Enhancing Throughput Using Agile Beam Switching and User Scheduling in Cellular Systems

In this paper, we investigate agile beamforming using Massive MIMO rectangular arrays for improving the performance of current LTE/LTE-A networks. Multi-antenna technologies like Full-dimension (FD) MIMO and the required CSI feedback mechanisms have been standardized in 3GPP Release 13/14 and 5G New Radio (NR), but their use in legacy LTE releases is limited. We show that large arrays can be leveraged to provide significant throughput improvements even in legacy LTE (Release 8) systems. Our main approach consists of switching narrow beams at the radio unit (RU) and scheduling users at the baseband unit (BBU) in such a way that users throughout the sector experience an SINR boost due to beamforming. The base station (eNB) improves the SINR in different regions of the sector by swiftly switching between different narrow beams in tight synchronization with the CSI feedback and scheduling latency mechanisms of the LTE protocol, and then schedules a user (UE) from within the high-SINR region. We consider the practically relevant case where there is no coordination between the baseband unit (BBU) and the radio unit (RU) as well as the advanced case where co-ordination is possible. Through simulation results, we demonstrate significant improvements in the average and cell-edge throughput, when compared to a conventional wide-beam system.