MIMO Radar
MIMO → Multi-Input Multi-Output
MIMO Radar is a technique that uses multiple separate transmitter and
receiver elements. The signals transmitted from each element are
orthogonal and therefore uniquely distinguishable. Each receiver
element sees a unique version of each transmitted signal. The received
signals will differ between each element according to their
locations.
Imagine one scatterer within reach from the transmitted signals. The
received signals will all be result of the backscatter from this one
target. To reach each receiver element, the received signals traveled
a slightly different distance. This variation in distance traveled
results in a phase difference between each receiver element for each
signal transmitted.
This phase difference due to spatial differences of the elements can
be corrected to form coherent signals. This is the same processing
technique for beamforming in Phased Array Antennas. In MIMO, there are
multiple transmitters that are also spatially separated. The receiver
elements receive those signals with the additional travel distance
based on that transmitter's location. Consequently, the product of the
number of transmitters and receivers is the max number of effective
received signals.
This results in dramatically increasing the array size with virtual
elements and much finer resolution.