Fresnel Zones Modeling and Analysis of Motion Detection for Multi-Antenna ISAC Systems

Channel state information (CSI) based sensing approaches have unique advantages for motion detection. However, due to the introduction of additional angle information in multi-antenna system, the mapping relationship between channel gain and motion state is changed in the integrated sensing and communication (ISAC) scenario, which will affect the sensing performance. In this paper, we first characterize a multi-antenna Fresnel zones model that establishes a mapping relationship between the target motion parameters and channel gain. Then, we reveal that the motion state of sensing target is affected by both the path length and angle of arrival (AoA). Moreover, the analytic expressions of variation of channel amplitude related to path length and AoA are obtained. Finally, numerical results corroborate the theoretical analysis and hardware system shows the proposed sensing model can effectively detect the motion state of sensing target.