  The opportunistic beamforming in the downlink of multiple-input single-output
(MISO) systems forms $N$ transmit beams, usually, no more than the number of
transmit antennas $N_t$. However, the degrees of freedom in this downlink is as
large as $N_t^2$. That is, at most $N_t^2$ rather than only $N_t$ users can be
simultaneously transmitted and thus the scheduling latency can be significantly
reduced. In this paper, we focus on the opportunistic beamforming schemes with
$N_t<N\le N_t^2$ transmit beams in the downlink of MISO systems over Rayleigh
fading channels. We first show how to design the beamforming matrices with
maximum number of transmit beams as well as least correlation between any pair
of them as possible, through Fourier, Grassmannian, and mutually unbiased bases
(MUB) based constructions in practice. Then, we analyze their system throughput
by exploiting the asymptotic theory of extreme order statistics. Finally, our
simulation results show the Grassmannian-based beamforming achieves the maximum
throughput in all cases with $N_t=2$, 3, 4. However, if we want to exploit
overall $N_t^2$ degrees of freedom, we shall resort to the Fourier and
MUB-based constructions in the cases with $N_t=3$, 4, respectively.
