# Introduction to Open Radio Access Network (O-RAN)
Open RAN is about disaggregated RAN functionality built using open interface specifications between elements. It can be implemented in vendor-neutral hardware and software-defined technology based on open interfaces and community-developed standards

Figure 1 depicts the evolution of the Radio Access Network (RAN) from the traditional to the Open RAN strategy. The traditional method of providing RAN is to use a single black box, and the internal interfaces within that box are closed and controlled by a single vendor. Moving towards Open RAN (O-RAN), we are dividing the base station's many functions into the following entities with open interfaces: a centralized unit (CU), a distributed unit (DU), and a remote unit (RU).
Fig. 1. RAN Transformation

#### RICs are classified into two types:
Non-real-time and near-real-time. Both are logical functions for controlling and optimizing an O-RAN's and resources.
1. A near-real-time RIC regulates and optimizes elements and resources more precisely through granular data collecting and exchange via the E2 interface. The near-real-time RIC is linked to the O-CU and O-DU via the E2 interface.

2. A non-real-time RIC employs AI and machine learning procedures, which include model training, to learn how to better govern and utilize RAN elements and resources.

The O-Cloud is a cloud computing platform that uses the O-RAN architecture to connect physical infrastructure nodes. It also develops and hosts the virtual network functions (VNFs) that the RICs and other infrastructure components use.

The radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol are all hosted by the O-CU, which is another logical node (PDCP). The O-CU control plane hosts the RRC and control plane component of the PDCP, while the O-CU control plane hosts the RRC and control plane section of the PDCP. The SDAP and the user plane component of the PDCP are hosted in the user plane portion.

### Benefits

Network operators have more options for RAN elements with an open RAN ecosystem. Network operators can adjust the functionality of their RANs to their own demands thanks to a multi-vendor catalog of technologies. When enterprises are able to move away from a single RAN vendor's equipment and software stack, total vendor lock-in is no longer an issue.
Virtualization, which is a key component of open RAN standards, has a number of advantages. Network operators, for example, can have a faster time to market with a vRAN architecture than they would with a hardware-based infrastructure since adding a new feature to the network can be as simple as remotely upgrading the network's VNFs. Network administrators can also benefit from automation and enhanced network visibility thanks to the virtualized components of an open RAN design discussed above.
New equipment providers can enter the market thanks to open RAN standards. An infusion of new vendors will increase competition and, in theory, cut costs, which will benefit customers.

#### Challenges
However, before competition can cut costs, major RAN suppliers must widely implement open RAN interfaces and features. Rakuten's LTE RAN in Japan is the first large-scale RAN that is totally based on open RAN technology as of January 2021. Because everything is proprietary, being stuck with a vendor can mean spending more money. When something goes wrong, the customer can go directly to the seller for assistance. When an organization employs a multi-vendor approach, it requires time and money to isolate and identify the problem and then obtain IT support from the appropriate vendor, whereas a company committed to a single vendor does not have to hunt for the guilty party.