  Vehicle-to-everything (V2X) communication enables vehicles, roadside
vulnerable users, and infrastructure facilities to communicate in an ad-hoc
fashion. Cellular V2X (C-V2X), which was introduced in the 3rd generation
partnership project (3GPP) release 14 standard, has recently received
significant attention due to its perceived ability to address the scalability
and reliability requirements of vehicular safety applications. In this paper,
we provide a comprehensive study of the resource allocation of the C-V2X
multiple access mechanism for high-density vehicular networks, as it can
strongly impact the key performance indicators such as latency and packet
delivery rate. Phenomena that can affect the communication performance are
investigated and a detailed analysis of the cases that can cause possible
performance degradation or system limitations, is provided. The results
indicate that a unified system configuration may be necessary for all vehicles,
as it is mandated for IEEE 802.11p, in order to obtain the optimum performance.
In the end, we show the inter-dependence of different parameters on the
resource allocation procedure with the aid of our high fidelity simulator.

Networking and Internet Architecture