IQ Imbalance Robust and Low PAPR OFDM Radar Waveform

We address jointly the problem of IQ imbalance and PAPR in OFDM radars. IQ imbalance is known to cause severe distortion in OFDM receivers, manifesting itself as interference from one side of the received spectrum to the other side and vice versa. Various methods have been designed in the wireless communications context to estimate and compensate the receiver IQ imbalance. We adopt here a different approach where the radar waveform is designed to be robust against IQ imbalance. We derive an analytical criterion to achieve this robustness. In addition, we also show that this waveform design can be adapted to keep the OFDM waveform PAPR below 3dB, regardless of the number of sub-carriers, thereby relaxing the usual OFDM power amplifier back-off requirement. We validate the effectiveness of this joint design with simulation results.