IET Radar, Sonar & Navigation
Research Article
SFMM design in colocated CS-MIMO radar for
jamming and interference joint suppression
ISSN 1751-8784
Received on 11th October 2017
Revised 13th March 2018
Accepted on 15th March 2018
E-First on 17th April 2018
doi: 10.1049/iet-rsn.2017.0444
www.ietdl.org
Wei Xiong
1,2
, Maria Greco
3
, Fulvio Gini
3
, Gong Zhang
1
, Zhenni Peng
4
1
Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing
211106, People's Republic of China
2
Leihua Electronic Technology Research Institute, Aviation Industry Corporation of China, Wuxi 214063, People's Republic of China
3
Dipartimento di Ingegneria dell’ Informazione, University of Pisa, Pisa 56122, Italy
4
Key Laboratory of Advanced Technology for Small and Medium-sized UAV, Ministry of Industry and Information Technology, Nanjing 210016,
People's Republic of China
E-mail: gzhang@nuaa.edu.cn
Abstract: This study focuses on the problem of joint suppression of active jamming in target sector-of-interest (SOI) and out-of-
sector interference for colocated compressive sensing multiple-input–multiple-output (CS-MIMO) radar. Three effective
strategies for spatial filter measurement matrix (SFMM) design are outlined. Unlike the previous reported Capon beamformer
and minimum variance distortionless response beamformer, the proposed design strategies only depend on the target spatial
SOI rather than the accurate directions-of-arrival (DOAs) of targets, jammers and interfering sources to obtain deep nulls or
notches for the SOI jamming and low-attenuation levels for the out-of-sector interference. The SFMM design criteria are derived
using the second-order cone programming and solved as convex optimisation problems. The proposed approaches can
simultaneously suppress the SOI jamming and attenuate the out-of-sector interference. Meanwhile, better DOA estimation
accuracy can be achieved. Simulation results demonstrate the superiority of the proposed approaches over the other methods
for colocated CS-MIMO radar.
1 Introduction
Unlike the distributed multiple-input–multiple-output (MIMO)
radar, the antennas in colocated MIMO radar are closely spaced so
that, in the far-field, they look at the target under the same aspect
and, contrary to the phased array (PA) systems, waveform diversity
allowed by the transmit and receive arrays can be exploited [1, 2].
It has been shown that the colocated MIMO radars have some
advantages over PA radars such as the extended virtual array
aperture, the increased upper limit on the number of detectable
targets, improved parameter identifiability and angular resolution
and so on [1–5]. In the last decade, by exploiting the target sparsity
in the target space/scene, compressive sensing (CS) theory has
been successfully applied to MIMO radars and has shown great
potentials in target parameter estimation [6], Synthetic Aperture
Radar (SAR) imaging [7], waveform design [8] and interference
attenuation [9]. CS-MIMO radar systems have been proposed in
[6–8] and the beamforming techniques for colocated CS-MIMO
radars have also been studied to achieve processing gain or the
desired beampattern to suppress the target-like interference [9, 10].
Colocated CS-MIMO radar can achieve either the same
localisation performance as traditional methods with significantly
fewer measurements or significantly improved performance with
the same number of measurements [10]. However, the assumed
target sparsity decreases in the presence of clutter, interference and
jamming, and the parameter estimation performance would
degrade severely. Yu et al. [10] proposed a Capon-like
beamforming method to suppress clutter in the context of colocated
CS-MIMO radar. However, when the clutter covariance and
directions-of-arrival (DOAs) of interfering sources and/or jammers
are unknown, conventional methods such as the Capon
beamformer [10] and the minimum variance distortionless response
beamformer of [11, 12] fail. Without prior knowledge of the clutter
covariance function, the Capon beamforming does not enable to
improve the DOA estimation performance of colocated CS-MIMO
radar. Under the assumption of known spatial sector-of-interest
(SOI), where the targets are likely to be located, Hassanien and
Vorobyov [4] proposed a transmit beamspace energy focusing
technique for colocated MIMO radars with application to DOA
finding for multiple targets and simultaneously suppressing the
interference and clutter out of the spatial SOI. Spheroidal
sequences were employed to design the transmit beamspace matrix
so that the ratio of the energy radiated within the desired spatial
SOI to the total radiated energy was maximised [4]. For a better
DOA estimation of colocated MIMO radar in the presence of
interference and jamming, Li et al. [13] proposed three reduced
dimension beamspace matrices to achieve reasonable tradeoffs
between the desired SOI source distortion and the out-of-sector
interference/jamming (possibly in-sector) attenuation. However,
the beamspace matrix was developed by minimising the output
power of the total received signal followed by a transformation.
The transformed target signal would be also attenuated while
minimising the power of the transformed interference and
jamming. Similarly, Tao et al. [9] proposed a spatial filter
measurement matrix (SFMM) design method for colocated CS-
MIMO radar based on the pass-band beamforming for spatial target
sectors and lower gain beamforming for out-of-sector areas to
suppress the possible interference or clutter. However, it can be
seen that the attenuation levels for spatial areas out-of-sector are
limited. Only if the interference-to-noise ratio (INR) or clutter-to-
NR (CNR) is small, the out-of-sector interference or clutter would
be suppressed. Moreover, the case of possible jamming in the SOI
is not considered. Actually, with the development of electronic
countermeasure (ECM), the important target is often protected by
the countermeasure system to prevent radars from operating as well
as possible.
As an important ECM, active jamming often takes the form of
high-power transmission and blocks the radar receive system with
highly concentrated energy [14]. In view of the closed element
spacing of transmit and receive arrays, colocated CS-MIMO radars
can be blocked by active jamming. Moreover, terrain-scattered
jamming also is a typical active jamming example, which occurs in
a dispersive manner when the ground reflects the power
transmitted by a high-power jammer [11, 15]. It shows up as a
IET Radar Sonar Navig., 2018, Vol. 12 Iss. 7, pp. 702-710
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