| 1. |
- Amani, Navid, 1985, et al.
(författare)
-
Array Configuration Effect on the Spatial Correlation of MU-MIMO Channels in NLoS Environments
- 2020
-
Ingår i: 14th European Conference on Antennas and Propagation, EuCAP 2020. ; 2020:March
-
Konferensbidrag (refereegranskat)abstract
- In this paper, three different base-station antenna (BSA) configurations are compared in terms of inter-user spatial correlation in a two dimensional (2D) non-line-of-sight (NLoS) environment. The three configurations are: (i) a regular uniform linear array (ULA); (ii) a periodic sparse array; and (iii) an aperiodic sparse array. Electromagnetic modeling of the NLoS channel is proposed where scatterers are considered as resonant dipoles confined in clusters of scatterers (CoSs). While the probability of facing highly correlated user-equipments (UEs) in a multi-user multiple-input multiple-output (MU-MIMO) system is decreasing as the richness of mutipath increases, the sparsity (increased inter-element spacing) is seen to be capable of reducing this probability as well. This is due to the larger spatial variations experienced by the sparse array. Moreover, the results show that further improvement can be achieved by deploying an aperiodic distribution of antenna elements into the sparse antenna aperture.
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| 2. |
- Bärring, Maja, 1988, et al.
(författare)
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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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| 3. |
- Glazunov, Andres Alayon, 1969, et al.
(författare)
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Capacity Gains of (3 × 3)×(3 × 3) MIMO Fixed Links with Planar Aperiodic Sparse Arrays in Pure-LOS Channels
- 2018
-
Ingår i: Proceedings of the 2018 8th IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC 2018. ; , s. 734-736
-
Konferensbidrag (refereegranskat)abstract
- © 2018 IEEE. Presented is an analysis of the topology of a 3 × 3 element planar (square) array antenna with vertically polarized isotropic antenna elements. The focus has been on fixed multiple-input multiple-output communication links in pure line-of-sight channels. An empirical equation is presented for the mid-elements' relative position on the sides of the square array achieving near-optimal (3 × 3) × (3 × 3) multiple-input multiple-output capacity. It is observed that the position is a function of both the separation distance between transmit and receive antennas and the wavelength of the transmit signal in a similar way as for 3 × 3 systems with linear arrays. The capacity gains of the aperiodic planar array over the uniform planar array antenna configurations are presented. It is shown that considerable capacity gains in capacity can be obtained by choosing the right array topology following a simple design rule.
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| 4. |
- Iupikov, Oleg, 1983, et al.
(författare)
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Indoor Received Power Prediction Based on Physical Optics (PO): Simulations and Experimental Validation in Industrial Environment
- 2019
-
Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
-
Konferensbidrag (refereegranskat)abstract
- This study presents an approach based on Physical Optics computations to predict the receive signal power in an indoor environment. The application in focus pertains the development of highly reliable manufacturing industry processes where wireless communications plays a key role. Our proposed numerical method shows a good agreement with measurement data. It is therefore suggested that Electromagnetic modelling based on computationally efficient Physical Optics algorithms can be used as a complement, an alternative or even a replacement for empirical models requiring time consuming measurement campaigns.
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| 5. |
- Maaskant, Rob, 1978, et al.
(författare)
-
Spatial Power Combining and Splitting in Gap Waveguide Technology
- 2016
-
Ingår i: IEEE Microwave and Wireless Components Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-1764 .- 1531-1309. ; 26:7, s. 472-474
-
Tidskriftsartikel (refereegranskat)abstract
- A single-layer spatial power splitter-combiner structure is packaged in gap waveguide technology. The measured metal-only back-to-back structure features an average insertion loss less than 2.3 dB and a return loss larger than 10 to 20 dB over the entire 75-110 GHz W-band. The design procedure is outlined and the measured and simulated results are shown to be in good agreement. The structure can be used as a stand-alone power splitter and/or combiner (single-mode, all-excited in-phase channels), a quasi-optical beamformer to excite an array of slot antennas in the top ground plane by ridge gap waveguides, or as a back-to-back RF component in grid amplifier designs.
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| 6. |
- Meyer, E., et al.
