  This paper presents a framework that enables characterizing analytically the
spectral efficiency achievable by D2D (device-to-device) communication
integrated with a cellular network. This framework is based on a stochastic
geometry formulation with a novel approach to the modeling of interference and
with the added possibility of incorporating exclusion regions to protect
cellular receivers from excessive interference from active D2D transmitters. To
illustrate the potential of the framework, a number of examples are provided.
These examples confirm the potential of D2D communication in situations of
strong traffic locality as well as the effectiveness of properly sized
exclusion regions.
