| 1. |
- Garcia, Gabriel, 1985, et al.
(författare)
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Fast in-Band Position-Aided Beam Selection in Millimeter-Wave MIMO
- 2019
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Ingår i: IEEE Access. - 2169-3536 .- 2169-3536. ; 7, s. 142325-142338
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Tidskriftsartikel (refereegranskat)abstract
- Millimeter-wave (mm-wave) and massive multiple-input-multiple-output technologies appear as key enablers in future emerging wireless communication systems. Propagation in mm-wave communications is well described by geometric channel models, where a clear relation between communication and positioning arises. On one hand, initial access, a procedure that precedes high data rate transmission and consists of beam selection and alignment between two devices, can benefit from position information. On the other hand, accurate positioning relies on high-quality communication links with proper beam alignment. This work analyzes the interplay between communication and positioning, proposes a new in-band position-aided beam selection protocol considering scenarios with line-of-sight and reflected paths, and possible beam alignment errors. Simulation results show significant reductions in latency with respect to standard beam selection protocols.
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| 2. |
- Aydogdu, Canan, 1978, et al.
(författare)
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A Solution for Removing Automotive Radar Interference: Radar Communications
- 2018
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Ingår i: Swedish Transportation Research Conference.
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Konferensbidrag (refereegranskat)abstract
- Automotive radar is becoming an indispensable equipment in modern cars, for different functions including lane keeping, speed control and parking, especially due to its immunity to bad weather conditions [1]. Likewise, vehicle-to-vehicle (V2V) communication is on the way to become a standard, having proven its value in dissemination of safety critical information [2]. However, the widespread use of both technologies lead to problems, cutting short future plans for autonomous driving and safety. Increased penetration rate and density of automotive radars lead to increased mutual interference, which in turn result with reduced detection probability and ghost detections [3]. Similarly, Omni-directional V2V communication transmissions result in high interference with an increased number of vehicles [4]. This interference leads to packet losses, especially in emergency situations when many vehicles emit warning messages, in turn affecting system-wide safety.
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| 3. |
- Aydogdu, Canan, 1978, et al.
(författare)
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Improved Pedestrian Detection under Mutual Interference by FMCW Radar Communications
- 2018
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Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. - 9781538660096 ; , s. 101-105
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Konferensbidrag (refereegranskat)abstract
- The widespread of automotive radars leads to increase of mutual interference, which in turn degrades road safety. The effect of mutual interference with a focus on detection of pedestrians is investigated. It is shown that detection of pedestrians degrades in the presence of mutual interference. A joint radar communication solution is proposed that increases pedestrian detection probability with negligible impact in the ranging error.
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| 4. |
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| 5. |
- Aydogdu, Canan, 1978, et al.
(författare)
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Radar communications for combating mutual interference of FMCW radars
- 2019
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Ingår i: IEEE National Radar Conference - Proceedings. - 1097-5659.
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Konferensbidrag (refereegranskat)abstract
- Commercial automotive radars used today are based on frequency modulated continuous wave signals due to the simple and robust detection method and good accuracy. However, the increase in both the number of radars deployed per vehicle and the number of such vehicles leads to mutual interference, cutting short future plans for autonomous driving and active safety functionality. We propose and analyze a radar communications (RadCom) approach to reduce this mutual interference while simultaneously offering communication functionality. We achieve this by frequency division multiplexing radar and communications, where communications is built on a decentralized carrier sense multiple access protocol and is used to adjust the timing of radar transmissions. Our simulation results indicate that radar interference can be significantly reduced, at no cost in radar accuracy.
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| 6. |
- Aydogdu, Canan, 1978, et al.
(författare)
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RadChat: Spectrum Sharing for Automotive Radar Interference Mitigation
- 2021
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Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 22:1, s. 416-429
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Tidskriftsartikel (refereegranskat)abstract
- In the automotive sector, both radars and wireless communication are susceptible to interference. However, combining the radar and communication systems, i.e., radio frequency (RF) communications and sensing convergence, has the potential to mitigate interference in both systems. This article analyses the mutual interference of spectrally coexistent frequency modulated continuous wave (FMCW) radar and communication systems in terms of occurrence probability and impact, and introduces RadChat, a distributed networking protocol for mitigation of interference among FMCW based automotive radars, including self-interference, using radar and communication cooperation. The results show that RadChat can significantly reduce radar mutual interference in single-hop vehicular networks in less than 80 ms.
