Virtual Drive Testing Over-The-Air for Vehicular Communications

Multiple-input multiple-output (MIMO) over-the-air (OTA) testing is a standardized procedure to evaluate the performance of MIMO-capable devices such as mobile phones and laptops. With the growth of the vehicle-to-everything (V2X) service, the need for vehicular communication testing is expected to increase significantly. The so-called multi-probe anechoic chamber (MPAC) setup is standardized for MIMO OTA testing. Typically, a test zone of 0.85 wavelength in diameter can be achieved with an 8-probe MPAC setup, which can encompass device-under-test (DUT) of small form factors. However, a test zone of this size may not be large enough to encompass DUTs such as cars. In this article, the sufficient number of OTA probes for the MPAC setup for car testing is investigated with respect to the emulation accuracy. Our investigation shows that the effective antenna distance of the DUT is more critical than its physical dimensions to determine the required number of OTA probes. In addition, throughput measurements are performed under the standard SCME UMa and UMi channel models with the 8-probe MPAC setup and the wireless cable setup, i.e. another standardized testing setup. The results show reasonably good agreement between the two setups for MIMO OTA testing with cars under the standard channel models.