coverage enabled by the baseline NR system. The flexibility of NR sidelink framework would allow easy extension of NR system to support the future development of further advanced V2X services. More specifically, the NR V2X enhancements include the following areas [11]: Sidelink design: Identify technical solutions for NR sidelink to satisfy the requirements of advanced V2X services, including support of sidelink unicast, sidelink groupcast, and sidelink broadcast; study NR sidelink physical layer structure and procedure(s); study sidelink synchronization mechanism; study sidelink resource allocation mechanism; and study sidelink L2/L3 protocols. Uu enhancements for advanced V2X use cases: Evaluate whether Rel-15 NR Uu and/or LTE Uu interfaces could support advanced V2X use cases and identify enhancements, if any, that are needed to meet advanced V2X use cases. Uu-based sidelink resource allocation/configuration (LTE V2X mode 3 and mode 4): Identify necessary enhancements of LTE Uu and/or NR Uu to control NR sidelink through the cellular network and further identify the necessary enhancements of NR Uu to control LTE sidelink from the cellular network. 796 Chapter 7 RAT/interface selection for operation: Study if additional mechanisms are required to decide whether LTE PC5, NR PC5, LTE Uu, or NR Uu should be utilized for operation. Quality of service (QoS) management: Study technical solutions for QoS management of the radio interface (including Uu and sidelink) used for V2X operations. In-device coexistence: Study the feasibility of the coexistence mechanisms when NR sidelink and LTE sidelink technologies are implemented in the same vehicle for the non-co-channel scenarios such as advanced V2X services provided by NR sidelink while coexisting with V2X service provided by LTE sidelink in different channels. Sidelink operating bands: Sidelink frequency bands include both unlicensed ITS bands and licensed bands in FR1 and/or FR2. The target is to have a common sidelink design for both FR1 and FR2. For groupcast V2X c