  Full-duplex (FD) communication is optimistically promoted to double the
spectral efficiency if sufficient self-interference cancellation (SIC) is
achieved. However, this is not true when deploying FD-communication in a
large-scale setup due to the induced mutual interference. Therefore, a
large-scale study is necessary to draw legitimate conclusions about gains
associated with FD-communication. This paper studies the FD operation for
underlay device-to-device (D2D) communication sharing the uplink resources in
cellular networks. We propose a disjoint fine-tuned selection criterion for the
D2D and FD modes of operation. Then, we develop a tractable analytical
paradigm, based on stochastic geometry, to calculate the outage probability and
rate for cellular and D2D users. The results reveal that even in the case of
perfect SIC, due to the increased interference injected to the network by
FD-D2D communication, having all proximity UEs transmit in FD-D2D is not
beneficial for the network. However, if the system parameters are carefully
tuned, non-trivial network spectral-efficiency gains (64 shown) can be
harvested. We also investigate the effects of imperfect SIC and D2D-link
distance distribution on the harvested FD gains.
