Optimized Power Control for Massive MIMO with Underlaid D2D Communications

In this work, we consider device-to-device (D2D)
communication that is underlaid in a multi-cell massive multipleinput
multiple-output (MIMO) system and propose a new framework
for power control and pilot allocation. In this scheme,
the cellular users (CUs) in each cell get orthogonal pilots
which are reused with reuse factor one across cells, while
all the D2D pairs share another set of orthogonal pilots. We
derive a closed-form capacity lower bound for the CUs with
different receive processing schemes. In addition, we derive a
capacity lower bound for the D2D receivers and a closed-form
approximation of it. We provide power control algorithms to
maximize the minimum spectral efficiency (SE) and maximize
the product of the SINRs in the network. Different from prior
works, in our proposed power control schemes, we consider joint
pilot and data transmission optimization. Finally, we provide a
numerical evaluation where we compare our proposed power
control schemes with the maximum transmit power case and
the case of conventional multi-cell massive MIMO without D2D
communication. Based on the provided results, we conclude that
our proposed scheme increases the sum SE of multi-cell massive
MIMO networks.