Advances in antenna pattern-based MIMO OTA test methods

This paper discusses recent developments with the two-stage MIMO OTA test method. It first introduces the concept of the two-stage method which is based on a first stage of antenna pattern measurement followed by a second stage of throughput measurement using a signal generated by convolving the device antenna pattern with the desired spatial channel model. The resulting signal is applied to the DUT either through a conducted or radiated connection. The radiated version of the two-stage method was approved by 3GPP in Technical Report 37.977 v12.0.0 [1]. The primary advantage of the two-stage method is that arbitrary 2D or 3D spatial channel models can be emulated without the need for the conventional multi-probe anechoic chamber approach which is significantly more complex and expensive. The extension of the two-stage method to active antenna systems was covered in [2]. This present paper will review recent two-stage work in CTIA and 3GPP including the specification of an antenna test function (ATF) in 3GPP Technical Report 36.978 [3] which has been designed with future flexibility for supporting higher order MIMO and carrier aggregation.