An Explicit Reservation-Augmented Resource Allocation Scheme for C-V2X Sidelink Mode 4

In the autonomous sidelink resource scheduling for Cellular V2X (C-V2X), the standard sensing-based semi-persistent scheduling (SPS) algorithm relies on several mechanisms such as random resource selection, resource utilization pattern monitoring, and probabilistic reselection to minimize packet collisions and to cope with vehicular topology changes. Even so, the collision probability is still not negligible, and its performance is far from the projected requirements for low latency and high reliability applications for future C-V2X communication. In this article, we propose a reservation mechanism that supplements the standard SPS for C-V2X Sidelink Mode 4, which visibly improves the performance in face of congestion and in the fringe of the communication range. In particular, we demonstrate that the reservation achieves the best performance if made much earlier than actual use of the reserved resource at least by an average of one second.