  The Third Generation Partnership Project (3GPP) has recently published its
Release 16 that includes the first Vehicle to-Everything (V2X) standard based
on the 5G New Radio (NR) air interface. 5G NR V2X introduces advanced
functionalities on top of the 5G NR air interface to support connected and
automated driving use cases with stringent requirements. This paper presents an
in-depth tutorial of the 3GPP Release 16 5G NR V2X standard for V2X
communications, with a particular focus on the sidelink, since it is the most
significant part of 5G NR V2X. The main part of the paper is an in-depth
treatment of the key aspects of 5G NR V2X: the physical layer, the resource
allocation, the quality of service management, the enhancements introduced to
the Uu interface and the mobility management for V2N (Vehicle to Network)
communications, as well as the co-existence mechanisms between 5G NR V2X and
LTE V2X. We also review the use cases, the system architecture, and describe
the evaluation methodology and simulation assumptions for 5G NR V2X. Finally,
we provide an outlook on possible 5G NR V2X enhancements, including those
identified within Release 17.
