Priori-aided channel tracking for millimeter-Wave beamspace massive MIMO systems

Abstract

Beamspace MIMO can utilize beam selection to reduce the number of required RF chains in mmWave massive MIMO systems. However, beam selection requires the information of beamspace channel of large size. This is a challenging task, since the user mobility usually leads to the fast variation of mmWave beamspace channels, and the real-time channel estimation involves unaffordable pilot overhead. To solve this problem, in this paper we propose a priori-aided (PA) channel tracking scheme. Specifically, by considering a practical user motion model, we first excavate a temporal variation law of the physical direction between the base station and each mobile user. Then, based on the special sparse structure of mmWave beamspace channels, we propose to utilize the obtained beamspace channels in the previous time slots to predict the prior information of the beamspace channel in the following time slot. Finally, aided by the obtained prior information, the time-varying beamspace channels can be tracked with low pilot overhead. Simulation results verify that the proposed PA channel tracking scheme can achieve much better performance than conventional schemes.