it has a great impact on the beam ripple and width of the radiation pattern of an antenna. Due to the limited thickness of the outer wall of slotted waveguide antennas, it is not possible to shape this outer wall, which acts as the ground plane of the antenna. Conformal transformation optics presents a solution to virtually add a deformation without needing to change the physical shape of the ground plane. Although conformal transformation optics can also be applied to transverse-magnetic waves, large fluctuations in the dielectric constant with respect to the wavelength cannot be supported in practice. In order to mitigate this problem, we have proposed a rescaling of the dielectric constant. Furthermore, we derive the connection between conformal transformation optics and transverse electromagnetic modes, which serve as a tool for joint optimization of the radiation pattern together with the conformal transformation. This method is then used to optimize the radiation pattern of a slot antenna and evaluated for increasing curvature within the conformal transformation.Numerical computations have shown promising results, i.e. a reduction of the farfield ripple from 1.92 dB to 0.64 dB at a half-power beam-width of 112° at 77 GHz. This is a promising result for designing automotive radars with a wide field of view, especially, for advanced driver-assistance systems used in the corner radars. This will contribute to further improving safety on the roads.
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31.
  • Yang, Wenfei, et al. (författare)
  • Line-of-Sight Probability for Channel Modeling in 3-D Indoor Environments
  • 2020
  • Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:7, s. 1182-1186
  • Tidskriftsartikel (refereegranskat)abstract
    • A three-dimensional (3-D) analytical indoor line-of-sight (LOS) probability model is given in this letter. According to the indoor layout of a specific building, the proposed closed-form model can be used to compute the LOS probability in a 3-D environment. The model is validated in both single rooms and a typical office building by Monte Carlo simulations. Moreover, the coverage rate in a typical office building with a 3-D ultra-dense small cells network is evaluated based on the proposed LOS probability model. The numerical results show that the proposed model matches the simulations well in terms of both the LOS probability and the coverage rate.
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32.
  • Yong, Wai Yan, et al. (författare)
  • 4×4 magneto-electric dipole array with single-layer corporate-feed ridge gap waveguide for mmWave applications
  • 2021
  • Ingår i: 2020 International Symposium on Antennas and Propagation, ISAP 2020. ; , s. 573-574
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents simulations results of a 4×4 magneto-electric dipole (MED) array antenna fed by a single- layer corporate-feed ridge gap waveguide (RGW) for millimeter wave applications. The designed antenna model consists of two unconnected metal layers: the top radiating layer and the bottom corporate-feed RGW layer. Hence, the antenna profile can be lowered since no intermediate cavity layer is required. The MED radiating element shows a larger impedance bandwidth compared to the conventional single layer array antenna. The S11 ≤ -10 dB bandwidth of the simulated antenna is from 24 - 29 GHz, resulting in a 18.9% impedance bandwidth. The realized antenna gain is greater than approximately 19.6 dBi.
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33.
  • Yong, Wai Yan, et al. (författare)
  • 5G Wideband Magneto-Electric Dipole Antenna Fed by a Single-Layer Corporate-Feed Network based on Ridge Gap Waveguide
  • 2020
  • Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020.
  • Konferensbidrag (refereegranskat)abstract
    • This paper proposes a wideband magneto-electric (ME) dipole fed by a single-layer corporate-feed network based on the ridge gap waveguide (RGW) transmission line technology for 5G backhauling applications. The proposed antenna is composed of two layers. The top layer is the radiating layer that is composed of the 2 x 2 ME-dipole antenna element. The bottom layer is the corporate-feed network designed based on RGW. The proposed solution differs from the conventional solution where a slot antenna is fed by RGW and a cavity layer is to excite the radiating elements in order to provide a large spacing for the corporate-feed network in the design of the array antenna. Our new design allows for a smaller antenna volume as it excited the antenna directly by the RGW without the need of cavity layer. In addition, with the use of the ME-dipole radiating element, the bandwidth performance supported by the proposed design is larger as compared to the existing conventional designs. From the obtained simulation results, the proposed antenna produces S-11 <= -10 dB over 24 - 30 GHz resulting in a 22% fractional bandwidth. The maximum directivity over the operating bandwidth of the simulated 2 x 2 ME-dipole antenna element is approximately 15.4 dBi. Thus, the proposed antenna is a good candidate for low profile fixed-beam applications.
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34.
