Channel Estimation for Hybrid Multi-Carrier mmWave MIMO Systems Using 3-D Unitary Tensor-ESPRIT in DFT beamspace

In this work we propose a gridless channel estimation scheme for MIMO systems in the millimeter wave (mmWave) band which is based on R-D Unitary Tensor-ESPRIT in DFT beamspace. Compared to conventional ESPRIT based algorithms in element space, the beamspace approach can be applied to MIMO systems with hybrid architectures. Moreover, the proposed scheme can significantly reduce the training overhead for communication systems operating in the mmWave band. The proposed algorithm involves coarse and fine estimation steps. During the coarse estimation step, Unitary Tensor-ESPRIT in element-space is applied to the array with a reduced size aperture to obtain initial information about the angular profiles, such as directions of arrival (DoAs), directions of departure (DoDs), and propagation delays. Based on these estimates, in a second step the fine estimation of angular profiles, propagation delays and channel gains is performed applying 3-D Unitary Tensor-ESPRIT in DFT beamspace. We explain how to combine received signals from different sectors of interest (SoIs) and to perform joint processing. Simulation results show the tensor gain for the proposed algorithm in addition to the improved channel estimation.