Modeling Multi-mode D2D Communications in LTE

In this work we propose a roadmap towards the analyt-ical understanding of Device-to-Device (D2D) communica-tions in LTE-A networks. Various D2D solutions have been proposed, which include inband and outband D2D transmis-sion modes, each of which exhibits different pros and cons in terms of complexity, interference, and spectral efficiency achieved. We go beyond traditional mode optimization and mode-selection schemes. Specifically, we formulate a general problem for the joint per-user mode selection, connection ac-tivation and resource scheduling of connections. 1