The construction of a virtual array response is integral to the process of target detection for coherent airborne multiple input multiple output (MIMO) radars. Multiple scatterers on a target with complex scattering characteristics have an impact on the virtual array response. In this paper, an analytical expression for the virtual array response of a target is derived in terms of the response vectors of uniform linear arrays involving scatterer characteristics at multiple delays, the auto-ambiguity function and cross-ambiguity function of transmitted signals. Clutter at the same Doppler as the target is modeled similarly as signal returns from an ensemble of scatterers distributed in range. Analysis shows that the ideal Vandermonde vector of the virtual array response to a point scatterer must be modified to account for multiple scatterers and can provide a basis to develop detection/classification algorithms for coherent MIMO radar. A likelihood ratio test formulation of the detection problem is shown to result in the adaptive coherence estimator (ACE) test. The detection performance of the ACE test is derived in terms of parameters such as the signal-to-noise ratio, dimensionality of the MIMO clutter subspace, and the mismatch angle between the virtual array vector for an assumed target scatter model and the signal component of the actual virtual array vector. Illustrative results are presented using a fast-time orthogonal waveforms proposed in the literature as an example. Pulses in the example signal set comprise a sequence of frequency hopping subpulses and the frequency hopping sequences of these waveforms are derived from a subset of the Reed-Solomon code and the waveforms have several interesting properties including insensitivity to frequency errors.
Coherent Airborne MIMO Detection of Multiscatter Targets
IEEE Transactions on Aerospace and Electronic Systems ; 54 , 2 ; 978-991
2018-04-01
840615 byte
Article (Journal)
Electronic Resource
English
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