(författare)
-
The state of the art in beyond 5G distributed massive multiple-input multiple-output communication system solutions
- 2022
-
Ingår i: Open Research Europe. - : F1000 Research Ltd. - 2732-5121. ; 2
-
Forskningsöversikt (refereegranskat)abstract
- Beyond fifth generation (5G) communication systems aim towards data rates in the tera bits per second range, with improved and flexible coverage options, introducing many new technological challenges in the fields of network architecture, signal pro- cessing, and radio frequency front-ends. One option is to move towards cell-free, or distributed massive Multiple-Input Multiple-Output (MIMO) network architectures and highly integrated front-end solutions. This paper presents an outlook on be- yond 5G distributed massive MIMO communication systems, the signal processing, characterisation and simulation challenges, and an overview of the state of the art in millimetre wave antennas and electronics.
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| 7. |
- Pivnenko, Sergiy, et al.
(författare)
-
Using a Conical Horn as Compact Antenna Test Range Feed in Millimetre Bands
- 2022
-
Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
-
Konferensbidrag (refereegranskat)abstract
- Using a conical horn as a feed for a single offset-fed Compact Antenna Test Range (CATR) is described. Although such horn has larger variation of the phase centre with frequency and slightly different beamwidth in the E-plane and H-plane within the used field of view, as compared to a specially designed corrugated horn feed, good results were obtained for the measured amplitude and phase variations in the Quiet Zone at mm-band. Some details of application of conventional conical horns as CATR feeds are also explained.
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| 8. |
- Shah, Waqar Ali, 1987, et al.
(författare)
-
W-band spatial power combiner and splitter in gap waveguide technology
- 2016
-
Ingår i: 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016, Fajardo, Puerto Rico, 26 June - 1 July 2016. - 1522-3965. ; , s. 255-256
-
Konferensbidrag (refereegranskat)abstract
- A passive power splitter and combiner has been designed in-between two metallic ground plates using gap waveguide technology. The measured insertion loss is smaller than 2.3 dB and the return loss is larger than 10 dB over the entire W-band (75-110 GHz). The design procedure has been detailed and the simulated and measured results for the proposed structure are shown. The designed structure can be used as a passive power splitter or combiner, as a grid amplifier in a back-to-back RF chain, or as a quasi-optical beamforming component in beam steering antenna arrays.
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| 9. |
- Svensson, Arne, 1955, et al.
(författare)
-
In memory of Professor Per-Simon Kildal
- 2016
-
Ingår i: IEEE Antennas and Propagation Magazine. - 1045-9243. ; 58:4, s. 116-117
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Uz Zaman, Ashraf, 1975, et al.
(författare)
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3D Printed Periodic Structures for RF Packaging of Integrated Array Module at sub-6GHz Band
- 2021
-
Ingår i: 2021 International Symposium on Antennas and Propagation, ISAP 2021.
-
Konferensbidrag (refereegranskat)abstract
- Wideband PMC packaging solution fabricated by low cost 3D printing technology has been proposed as an alternative to conventional metal wall solution for isolating critical active circuits in integrated arrays operating at sub-6GHz. The two proposed periodic structures named as triangular pins and conical pins produce a parallel-plate stopband over the frequency range from 2.5-6GHz and 2.1-5.5GHz respectively. A test structure, containing passive microstrip lines placed on a FR4 substrate, has been used to verify the packaging performance of the proposed 3D printed structures and the measured isolation performance of the newly proposed periodic structures agree very well with the simulated performance. Isolation level better than 40-50dB has been demonstrated within the band of interest.
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| 11. |
- Adams, E. A. K., et al.
(författare)
-
First release of Apertif imaging survey data
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 667
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Apertif is a phased-array feed system for the Westerbork Synthesis Radio Telescope, providing forty instantaneous beams over 300 MHz of bandwidth. A dedicated survey program utilizing this upgrade started on 1 July 2019, with the last observations taken on 28 February 2022. The imaging survey component provides radio continuum, polarization, and spectral line data. Aims. Public release of data is critical for maximizing the legacy of a survey. Toward that end, we describe the release of data products from the first year of survey operations, through 30 June 2020. In particular, we focus on defining quality control metrics for the processed data products. Methods. The Apertif imaging pipeline, Apercal, automatically produces non-primary beam corrected continuum images, polarization images and cubes, and uncleaned spectral line and dirty beam cubes for each beam of an Apertif imaging observation. For this release, processed data products are considered on a beam-by-beam basis within an observation. We validate the continuum images by using metrics that identify deviations from Gaussian noise in the residual images. If the continuum image passes validation, we release all processed data products for a given beam. We apply further validation to the polarization and line data products and provide flags indicating the quality of those data products. Results. We release all raw observational data from the first year of survey observations, for a total of 221 observations of 160 independent target fields, covering approximately one thousand square degrees of sky. Images and cubes are released on a per beam basis, and 3374 beams (of 7640 considered) are released. The median noise in the continuum images is 41.4 uJy beam(-1), with a slightly lower median noise of 36.9 uJy beam(-1) in the Stokes V polarization image. The median angular resolution is 11.6 ''/sin delta. The median noise for all line cubes, with a spectral resolution of 36.6 kHz, is 1.6 mJy beam(-1), corresponding to a 3-sigma H i column density sensitivity of 1.8 x 10(20) atoms cm(-2) over 20 km s(-1) (for a median angular resolution of 24 '' x 15 ''). Line cubes at lower frequency have slightly higher noise values, consistent with the global RFI environment and overall Apertif system performance. We also provide primary beam images for each individual Apertif compound beam. The data are made accessible using a Virtual Observatory interface and can be queried using a variety of standard tools.
