Open RAN, is the final piece of the unbundling puzzle that enables mobile network operators to use equipment from multiple vendors and still ensure interoperability. The mobile, or cellular/wireless network comprises two domains: the Radio Access Network (RAN) and the Core Network (Core). 
 

The key concept of Open RAN is “opening” the protocols and interfaces between these various building blocks (radios, hardware and software) in the RAN. The O-RAN ALLIANCE has defined 11 different interfaces within the RAN including those for:

• Fronthaul between the Radio Unit and the Distributed Unit

• Midhaul between the Distributed Unit and the Centralised Unit

• Backhaul connecting the RAN to the Core