Towards Adaptive MIMO Radar – Receiver Processing for Orthogonally Coded FMCW Waveforms

In this paper, a novel design and processing of nearly orthogonal waveforms based on frequency-modulated continuous-wave (FMCW) signals for multiple-input, multiple-output (MIMO) radars is presented. The design, implementation and results of the complete system, capable of detection and imaging of radar targets, are here described. The orthogonality of sounding signals is critical for multi-channel radar applications since the interference between signals can significantly limit the radar's ability for observation of weak targets in presence of stronger targets and background clutter. The orthogonal waveforms are designed by coding consecutive complex FMCW signals in a frame so that they can be sent to the different transmit antennas of the radar allowing the simultaneous operation of all transmit channels. Moreover, a radar receiver processing, based on a complex frame based convolution between transmit and received waveforms together with 4-dimensional Fast Fourier Transform (4D-FFT) beamforming, is presented.