Pi/K Phase Modulation for Large Scale MIMO Digitally Modulated Radars in Automotive Applications

It has been shown in previous works that the range sidelobes due to analog front-end non-idealities in Digitally Modulated Radars can be reduced by using a progressive phase rotation on top of the transmitted code sequence while providing MIMO capabilities at the same time. This technique is called π/K -MIMO. However, this requires to repeat the code sequence multiple times which degrades the maximum unambiguous Doppler. The purpose of this paper is to provide an analytical expression of the minimum required number of code sequences repetitions for a given number of transmitters and to compare its performances with more conventional MIMO schemes such as Range-Domain MIMO. In addition, we will show that it is possible to preserve all those properties even in presence of Doppler frequency shift.