Blind Velocities Mitigation For DDMA MIMO GMTI Radar Via Multi-Frequency Signals

Multiple-Input Multiple-Output (MIMO) radar has a potential advantage to improve the performance of ground moving target indication (GMTI) radar due to the larger virtual array. Waveform design is a key point to implement MIMO GMTI radar. Doppler division multiple access (DDMA) waveforms are a class of almost ideal orthogonal waveform, which can separate the echoes from different transmitters in Doppler domain. However, the high PRF is required in DDMA MIMO GMTI radar. In other words, blind velocities will arise in DDMA systems. Especially, the problem is worse in the MIMO radar with high carrier frequency, large number of transmitters, and/or low pulse repetition frequency (PRF). The blind velocities are related to the carrier frequencies. Employing multi-frequency signals is an efficient method to mitigate blind velocities. In this paper, a method called “multi-frequency DDMA” is proposed. Multiple signals with different carrier frequencies are transmitted by multiple transmitters. Theoretical analysis and simulation results demonstrate it is effective to mitigate blind velocities for MIMO GMTI radar with DDMA waveforms to employ multi-frequency signals.