  Millimeter-wave (mmWave) communications plays an important role for future
cellular networks because of the vast amount of spectrum available in the
underutilized mmWave frequency bands. To overcome the huge free space
omnidirectional path loss in those frequency bands, the deployment of a very
large number of antenna elements at the base station is crucial. The
complexity, power consumption and costs resulting from the large number of
antenna elements can be reduced by limiting the number of RF chains. This leads
to hybrid precoding and combining, which, in contrast to the traditional fully
digital precoding and combining, moves a part of the signal processing from the
digital to the analog domain. This paper proposes new algorithms for the design
of hybrid precoders and combiners in a multiuser scenario. The algorithms are
based on the previously proposed Linear Successive Allocation method developed
for the traditional fully digital version. It successively allocates data
streams to users and suppresses the respective interstream interference in two
stages, which perfectly matches the hybrid architecture. Furthermore, a
low-complexity version is developed by exploiting the typical structure of
mmWave channels. The good performance of the proposed method and its
low-complexity version is demonstrated by simulation results.
