The Coupling Effect of Sensing Targets on the Environment for 3GPP ISAC Channels: Observation, Modeling, and Validation

Integrated Sensing And Communication (ISAC) has been identified as a key 6G application by International Telecommunication Union (ITU) and 3rd Generation Partnership Project (3GPP), with standardization efforts already underway. Sensing tasks, such as target localization, demand more precise characterization of the sensing target (ST) in ISAC channel modeling. The ST couples complexly with environmental scatterers, potentially blocking some multipaths and generating new ones, resulting in power variations compared to the original channel. To accurately model this effect, this paper proposes and validates a coupled ISAC channel model based on measurements. In this work, we first conduct ISAC channel measurements in an indoor factory scenario at 105 GHz, where the multipath power variations caused by the ST’s interaction with the environment are clearly observed. Then, we propose an ISAC channel modeling framework that incorporates two novel parameters: the Blockage-Region Coupling Factor (BR-CF) and the Forward-Scattering (FS)-CF, which characterize the spatial region and intensity of the coupling effect, respectively. Finally, the proposed model is validated through similarity comparison with measured data, demonstrating higher accuracy for both LoS and NLoS scenarios compared to the uncoupled model. This realistic ISAC channel model provides an effective framework for capturing the ST-environment coupling effect, supporting the design and evaluation of ISAC technologies.