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| 7. |
- Cordes, Kai, et al.
(författare)
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Radio-Based Positioning and Video-Based Positioning
- 2021
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Ingår i: Cellular V2X for Connected Automated Driving. - : Wiley. ; , s. 223-249
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter provides an overview of state-of-art radio- and image-based positioning tailored to the localization of connected autonomous vehicles. It evaluates the achievable accuracy of video-based vehicle positioning. Therefore, the accuracy achieved in the 5GCAR Lane Merge Coordination use case, using a set of monocular cameras for vehicle positioning, is compared to the accuracy achieved in literature. The chapter addresses the technology and performance requirements of legacy solutions along with the details of time-based, angular-based, and video-based positioning. Some of the proposed methods closely follow the long term evolution and the new radio standards; others show more innovative solutions that can achieve a high level of accuracy. Video-based positioning requires additional infrastructure (camera installation), but the camera locations are flexible. In the 5GCAR project, a mast with 10 m height is chosen for installation. Finally, the chapter concludes with a comprehensive set of simulations highlighting the pros and cons of each solution.
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| 8. |
- Garcia, Nil, 1983, et al.
(författare)
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Cramér-Rao Bound Analysis of Radars for Extended Vehicular Targets With Known and Unknown Shape
- 2022
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Ingår i: IEEE Transactions on Signal Processing. - 1941-0476 .- 1053-587X. ; 70, s. 3280-3295
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Tidskriftsartikel (refereegranskat)abstract
- Due to their shorter operating range and large bandwidth, automotive radars can resolve many reflections from their targets of interest, mainly vehicles. This calls for the use of extended-target models in place of simpler and more widely-adopted point-like target models. However, despite some preliminary work, the fundamental connection between the radar’s accuracy as a function of the target vehicle state (range, orientation, shape) and radar properties remains largely unknown for extended targets. In this work, we first devise a mathematically tractable analytical model for a vehicle with arbitrary shape, modeled as an extended target parameterized by the center position, the orientation (heading) and the perimeter contour. We show that the derived expressions of the backscatter signal are tractable and correctly capture the effects of the extended-vehicle shape. Analytical derivations of the exact and approximate hybrid Cramér-Rao bounds for the position, orientation and contour are provided, which reveal connections with the case of point-like target and uncover the main dependencies with the received energy, bandwidth, and array size. The theoretical investigation is performed on the two different cases of known and unknown vehicle shape. Insightful simulation results are finally presented to validate the theoretical findings, including an analysis of the diversity effect of multiple radars sensing the extended target.
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| 9. |
- Garcia, Nil, 1983, et al.
(författare)
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Direct Localization for Massive MIMO
- 2017
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Ingår i: IEEE Transactions on Signal Processing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1941-0476 .- 1053-587X. ; 65:10, s. 2475-2487
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale MIMO systems are well known for their advantages in communications, but they also have the potential for providing very accurate localization, thanks to their high angular resolution. A difficult problem arising indoors and outdoors is localizing users over multipath channels. Localization based on angle of arrival (AOA) generally involves a two-step procedure, where signals are first processed to obtain a user's AOA at different base stations, followed by triangulation to determine the user's position. In the presence of multipath, the performance of these methods is greatly degraded due to the inability to correctly detect and/or estimate the AOA of the line-of-sight (LOS) paths. To counter the limitations of this two-step procedure which is inherently suboptimal, we propose a direct localization approach in which the position of a user is localized by jointly processing the observations obtained at distributed massive MIMO base stations. Our approach is based on a novel compressed sensing framework that exploits channel properties to distinguish LOS from non-LOS signal paths, and leads to improved performance results compared to previous existing methods.
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| 10. |
- Garcia, Nil, 1983, et al.
(författare)
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Location-aided mm-wave channel estimation for vehicular communication
- 2016
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Ingår i: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC. ; 2016-August
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Konferensbidrag (refereegranskat)abstract
- Millimeter-wave (mm-wave) communication is a promising technology for next-generation wireless systems. One challenging application lies in the vehicular domain, where mm-wave should support ultra-fast and high-rate data exchanges among vehicles and between vehicles and infrastructure. To achieve ultra-fast initial access between nodes, we propose a location-aided beamforming strategy and analyze the resulting performance in terms of antenna gain and latency. We find that location information can significantly speed up initial access.
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