Joint Features Extraction for Multiple Moving Targets Using (Ultra-)Wideband FMCW Signals in the Presence of Doppler Ambiguity

Abstract

This article addresses the joint estimation of range, velocity and azimuth for multiple fast-moving targets using (ultra-)wideband (UWB) frequency-modulated continuous-wave (FMCW) radar with a phased array in the presence of Doppler ambiguities. The range migration of moving targets is described with the coupling of the fast-time and slow-time (chirp index), leading to the smearing of the target Doppler spectrum. This phenomenon degrades the performance of conventional detection and estimation techniques. As with range-Doppler processing, the estimation accuracy for direction-of-arrival (DOA) with conventional narrowband-based algorithms significantly degrades if a UWB signal is deployed. For the FMCW waveform, the wideband DOA differs from the narrowband DOA due to an extra coupling term, similar to the range migration problem. A novel spectral normbased algorithm for joint estimation of range, velocity and DOA of fast-moving targets is proposed, taking the appropriate wideband signal model with the coupling terms into account. The proposed spectral norm-based algorithm avoids off-grid peak search and can be easily accelerated with power iteration; it outperforms conventional coherent integration methods in both accuracy and efficiency when using moderate data size. The advantages of the proposed algorithm and its super-resolution capability are validated with numerical simulations.

An Approach for High-Angular Resolution Implementation in Moving Automotive MIMO Radar

“…However, DBF is not a high-resolution angle-finding method. Higher angular resolution can be achieved with Minimum Variance Distortionless Response (MVDR) [6], subspace-based methods, such as multiple signal classification (MUSIC) and estimation of signal parameters via rational invariance techniques (ESPRIT) [7], sparse sensing-based methods [8], using the movement of radar [9], and the iterative adaptive approach (IAA) [10]. Those are proposed to break the Rayleigh limits under current configuration by signal processing or information theory.…”

Motion parameter estimation of high‐speed manoeuvering targets based on hybrid integration and synchrosqueezing transform

“…Over the last few decades, more and more low-observable high-speed and manoeuvering targets have emerged in the radar field of view. There is a growing need for the high precision motion information of the manoeuvering target, since it is very meaningful for the target detection, tracking, imaging, classification, and identification [1][2][3][4][5][6][7][8][9][10][11]. It is well known that the coherent or non-coherent integration is a powerful approach to improve the signal-to-noise ratio (SNR) of radar returns, which is extremely helpful for the estimation of the target's motion parameters [1].…”

“…However, for a high-speed target moving with sufficient manoeuverability, the energy of echo signal would spread in different range cells, and the Doppler spectrum of echo signal may be ambiguous, spreading, split, skew, and wrapping during the observation time interval, for a radar system adopting the low-pulse repetition frequency (PRF) scheme to increase the range unambiguous observation scope. Direct integration of the echo signal among multiple pulses cannot efficiently exploit the echo signal energy, the performance of a traditional radar system would be seriously deteriorated [4,5,9,10,[12][13][14][15]. In the case of multiple targets, the situation is more challenging.…”

A Novel Approach to Unambiguous Doppler Beam Sharpening for Forward-Looking MIMO Radar

“…The work in [35] uses the residual motion compensation to improve the SAR image quality for automotive. The velocity information was also used for wideband DOA estimation with compensation of range migration and the presence of Doppler ambiguity in [36] and for high angular resolution imaging in [37] and [38].…”

“…However, all the aforementioned algorithms [32], [33], [34], [35], [36], [37], [38] do not consider the ambiguity problem in case of the forward-looking radar. To our best knowledge, compared with [21] and [24], this article is the first to solve the ambiguity in DBS for forward-looking MIMO radar.…”