The future of MIMO over-the-air testing

Wireless radios implementing multiple-antenna or adaptive antenna technologies are pervading LTE and Wi-Fi. These technologies involve some level of interaction with the RF environment, and their dynamic nature means that traditional performance tests that do not adequately reflect the real-world environment will not provide the desired device performance information. In fact, the benefits of some of these approaches can only be tested in an over-the-air environment that reflects an expected use case. This article describes some of the challenges and issues with RF performance tests in a multiple-input multiple-output over-the-air environment, surveys recent approaches used to address these topics, and covers some open areas of current work.