On the Effect of Oscillator Phase Noise on the Performance of OFDM Systems in Sub-THz Band

This paper presents an in-depth analysis of effect of oscillator phase noise (PN) on the performance of orthogonal frequency division multiplexing (OFDM) systems in sub-terahertz (Sub-THz) band. We use the empirical PN measurement of current Sub-THz signal sources to propose a two-part PN model that captures the unique characteristics of PN in Sub-THz band. Subsequently, the proposed model is used to analyze the performance of OFDM systems affected by PN. Our analysis reveals some key distinctions between the effect of PN on the OFDM systems operating at Sub-THz and the same systems operating at conventional microwave frequency bands. In particular, we show that in these systems: 1) the PN floor has a significant effect on the performance degradation, 2) the assumption of PN being a low-pass process is inaccurate, and 3) the existing OFDM PN mitigation schemes are less effective. To verify our analysis the upper bound on the signal-to-interference-and-noise ratio (SINR) after using the existing PN mitigation schemes under limited computational complexity constraint is derived and the effect of PN floor on the SINR is analytically calculated.