The introduction of O-RAN

# The introduction of O-RAN ## What is O-RAN? ### The structure and features of O-RAN The traditional RAN architectures were based on a **monolithic** building blocks; however it was felt that dividing RAN into CU,DU and RU can brings flexibility. Moreover, a split architecture allows coordination for performance features, load management, real-time performance optimization and enables adaptation to various use senarios. It also allows much more equipment firms to invest in the industry. Meanwhile, the operators can optimize the equipment from the equipments films. * RU(radio unit) handles the digital front end (DFE) and the parts of the PHY layer. * DU sits close to the RU and runs the RLC, MAC, and parts of the PHY layer. * CU runs the RRC and PDCP layers. AU, CU and DU are defined as **O-AU, O-CU and O-DU** by O-RAN Alliance. ## The techs that related to 5G and O-RAN ### CUPS architecture CUPS(Control User Plane Separation) in mobile networks refer to the separation between control plane functions and user plane functions. #### Why CUPS required? * Large Volume Data Support: With the rapidly growing demand of connected devices, mobile operator’s user data traffic has been doubling on an annual basis in recent years. * Customer Experience and Low Latency : There is a strong consumer demand for user experience improvements, with lower latency being one of the critical standard to be met on the way. #### The adventage of CUPS * CUPS can make user plane functions scale independently, allowing operators for a more flexible deployment. For instance, if data traffic increases, more data plane nodes can be added without affecting the control plane functions. * CUPS locates and scales control plane and user plane resources of the EPC nodes independently. * CUPS enables SDN(Software-Defined Networking) to deliver user plane data more efficiently. #### SDN(Software-Defined Networking) SDN is a network architecture that iNetwork Virtualization Functions composed by an infrastructure layer, a controller layer and an application layer. SDN holds the adventages of being efficient, agile and centrally managed by controller software. This architecture decouples the network control and forwarding functions and enable the network control to become directly programmable. The OpenFlow protocol is a foundational element for building SDN solutions. #### NFV(Network Virtualization Function) Network functions virtualization (NFV) is a way to virtualize network services, such as routers, firewalls, and load balancers, that have traditionally been run on proprietary hardware. #### NFV architecture * Virtualized network functions(VNFs) are software applications that deliver network functions such as file sharing, directory services, and IP configuration. * Network functions virtualization infrastructure(NFVi) consists of the infrastructure components—compute, storage, networking—on a platform to support software. * Management, automation and network orchestration (MANO) provides the framework for managing NFV infrastructure and provisioning new VNFs. :::warning **Glossary:** >**EPC(evolved packet core)**:It is the latest evolution of the 3GPP core network architecture. >**Control plane**:consisting of RRC.It take care of the user connection management, as well as defining QoS policies, performing user authentication, etc. >**User plane**:Consisting of PDCP, RLC, MAC, PHY layer, it deal with data traffic forwarding >**OpenFlow** It enables network controllers to determine the path of network packets across a network of switches. :::