Massive MIMO Beamforming With Transmit Diversity for High Mobility Wireless Communications

Abstract

Providing stable and fast data transmission service is challenging in a high mobility wireless communication system, where massive multiple-input multiple-output (MIMO) beamforming is deemed as a potential solution. In the literature, the majority of previous works focused on how to optimize the beamforming scheme with traditional side information like perfect or imperfect channel state information (CSI) in non-mobile or low mobility scenarios. However, it is hard to either track the channel or obtain perfect CSI in the high mobility scenario without large online computation, because the wireless channel appears to be fast time varying and double-selective in the spatial-temporal domain. In this paper, by exploiting the special characters in the high mobility scenario, we introduce an applicable low-complexity beamforming scheme with transmit diversity in the high mobility scenario with the aid of location information. The beam is generated and selected mainly based on the location information, where the beam weight is optimized to maximize the total service that one BS can provide. Moreover, to guarantee a full diversity gain in this joint scheme, an optimal beam selection algorithm is proposed. Besides, to maximize the total service competence of one base station, a closed-form power allocation solution for the multi-user scenario is derived. To solve the potential inter-beam interference in massive MIMO system, a location-aided algorithm is proposed to eliminate the interference and maximize the mobile service of the whole train at the same time. Theoretical analysis and multiple simulation results show that our scheme approaches the theoretical performance bound of adaptive beamforming scheme but with much lower complexity.