  • Yong, Wai Yan, et al. (författare)
  • A Bandwidth-Enhanced Cavity-Backed Slot Array Antenna for mmWave Fixed-Beam Applications
  • 2020
  • Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757 .- 1536-1225. ; 19:11, s. 1924-1928
  • Tidskriftsartikel (refereegranskat)abstract
    • A bandwidth-enhanced 8\times 8 cavity-backed slot array antenna for fixed beam applications is presented. The antenna consists of four 2\times 2 subarrays fed by ridge gap waveguide and a modified bow-tie coupling slot in the cavity layer. The proposed bow-tie coupling slot provides additional \text{10}\% impedance bandwidth as compared to the traditional rectangular coupling slot. The fabricated prototype demonstrates an S 11 leq -10,dB fractional impedance bandwidth and a 3\,dB gain-drop bandwidth of approximately \text{28}\% and \text{25}\%, respectively, with peak gain of 26.4\,dBi, aperture efficiency >\text{60}\% and cross-polar discrimination >40\,dB. Measurements show good agreement with simulations. Moreover, we show the impact of the dimensions and shape of the cavity coupling slot on the bandwidth enhancement. The bandwidth enhancement is explained by the double-ridge slot behavior of the bow-tie coupling slot, which shows a more wideband behavior than the traditional rectangular coupling slot behaving like a cross section of a waveguide.
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35.
  • Yong, Wai Yan, et al. (författare)
  • Design and Characterization of the Fully Metallic Gap Waveguide-Based Frequency Selective Radome for Millimeter Wave Fixed Beam Array Antenna
  • 2023
  • Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; 71:1, s. 531-541
  • Tidskriftsartikel (refereegranskat)abstract
    • This article presents a bandpass frequency selective surface (FSS) radome based on fully metallic gap waveguide (GW) technology. The element of the proposed FSS radome consists of a conventional cross-dipole slot etched on metallic plates and positioned over a groove GW cavity. A design with a single GW-cavity layer was initially produced which was later optimized for performance, to comprise a dual GW-cavity layer, while considering both functionality and manufacturability. It is shown that the proposed FSS element offers a stable and wide bandpass (from 26 to 30 GHz) performance in the broadside direction for both transverse electric (TE) and transverse magnetic (TM) polarizations. For oblique angle of incidence, the suggested FSS element works up to 30° with a reduction in usable bandpass bandwidth performance to 26-28 GHz for both TE and TM polarizations. A $20 \times 20$ -element GW-FSS array prototype has been fabricated and measured, which was integrated with a fixed-beam array antenna to further validate its functionality as a filtering radome. The findings show an excellent agreement between simulations and measurements. Hence, the proposed GW-FSS represents a great opportunity to develop an all-metallic FSS with low insertion loss, sharp-roll-off filtering, wideband performance, and inexpensive fabrication cost.
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36.
  • Zetterström, Oskar, et al. (författare)
  • A 28-port MIMO Cube for Micro Base Station Applications
  • 2020
  • Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-926X .- 1558-2221. ; 68:5, s. 3443-3452
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel multi-band, dual-polarized, 28-port multiple-input multiple-output (MIMO) cube is presented. The cube structure enables dense placement of the antennas, whilst still allowing for low correlation between the individual antenna ports. The total size of the cube is roughly 2×2×7 λ30, where λ0 is the wavelength at the lowest used frequency. The novelty of the design lies in the use of a combination of orthogonally polarized endfire and broadside radiating antenna elements. Full use of all facets of the cube is achieved without the need to sacrifice bottom or top facets for mounting. Therefore, full azimuthal coverage for communication in two orthogonal polarizations is readily achieved. The system operates in both cellular and Wi-Fi 2:4, 5:5 GHz bands, with a targeted |S11| below –10 dB. The MIMO performance of the system is evaluated in two environments: the Rich Isotropic Multipath environment and the Random Line-of-Sight environment. These two scenarios represent the edge environments of any real-life propagation scenario in terms of the directional distribution of outgoing or incoming waves at a MIMO transceiver. The intended application of the system is micro base stations and repeaters, with possible extension to massive MIMO.
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37.
  • Zhang, Jiliang, et al. (författare)
  • Fundamental Wireless Performance of a Building
  • 2021
  • Ingår i: IEEE Wireless Communications. - 1536-1284 .- 1558-0687. ; 29:1, s. 186-193
  • Tidskriftsartikel (refereegranskat)abstract
    • Over 80 percent of wireless traffic already takes place in buildings. Like water, gas, and electricity, wireless communication is becoming one of the most fundamental utilities of a building. It is well known that building structures have a significant impact on in-building wireless networks. If we seek to achieve the optimal network performance indoors, buildings should be designed with the objective of maximizing wireless performance. So far, wireless performance has not yet been considered when designing a building. In this article, we introduce a novel and interdisciplinary concept of building wireless performance (BWP) to a wide audience in both wireless communications and building design, emphasizing its broad impacts on wireless network development and deployment, and on building layout/material design. We first give an overview of the BWP evaluation framework proposed in our state-of-the-art works and explain their interconnections. Then, we outline the potential research directions in this exciting research area to encourage further interdisciplinary research.
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38.
