Sparse Automotive MIMO Radar for Super-Resolution Single Snapshot DOA Estimation With Mutual Coupling

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

Gapwaveguide Automotive Imaging Radar Antenna with Launcher in Package Technology

A 77 GHz gapwaveguide radar antenna system with launcher-in-package (LiP) technology is presented in this paper for automotive imaging applications. Firstly, state-of-the-art LiP technology integrated with radar transceivers is proposed. The transceivers are equipped with waveguide interfaces for RF connection, enabling direct integration with waveguide antennas. Robust interconnects for coupling transceivers to waveguide antennas with non-galvanic contacts are proposed using gapwaveguide packaging technology. A simultaneous multi-mode imaging radar system using 4 cascaded aforementioned transceivers is introduced. Designated antenna elements of the system are realized by slot arrays with center-fed ridge gapwaveguides. Ultimately, the imaging radar antenna has a top radiating slot layer, a middle distribution layer and a bottom interconnect layer capable of accommodating 4 LiP radar transceivers with considerable assembly tolerance which is really one of the key aspects for commercial automotive radar applications. Input matching and radiation patterns of the antenna are verified by measurement. The results indicate that the proposed gapwaveguide imaging radar antenna in conjunction with the novel LiP packaging is able to serve the radar system properly. To the best of the authors’ knowledge, the proposed gapwaveguide antenna system is the first imaging radar antenna system ever developed for LiP components. This work provides a compact, high-efficiency and cost-effective solution for the integration of complex radar systems with waveguide antennas

Enhanced interference detection method in automotive FMCW radar systems

In the coming years, automotive radar sensors will play a crucial role in the autonomous driving tasks. A future challenge to be addressed is represented by the potential radar to radar interference. Frequency Modulated Continuous Wave (FMCW) radar to radar interference can cause severe dynamic range penalties in the radar receiver which lead to a reduction of maximum detectable range as well as sensitivity losses. State of the art FMCW to FMCW radar interference detection techniques are prone to miss weak interference. Though weak, this interference can still decrease sensitivity. A high pass filter can be applied before the first stage of range processing to reduce the contribution of the close and strong reflectors in the interference detection process. By applying this filter, the return from close targets can be suppressed to a certain extent, preferably below the noise floor, such that only the interference can be effectively considered in the interference detection process. This allows the detection of interference with a lower power than the return from the close targets

Doppler Influence on Waveform Orthogonality in 79GHz MIMO Phase-Coded Automotive Radar

Utilization of phase-coded waveforms in automotive MIMO radars for short to medium range applications is studied. Performances of three most-promising binary code families (Gold, APAS and ZCZ sequences) are compared. Design tradeoffs of practical implementation of phased-coded waveforms for MIMO radar are analyzed for the first time for a possible future System on Chip implementation. Orthogonality of the waveforms in case of moving targets is analyzed. The implications of the code properties for the Range-Doppler map, as well as the Range-Angular map, are pointed out. Doppler frequency shift impact on such performance indicators as the target peak power and range sidelobe levels in the range-Doppler plane, as well as the range and azimuth sidelobe behavior, and the angular error in the azimuthal plane have been comprehensively studied for the first time. It is shown that the time-staggered transmit scheme with autocorrelation properties only (while introducing azimuthal errors) results in improved performance compared to code division multiplexing with auto- and cross-correlation properties.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Microwave Sensing, Signals & System

Uncorrelated Interference in 79 GHz FMCW and PMCW Automotive Radar

An extensive comparison on radar-to-radar interference in frequency-modulated continuous wave (FMCW) and binary phase-modulated continuous wave (PMCW) radars is performed. The noise-plus-interference power for FMCW-to-FMCW and PMCW-to-PMCW interference in a single victim and single interferer environment is compared for generalized waveform-based scenarios. It is proven that the interference suppression is equal in FMCW and PMCW radars in case the time-bandwidth product in both systems is equal.</p

Uncorrelated interference in 79 GHz FMCW and PMCW automotive radar

An extensive comparison on radar-to-radar interference in frequency-modulated continuous wave (FMCW) and binary phase-modulated continuous wave (PMCW) radars is performed. The noise-plus-interference power for FMCW-to-FMCW and PMCW-to-PMCW interference in a single victim and single interferer environment is compared for generalized waveform-based scenarios. It is proven that the interference suppression is equal in FMCW and PMCW radars in case the time-bandwidth product in both systems is equal

Uncorrelated Interference in 79 GHz FMCW and PMCW Automotive Radar

An extensive comparison on radar-to-radar interference in frequency-modulated continuous wave (FMCW) and binary phase-modulated continuous wave (PMCW) radars is performed. The noise-plus-interference power for FMCW-to-FMCW and PMCW-to-PMCW interference in a single victim and single interferer environment is compared for generalized waveform-based scenarios. It is proven that the interference suppression is equal in FMCW and PMCW radars in case the time-bandwidth product in both systems is equal.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Microwave Sensing, Signals & System

Fusion of Data from Multiple Automotive Radars for High-Resolution DoA Estimation

High angular resolution is in high demand in automotive radar. To achieve a high azimuth resolution a large aperture antenna array is required. Although MIMO technique can be used to form larger virtual apertures, a large number of transmitter-receiver channels are needed, which is still technologically challenging and costly. To circumvent this problem, we propose a high-resolution Direction of Arrival (DoA) estimation by using multiple small radar sensors distributed on the fascia of the automobile. To exploit the diversity gain due to different target observation angles by different radars, a block Focal Under determined System Solver based approach is proposed to incoherently fuse the data from multiple small MIMO sensors. This method significantly improves the DoA estimation compared to single sensor, decreases probability of false alarm and increases probability of multiple target detection. Its performance is demonstrated through both numerical simulations and experimental results.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Microwave Sensing, Signals & System

Worldwide Techniques and Outcomes in Robot-assisted Minimally Invasive Esophagectomy (RAMIE):Results From the Multicenter International Registry

OBJECTIVE: This international multicenter study by the Upper GI International Robotic Association aimed to gain insight in current techniques and outcomes of RAMIE worldwide. BACKGROUND: Current evidence for RAMIE originates from single-center studies, which may not be generalizable to the international multicenter experience. METHODS: Twenty centers from Europe, Asia, North-America, and South-America participated from 2016 to 2019. Main endpoints included the surgical techniques, clinical outcomes, and early oncological results of ramie. RESULTS: A total of 856 patients undergoing transthoracic RAMIE were included. Robotic surgery was applied for both the thoracic and abdominal phase (45%), only the thoracic phase (49%), or only the abdominal phase (6%). In most cases, the mediastinal lymphadenectomy included the low paraesophageal nodes (n=815, 95%), subcarinal nodes (n = 774, 90%), and paratracheal nodes (n = 537, 63%). When paratracheal lymphadenectomy was performed during an Ivor Lewis or a McKeown RAMIE procedure, recurrent laryngeal nerve injury occurred in 3% and 11% of patients, respectively. Circular stapled (52%), hand-sewn (30%), and linear stapled (18%) anastomotic techniques were used. In Ivor Lewis RAMIE, robot-assisted hand-sewing showed the highest anastomotic leakage rate (33%), while lower rates were observed with circular stapling (17%) and linear stapling (15%). In McKeown RAMIE, a hand-sewn anastomotic technique showed the highest leakage rate (27%), followed by linear stapling (18%) and circular stapling (6%). CONCLUSION: This study is the first to provide an overview of the current techniques and outcomes of transthoracic RAMIE worldwide. Although these results indicate high quality of the procedure, the optimal approach should be further defined