University of Teramo
In this paper, the authors jointly address two fundamental issues in Device-To-Device (D2D) overlaid cellular networks: how to partition the spectrum assuming orthogonal cellular and D2D transmissions, and what is the optimal threshold for distance-based D2D mode selection? To this end, they first derive rate expressions for both cellular and D2D users. Three design criteria - (weighted) max-sum, max-min and proportional fairness - are considered and optimal spectrum partition rules are derived. Finally, they validate their model and give rules of thumb for optimizing the spectrum partition and mode selection.