  Millimeter wave (mmWave) MIMO will likely use hybrid analog and digital
precoding, which uses a small number of RF chains to avoid energy consumption
associated with mixed signal components like analog-to-digital components not
to mention baseband processing complexity. However, most hybrid precoding
techniques consider a fully-connected architecture requiring a large number of
phase shifters, which is also energyintensive. In this paper, we focus on the
more energy-efficient hybrid precoding with sub-connected architecture, and
propose a successive interference cancelation (SIC)-based hybrid precoding with
near-optimal performance and low complexity. Inspired by the idea of SIC for
multi-user signal detection, we first propose to decompose the total achievable
rate optimization problem with non-convex constraints into a series of simple
sub-rate optimization problems, each of which only considers one sub-antenna
array. Then, we prove that maximizing the achievable sub-rate of each
sub-antenna array is equivalent to simply seeking a precoding vector
sufficiently close (in terms of Euclidean distance) to the unconstrained
optimal solution. Finally, we propose a low-complexity algorithm to realize
SICbased hybrid precoding, which can avoid the need for the singular value
decomposition (SVD) and matrix inversion. Complexity evaluation shows that the
complexity of SIC-based hybrid precoding is only about 10% as complex as that
of the recently proposed spatially sparse precoding in typical mmWave MIMO
systems. Simulation results verify the near-optimal performance of SIC-based
hybrid precoding.
