OTFS Waveform with Phase Noise in sub-THz

Abstract

The availability of large bandwidths in the sub-THz bands appears to be a solution for increasing the capabilities of future wireless communication technologies. However, phase noise generated by oscillators in these bands generates significant signal distortion which needs to be addressed. In this paper, we study the impact of phase noise on OTFS. We propose phase noise compensation scheme and associated frame format. Two dedicated pilot schemes are studied for the phase noise tracking: the first one consists in adding pilots in the delay-Doppler (DD) domain while the other in the delay-Time (DT) domain. We highlight that compensating phase noise in DT domain gives better performance. A comparison between OFDM, DFT-s-OFDM and OTFS according to the 5G-NR numerology is presented. We show that the OTFS waveform is robust to phase noise and may even significantly outperform OFDM and DFT-s-OFDM.

Wiener Interpolation Filter for Phase Noise Estimation in sub-THz Transmission

“…As a consequence, we need to adapt the interpolation matrices to include the ICI terms. The expression of the interpolation matrix Z can be written as follows [7]:…”

“…for DFT-s-OFDM systems [7]• (21) The vector C P E is the vector which contains the CPE in all rows. The term e jϕ ′ represents the exponential of the new PN vector ϕ ′ obtained after fast Fourier transformations.…”

“…For the PN estimation, we consider phase tracking reference signal (PTRS) distribution as depicted in Fig. 1-(a) in [7]. We consider a realistic channel estimation with noisy received pilots.…”

“…Another algorithm, which exploits an a priori knowledge of stochastic properties of PN, i.e. its power spectral density (PSD), is introduced in [7]. Performance comparison considering a DFT-s-OFDM system is given in [7], by considering the IF algorithm and other estimation algorithms.…”

“…its power spectral density (PSD), is introduced in [7]. Performance comparison considering a DFT-s-OFDM system is given in [7], by considering the IF algorithm and other estimation algorithms. The use of the IF leads to a good estimation of PN and therefore, the improvement of the system performance after PN compensation is highlighted.…”