  Underlay in-band device-to-device (D2D) communication can improve the
spectrum efficiency of cellular networks. However, the coexistence of D2D and
cellular users causes inter-cell and intra-cell interference. The former can be
effectively managed through inter-cell interference coordination and,
therefore, is not considered in this work. Instead, we focus on the intra-cell
interference and propose a D2D mode selection scheme to manage it inside a
finite cellular network region. The potential D2D users are controlled by the
base station (BS) to operate in D2D mode based on the average interference
generated to the BS. Using stochastic geometry, we study the outage probability
experienced at the BS and a D2D receiver, and spectrum reuse ratio, which
quantifies the average fraction of successfully transmitting D2D users. The
analysis shows that the outage probability at the D2D receiver varies for
different locations. Additionally, without impairing the performance at the BS,
if the path-loss exponent on the cellular link is slightly lower than that on
the D2D link, the spectrum reuse ratio can have negligible decrease while the
D2D users' average number of successful transmissions increases with increasing
D2D node density. This indicates that an increasing level of D2D communication
can be beneficial in future networks..
