Wireless Cable Testing for MIMO Radios: A Compact and Cost-effective 5G Radio Performance Test Solution

Over-the-air (OTA) radiated testing is seen as inevitable for future radio devices due to integrated transceiver radio designs. Wireless cable solution, which can achieve traditional cabled testing functionality OTA, has attracted great attention from industry, standardization, and academia in recent years for multiple-input multiple-output (MIMO) device performance testing. In state-of-the-art wireless cable solutions, the compensation of the transfer matrix between the OTA probes and antenna ports of the device under test (DUT) is implemented with the help of radio channel emulators (CEs). However, the radio CEs are not customized for such implementations, leading to expensive systems and a waste of valuable CE resources. Employing more probe antennas is a known and effective strategy to improve the robustness and quality of the wireless cable connection, which would further increase the system cost with existing implementations. To address these issues, a novel wireless cable implementation employing a stand-alone programmable amplitude and phase control network is proposed. Though simple and cost-effective, the proposed scheme is demonstrated to work in practice, and it is applicable for more generic testing scenarios where a CE is not required. The experiment validation measurements obtained in the vector network analyzer (VNA)-based passive measurement setup as well as in the active measurement setup clearly demonstrate the effectiveness and robustness of the proposed scheme.