Before we start looking into the 5G architecture, let us understand some of the terminologies involved:
5GC: 5G Core Network
AMF Function: Access and mobility Management
UPF: User Plane Function
NG-RAN: Next Generation Radio Access Network
gNB : Next generation NodeB
ng-eNB: Next generation eNB
ENDC: Evolved-Universal Terrestrial Radio Access New Radio Dual Connectivity
What are different types of NG-RAN available?
An NG RAN can be either of the following RAN’s:
A gNB that provides NR user plane and control plane protocol towards the UE. This will be your 5G RAN.
A ng-eNB that provides E-UTRA user plane and control plane protocol towards UR. This will be 4G RAN with additional functionality to handle 5G UE.
THe gNB and ng-eNB are connected with each other with the help of Xn interface.
Initial deployment will happen through ng-eNB as gNB will take time to formulate and available commercially.
Stand Alone and Non Stand Alone Architecture
Non Stand Alone Architecture
NSA means, initially 5G deployment will happen along with existing 4G networks.
It means, the speeds will not match the actual 5G speeds, but the implementation will be faster.
Here the primary network will be LTE eNB and secondary will be 5gNB.
It means in NSA 4G EPC core with Master LTE RAN and secondary 5G NR.
NSA is also known as E-UTRA-NR dual connectivity (EN-DC).
Different types of Non Stand Alone Architecture
There are different options of NSA architecture are possible.
Some of them are mentioned below:
A detailed explanation is there in next chapter.
Option 1: SA Deployment. 4G EPC with 4G Radio allows a 4G device to access a 4G only network.
Option 2: SA Deployment. 5G Core with 5G New Radio (NR) allows a 5G device to access a 5G only network.
Option 3: NSA Deployment. Traffic is split across 4G and 5G at eNodeB.
Option-3a: NSA Deployment. Traffic is split across 4G and 5G at EPC (S-GW).
Option-3x: NSA Deployment. Traffic is split across 4G and 5G at 5G cell.
Option 4: NSA Deployment. 5G NR and 4G Radio devices connect into 5G Core
Option 5: SA Deployment. 4G devices using 4G radio access network device to 5G Core
Option 7: LTE (Long Term Evolution) and 5G NR connect into 5G Core
Stand Alone Architecture
In Standalone architecture, all the components will be 5G components.
It will have 5G core and 5G NR access network.
Benefits of 5G NSA:
It will leverage existing network investments.
It will help to realize 5G sooner.
Benefits of 5G SA:
It is fully virtualized, cloud native architecture that is easy way to manage, develop and deploy.
It will enable end to end slicing of logically seperate services.
With the help of cloud-native micro-service based architecture, MNOs can also decide on a variety of deployment models such as on-premise private cloud, public cloud or hybrid.
All the above two deployment options are defined in TS 21.915.