Developing a MIMO Test Methodology using Dynamic Channel Models and Link Adaptation

Industry standards for over-the-air testing of LTE MIMO devices have used multi-probe anechoic chamber based systems, also known as the boundary array method, to evaluate device performance in a spatially static environment. The spatial distribution of clusters in the chosen channel models, such as the SCME Urban Micro and Urban Macro channel models, are fixed, and the only geometric variation relative to the device under test is accomplished by physically rotating the device in the generated test environment. For 5G FR1 testing, 3GPP has adopted a similar approach. However, in an effort to meet the desire of the North American cellular network operators to better understand the behavior of a device on a realistic network, the CTIA MIMO OTA working group is developing a test plan based on the use of dynamic channel models that vary the spatial configuration as a function of time, and allowing the communication tester base station emulator to perform link adaptation, allowing the device to choose the best MIMO or SISO diversity mode and data rate for a given channel condition. This paper will discuss the design considerations associated with developing this new channel model and the related test system requirements.