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| 12. |
- Adebahr, B., et al.
(författare)
-
Apercal - The Apertif calibration pipeline
- 2022
-
Ingår i: Astronomy and Computing. - : Elsevier BV. - 2213-1337. ; 38
-
Tidskriftsartikel (refereegranskat)abstract
- Apertif (APERture Tile In Focus) is one of the Square Kilometre Array (SKA) pathfinder facilities. The Apertif project is an upgrade to the 50-year-old Westerbork Synthesis Radio Telescope (WSRT) using phased-array feed technology. The new receivers create 40 individual beams on the sky, achieving an instantaneous sky coverage of 6.5 square degrees. The primary goal of the Apertif Imaging Survey is to perform a wide survey of 3500 square degrees (AWES) and a medium deep survey of 350 square degrees (AMES) of neutral atomic hydrogen (up to a redshift of 0.26), radio continuum emission and polarisation. Each survey pointing yields 4.6 TB of correlated data. The goal of Apercal is to process this data and fully automatically generate science ready data products for the astronomical community while keeping up with the survey observations. We make use of common astronomical software packages in combination with Python based routines and parallelisation. We use an object oriented module-based approach to ensure easy adaptation of the pipeline. A Jupyter notebook based framework allows user interaction and execution of individual modules as well as a full automatic processing of a complete survey observation. If nothing interrupts processing, we are able to reduce a single pointing survey observation on our five node cluster with 24 physical cores and 256 GB of memory each within 24 h keeping up with the speed of the surveys. The quality of the generated images is sufficient for scientific usage for 44% of the recorded data products with single images reaching dynamic ranges of several thousands. Future improvements will increase this percentage to over 80%. Our design allowed development of the pipeline in parallel to the commissioning of the Apertif system.
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| 13. |
- Adebahr, B., et al.
(författare)
-
The Apertif science verification campaign: Characteristics of polarised radio sources
- 2022
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 663
-
Tidskriftsartikel (refereegranskat)abstract
- Context. The characteristics of the polarised radio sky are a key ingredient in constraining evolutionary models of magnetic fields in the Universe and their role in feedback processes. The origin of the polarised emission and the characteristics of the intergalactic medium on the line of sight can be investigated using large samples of polarised sources. Ancillary infrared (IR) and optical data can be used to study the nature of the emitting objects. Aims. We analyse five early science datasets from the APERture Tile in Focus (Apertif) phased array feed system to verify the polarisation capabilities of Apertif in view of future larger data releases. We aim to characterise the source population of the polarised sky in the L-Band using polarised source information in combination with IR and optical data. Methods. We use automatic routines to generate full field-of-view Q- and U-cubes and perform rotation measure (RM)-Synthesis, source finding, and cross-matching with published radio, optical, and IR data to generate polarised source catalogues. All sources were inspected individually by eye for verification of their IR and optical counterparts. Spectral energy distribution (SED)-fitting routines were used to determine photometric redshifts, star-formation rates, and galaxy masses. IR colour information was used to classify sources as active galactic nuclei (AGN) or star-forming-dominated and early- or late-type. Results. We surveyed an area of 56 deg2 and detected 1357 polarised source components in 1170 sources. The fraction of polarised sources is 10.57% with a median fractional polarisation of 4.70 ± 0.14%. We confirmed the reliability of the Apertif measurements by comparing them with polarised cross-identified NVSS sources. Average RMs of the individual fields lie within the error of the best Milky Way foreground measurements. All of our polarised sources were found to be dominated by AGN activity in the radio regime with most of them being radio-loud (79%) and of the Fanaroff-Riley (FR)II class (87%). The host galaxies of our polarised source sample are dominated by intermediate disc and star-forming disc galaxies. The contribution of star formation to the radio emission is on the order of a few percent for 10% of the polarised sources while for 90% it is completely dominated by the AGN. We do not see any change in fractional polarisation for different star-formation rates of the AGN host galaxies. Conclusions. The Apertif system is suitable for large-area high-sensitivity polarised sky surveys. The data products of the polarisation analysis pipeline can be used to investigate the Milky Way magnetic field on projected scales of several arcminutes as well as the origin of the polarised emission in AGN and the properties of their host galaxies.
