  This work jointly addresses user scheduling and precoder/combiner design in
the downlink of a wideband millimeter wave (mmWave) communications system. We
consider Orthogonal Frequency Division Multiplexing (OFDM) modulation to
overcome channel frequency selectivity and obtain a number of equivalent
narrowband channels. Hence, the main challenge is that the analog preprocessing
network is frequency flat and common to all the users at the transmitter side.
Moreover, the effect of the signal bandwidth over the Uniform Linear Array
(ULA) steering vectors has to be taken into account to design the hybrid
precoders and combiners. The proposed algorithmic solution is based on Linear
Successive Allocation (LISA), which greedily allocates streams to different
users and computes the corresponding precoders and combiners. By taking into
account the rank limitations imposed by the hardware at transmission and
reception, the performance loss in terms of achievable sum rate for the hybrid
approach is negligible. Numerical experiments show that the proposed method
exhibits excellent performance with reasonable computational complexity.
