Dealing with the Mobility Problem of Massive MIMO using Extended Prony’s Method

Massive MIMO is a key technology for 5th generation (5G) mobile communications. The large excess of base station (BS) antennas brings unprecedented spectral efficiency. However, during the initial phase of industrial testing, a practical challenge arises which undermines the actual deployment of massive MIMO and is related to mobility. In fact, testing teams reported that in moderate-mobility scenarios, e.g., 30 km/h of UE speed, the performance may drop 50% compared to the low-mobility scenario, a problem not foreseen by theoretical papers on the subject. In order to deal with this challenge, we propose a Prony-based angular-delay domain (PAD) prediction method, which is built on exploiting the angle-delay-Doppler structure of the multipath. Our theoretical analysis shows that when the number of base station antennas and the bandwidth are large, the prediction error of our PAD algorithm converges to zero for any UE velocity level, provided that only two accurate enough previous channel samples are available. Simulation results show that under the realistic channel model of 3GPP in rich scattering environment, our proposed method even approaches the performance of stationary scenarios where the channels do not vary at all.