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| 14. |
- Aljarosha, Alhassan, 1982, et al.
(författare)
-
Toward Wide-Band Low-Loss Gap-Waveguide-Integrated Grid Amplifiers
- 2017
-
Ingår i: 2017 International Symposium on Antennas and Propagation (ISAP). - 9781538604656
-
Konferensbidrag (refereegranskat)abstract
- A passive W-band 19-channel spatial power splitter/combiner is presented, for the applications in grid amplifiers design. The design employs a linear array of chip-to-air-filled waveguide contactless connections, and are directly integrated within a single-layer. The meta-material-based gap waveguide is used; it enables a low-loss low-profile solution. The quasi optical beamformer gives rise to a parallel-plate planar waveguide field which excites an array of contactless chip-to-waveguide transitions via step-tapered ridge gap waveguides. The other beamformer restores the field distribution (after amplification) and excites a wave going towards the waveguide output. Furthermore, the gap waveguide technology isolates the amplifiers from one another and provides a packaging solution in a single unit. The simulated return loss of the back-to-back structure is larger than 12 dB, while the insertion loss is smaller than 1.2 dB over the entire W-band (75-110 GHz).
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| 15. |
- Amani, Navid, 1985, et al.
(författare)
-
MIMO Channel Capacity Gains in mm-Wave LOS Systems with Irregular Sparse Array Antennas
- 2017
-
Ingår i: APWC 2017.
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates potential advantages of linear irregular sparse antenna arrays over their regular counterparts in a mm-wave line-of-sight (LOS) multiple-input multiple-output (MIMO) scenario. The comparison is based on numerical computations of MIMO eigenvalues of the corresponding channel matrices and the resulting channel capacity. Identical linear antenna arrays are assumed at the transmitter and the receiver sides. The compared regular and irregular arrays have an equal aperture length. Mutual coupling between elements within an array is assumed negligible due to the array sparsity. A 4×4 MIMO channel is studied, where we change the position of the two inner elements to obtain irregularly spaced arrays. It is shown that for some specific distances between TX and RX, the irregular array distribution can significantly improve the channel capacity in LOS. This observation opts for reconfigurable array designs.
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| 16. |
- Amani, Navid, 1985, et al.
(författare)
-
Multi-Panel Sparse Base Station Design with Physical Antenna Effects in Massive MU-MIMO
- 2020
-
Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 69:6, s. 6500-6510
-
Tidskriftsartikel (refereegranskat)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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| 17. |
- Amani, Navid, 1985, et al.
(författare)
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Network model of a 5G MIMO base station antenna in a downlink multi-user scenario
- 2018
-
Ingår i: IET Conference Publications. - : Institution of Engineering and Technology. ; 2018:CP741
-
Konferensbidrag (refereegranskat)abstract
- A system level network model of a 5G base station antenna (BSA) with massive multiple-input multiple-output (MIMO) capabilities is presented that incorporates antenna mutual interaction and signal processing aspects. The combined transmitter-channel-receiver in such a system is modeled by cascading Z-matrices to interrelate the transmitter and receiver port voltages/ currents to one another. The developed model is then subjected to the zero-forcing (ZF) beamforming algorithm to compute the per-antenna transmit power for a specific minimum signal level at the receiver as well as the required BSA effective isotropic radiated power (EIRP). The presented initial results show that in a line-of-sight (LOS) environment the required EIRP to achieve a 1 Gbps bitrate user link in a 15-200 m coverage ranges from 25-48 dBm, which increases to 31-54 dBm after incorporating first-order mutual coupling effects among the BSA elements.
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| 18. |
- Amani, Navid, 1985, et al.
