Beam Squint and Aperture--Bandwidth Limitations in Wideband RIS-Assisted THz Links
Abstract
This paper analyzes the ergodic rate of a wideband reconfigurable intelligent surface (RIS)-assisted terahertz link under beam squint and finite-resolution phase control. Independent Rayleigh fading on the two RIS-assisted hops produces double-Rayleigh cascaded amplitudes. Exact second- and fourth-order channel moments are derived by incorporating the frequency-dependent array response and phase-quantization errors. Moment matching then provides a Gamma approximation for the received power on each subcarrier and a tractable closed-form approximation for the wideband ergodic rate. A first-null bandwidth approximation characterizes the aperture--bandwidth limitation of frequency-flat RIS control. Monte Carlo simulations validate the analytical framework.
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BibTeX
@misc{khalid2026beam,
title = {{Beam Squint and Aperture--Bandwidth Limitations in Wideband RIS-Assisted THz Links}},
author = {Waqas Khalid and Chiew Foong Kwong and David Chieng and Qianyu Liu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14037},
eprint = {2609.14037},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14037},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Beam Squint and Aperture--Bandwidth Limitations in Wideband RIS-Assisted THz Links
AU - Waqas Khalid
AU - Chiew Foong Kwong
AU - David Chieng
AU - Qianyu Liu
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2609.14037
UR - https://arxiv.org/abs/2609.14037
AB - This paper analyzes the ergodic rate of a wideband reconfigurable intelligent surface (RIS)-assisted terahertz link under beam squint and finite-resolution phase control. Independent Rayleigh fading on the two RIS-assisted hops produces double-Rayleigh cascaded amplitudes. Exact second- and fourth-order channel moments are derived by incorporating the frequency-dependent array response and phase-quantization errors. Moment matching then provides a Gamma approximation for the received power on each subcarrier and a tractable closed-form approximation for the wideband ergodic rate. A first-null bandwidth approximation characterizes the aperture--bandwidth limitation of frequency-flat RIS control. Monte Carlo simulations validate the analytical framework.
ER -