One of the key technologies for the fifth-generation (5G)mobile communication system is massive multiple-input multiple-output(MIMO) that applies beamforming in order to effectively compensate forlarge propagation losses in high frequency bands and enable the spatialmultiplexing of a large number of signal streams over multiple users. Tofurther improve a system throughput, a coordinated cluster system in whicha large number of massive MIMO base stations are deployed in high densityhas been investigated. The dense deployment greatly improves thesystem capacity by controlling base stations from a centralized base bandunit. However, when clusters are closely located in order to serve denselypopulated areas, inter-beam interference between adjacent clusters becomesmore severe. To suppress the interference to adjacent clusters, only a simplebeam switch control scheme at a cluster boundary has been investigated asa conventional scheme. In this paper, the scheduling algorithm for massiveMIMO downlink transmission near cluster boundaries, which combinestwo scheduling algorithms, has been proposed. In the proposed scheme,each base station divides its own cell to multiple areas, switches supportingareas sequentially, and serves users in those areas. The numerical resultsshow that the throughputs improve with a little reduction in a fairness index(FI) when the number of users per resource block is one. The FI reachesthe highest when the number of users per cell is equal to the number ofdivided areas. The proposed scheme reduces computational complexity ascompared with those of conventional two schemes.
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