  Proximity based applications are becoming fast growing markets suggesting
that Device-to-Device (D2D) communications is becoming an essential part of
future mobile data networks. We propose scalable admission and power control
methods for D2D communications underlay cellular networks to increase the reuse
of frequency resources and thus network capacity while maintaining QoS to all
users. The aim of the proposed methods is to maximize the number of D2D links
under QoS constraints, therefore maximizing network frequency reuse, while
considering different levels of complexity and available channel state
information (CSI) in a multi-cell environment. Numerical results show that by
using D2D and the proposed multi-cell interference coordination and low power
transmission method, the network spectral efficiency can be increased by as
much as ten times, while low outage probability can be assured to provided QoS
for all users.
