Phase Noise Tolerance for Low-Pilot-Overhead OFDM Terahertz Links Beyond 64-QAM

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Hauptverfasser: Liu, Bowen, Tanabe, Takasumi
Format: Preprint
Veröffentlicht: 2025
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author Liu, Bowen
Tanabe, Takasumi
author_facet Liu, Bowen
Tanabe, Takasumi
contents THz wireless communications have garnered significant attention due to their unprecedented data rates enabled by the abundant untapped spectrum. However, advanced modulation formats beyond 64-QAM remain largely unexplored, as phase errors introduced during up/down-conversion severely limit system performance. Particularly, OFDM transmission is highly susceptible to aggravated ICI induced by phase noise, undermining the orthogonality of subcarriers. While PLLs and pilot-assisted compensation can mitigate phase errors, excessive pilot overhead compromises spectral efficiency and energy consumption, and white phase noise remains unrecoverable. Therefore, quantifying phase noise tolerance is essential for practical physical layer protocols. Here, we reveal the impact of phase noise in a 64-QAM, 2048-subcarrier OFDM THz transmission system. 3σ-error estimation is proposed to quantify phase noise tolerance, indicating an intuitive EVM threshold of approximately 5%. This threshold further delineates the trade-offs among phase noise levels, SNR requirements, and pilot overhead. Moreover, by benchmarking representative oscillators with distinct phase noise spectra, microring resonators (MRRs) are identified as indispensable enablers for low-pilot-overhead OFDM THz links operating beyond 64-QAM.
format Preprint
id arxiv_https___arxiv_org_abs_2508_05026
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phase Noise Tolerance for Low-Pilot-Overhead OFDM Terahertz Links Beyond 64-QAM
Liu, Bowen
Tanabe, Takasumi
Optics
Signal Processing
THz wireless communications have garnered significant attention due to their unprecedented data rates enabled by the abundant untapped spectrum. However, advanced modulation formats beyond 64-QAM remain largely unexplored, as phase errors introduced during up/down-conversion severely limit system performance. Particularly, OFDM transmission is highly susceptible to aggravated ICI induced by phase noise, undermining the orthogonality of subcarriers. While PLLs and pilot-assisted compensation can mitigate phase errors, excessive pilot overhead compromises spectral efficiency and energy consumption, and white phase noise remains unrecoverable. Therefore, quantifying phase noise tolerance is essential for practical physical layer protocols. Here, we reveal the impact of phase noise in a 64-QAM, 2048-subcarrier OFDM THz transmission system. 3σ-error estimation is proposed to quantify phase noise tolerance, indicating an intuitive EVM threshold of approximately 5%. This threshold further delineates the trade-offs among phase noise levels, SNR requirements, and pilot overhead. Moreover, by benchmarking representative oscillators with distinct phase noise spectra, microring resonators (MRRs) are identified as indispensable enablers for low-pilot-overhead OFDM THz links operating beyond 64-QAM.
title Phase Noise Tolerance for Low-Pilot-Overhead OFDM Terahertz Links Beyond 64-QAM
topic Optics
Signal Processing
url https://arxiv.org/abs/2508.05026