Empirical Characterization of In-Vehicle Propagation at Different Frequency Bands

This paper presents an empirical characterization of in-vehicle radio wave propagation across multiple frequency bands, including FR1, FR2, FR3, and sub-THz. Measurements are conducted on three different car types in both line-of-sight and obstructed-line-of-sight conditions. Key propagation metrics, such as path loss, delay spread and transmission loss through different car components are evaluated in order to analyze radio channel characteristics for the purpose of designing future 6G in-vehicle sub-networks. The obtained results highlight significant differences in signal attenuation, time dispersion and scattering effects between the analyzed frequency bands, especially in obstructed line-of-sight scenarios when the wireless nodes are located in the vicinity of vehicle components like seats and under-seat areas.