Joint communication and sensing in satellite systems : passive and active sensing at mmWave and THz frequencies

Abstract

This thesis explores the integration of Joint Communication and Sensing (JCAS) in satellite systems operating in the millimeter-wave (mmWave) and terahertz (THz) bands (100-500 GHz). Motivated by the 6G IMT-2030 framework, JCAS seeks to improve spectrum efficiency by enabling sensing and communication to share the same hardware and resources. This work investigates the feasibility of performing both passive and active sensing using communication signals alone, eliminating the need for dedicated sensors.

A simulation framework is developed to evaluate satellite-based JCAS. Radiative transfer is used to compute the antenna temperature in the passive sensing case, based on thermal emissions from the Earth's surface, including land, ocean, and ice. Atmospheric absorption is included in the model. Detection of ice surfaces is demonstrated using Constant False Alarm Rate (CFAR)-based probability analysis. From a communication perspective, the signal-to-noise ratio (SNR) is analyzed under a defined link budget.

In active sensing, a virtual channel state information model simulates atmospheric losses under various weather conditions. SNR degradation thresholds are defined to classify weather types such as clouds and rain. This allows simultaneous communication and atmospheric sensing.

The results confirm that the reuse of communication signals enables effective sensing under realistic constraints. The findings support 6G satellite system design through improved hardware reuse, environmental awareness, and spectrum utilization.