  Channel state information (CSI) is important to reap the full benefits of
millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems.
The traditional channel estimation methods using pilot frames (PF) lead to
excessive overhead. To reduce the demand for PF, data frames (DF) can be
adopted for joint channel estimation and data recovery. However, the
computational complexity of the DF-based methods is prohibitively high. To
reduce the computational complexity, we propose a joint channel estimation and
data recovery (JCD) method assisted by a small number of PF for mmWave massive
MIMO systems. The proposed method has two stages. In Stage 1, differing from
the traditional PF-based methods, the proposed PF-assisted method is utilized
to capture the angle of arrival (AoA) of principal components (PC) of channels.
In Stage 2, JCD is designed for parallel implementation based on the multi-user
decoupling strategy. The theoretical analysis demonstrates that the PF-assisted
JCD method can achieve equivalent performance to the Bayesian-optimal DF-based
method, while greatly reducing the computational complexity. Simulation results
are also presented to validate the analytical results.
