  Massive multi-input multi-output (MIMO) uses a very large number of low-power
transmit antennas to serve much smaller numbers of users. The most widely
proposed type of massive MIMO transmit beamforming is zero-forcing, which is
based on the right inverse of the overall MIMO channel matrix to force the
inter-user interference to zero. The performance of massive MIMO is then
analyzed based on the throughput of cell-edge users. This paper reassesses this
beamforming philosophy, to instead consider the maximization of the energy
efficiency of massive MIMO systems in assuring the quality-of- service (QoS)
for as many users as possible. The bottleneck of serving small numbers of users
by a large number of transmit antennas is unblocked by a new time-fraction-wise
beamforming technique, which focuses signal transmission in fractions of a time
slot. Accordingly, massive MIMO can deliver better quality-of-experience (QoE)
in assuring QoS for much larger numbers of users. The provided simulations show
that the numbers of users served by massive MIMO with the required QoS may be
twice or more than the number of its transmit antennas.
