Channel Estimation for Millimeter Wave MIMO Systems over Frequency Selective Channels via PARAFAC Decomposition

In this paper, the downlink channel estimation for millimeter wave (mmWave) MIMO systems over frequency selective channels is considered, where both the base station (BS) and the mobile station (MS) are equipped with massive number of antennas. We assume hybrid analog and digital beamforming structures are employed at BS and MS. To overcome the frequency selective fading, we employ orthogonal frequencydivision multiplexing (OFDM) in transmission. By exploiting the sparse scattering nature of mmWave channels, we propose a CANDECOMP/PARAFAC (CP) decomposition-based method for downlink channel estimation. Our analysis reveals that the uniqueness of the CP decomposition can be guaranteed even when the size of the tensor is small. Hence the proposed method has the potential to achieve substantial training overhead reduction. Simulation results show that the proposed method presents a clear advantage over the compressed sensing-based method in terms of both estimation accuracy and computational complexity.