# Introduction to Open RAN
## RAN (RADIO AREA NETWORK)
- is part of a mobile telecommunication system. It implements a radio access technology. Conceptually, it resides between a device such as a mobile phone, a computer, or any remotely controlled machine and provides connection with its core network (CN). Depending on the standard, mobile phones and other wireless connected devices are varyingly known as user equipment (UE), terminal equipment, mobile station (MS), etc. RAN functionality is typically provided by a silicon chip residing in both the core network as well as the user equipments [wiki](https://bit.ly/2Ul2Sec)
### **<font color=red>FACTS on OPEN RAN</font>**
* ### OPEN RAN – is an open RAN network meaning t***hat any vendor’s equipment would work on any part of the network regardless of whose core was managing the network***
* **does not mean Open Source**
* Open RAN vendors do not necessarily have to be part of some group, but it helps

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### Typical vs. Disaggregated Mobile Network Architecture
In the DISAGGREGATED, the core network and Access Network is sub-categories.

#### **A. DISAGGREGATION OF CORE NETWORK and ITS VIRTUALISATION SAMPLES**
* 3GPP Started the journey with Control and User Plane Separation (CUPS) of EPC nodes in 3GPP Release-14
* 5G Core (5GC) continues this Control & User Plane Separation with the Service Based Architecture (SBA)
* From Classical Network Appliance Approach (e.g. Fragmented, purpose-built hardware, physical install per applicance per site, hardware development) to Network Function Virtualisation Approarch (e.g. Automatic Orchestraion and remote installation, Commercial off-the-shelf Hardware)
* From the use of multiple physical hardware for several operations to containing it to on physical software(mobile phone)

#### **B. DISAGGREGATION OF ACCESS NETWORK and ITS VIRTUALISATION APPROACH**


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#### ADDITIONAL INPUTS ON O-RAN
* **Split Option 7-2x adopted in O-RAN fronthaul specifications**
* **Tradeoffs in O-DU AND O-RU Functional splitting**
* **Founding of O-RAN Allicance**
* **O-RAN Alliance reference architecture**