3D channel emulation in a multi-probe setup

Introduction: As a solution to evaluate multiple input multiple output (MIMO) device performance in realistic conditions in the lab, MIMO over the air (OTA) testing has attracted huge interest from both industry and academia, see e.g. [1]. One promising candidate is the multi-probe based anechoic chamber method. Several papers have discussed OTA testing setups for MIMO devices with emphasis on channel modeling, where the goal is to accurately reproduce realistic 2D channels in the test area with a limited number of OTA probes [1]. However, the 2D channel model is not generally valid. Measurements have demonstrated that elevation spread can not be ignored in many propagation environments, see e.g. [2, 3], and thus emulation of 3D models is required. Very few contributions have addressed this issue. In [4], it was briefly mentioned that probes in a 3D setup were used to emulate 3D channel models, but no algorithm description is given. The 3D channel emulation technique has also been implemented in a commercial channel emulator, the Elektrobit Propsim F8, where the Laplacian distributions are defined for the power azimuth spectrum (PAS) and the power elevation spectrum (PES). However, a description of the implemented channel emulation algorithm is not available. This letter presents a new channel emulation technique for arbitrary 3D channel models.