SPARSE RECOVERY ASSISTED DOA ESTIMATION UTILIZING SPARSE BAYESIAN
LEARNING
Min Huang, Lei Huang
College of Information Engineering, Shenzhen University, China
ABSTRACT
This paper proposes a novel approach to sparse recovery as-
sisted direction-of-arrival (SR-DOA) estimation. By exploit-
ing the sparsity inherent in the spatial spectrum, the DOA es-
timation is formulated as a sparse nonnegative least squares
problem. Meanwhile, in order to enhance the estimation accu-
racy, the devised method is able to suppress the additive Gaus-
sian noise but at the expense of a few degrees-of-freedom,
and mitigate the sampling errors by exploiting its asymptotic
distribution. Subsequently, the sparse Bayesian learning with
nonnegative Laplace prior is utilized to yield the DOA esti-
mation. The performances of the proposed SR-DOA estima-
tor along with other two existing approaches are investigated
and compared. Numerical results show that the proposed SR-
DOA algorithm is superior to the state-of-the-art methods in
terms of the estimation accuracy.
Index Terms— DOA, sparse recovery, sparse nonnega-
tive least squares problem, sparse Bayesian learning, nonneg-
ative Laplace prior
1. INTRODUCTION
Since direction-of-arrival (DOA) estimation can be widely
used in many areas, such as radar, sonar and wireless com-
munications, it has received considerable attention in litera-
ture. However, the estimation performances of the existing
algorithms usually degrade seriously in the situations of low
signal-to-noise ratio (SNR) or small number of snapshots.
Because the number of source signals is usually limited,
the spatial spectrum observed is sparse. Thus, by properly u-
tilizing the compressive sensing techniques, the sparse prop-
erty inherent in the array signal model can be exploited to im-
prove the DOA estimation performance. In particular, DOA
is estimated by minimizing the data fitting error as well as the
This work was supported in part by the Natural Science Founda-
tion of China under Grants U1501253, 61601300, 6160010632, 61501300,
61601304 and 61501485; in part by the China Postdoctoral Science Foun-
dation under Grant 2016M592535; in part by the Natural Science Fund-
ing of Guangdong Province under Grant 2017A030313336; in part by the
Foundation of Shenzhen under Grants JCYJ20170302142545828 and J-
CYJ20160520165659418; in part by the Foundation of Shenzhen University
under Grants 2016057 and 201557; and in part by the China Scholarship
Council.
sparsity of solution. In [1], the sparsity of solution is gen-
erated by forming an ℓ
1
-norm penalty function. In order to
enforce the sparsity of solution, a weighted ℓ
1
-norm penal-
ty function which utilizes the property of noise subspace is
proposed by [2]. In addition, the regularization parameter,
which is used to control the trade-off between the data fitting
error and the sparsity of solution, is obtained with the aid of
the Lagrangian duality in [3, 4]. Although, the regularization
parameter derived in [4] does not rely on any a pr iori knowl-
edge, it is suboptimal because it only satisfies the sufficient
conditions of optimal solution. Furthermore, when the grid
is dense, the computational complexities of the above algo-
rithms are unaffordable.
Alternatively, the sparse Bayesian learning (SBL) [5],
which avoids the regularization parameter selection, can be
used to solve the sparse recovery problem. Specifically, the
DOA is determined by maximizing its posterior probability,
namely, the product of the likelihood probability and the prior
probability. In order to obtain more degrees-of-freedom (D-
OFs) to estimate DOA, the DOA estimation problem is firstly
converted to a sparse nonnegative least squares (S-NNLS)
problem [6]. Then, the nonnegative Gaussian probability
density function (PDF) is considered as the prior probability
to solve the S-NNLS problem [7]. To enforce the sparsity
of solution, the nonnegative Gaussian PDF is replaced by
the Laplace PDF [8]. Although it is is not conjugate to the
Gaussian likelihood function, it can be implemented by a
hierarchical way. In other words, the Laplace PDF can be
constructed by Gaussian PDF and Exponential PDF. Nev-
ertheless, according to [9, 10], the power of Gaussian noise
estimated by SBL may not be accurate, leading performance
degradation.
In this paper, a sparse recovery assisted DOA (SR-DOA)
estimator is proposed. First, we show that the high-resolution
DOA estimation can be formulated as a sparse optimization
problem. Second, a selection matrix is designed for mitigat-
ing the effect of additive Gaussian noise but at the expense of
a small amount of DOFs. Third, a whitening filter is intro-
duced for coping with the sampling errors. Last, SBL with
nonnegative Laplace is used to determined the DOAs. Our
simulation results show that the proposed SR-DOA estimator
outperforms all the benchmark DOA estimators when SNR is
in low region.