OTFS Modulation with Phase Noise in mmWave Communications

Orthogonal time frequency space modulation (OTFS) modulation is a 2-dimensional modulation technique designed in delay-Doppler domain, suited for doubly dispersive wireless channels. OTFS modulation has been shown to achieve superior error performance compared to the conventional multi-carrier systems. In this paper, we investigate the effect of phase noise on the performance of OTFS modulation in mmWave communications, where oscillator phase noise and Doppler shifts are typically high. Towards this, we first develop a vectorized formulation of the input-output relation for OTFS modulation (with OFDM as the inner core) in the delay-Doppler domain, incorporating oscillator phase noise in the effective channel. Using a message passing based signal detection algorithm, we show that OTFS is more robust to oscillator phase noise than OFDM in high Doppler mmWave channels. At an SNR for 14 dB, OTFS achieves two to three order better BER performance compared to OFDM in the presence of oscillator phase noise in a 28 GHz system.