(författare)
-
Per-Antenna Power Distribution of a Zero-Forcing Beamformed ULA in pure LOS MU-MIMO
- 2018
-
Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 22:12, s. 2515-2518
-
Tidskriftsartikel (refereegranskat)abstract
- An analytical model is presented to determine the per-antenna power distribution of a beamformed M-element uniform linear array (ULA) as a base station antenna (BSA). The analysis assumes a single sector cell serving two user equipments (UEs) in a downlink multiuser multiple-input multiple-output (MU-MIMO) system employing zeroforcing (ZF) transmission. Determinative design parameters of the BSA configuration are identified. Afterwards, their effects on the power spread across the array are investigated when the positions of the users are random and they are uniformly distributed over the cell. It is shown that the power distribution across the ULA antenna aperture is a periodic function whose characteristics mainly depend on the angular separation of two UEs and the number of BSA elements. A significant variation between ULA input powers is seen to occur if the number of elements in the ULA is smaller than one period of this power distribution function. In order to mitigate the dynamic range of the power variation across the array, an upper bound for the inter-element spacing, depending on the field-of-view (FoV) of the BSA, is defined. It is shown that, in a 20-element ULA, increasing the inter-element spacing from 0.5-wavelength to 1.4-wavelength reduces the power variation from 19 dB to 10 dB for differentiating two close-by UEs with 1 degree angular separation.
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| 19. |
- Amani, Navid, 1985, et al.
(författare)
-
Sparse Array Synthesis Including Mutual Coupling for MU-MIMO Average Capacity Maximization
- 2022
-
Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X .- 1558-2221. ; In Press, s. 1-1
-
Tidskriftsartikel (refereegranskat)abstract
- A hybrid optimization algorithm including mutual coupling (MC) is proposed to synthesize an irregular sparse array (ISA) for average capacity maximization in a multi-user multiple-input multiple-output (MU-MIMO) system. The hybrid approach is composed of two phases to sub-optimally determine the location of a fixed number of omni-directional thin dipole antennas in an arbitrary sparse aperture via a diagonal antenna selection matrix. In Phase I, the problem is relaxed to a convex optimization by ignoring the MC and weakening the constraints. The output of Phase I is accounted as a reliable initial guess for the genetic algorithm (GA) in Phase II, which incorporates the MC effects through the coupling matrix and avoids the convex relaxation technique. The proposed approach outperforms the conventional GA with a random initial population, while it avoids trying several starting positions. Meanwhile, the undesirable appearance of grating lobes, due to the under-sampling, and the degrading MC effects are suppressed by aperiodicity. It is observed that, doubling the conventional inter-element spacing (half-wavelength) and finding the location of eight dipoles in a sparse aperture by the proposed method improves the average capacity by 3.27-11.9% when the number of users varies from two to eight and the signal-to-noise ratio (SNR) is 30dB.
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| 20. |
- Amani, Navid, 1985, et al.
(författare)
-
Sparse Automotive MIMO Radar for Super-Resolution Single Snapshot DOA Estimation With Mutual Coupling
- 2021
-
Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 9, s. 146822-146829
-
Tidskriftsartikel (refereegranskat)abstract
- A novel sparse automotive multiple-input multiple-output (MIMO) radar configuration is proposed for low-complexity super-resolution single snapshot direction-of-arrival (DOA) estimation. The physical antenna effects are incorporated in the signal model via open-circuited embedded-element patterns (EEPs) and coupling matrices. The transmit (TX) and receive (RX) array are each divided into two uniform sparse sub-arrays with different inter-element spacings to generate two MIMO sets. Since the corresponding virtual arrays (VAs) of both MIMO sets are uniform, the well-known spatial smoothing (SS) algorithm is applied to suppress the temporal correlation among sources. Afterwards, the co-prime array principle between two spatially smoothed VAs is deployed to avoid DOA ambiguities. A performance comparison between the sparse and conventional MIMO radars with the same number of TX and RX channels confirms a spatial resolution enhancement. Meanwhile, the DOA estimation error due to the mutual coupling (MC) is less pronounced in the proposed sparse architecture since antennas in both TX and RX arrays are spaced larger than half wavelength apart.
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| 21. |
- Amani, Navid, 1985, et al.
