Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Interference Mitigation Techniques in FMCW Automotive Radars
Blekinge Institute of Technology, Faculty of Engineering, Department of Mathematics and Natural Sciences. (Systems Engineering)
2020 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Radar has emerged as an important sensor for scenario perception in automated driving and surveillance systems. The exponential increase of radar units in traffic and their operating frequency limitations have given rise to the problem of mutual interference. Radar's performance degrades in the presence of interference, which can result in false alarms and missed detections. In the case of safety-oriented systems (such as automatic emergency braking, blind-spot detection and obstacle detection at level crossings), radar's degraded performance can result in accidents. Therefore, it is important to mitigate the effect of mutual interference to make modern radar applications safe and reliable. The goal of this work is to develop signal processing techniques for interference mitigation in frequency modulated continuous wave (FMCW) radars operating at 77-81 GHz.

The thesis investigates radar interference suppression in the spatial domain, using antenna arrays. The interference is suppressed by placing notches in the antenna radiation pattern in the direction of the interference source by employing digital beamforming.

The array aperture (size) determines the beam-width and notch resolution of the receiving antenna. Narrow notches are desirable since they lead to a smaller suppressed region in the radar's field of view. It is demonstrated that an extended virtual aperture in a multiple-input-multiple-output (MIMO) FMCW radar does not offer an improved notch resolution for interference suppression due to a non-coherent interference signal in the virtual aperture. Moreover, it is shown that the calibration mismatches of the receiving array completely change the final antenna beam-pattern compared to the theoretical one.

Additionally, an adaptive beamforming approach of interference suppression based on the least mean squares (LMS) algorithm is presented, which is evaluated using outdoor measurements from a 77GHz FMCW radar. The results demonstrate that the proposed technique suppresses interference successfully, resulting in a signal to interference plus noise ratio (SINR) improvement. It is also shown that complex-baseband (IQ) receivers achieve better interference suppression compared to real-baseband receivers when spatial domain methods are employed.

The final research publication deals with interference mitigation in the time-domain intermediate frequency signal. The disturbed samples in the received signal are detected, removed, and reconstructed based on an estimated autoregressive (AR) signal model. The baseband signal coherence in both fast- and slow-time makes it possible to perform signal reconstruction in both dimensions. With the help of outdoor measurements covering selected scenarios, it is demonstrated that by carefully selecting the signal reconstruction dimension, a better SINR and side-lobe suppression can be achieved.

Place, publisher, year, edition, pages
Karlshamn: Blekinge Tekniska Högskola, 2020. , p. 78
Series
Blekinge Institute of Technology Licentiate Dissertation Series, ISSN 1650-2140 ; 3
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:bth-19362ISBN: 978-91-7295-401-4 (print)OAI: oai:DiVA.org:bth-19362DiVA, id: diva2:1421631
Presentation
2020-05-07, Ateljen 3-104, Biblioteksgatan 4, BTH Campus Karlshamn, Karlshamn, 10:00 (English)
Opponent
Supervisors
Available from: 2020-04-06 Created: 2020-04-03 Last updated: 2020-05-15Bibliographically approved
List of papers
1. Adaptive digital beamforming for interference suppression in automotive FMCW radars
Open this publication in new window or tab >>Adaptive digital beamforming for interference suppression in automotive FMCW radars
2018 (English)In: 2018 IEEE Radar Conference, (RadarConf 2018), Institute of Electrical and Electronics Engineers Inc. , 2018, p. 252-256Conference paper, Published paper (Refereed)
Abstract [en]

