The Fairy Tale of Simple All-Digital Radars: How to Deal With 100 Gbit/s of a Digital Millimeter-Wave MIMO Radar on an FPGA [Application Notes]

Schweizer, Benedikt; Grathwohl, Alexander; Rossi, Gilberto; Hinz, Philipp; Knill, Christina; Stephany, Simon; Ng, Herman Jalli; Waldschmidt, Christian

doi:10.1109/mmm.2021.3069602

Cited by 30 publications

(12 citation statements)

References 46 publications

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“…As in [3], the PAPR was calculated assuming an oversampling factor of 20 to capture fast variations of time-domain signals. The particularly low baseband PAPR for the considered OCDM-based radar system and its MU/MIMO variant is explained by the single active subchirp in ( 25) and (37), which yields a complex exponential signal with a virtually constant envelop in the discrete-time domain after the IDFnT in (1). As for the sector-modulated OCDM-based RadCom system, the presence of active, modulated subchirps in (40) yields nearly 6 dB higher average PAPR.…”

Section: Numerical and Measurement Resultsmentioning

confidence: 99%

“…A LL-digital radar systems have been increasingly gaining attention in recent years. While they impose the challenge of handling high data rates resulting from the use of digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) with high resolutions and sampling rates [1], their use enables a wide range of possibilities. Among these are enabling efficient multi-user (MU) or multiple-input multiple-output (MIMO) operation, e.g., for distributed radar sensing or direction of arrival (DoA) estimation [2], while also yielding high unambiguous velocity and fine range resolution.…”

Section: Introductionmentioning

confidence: 99%

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Discrete-Fresnel Domain Channel Estimation in OCDM-based Radar Systems

Oliveira¹,

Nuß²,

Alabd³

et al. 2022

Preprint

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In recent years, orthogonal chirp-division multiplexing (OCDM) has been increasingly considered as an alternative multicarrier scheme, e.g., to orthogonal frequency-division multiplexing, in digital communication applications. Among reasons for thar are its demonstrated superior performance resulting from its robustness to impairments such as frequency selectivity of channels and intersymbol interference. Furthermore, the socalled unbiased channel estimation in the discrete-Fresnel domain has also been investigated for both communication and sensing systems, however without considering the effects of frequency shifts. This article investigates the suitability of the aforementioned discrete-Fresnel domain channel estimation in OCDMbased radar systems as an alternative to the correlation-based processing previously adopted, e.g., in the radar-communication (RadCom) literature, which yields high sidelobe level depending on the symbols modulated onto the orthogonal subchirps. In this context, a mathematical formulation for the aforementioned channel estimation approach is introduced. Additionally, extensions to multi-user/multiple-input multiple-output and RadCom operations are proposed. Finally, the performance of the proposed schemes is analyzed, and the presented discussion is supported by simulation and measurement results. In summary, all proposed OCDM-based schemes yield comparable radar sensing performance to their orthogonal frequency-division multiplexing counterpart, while achieving improved peak-to-average power ratio and, in the RadCom case, communication performance.

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Section: Numerical and Measurement Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Discrete-Fresnel Domain Channel Estimation in OCDM-based Radar Systems

Oliveira¹,

Nuß²,

Alabd³

et al. 2022

Preprint

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“…The evaluation is performed using simulations and measurements. For the measurements, a MIMO-OFDM frontend with N Tx = 4 transmit channels is used in combination with a Xilinx RFSoC to generate and store the baseband signals [18], [19]. The radar operates at the automotive frequency band at 77 GHz.…”

Section: Comparison and Evaluationmentioning

confidence: 99%

Multiplexing of OFDM-Based Radar Networks

Werbunat¹,

Sgroi²,

Knill³

et al. 2021

2021 IEEE Radar Conference (RadarConf21)

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Radar networks offer the opportunity of enhancing the radar sensing performance beyond the inherent limitations of single multiple-input multiple-output (MIMO) radars. Different locations of the individual sensor nodes allow for diverse observation angles on the targets. Moreover, in case of a coherent network, such as radar-repeater networks, the direction of arrival (DoA) capabilities are increased. However, a crucial point in exploiting the full potential of a sensor network is the separability of the signals originating from the different sensor nodes during operation, while preserving reasonable radar sensing performance of the individual sensors and the network. In this paper multiplexing methods for an orthogonal frequencydivision multiplexing (OFDM)-based radar network are proposed and investigated. The first method combines traditional time and frequency multiplexing, while the second method applies a random assignment in combination with a compressed sensingbased signal evaluation. Both methods are compared with the traditional FDM multiplexing for MIMO-OFDM. For this purpose, performance criteria are proposed and the concepts are evaluated based on measurements and simulations.

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“…Although inherently high data rates to digital radar systems based on modulation schemes such as orthogonal frequency-division multiplexing (OFDM) [9,10] and orthogonal chirp-division multiplexing (OCDM) [11,12] are also an issue in PMCW [13], the overall system complexity and efficiency of PMCW-based radar systems can be improved with respect to other digital radar modulation schemes if a pseudorandom binary sequence (PRBS) is adopted as a base radar signal. The main advantages of the use of PRBSs comprise the lower linearity requirements and higher efficiency of power amplifiers (PAs) due to the possibility of operating near saturation since a continuous wave (CW)-like signal is transmitted [14], the lack of need for I/Q modulation at the transmitter, and the possibility to use linear-feedback shift registers (LFSRs) instead of digital-to-analog converters (DACs) if PRBSs such as m-sequences are adopted.…”

Section: Introductionmentioning

confidence: 99%

Doppler Shift Tolerance of Typical Pseudorandom Binary Sequences in PMCW Radar

Oliveira

Antes

Nuß

et al. 2022

Sensors

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In the context of all-digital radar systems, phase-modulated continuous wave (PMCW) based on pseudorandom binary sequences (PRBSs) appears to be a prominent candidate modulation scheme for applications such as autonomous driving. Among the reasons for its candidacy are its simplified transmitter architecture and lower linearity requirements (e.g., compared to orthogonal-frequency division multiplexing radars), as well as its high velocity unambiguity and multiple-input multiple-output operation capability, all of which are characteristic of digital radars. For appropriate operation of a PMCW radar, choosing a PRBS whose periodic autocorrelation function (PACF) has low sidelobes and high robustness to Doppler shifts is paramount. In this sense, this article performs an analysis of Doppler shift tolerance of the PACFs of typically adopted PRBSs in PMCW radar systems supported by simulation and measurement results. To accurately measure the Doppler-shift-induced degradation of PACFs, peak power loss ratio (PPLR), peak sidelobe level ratio (PSLR), and integrated-sidelobe level ratio (ISLR) were used as metrics. Furthermore, to account for effects on targets whose ranges are not multiples of the range resolution, oversampled PACFs are analyzed.

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The Fairy Tale of Simple All-Digital Radars: How to Deal With 100 Gbit/s of a Digital Millimeter-Wave MIMO Radar on an FPGA [Application Notes]

Cited by 30 publications

References 46 publications

Discrete-Fresnel Domain Channel Estimation in OCDM-based Radar Systems

Discrete-Fresnel Domain Channel Estimation in OCDM-based Radar Systems

Multiplexing of OFDM-Based Radar Networks

Doppler Shift Tolerance of Typical Pseudorandom Binary Sequences in PMCW Radar

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