Towards 5G

9Device-to-Device Communications

Andreas F. Molisch,¹ Mingyue Ji,² Joongheon Kim,³ Daoud Burghal,¹ and Arash Saber Tehrani¹

¹ University of Southern California, Los Angeles, CA, USA

² University of Utah, Salt Lake City, UT, USA

³ Chung-Ang University, Korea

9.1 Introduction and Motivation

For many years, the worlds of infrastructure-based wireless communications on one hand, and ad-hoc networks on the other hand, remained essentially separate. Infrastructure-based communications occurs commonly in licensed bands, and are carefully planned. Ad-hoc networks operating in the same band were, at best, seen as interference sources that might need to be accommodated. However, in the past 5 years, a new paradigm has emerged: device-to-device D2D communications, where devices – non-infrastructure wireless nodes – talk directly with each other (similar to ad-hoc networks), but they do so in coordination with, and possibly under the instruction of, the infrastructure nodes; see also Doppler et al. (2009b) and Wei et al. (2014b).

D2D is motivated largely by the eternal quest for higher spectral efficiencies. The change in usage patterns for phones has greatly increased the demand for communications between nearby devices. Phones are a major repository of photographs, music, movies, and so on. It has become common for friends to electronically exchange such media when they are nearby, often in the course of a conversation. Thus, devices wishing to communicate with other devices that might ...