round xli coordination is desired. The higher layers of NR radio protocol stack can be moved to the CU, if a low performance transport mechanism is used between the CU and the DU (s), because in this case the requirements on the transport layer in terms of bandwidth, delay, synchronization, and jitter are relatively relaxed. Co-sited deployment with LTE: In this scenario, the NR functions are co-located with LTE counterparts either as part of the same base station or as multiple base stations at the same site. Co-located deployment can be applicable in all NR deployment scenarios such as urban macro. As shown in Fig. 8, in this scenario it is desirable to fully utilize all spectrum resources assigned to both radio access technologies (RATs) using load balancing or connectivity via multiple RATs (e.g., utilizing lower frequencies as wide- area coverage layer for the cell-edge users). Shared RAN deployment: The NR supports shared RAN deployments, implying multiple hosted core operators. The shared RAN topology can cover large geographical areas as in the case of national or regional network deployments. The shared RAN architecture can also be heterogeneous; that is, limited to a few smaller areas, as in the case of shared in-building RANs. A shared RAN should be able to efficiently interoperate with a non-shared RAN. Each core operator may have its own non-shared RAN serving areas adjacent to the shared RAN. The mobility between the non-shared RAN and the shared RAN is supported in a manner similar to that of LTE. The shared RAN may operate either in the shared spectrum or in the spectrum of each host operator (see Fig. 8). The cell layouts corresponding to the prominent deployment scenarios for NR are shown in Fig. 9. In the homogeneous deployment scenario, all cells (macro or small cell only) pro- vide the same coverage, whereas in the heterogeneous deployment scenarios, cells of differ- ent sizes have overlapped coverage, that is, a combination of macro and small cells where typically macrocells provide wide-are