Enhanced 5G V2X services using sidelink device-to-device communications

In this paper, we present advances of sidelink (SL) device-to-device (D2D) communications as a key-enabling technology for 5G enhanced vehicular-to-everything (eV2X) communications. We provide an overview about the resource allocation and scheduling of different SL D2D modes under in-coverage and out-of-coverage application scenarios. Moreover, we present the scheduling for SL D2D V2X communications, which relies on semi-persistent scheduling (SPS) as proposed within the 3GPP specification. Simulations were carried out to evaluate the performance in terms of collision probability assuming different values of the key parameters such as resource reselection interval (RRI) and resource selection window. We finally discuss about the open technical challenges for ultra-reliable and low-latency communications as distilled from the 5G V2X use cases introduced in 3GPP Rel.15. A cooperative resource allocation and scheduling solution is also given, where a more detailed version is considered our future work on this topic.