Outage Protection for Cellular-Mode Users in Device-to-Device Communications through Stochastic Optimization

Coexistence between cellular-mode and D2D-mode users that share the same radio resource is one key problem for D2D communications. While related work has investigated transmission power control for interference management, most approaches have considered only the long-term channel gain without specifically addressing the stochastic fluctuations of the channel. In this paper, we investigate interference management under Rayleigh channel fading through stochastic optimization. We first transform the objective and constraint functions in stochastic forms into equivalent yet deterministic forms, and then we propose a low-complexity method to solve the formulated nonlinear problem. The proposed method relaxes and separates the constraint functions into simpler ones, and then solves the linearized problem using an iterative algorithm while simultaneously shrinking the search space. Simulation results demonstrate that the outage probability of the cellular- mode user can be maintained below the desired threshold despite the uncertainty of channel conditions, while the sum rate of D2D- mode users outperforms baseline methods under the same constraint.