# OpenCare5G: O-RAN in Private Network for Digital Health Applications
## 3 Proposed Solution
### Virtualization and Containerization for vDUI and vCU  
Figures 2 and 3 show the implementation of the Airspan O-RANGE Software architecture through to Figure 13 with container network functions (CNF) for vDU using Docker Engine and container and virtualized network functions (vCU) with hypervisor. These will be used in the project to serve the vRAN, to allow a modular, scalable architecture that is flexibile in its implementation. Figure 13 shows:  
* Block 1, the physical hardware infrastructure of the O-DU and O-CU servers, network and storage in COTS;
* Block 2, the Host Server for the host operating system (HOS) connected to the network, offering information, resources, services and applications needed by the user and other nodes in the network;
* Block 3 provides virtual containers with Docker Engine, which is the heart of the Docker System to realize the client-server architecture application installed on the host server [55]. The system uses Container Docker and Machine Virtualization (VM) concepts over the hypervisor. With containers, processing is performed directly on the host server, using the Docker mechanism to make it faster and lighter [55]. In Block 4, we have the container network functions CNF with implementation via POD (Passed Out Drunk) of K8s with Docker, realizing a set of one or more Linux containers in the K8s application. * PODs are composed of a container in the most common use cases or several tightly coupled containers. These containers are grouped into PODs so that resources are shared more efficiently. That is, we will have 1-n application containers (App) on top of the vDU, as the containers are abstractions in the 1-n application layer with Docker (Bins/Libs) packaging the application and its dependencies into the container in a single operating system (OS) with resources shared between containers [55];  
Figure 13: Architecture of Container Network Functions (CNF) with applications running on O-DU/O-CU Servers with OpenRange Software for vDU and vCU. Based on [46]. * Each application in the project virtual container runs in its own isolated process controlled by the Docker Engine, as if it were a host operating system. However, it will not virtualize the entire environment on the cDU and cvCU Servers. It will work on top of the n application and its dependencies, creating virtualization only at the host operating system level and not on the entire server, making the project system light and managing to initialize the applications in seconds compared to the traditional VMs. Less RAM, CPU and storage will thus be used to offer lower latency [55]. Five new application protocols were introduced into the Airspan O-RANGE software architecture in the project using vCU-CP and vCU-UP with end-to-end control plane protocols, depicted in Figure 13:  
* F1 AP (F1 Application Protocol) is used to relay Packet Data Convergence Protocol (PDCP) CP messages and Radio Resource Control (RRC) messages between the gNB-DU and the gNB-CU-CP;
* E1 AP (E1 Application Protocol) is used to program GTP-U tunnels for the datapath in gNB-CU-DP;
* XnAP (Xn Application Protocol) is the control protocol used between gNBs to support a variety of O-RAN-related procedures, such as establishing dual connectivity, coordinating Xn-based handovers (duplication), O-RAN data forwarding and paging. It is used in the SCTP sublayer to coordinate gNB-CU-MC functionality (MultiCast functionality within gNB-CU);
* NG-AP (NG Application Protocol) provides CP signaling between the node via NG-RAN and the access and mobility management function (AMF). The services provided by the NG-AP are divided into UE-associated and non-UE-associated;
* SCTP (Flow Control Transport Protocol) is similar to TCP in terms of fundamentals, but adds features that compensate for some weaknesses of TCP. There is a need to implement requirements to provide a base virtual port for Single Root Input/Output Virtualization (SR-IOV) to allow isolating resources via PCI Express between different users on the server O-DU.