5G Advanced: Sidelink Evolution.

Third Generation Partnership Project (3GPP) standardization studied sidelink operation for 5G New Radio (NR), targeting advanced vehicle-to-everything (V2X) services in Release 16/17. 3GPP recently approved 5G Advanced study item, which includes NR sidelink for unlicensed operation, NR sidelink positioning for commercial devices, public safety, and V2X services. This article presents an overview of NR sidelink use case, requirements to be studied in 5G advanced, and discusses potential improvements needed in the physical layer. Furthermore, this article outlines design improvements needed in the NR sidelink physical layer, addressing it to meet regulatory requirements to operate in the unlicensed band, relative positioning calculation between peer sidelink devices, using sidelink relative positioning methods, and, finally, to meet ultra-low latency. Very high reliability enhancement is required for Industrial Internet of Things (IIoT) use case, such as end-to-end latency of 1msec, hi gh reliability up-to 99.9999 percen, t and tight requirement for clock synchronicity at $1\ \mu\mathrm{s}$ .