Low complexity channel estimation in 3D MIMO systems

Considering the three dimensional (3D) channel with elevation effect, a two dimensional (2D) antenna array was employed in a generic ray-based 3D multi-input multi-output (MIMO) system. Through utilizing the channel spatial correlation between antennas at the transmitter side, we propose a cascaded MMSE channel estimation with low computational complexity. Numerical results show that the proposed cascaded MMSE channel estimation has comparable MSE and BER performances with traditional MMSE channel estimation with significantly decrease in computational complexity. The results also demonstrate that the channel estimation in spatial domain can be decomposed into horizontal domain and vertical domain.