Design and Evaluation of a Hybrid D2D Discovery Mechanism in 5G Cellular Networks

Device-to-device (D2D) communications allow devices to communicate directly without using base stations for relaying, yielding several merits such as increasing the spectral efficiency and system capacity, reducing network latency and power consumption of UEs, offloading the 5G cellular networks, and extending the network coverage. However, to realize D2D communications, the first challenging issue is how to efficiently find target devices in proximity for communications. Therefore, in this paper we intend to design a hybrid D2D discovery mechanism and evaluate its performance. Simulation results demonstrate that the proposed D2D discovery mechanism achieves better performance in terms of power consumption and discovery time, compared with the direct discovery scheme that purely utilizes the contention-based transmission scheme and operates in the unlicensed band.