  Device-to-Device (D2D) communications underlaying cellular networks is a
viable network technology that can potentially increase spectral utilization
and improve power efficiency for proximitybased wireless applications and
services. However, a major challenge in such deployment scenarios is the
interference caused by D2D links when sharing the same resources with cellular
users. In this work, we propose a channel allocation (CA) scheme together with
a set of three power control (PC) schemes to mitigate interference in a D2D
underlaid cellular system modeled as a random network using the mathematical
tool of stochastic geometry. The novel aspect of the proposed CA scheme is that
it enables D2D links to share resources with multiple cellular users as opposed
to one as previously considered in the literature. Moreover, the accompanying
distributed PC schemes further manage interference during link establishment
and maintenance. The first two PC schemes compensate for large-scale path-loss
effects and maximize the D2D sum rate by employing distance-dependent pathloss
parameters of the D2D link and the base station, including an error estimation
margin. The third scheme is an adaptive PC scheme based on a variable target
signal-to-interference-plus-noise ratio, which limits the interference caused
by D2D users and provides sufficient coverage probability for cellular users.
Closed-form expressions for the coverage probability of cellular links, D2D
links, and sum rate of D2D links are derived in terms of the allocated power,
density of D2D links, and path-loss exponent. The impact of these key system
parameters on network performance is analyzed and compared with previous work.
Simulation results demonstrate an enhancement in cellular and D2D coverage
probabilities, and an increase in spectral and power efficiency.
