Phase Noise Model Selection for Sub-THz Communications

To face the exponential data traffic growth, the sub-THz spectrum (100-300 GHz) is envisioned for wireless communications. However, sub-THz systems are critically impacted by the strong phase noise of high frequency oscillators. This paper discusses the appropriate choice of phase noise model for sub-THz communications. Two phase noise models are introduced and compared: one correlated, accurate but complex, and another uncorrelated, analytically simpler. The expression of the likelihood ratio enables us to propose an analytical condition to select the best of the two models for a measured oscillator spectral characteristic. Numerical simulations are performed with realistic phase noise generated according to a state-of-the-art sub-THz oscillator and show that an uncorrelated Gaussian process is appropriate to model the impact of phase noise in sub-THz systems. Eventually, the proposed results are applied to link adaptation in the presence of phase noise in order to choose the most robust scheme between a coherent and a differential modulation.