Proximate Device Discovery for D2D Communication in LTE Advanced: Challenges and Approaches

LTE D2D communication, which emerges as a SoLoMo network enabler, has become an essential part of our everyday life and brings benefits to subscribers and telecommunication operators alike. Proximate device discovery, or peer discovery, is an essential part in the D2D technology since the node first needs to find its neighbors before initiating D2D communication. With functions of intelligent discovery, context awareness and interactive exchange, D2D communication facilitates content sharing of a device with others. A plethora of works about device discovery have been carried out in ad hoc networks. However, as a new feature in LTE systems, the special characteristics of proximate device discovery raise several unique challenges. In this article, variant aspects of proximate device discovery are surveyed. We first overview the fundamentals of peer discovery, including basic concepts, application scenarios, associated requirements, along with the current standardization progress. The key challenges and open issues in the design of device discovery signals and device discovery protocols for D2D communication in centralized and distributed situations are respectively surveyed. Possible approaches to address these challenges are discussed.