Distributed
MIMO Radar
This work
has been supported by ONR under grant ONR-N-00014-09-1-0342
A Multiple-Input Multiple-Output (MIMO)
radar system, unlike a conventional transmit beamforming radar system,
transmits multiple non-coherent waveforms via its antennas. The multiple
waveforms provide diversity that enables significant performance improvement.
The MIMO radar problem has been well formulated and analyzed for the case of
linear transmit and receiver arrays.
In the proposed work, we plan to leverage our recent work on cooperative
beamforming to investigate the feasibility of MIMO radar based on randomly
dispersed nodes of a wireless network, such as a sensor network. An adaptive,
cross-layer approach will be developed, wherein a central station determines
the optimum number of required transmit and receive nodes, the optimum node
locations, and the node waveforms.
The optimization criterion will take into account the available network energy
and node signal-to-interference ratio. A selected set of M nodes act as transmitters, and another set act
as receivers. At a single receive node, based on knowledge of the transmitter
waveforms and via cross-correlation operations, one can obtain information
equivalent to that collected at a virtual subarray of M elements. Thus, each
receiver can provide information about the target location. Location estimates
from various receive nodes can be passed to a fusion center for further
refinement of the estimate, resulting in high resolution. The proposed project
will consider waveform design, beampattern design, techniques for optimal
selection of transmit nodes in order to meet certain resolution requirements,
and performance analysis in the presence of clutter. Since the proposed
distributed system obtains random spatial samples of the electromagnetic wave,
the applicability of ideas that have emerged in the area of compressive
sampling will be investigated for their use in reducing the amount of sampling
needed for target localization. The vulnerability of the proposed radar to
malicious nodes will be studied, and novel physical layer based approaches for
maintaining security will be proposed. The advantages of using the proposed
distributed approach as opposed to using a standard linear array are the
following: (i) in a high density network there are many degrees of freedom to
design the beampattern as desired around the look direction, which is important
for clutter reduction, reduction of
scanning time, or for avoiding malicious nodes who may attempt to intercept the
node waveforms; (ii) no pre-existing infrastructure is required and the
proposed system can be easily deployed; (iii) the proposed system is energy
efficient - by appropriately selecting the set of transmitters and receivers we
can use network energy in a distributed fashion; (iv) the resolution can be easily adjusted by
employing more transmit nodes/receive; and (v) the radar system is robust; even if
some node gets deactivated the system
performance will not be affected.
Collaborator: H. V. Poor, Princeton University