entity (a) CU-CP and CU-UP centralized (b) CU-CP distributed and CU-UP centralized Central CP entity -Xn-C CU-CP Distributed entity CU-UP LowLat (c) CU-CP centralized and CU-UP distributed Figure 4.4.1 Deployment scenarios for CU/UP separation. (Source: Reproduced by permission of © 3GPP). 3. Ensure low latency for user-plane traffic, which is important for some applications, e.g. critical MTC. These deployment options trade off applicability to cloud deployments, control-plane latency, and user-plane latency, and thus give operators sufficient flexibility to meet diverse requirements of different applications of 5G. The study report (3GPP TR 38.806) also summarizes the following advantages that control-user plane separation could bring: Flexibility to operate and manage complex networks, efficiently supporting different transport network topologies. Ability to tailor NG-RAN deployment to address various service requirements. Alignment with the SDN concept of a functional decomposition of the RAN into user- and control-plane entities. Independent scaling of control and user plane, allowing, e.g. addition of new UP hard- ware resources when required. Support of multi-vendor interoperability between NG-RAN control- and user-plane net- work nodes provided by different vendors. Capability to deploy separate control- and user-plane network nodes while optimizing for desired scenarios and performance in terms of throughput and latency. For example, a gNB-CU-CP can be deployed in close proximity to a gNB-DU to optimize for critical control-plane latency. Additionally, a gNB-CU-UP can be deployed in a centralized man- ner, e.g. in a regional or national data center, allowing resource sharing and supporting 4.4 Control-User Plane Separation cloud implementation. Furthermore, a gNB-CU-UP can be deployed close to a gNB-DU to provide a local termination point for ultra-reliable low-latency communication (URLLC) traffic, thus significantly improving latency. Support of centralized RRM within a single gNB-CU-CP controlling a l