Arbitary direction path generation for MIMO channel emulator

MIMO channel emulation systems have been studied and developed to achieve the evaluation for the MIMO transmission technique of user equipments (UEs) with multiple antennas. The system can generate a multipath with a spatial signature by transmitting signals from multiple probe antennas set around the UE. The resolution of the emulated spatial distribution of the multipath is improved as the number of probe antennas increase, while the MIMO channel emulator controlling the transmit signals becomes complicated and expensive. This paper proposes the novel method for the MIMO channel emulator to achieve the emulation of the arbitrary multipath with the finite number of the probe antennas. The method weights the transmit signals with the criterion to minimize the vector error between the array steering vector of MIMO antenna in the desired arbitrary direction of the path and the combining weighted vectors in the directions of the probe antennas. It is verified that the proposed method with the number of the probe antenna M can achieve the evaluation for the MIMO antenna with M-1 branches under the arbitrary multipath environment.