This paper addresses the problem of mutual interference between automotive radars. This problem is getting more attention with an increase in the number of radar systems used in traffic. An adaptive digital beamforming technique is presented here which suppresses the interference without the exact knowledge of the interfering signal's Direction of Arrival (DoA). The proposed technique is robust and does not rely on any calibration for the interference cancellation. The adaptive interference suppression method is evaluated using a simulated scenario. Up to about 20-23 dB improvement in the target Signal to Interference and Noise Ratio (SINR) is measured in the simulation and a better detection performance is achieved using the proposed interference suppression technique. © 2018 IEEE.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2018
Series
IEEE Radar Conference
Keywords
Beamforming, Frequency modulation, Radar systems, Signal to noise ratio, Adaptive digital beamforming, Adaptive interference suppression, Automotive radar, Detection performance, Interference cancellation, Interfering signals, Mutual interference, Target signals, Radar interference
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-16910 (URN)10.1109/RADAR.2018.8378566 (DOI)000442172700046 ()2-s2.0-85049977586 (Scopus ID)978-1-5386-4167-5 (ISBN)
Conference
2018 IEEE Radar Conference,Oklahoma City
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2020-04-07Bibliographically approved
2. Signal Reconstruction for Automotive Radar Interference Mitigation
Open this publication in new window or tab >>Signal Reconstruction for Automotive Radar Interference Mitigation
(English)Manuscript (preprint) (Other academic)
Keywords
Automotive radar, Autoregressive (AR) modelling, Chirp Sequence (CS), Frequency Modulated Continuous Wave (FMCW), interference mitigation, signal reconstruction
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Signal Processing
Identifiers
urn:nbn:se:bth-19375 (URN)
Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2020-04-07Bibliographically approved
3. Experimental Evaluation of Adaptive Beamforming for Automotive Radar Interference Suppression
Open this publication in new window or tab >>Experimental Evaluation of Adaptive Beamforming for Automotive Radar Interference Suppression
2020 (English)In: IEEE Radio and Wireless Symposium, RWS, IEEE, 2020, p. 183-186, article id 9049982Conference paper, Published paper (Refereed)
Abstract [en]

Mutual interference between automotive radars can make it difficult to detect targets, especially the weaker ones, such as cyclists and pedestrians. In this paper, the interference suppression performance of a Least Mean Squares (LMS) algorithm-based adaptive beamformer is evaluated using measurements from a 77 GHz Frequency Modulated Continuous Wave (FMCW) radar in an outdoor environment. It is shown that the adaptive beamformer increases detection performance and that the interference is suppressed down to the noise floor of the radar in the Range-Doppler domain. In the paper, real baseband sampling and complex-baseband sampling (IQ) radar receivers are compared in the context of interference suppression. The measurements show that IQ receivers are more beneficial in the presence of interference.

Place, publisher, year, edition, pages
IEEE, 2020
Keywords
Automotive radar, Frequency Modulated Continuous Wave (FMCW), interference mitigation, digital beamforming
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-19368 (URN)10.1109/RWS45077.2020.9049982 (DOI)
Conference
IEEE Radio and Wireless Symposium, RWW 2020; San Antonio; United States; 26 January 2020 through 29 January 2020
Note

Sponsorer: AESS,APS,IEEE,MTT-S

Available from: 2020-04-07 Created: 2020-04-07 Last updated: 2020-04-24Bibliographically approved
4. Analytical and Experimental Investigations on Mitigation of Interference in a DBF MIMO Radar
Open this publication in new window or tab >>Analytical and Experimental Investigations on Mitigation of Interference in a DBF MIMO Radar
2017 (English)In: IEEE transactions on microwave theory and techniques, ISSN 0018-9480, E-ISSN 1557-9670, Vol. 65, no 5, p. 1727-1734Article in journal (Refereed) Published
Abstract [en]

As driver assistance systems and autonomous driving are on the rise, radar sensors become a common device for automobiles. The high sensor density leads to the occurrence of interference, which decreases the detection capabilities. Here, digital beamforming (DBF) is applied to mitigate such interference. A DBF system requires a calibration of the different receiving channels. It is shown how this calibration completely changes the DBF beam pattern required to cancel interferences, if the system has no IQ receiver. Afterward, the application of DBF on a multiple-input multiple-output (MIMO) radar is investigated. It is shown that only the real aperture and not the virtual one can be used for interference suppression, leading to wide notches in the pattern. However, for any target the large virtual aperture can be exploited, even if interferers are blinded out. Moreover, the wide notches for interference suppression of the real aperture appear narrow in the virtual aperture for target localization. The results are verified by measurements with time-multiplexing MIMO radar.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
Keywords
Automotive radar, beamforming, multiple-input multiple-output (MIMO), radar receivers, radar systems, signal processing
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:bth-14477 (URN)10.1109/TMTT.2017.2668404 (DOI)000401086300009 ()
Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2020-04-07Bibliographically approved

Open Access in DiVA

fulltext(27645 kB)4 downloads
File information
File name FULLTEXT02.pdfFile size 27645 kBChecksum SHA-512
7b9c0ee0460431eb6d69af0896783356b804c96e33561aeb33e7ba03b8978654cdf928de82527bfcb33d1550517bb0020f55c74121b75745e08f1572e2b3c4c1
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Rameez, Muhammad
By organisation
Department of Mathematics and Natural Sciences
Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 14 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 134 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf