OTA Test Method in Extreme Temperature for 5G Massive MIMO Devices

Over-the-air testing of 5G Massive MIMO radio base stations was introduced in 3GPP standards and national regulations already a few years ago. One of the most challenging situations is when measurements are performed under extreme temperature conditions. 3GPP radiated conformance testing standards mention two methods: a direct method and a relative method. However, very few details about test method implementation are available in the standard. In this paper we propose a practical implementation of these two methods, and we investigate which aspects are important for achieving consistent results. Through experimental validation we conclude that similar results can be obtained by both methods, and we discuss a number of implementation details that can be included in the standard.