A Non-Kronecker Structured PFS Method for Channel Emulation in Multiprobe OTA Setups

The realistic channel environment can be characterized by a geometry-based stochastic channel (GBSC) model composed of multiple clusters, each of which consists of many rays. For the GBSC model, the power angle of arrival (AoA) spectrum of a cluster depends on the power angle of departure-Doppler (AoD-Doppler) spectrum. Hence, this model is non-Kronecker structured. In over-the-air (OTA) testing, the prefaded signal synthesis (PFS) method is valid for emulating the GBSC to measure devices under test (DUTs). However, the emulated channel under the conventional PFS method is a Kronecker case due to the independently and identically distributed fading sequences between probes when synthesizing clusters. It will lead to inaccurate link characteristics for emulation. Therefore, a non-Kronecker structured PFS (NKSPFS) method is proposed. Specifically, the rays mapped to probes are individually weighted to ensure that fading sequences between probes are independent but not identically distributed. To determine the ray weights without degrading marginal correlations for emulation, the constraints are introduced on the deviation between the target spatial-temporal correlation and the emulated spatial-temporal correlation according to the emulated spatial correlation and temporal correlation. Simulation results show that the proposed NKSPFS method outperforms the conventional PFS method in OTA testing of multi-antenna devices.