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

Over-the-air (OTA) radiated testing is seen inevitable
for future radio devices due to integrated transceiver
radio designs. Wireless cable solution, which can achieve traditional
cabled testing functionality over-the-air, 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 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 system and waste of valuable CE resource.
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 experimental validation measurements
obtained in the VNA based passive measurement setup
as well as in the active measurement setup clearly demonstrate
the effectiveness and robustness of the proposed scheme.