Wideband Beamspace Channel Estimation Based on OAMP Approach

Millimeter-wave (mmWave) Massive multiple-input multiple-output (Massive MIMO) system equipped with lens antenna arrays (LAAs), which is known as beamspace Massive MIMO, has demonstrated substantial potential to provide high data rates in the future wireless communication networks since it can achieve sufficient beamforming gain with a limited number of radio frequency (RF) chains. However, the beam squint effect in wideband beamspace Massive MIMO systems causes channel estimation to be complicated significantly. To address this problem, we investigate a channel estimator based on the orthogonal approximate message passing (OAMP) algorithm to improve the estimation performance. Specifically, the wideband beamspace channel estimation is firstly considered as the sparse image reconstruction problem. Then, by exploiting the OAMP-based scheme, sparse image can be accurately reconstructed, which can solve the beamspace channel estimation problem efficiently. Finally, the numerical results verify the effectiveness of the proposed estimation method and highlight its excellent performance of the channel estimation compared with different schemes.