  • Zhang, Jiliang, et al. (författare)
  • Generalized Polarization-Space Modulation
  • 2020
  • Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 68:1, s. 258-273
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel generalized polarization-space modulation (GPSM) is proposed for polarized multiple-input multiple-output (MIMO) systems with a limit number of radio frequency (RF) chains. In the spatial domain, multiple dual-polarized (DP) transmit antennas are activated, and then combinations of those indices are used to convey information. While in the polarization domain, depending on the random input bits, only one polarization state is selected for each active DP transmit antenna to transmit information following the rule of the polarized shift keying. At the receiver, the maximum likelihood detector is employed as a benchmark to detect information bits being used to select the polarization state and activated DP antennas. In the detector, imperfect channel state information (CSI) is taken into account. Two less computationally complex detectors, i.e., a linear detector and a sphere decoding (SD) detector are proposed to relieve the computational burden. Sacrificing the average bit error probability (ABEP) performance, the proposed linear detector can reduce the computational complexity significantly. The proposed SD detector can achieve the optimum ABEP performance, while reducing computational complexity by reducing the search space. A closed-form union upper bound (UUB) on the ABEP of the GPSM system with imperfect CSI at the receiver is analytically derived and validated through simulations. From the UUB, a loose asymptotic bound on the ABEP, which sheds light on deriving the diversity gain and the coding gain, is derived. Numerical results show that the signal-to-noise ratio loss caused by increasing the number of transmit antennas is less than 3 dB while the spectral efficiency is increased by 7 b/z/Hz. Therefore, the GPSM can be a promising candidate of down link massive MIMO systems to achieve a high spectral efficiency with a limit number of RF chains.
  •  
39.
  • Zhang, Jiliang, et al. (författare)
  • Two-Ray Reflection Resolution Algorithm for Planar Material Electromagnetic Property Measurement at the Millimeter-Wave Bands
  • 2020
  • Ingår i: Radio Science. - 0048-6604 .- 1944-799X. ; 55:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Electromagnetic (EM) reflection properties of building materials and structures have been investigated through practical measurements. However, the finite thickness of measured materials makes it challenging to resolve the rays reflected from the front and the back surfaces. In this paper, we therefore present a three-step minimum least squares-based algorithm to resolve two closely adjacent rays reflected from the front and the back surfaces of a board-shaped material. Our analytical and numerical results show that the proposed algorithm achieves the Cramér-Rao lower bound. The proposed algorithm is validated using measurement data for various materials and incident angles in the 40–50 GHz frequency band. The validation results show that the proposed algorithm is capable of resolving two closely adjacent rays with a root-mean-square deviation that is smaller than 0.08. Main applications of the proposed algorithm can be found in the frequency domain measurements of the EM wave reflections by typical building structures, e.g., window glass, doors, ceiling, and floors.
  •  
40.
  • Zhang, Jiliang, et al. (författare)
  • Wireless Energy Efficiency Evaluation for Buildings Under Design Based on Analysis of Interference Gain
  • 2020
  • Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 69:6, s. 6310-6324
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we present part of our ground-breaking work that bridges building design and wireless network deployment. The original contributions lie in: i) defining interference gain (IG) as an intrinsic figure of merit (FoM) of a building & x2019;s wireless performance in terms of interference signal blockage; ii) developing analytic models to calculate IG; and iii) developing a novel method to calculate the optimum transmitting power to achieve the maximum IG of a building. The IG is derived as an integral transform of the probability density function (PDF) of the distance from a probe user equipment (UE) with a random position relative to a wall, and with a uniformly distributed direction. Furthermore, the PDF of the random distance is derived in closed-form for rectangular rooms to facilitate fast computation of the IG of a building under design (BUD) tiled by rectangular rooms and corridors. For BUD with irregular rooms, a random shooting algorithm (RSA) is proposed to numerically compute the PDF. The closed-form expression and the RSA are compared and validated. Numerical results show the validity of both the model to calculate IG and the methodology to derive the optimum transmitting power to achieve the maximum IG of a given building. The results shed light to architects on how to design buildings with desirable wireless performance and for radio engineers on how densely wireless access points can be deployed to approach the intrinsic wireless performance of a building.
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41.
  • Zhang, Jiliang, et al. (författare)
  • Wireless Performance Evaluation of Building Layouts: Closed-Form Computation of Figures of Merit
  • 2021
  • Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 69:7, s. 4890-4906
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a part of our ground-breaking work on evaluation of buildings in terms of wireless friendliness at the building-design stage. The main goal is to devise building design practices that provide for a good performance of wireless networks deployed in buildings. In this paper, the interference gain (IG) and power gain (PG) are defined as two figures of merit (FoM) of the wireless performance of buildings. The FoMs bridge the gap between building design and wireless communications industries. An approach to derive exact closed-form equations for these FoMs is proposed for the first time. The derived analytic expressions facilitate straightforward and more computationally efficient numerical evaluation of the proposed FoMs as compared to Monte Carlo simulations for well-known indoor propagation models. It is shown that the derived closed-form expression can be readily employed to evaluate the impact of building properties, such as the sizes and the aspect ratios (ARs) of rooms, on the wireless performance. The proposed approach sheds light to architects on evaluation and design of wireless-friendly building layouts.
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