Abstract:
Compressed Sensing (CS) has been recently applied to direction of arrival (DOA) estimation, leveraging the fact that
a superposition of planar wavefronts corresponds to a sparse
angular power spectrum. However, to apply the CS framework we need to construct a finite dictionary by sampling the
angular domain with a predefined sampling grid. Therefore,
the target locations are almost surely not located exactly on a
subset of these grid points. This leads to a model mismatch
which deteriorates the performance of the estimators. In this
paper we take an analytical approach to investigate the effect
of such grid offsets on the recovered spectra. We show that
each off-grid source can be well approximated by the closest
two neighboring points on the grid. We propose a simple and
efficient scheme to estimate the grid offset for a single source
or multiple well-separated sources. We also discuss a numerical procedure for the joint estimation of the grid offsets of
closer sources. Simulation results demonstrate the effectiveness of the proposed methods.