(författare)
-
Towards a Generic Model for MU-MIMO Analysis Including Mutual Coupling and Multipath Effects
- 2019
-
Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019. ; 2019
-
Konferensbidrag (refereegranskat)abstract
- A network model which accounts for antenna mutual coupling and multipath effects in a wireless channel is proposed as a tool to qualitatively evaluate the performance of a multi-user multiple-input multiple-output (MU-MIMO) system. The system performance is assessed when a zero-forcing (ZF) beamformed conventional uniform linear array (ULA) and a sparse array are employed as one sector of a base station antenna (BSA) in a single-cell network. It is shown that highly correlated user equipments (UEs) in a line-of-sight (LOS) scenario can be decorrelated to some extents, by a scattering environment in a non-line-of-sight (NLOS) scenario. This occurs due to increase of the spatial variation by a multipath effect. Furthermore, in both environments a sparse array realized by an increased interelement spacing is also capable for correlation reduction among users due to the narrower beams.
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| 22. |
|
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| 23. |
- Ayebe, Mustafa, 1997, et al.
(författare)
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Systematic Self-Interference Mitigation in Full Duplex Antenna Arrays Via Transmit Beamforming
- 2023
-
Ingår i: 2023 International Conference on Electromagnetics in Advanced Applications, ICEAA 2023. ; , s. 158-163
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Konferensbidrag (refereegranskat)abstract
- The optimal antenna array excitation vector is derived that maximizes the (realized) array gain in a particular direction while preventing the coupled input power to the low-noise amplifiers on the receive side to exceed a certain maximum threshold level. This is very useful for in-band full-duplex systems where the hardware complexity for self-interference cancellation must be minimized. In this approach, the perfect nulling of interference on the RX side is not required, sparing degrees of freedom for the TX beamformer. We evaluate the performance of the proposed TX beamforming algorithm by showing numerical results of the 25 x-polarized TX and 25 RX with 0.5λ element spacing and λ gap distance between the TX and RX sub-array.
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| 24. |
- Bencivenni, Carlo, 1986, et al.
(författare)
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A Simple Method for Optimal Antenna Array Thinning Using a Broadside MaxGain Beamformer
- 2013
-
Ingår i: 7th European Conference on Antennas and Propagation, EuCAP 2013, Gothenburg, Sweden, 8-12 April 2013. - 2164-3342. - 9788890701832 ; , s. 1799-1802
-
Konferensbidrag (refereegranskat)abstract
- A simple and effective method for optimal antenna array thinning employing a broadside-scanned maximum gain beamformer is presented. Starting from a fully populated λ/2-spaced regular lattice, the array is thinned by progressively 'turning off' the element(s) with the lowest weight(s) of the weight vector realizing maximum gain. The accuracy and effectiveness of the method is validated against a rigorous combinatorial search method that can be used to find the optimal irregular array configuration solution in small to moderate-sized arrays. Furthermore, to evaluate the robustness of the proposed approach, the effects of beam steering have been investigated for linear arrays consisting of 10-40 antenna elements as well. Good results can be obtained for close to broadside scanned arrays, which is of importance for the directly radiating arrays that are currently being considered as modern satellite systems.
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| 25. |
- Bencivenni, Carlo, 1986, et al.
(författare)
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Aperiodic Array Antennas for Future Satellite Systems
- 2014
-
Ingår i: Swedish Microwave Days March 11-12, 2014, Gothenburg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- Today, most satellite systems employ reflector antennas to generate narrow beams covering a certain area of Earth’s surface from orbit. However, the performance specification of modern communication systems require an increasing demand on the multi-beam, multi-channel, dual-polarization and beam shaping capabilities, which renders the design of such complex systems to a major challenge.A worldwide view is that Direct Radiating Arrays (DRAs) will be part of the future satellite systems. DRAs can handle these complexities, but the design solutions, based on conventional regular arrays are expensive due to a large number of required array elements (100-1000 in dense array for geosynchronous orbit) and active components, such as low noise and power amplifiers. For this reason, aperiodic or sparse arrays, where the array layout is optimized, constitute a very attractive solution for minimizing the number of elements and thus the cost.To design aperiodic arrays, Array Signal Processing (ASP) based methods are commonly used, which are advantageous when optimizing for complex antenna beam specifications [1-2], but often assume idealized antenna elements (e.g. isotropic radiators or uniform field apertures) while ignoring antenna mutual coupling and edge truncation effects. Electro-Magnetic Simulations (EMS) overcome these drawbacks [3], but their use is limited to simplistic ASP schemes. Due to extreme computational demands, such methods are primarily used to evaluate beam performance degradation effects, but do not incorporate sparse array ASP design procedures, and hence, these approaches result in suboptimal solutions. Our aim is to enhance the current methodology by accounting for realistic elements and critical array effects in a rigorous numerical manner, while adapting advanced ASP algorithms for fulfilling the required specifications
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