Doppler division multiplexing using non-power-of-two PSK orders

Doppler-division multiplexing (DDM) is one of the preferred methods to enable transmit (Tx) multiplexing in automotive radar systems. Typically today automotive radars employ a low phase shift keying (PSK) order which is power-of-two restricting the number of available shifts in the Doppler spectrum and creating scalability issues when trying to multiplex more Tx. To address this, we propose to use odd-DDM (ODDM), which uses non-power-of-two PSK orders to enable the configuration of more Doppler shifts. In this work, we present the radar signal processing implications of using ODDM. We show that ODDM requires complex window corrections or mixed-radix fast Fourier transform (FFT) processing to address amplitude and phase distortion of the Tx-shifted peaks. Our simulation shows that both approaches restore sensitivity at angle estimation level, improving the scalability of DDM-modulated systems.