Title: Beamspace SU-MIMO for Future Millimeter Wave Wireless Communications,
Abstract: For future networks (i.e., the fifth generation (5G) wireless networks and
beyond), millimeter-wave (mmWave) communication with large available unlicensed
spectrum is a promising technology that enables gigabit multimedia
applications. Thanks to the short wavelength of mmWave radio, massive antenna
arrays can be packed into the limited dimensions of mmWave transceivers.
Therefore, with directional beamforming (BF), both mmWave transmitters (MTXs)
and mmWave receivers (MRXs) are capable of supporting multiple beams in 5G
networks. However, for the transmission between an MTX and an MRX, most works
have only considered a single beam, which means that they do not make full
potential use of mmWave. Furthermore, the connectivity of single beam
transmission can easily be blocked. In this context, we propose a single-user
multi-beam concurrent transmission scheme for future mmWave networks with
multiple reflected paths. Based on spatial spectrum reuse, the scheme can be
described as a multiple-input multiple-output (MIMO) technique in beamspace
(i.e., in the beam-number domain). Moreover, this study investigates the
challenges and potential solutions for implementing this scheme, including
multibeam selection, cooperative beam tracking, multi-beam power allocation and
synchronization. The theoretical and numerical results show that the proposed
beamspace SU-MIMO can largely improve the achievable rate of the transmission
between an MTX and an MRX and, meanwhile, can maintain the connectivity.