The latest Euro NCAP regulation, No. 79 specifies that a sensor should be able to detect vehicles approaching from the rear in an adjacent lane up to a distance $S_{\mathrm{rear}}$ . The distance Srear depends on the ego vehicle speed and the speed of the approaching vehicle. To meet these requirements, a radar sensor must be able to detect a vehicle that is moving at 130 kmph at a distance of 200 m away from the sensor.

To meet these requirements, the additional fourth transmitter in the AWR2944 is used to increase the azimuth angular resolution to approximately 9.5 degrees. In addition, the TX phase shifters and the capability to change the phase shift per chirp is leveraged to give a unique cyclic phase shift to each transmit channel. This unique cyclic phase shift allows separation of the TX channel in the Doppler domain, a MIMO scheme known as Doppler division multiple access (DDMA). DDMA permits an increase in the SNR by ${\mathrm{10log}}_{\mathrm{10}}$ (Nt) = 6 dB over standard Time Division multiplexing schemes where Nt is the number of transmit channels. This increase in SNR results in larger detection ranges.