Pointing-Error-Induced Fading in an Open-Loop THz Uplink with Hardware Impairments

TL;DR

This paper models and analyzes the impact of pointing errors caused by hardware and mechanical limitations on high-frequency THz satellite uplinks, providing insights for system design and performance optimization.

Contribution

It introduces a comprehensive mathematical model of mechanical tracking dynamics including latency and limits, linking hardware constraints to communication performance in THz uplinks.

Findings

Pointing errors significantly affect link quality in THz satellite communications.

Trade-offs between beam directivity and pointing tolerance are quantified.

Design guidelines for hardware and control strategies are proposed.

Abstract

We analyze the open-loop mechanical tracking performance of a sub-Terahertz (sub-THz) and Terahertz (THz) uplink communication system. These high-frequency bands enable multi-gigabit links through large bandwidths and narrow beams, but require precise pointing to overcome spreading loss. A tracking system can be used to orient horn antennas toward mobile targets. We develop a mathematical model that captures the mechanical dynamics of a real tracking system, which includes motion latency and acceleration and velocity limits, to quantify pointing errors during satellite passes and integrate these effects into the link budget. We evaluate the trade-offs between beam directionality and pointing tolerance across different Low Earth Orbit (LEO) satellite trajectories and control strategies. The results link the hardware limitations to the communications performance, providing design guidelines for high-frequency Non-Terrestrial Network (NTN) uplink under practical mechanical constraints.