Bi-static Reflectivity Patterns of Vulnerable Road Users in the C-V2X Frequency Range

Automated and connected driving is a key technology for the future mobility. The sensor data fusion of different cooperating mobile nodes will become an essential factor to achieve this goal. Current developments show an enormous potential to increase the environmental awareness through joint communication and radar sensing. In this respect, future radio channel models aim to include bi-static reflectivities and radar cross-sections of road users in the nearfield as well as the far-field. This paper presents indoor measurements of the bi-static reflectivity of vulnerable road users between 1 GHz and 10 GHz, using a bicycle as an example. The measurement setup using two independent turntables covers the entire angular range of illumination and observation angles. Suitable signal postprocessing methods, i.e., phase-coherent background subtraction and time-domain gating, minimize the antenna crosstalk and unwanted reflections. The results are compared with electromagnetic full-wave simulations and are evaluated in time and frequency domain. The resulting data show that, depending on the illumination and observation angles, the bi-static reflectivity of the bicycle is maximum around the forward-scattering region and around specular reflection over the entire frequency range.