GPP TR 36.213, 2018) of two direct communications modes for broadcast interac- tions over the sidelink, namely Mode 3 or scheduled, and Mode 4 or autonomous. In Mode 3, operating only in-coverage of an eNodeB, the allocation of radio resources is supervised by the network, but a specific resource allocation design is left to the operators. In Mode 4, instead, preconfigured resources can be accessed by vehicles in an autonomous man- ner without the network control, both in- and out-of coverage of an eNodeB (e.g. in urban canyons, tunnels). 13.3.1.2 The LTE-Uu Interface V2N communications occur over the conventional cellular LTE-Uu interface operating in the licensed spectrum. Less disruptive, although not negligible, modifications have been applied to this interface in order to support both unicast and multicast V2X communi- cations. The multicast primitive has especially catalyzed the interest of 3GPP and of the scientific community, because it enables efficient V2X information sharing (e.g. high defi- nition maps, infotainment services) with many vehicles. Some enhancements to the evolved multimedia broadcast multicast service (eMBMS) architecture have been specified to meet the latency requirements of V2X applications and the localized nature of their data traf- fic (3GPP TS 23.785, 2016; 3GPP TR 36.885, 2016; 3GPP TS 36.331, 2018), with promising results preliminarily shown in [5]. 13.3 V2X Communication Technologies application server S/P-GW V2X control function (pedestrian) application E-UTRAN application (stationary) LTE-Uu LTE-Uu (vehicle) (vehicle) application application Figure 13.1 Reference architecture for PC5 and LTE-Uu based V2X communications (3GPP TS 23.285, 2019). 13.3.1.3 Core Network Architectural enhancements have been specified in the LTE Evolved Packet System (EPS) to support the operations of VUEs (3GPP TS 23.285, 2019), as depicted in Figure 13.1. Two new entities have been added to manage V2X communications. The V2X control function is the logical function for V2X network-related actions;