  In this paper, we consider device-to-device (D2D) communication that is
underlaid in a multi-cell massive multiple-input 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
signal-to-interference-plus-noise ratios 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.
