Vehicle-to-Infrastructure Channel Measurement and Beamforming Analysis for the RMa Scenario

Vehicle-to-infrastructure (V2I) access has been considered as an important scenario in the emerging heterogeneous networks. To improve the link quality, the V2I channel characteristics should be investigated carefully. In this paper, we conduct a measurement campaign for the V2I channels in the rural macrocell (RMa) scenario at 3.5 GHz. We measured the spatial propagation characteristics of the multipath components (MPCs) in the up link from a roadside base station (BS) to a vehicle. In particular, we have obtained the azimuth and elevation angle of arrival (AoA/EoA) by using a massive multiple-input-multiple-output (MIMO) channel sounder. We find that the azimuth/elevation power spectrum (APS/EPS) can be well modeled by the Laplace distribution function. We also investigate the root-mean-square elevation/azimuth spread of arrival (ESA/ASA) and model their distributions by the normal distribution. Furthermore, we analyze the received signal power variation with the number of antenna array elements and the beamforming direction based on the established APS model. Finally, we analyze the interference in beamforming and its influence on the link performance. The measurement and analysis results can help to optimize the massive MIMO beamforming scheme for vehicular communications and tracking in the RMa V2I access network.