MIMO Radar: Diversity Means Superiority

A MIMO (multi-input multi-output) radar system, unlike a standard phased-array radar, can transmit via its antennas multiple probing signals that may be correlated or uncorrelated with each other. We provide herein an overview of our recent result, showing that this waveform diversity enables the MIMO radar superiority in several fundamental aspects, including: 1) significantly improved parameter identifiability, 2) direct applicability of adaptive arrays for target detection and parameter estimation, and 3) much enhanced flexibility for transmit beampattern design. Specifically, we show that 1) the maximum number of targets that can be uniquely identified by the MIMO radar is up to Mt times that of its phased-array counterpart, where Mt is the number of transmit antennas, 2) the echoes due to targets at different locations can be linearly independent of each other, which allows the direct application of many adaptive techniques to achieve high resolution and excellent interference rejection capability, and 3) the probing signals transmitted via its antennas can be optimized to obtain several transmit beampattern designs with superior performance. For example, the covariance matrix of the probing signal vector transmitted by the MIMO radar can be optimized to maximize the power around the locations of the targets of interest and also to minimize the cross-correlation of the signals reflected back to the radar by these targets, thereby significantly improving the performance of adaptive MIMO radar techniques. Additionally, we demonstrate the advantages of several MIMO transmit beampattern designs, including a beampattern matching design and a minimum sidelobe beampattern design, over their phased-array counterparts.