The decomposition method: Accelerated OTA test of MIMO devices

Several test methodologies have been proposed to evaluate the over-the-air (OTA) performance of multiple-input multiple-output (MIMO)-enabled LTE devices. Reproducible data throughput measurements as a function of downlink power are very time consuming for faded radio channels. Thus only a limited number of spatial channel parameters can be evaluated characterizing the OTA performance of a user equipment (UE) antenna system. We present a validation of the decomposition method. This method allows an acceleration of OTA testing by separating static and faded measurements using the two-channel setup. It stands out from other methods due to its simplicity and large quiet zone size for the UE. In this paper we show that it is allowed to separate static and faded measurements. We show the validation both by simulation results of a simplified MIMO transmission system and by experiments on commercial LTE devices. We present results for various correlation coefficients of base station and UE antenna systems.We also show the validity of the decomposition method with transmission systems employing LTE reference antennas by simulation.