MIMO radar

Multiple-input multiple-output (MIMO) radar is an extension of a traditional radar system to utilize multiple-inputs and multiple-outputs (antennas), similar to MIMO techniques used to increase the capacity of a radio link.

[1] [2] MIMO radar is an advanced type of phased array radar employing digital receivers and waveform generators distributed across the aperture.

However, instead of distributing the radar elements throughout the surveillance area, antennas are closely located to obtain better spatial resolution, Doppler resolution, and dynamic range.

[4] In a traditional phased array system, additional antennas and related hardware are needed to improve spatial resolution.

MIMO radar systems transmit mutually orthogonal signals from multiple transmit antennas, and these waveforms can be extracted from each of the receive antennas by a set of matched filters.

For example, if a MIMO radar system has 3 transmit antennas and 4 receive antennas, 12 signals can be extracted from the receiver because of the orthogonality of the transmitted signals.

That is, a 12-element virtual antenna array is created using only 7 antennas by conducting digital signal processing on the received signals, thereby obtaining a finer spatial resolution compared with its phased array counterpart.

receive antenna, each of which contains the information of an individual transmitting path(

[5][1][6] If the placements of the transmit and receive antenna array are expressed as two vectors

respectively, the placement vector of the virtual array is equal to the convolution of

In the second example, a nine-element virtual array is obtained by increasing the distance between the transmit antennas, implying that a better spatial resolution can be achieved.

[7][8] There are a variety of orthogonal signal sets used in the field of MIMO radar.

[9] In this approach, the total amount of available subcarriers is distributed among different transmit antennas in an interleaved way.