  Dynamic subarray achieves a compromise between sum rate and hardware
complexity for millimeter wave (mmWave) massive multiple-input multiple-output
(MIMO) systems in which antenna elements are dynamically partitioned to radio
frequency (RF) chain according to the channel state information.} However,
multi-user hybrid precoding for the dynamic subarray is intractable to solve as
the antenna partitioning would result in the user unfairness and multi-user
interference (MUI). In this paper, a novel multi-user hybrid precoding
framework is proposed for the dynamic subarray architecture. Different from the
existing schemes, the base station (BS) firstly selects the multi-user set
based on the analog effective channel. And then the antenna partitioning
algorithm allocates each antenna element to RF chain according to the maximal
increment of the signal to the interference noise ratio (SINR). Finally, the
hybrid precoding is optimized for the dynamic subarray architecture. By
calculating SINRs on the analog effective channels of the selected users, the
antenna partitioning can greatly reduce computation complexity and the size of
the search space. Moreover, it also guarantees the user fairness since each
antenna element is allocated to acquire the maximal SINR increment of all
selected users. \textcolor{blue}{Extensive simulation results demonstrate that
both the energy efficiency and sum rate of the proposed solution obviously
outperforms that of the fixed subarrays, and obtains higher energy efficiency
with slight loss of sum rate compared with the fully-connected architecture.
