Device-to-Device Communications for 5G Internet of Things

The proliferation of heterogeneous devices connected through large-scale networks is a clear sign that the vision of the Internet of Things (IoT) is getting closer to becoming a reality. Many researchers and experts in the field share the opinion that the next-to-come fifth generation (5G) cellular systems will be a strong boost for the IoT deployment. Device-to- Device (D2D) appears as a key communication paradigm to support heterogeneous objects interconnection and to guarantee important benefits. In this paper, we thoroughly discuss the added-value features introduced by cellular/noncellular D2D communications and its potential in efficiently fulfilling IoT requirements in 5G networks. State-of-the-art solutions, enabling radio technologies, and current standardization activities for D2D communications are surveyed and their pros and cons with reference to manifold IoT use cases pointed out. Future research directions are then presented towards a fully converged 5G IoT ecosystem.