D2DArchitecture in Unlicensed Spectrum

Abstract

AbstractThe growing number of mobile devices increasingly demands the capacity of cellular networks. The device‐to‐device (D2D) communication that enables direct links between near‐by devices has been envisioned as a complementary technology to cellular networks for 5G and beyond. Offloading traffic from traditional network‐centric communications to direct D2D networks increases the network capacity and spectral efficiency, as well as sharing the computation loading at the base station.The D2D communications can be classified intoD2D‐Licensed(D2D‐L) andD2D‐Unlicensed(D2D‐U) for D2D operating in licensed and unlicensed bands respectively. The D2D‐L can be further classified into overlay and underlay D2D‐L and the D2D‐U can be further classified into controlled and autonomous. In this article, we will discuss the D2D communication architecture to illustrate the control signal plane and data signal plane operations. The D2D communication network is suitable for many applications, such as relaying, offloading, proximity service (ProSe), content‐aware service, content distribution, and critical communications. We will discuss the interesting applications and use cases. Instead of relying on the cellular links, the D2D communications open the horizons of device‐centric communication which enables new services such as proximity service (ProSe), and content‐aware service, and so on.Nevertheless, there are challenges for D2D communications, which require enabling technologies to make it happen. In this article, we present a survey of existing and expected technologies in related aspects such as interference management, device discovery, and network security in D2D networks.