I. Introduction
As a promising solution to evaluate multiple-input multiple output (MIMO) device performance in realistic situations in the lab, MIMO over the air (OTA) testing has attracted huge interest from both industry and academia. Standardization work for the development of the MIMO OTA test methods is ongoing in CTIA, 3GPP and COST IC1004 [1]. Single-input single output (SISO) OTA testing were standardized by CTIA and 3GPP around ten years ago. Two figure of merits (FoMs) were selected in SISO OTA for device evaluation: Total Radiated Power (TRP) and Total Reference Sensitivity (TRS) [2]. However, the methods developed for SISO OTA could not be directly adopted to evaluate MIMO device performance. The main challenges in evaluating MIMO devices is first to define the appropriate channel model used for performance evaluation and then to physically create that environment and test the device. Geometry-based stochastic channel models (GSCM) such as SCM, SCME, WINNER etc., are considered well suited for various typical scenarios and hence used in MIMO OTA testing [3].