EURASIP Journal on Advances
in Signal Processing
Li et al. EURASIP Journal on Advances in Signal
Processing
(2016) 2016:97
DOI 10.1186/s13634-016-0395-2
RESEARCH Open Access
Reduced-dimension space-time adaptive
processing based on angle-Doppler
correlation coefficient
Ruiyang Li
*
, Jun Li, Wei Zhang and Zishu He
Abstract
Traditional space-time adaptive processing (STAP) is a strategy for clutter suppression in airborne radar, which
requires a large number of computational complexity and secondary data. In order to address the problem,
reduced-dimension (RD) STAP is generally used. We propose a novel RD STAP through searching the best channels as
the auxiliary channels to cancel the interference. Based on the estimation of the clutter Fourier basis vectors offline, a
parameter named angle-Doppler correlation coefficient (ADC
2
) is constructed to evaluate the capability of each
auxiliary channel in clutter suppression, and the best sets of RD channels can be selected. The proposed algorithm can
achieve the best detection performance with the fixed number of auxiliary channel. When the degrees of freedom
(DOF) are restricted to a small value, only one auxiliary channel is needed to guarantee the SINR loss less than 3 dB.
Therefore, the requirement of the training sample can be reduced, which makes the proposed approach more
suitable for the heterogeneous clutter environments.
Keywords: Airborne radar, Space-time adaptive processing, Reduced-dimension, Clutter covariance matrix
1 Introduction
Space-time adaptive processing (STAP) plays an impor-
tant role in the areas of airborne radar and sonar systems,
which collect signals linearly from an array to detect weak
targets within severe clutter and jamming environments
[1, 2]. The clutter-plus-noise covariance matrix (CCM) is
employed to calculate the filter weights for clutter sup-
pression. It has been long known that increasing the
number of degrees of freedom (DOF) enables excellent
detection performance, but since the computational com-
plexity and the number of samples for estimation CCM
are limited, it is difficult to be implemented in practical
work [3]. In recent years, a large amount of productive
works have been studied aiming at STAP with few DOF
and secondary data and provide a better detection per-
formance in heterogeneous clutter and strong jammer
environment, including the knowledge-aided radar, the
multiple-input multiple-output radar, and the jamming
suppression in complex environment [4–6].
*Correspondence: realowen10@foxmail.com
School of Electronic Engineering, University of Electronic Science and
Technology of China (UESTC), 611731 Chengdu, People’s Republic of China
The foremost theory of STAP is to adjust the space-time
filter weights to maximize output signal-to-interference-
plus-noise ratio (SINR) adaptively with DOF as less
as possible. Therefore, the dimensionality reduction
and rank reduction techniques are explored extensively
and addressed in the literature. When it comes to
reduced-dimension (RD) STAP, some typical suboptimal
approaches like the factor approach [7], the joint domain
localized (JDL) [8], and the space-time multiple-beam
(STMB) [9] have been proposed, which employ a fixed
dimension reducing transformation prior to the process-
ing. Lately, a modified RD STAP was proposed by select-
ing auxiliary channels near the clutter ridge [10]. However,
none of the traditional RD STAP can select auxiliary
channels adaptively. A multistage multiple-beam (MSMB)
technique is proposed in [11, 12], based on the principle
of selecting auxiliary channels to cancel the interference
components in the main channel clearly. But it is not
appropriate for engineering applications because a large
amount of calculation is needed.
On the other hand, reduced-rank (RR) STAP
approaches make use of data-dependent transformations,
such as the principal components (PC) inverse [13], the
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