Design of orthogonal waveforms for MIMO radar with phase randomised frequency hopping (FH) sequence

MIMO radar covers a broad class of systems having multiple antennas at transmit and/or receive. The performance of the MIMO radar varies widely based on the system configuration. The waveform for MIMO radar can be orthogonal or correlated. In case of correlated waveform the covariance matrix has to be decided based on various system parameters before proceeding to waveform design. In many scenarios the waveform transmitted from different transmit elements are fully orthogonal. The use of orthogonal waveform ensures that the contribution of each transmit element can be extracted at the receiver and combined transmit-receive beamforming can be done. Irrespective of the processing involved the requirement to design orthogonal waveform mandates that they have impulse like autocorrelation and very low cross-correlation. This paper proposes to use phase randomised FH sequence for obtaining this objective. This also provides a large number of orthogonal waveforms. The study is also carried out to quantify the improvement in sidelobe level and doppler tolerance of the proposed waveform.