5G-NR Architecture

In 5G-NR there are two type of Architecture :

  • NSA (Non-Standalone)
  • SA (Standalone)


  • E-UTRA-NR Dual Connectivity (EN-DC).
  • UE is connected to NR and LTE simultaneously.
  • One eNB can be connected to many gNB and vice versa

Non-Standalone Base Station Architectures using the 4G Core Network (Options 3,3a and 3X)

  • In both cases, the 4G Node B provides control plane connectivity towards the Core Network and acts as the Master Node (MN). The 5G gNodeB has control plane connectivity across the X2 interface and acts as the Secondary Node (SN).
  • Option 3 -All user plane data tunnel through eNodeB . PDCP in eNodeB dynamically splits the downlink data between the eNode B and gNodeB.
Option 3

In Option 3a– user plane connectivity between the S-GW  and gNode B is provided .Here also eNodeB will remain the master node depending upon EPS type eNodeB may divide the work like Speech type data may be directed towards eNodeB and EPS transferring data may be directed towards gNodeB.

Option 3a

Option 3X

  • 3x has developed to overcome the issues of with Options 3 and 3a.
  • In this case, the user plane paths are between the eNode B, gNode B and S-GW.
Option 3x
  • The eNode B remains the Master Node and is able to control the selection of the downlink data path from the S-GW, i.e. the eNode B can provide the MME with the IP address of the gNode B for some EPS Bearers, while it can provide the MME with its own IP address for other EPS Bearers.
  • If coverage from the gNode becomes weak then the gNode B can dynamically forward data across the X2 interface towards the eNode B

Standalone (SA)

  • Standalone the core is 5G.
  • Master node will be of gNB.

5G CORE NETWORK Architecture

Below is the 5G Core architecture including all the components .

5G Network Functions:

S-GW and P-GW have been divided into session management function (SMF) and user plane function (UPF)

Functions :

(AUSF) :Subscriber authentication, during registration or re-registration with 5G, is managed by the Authentication Server Function.

(AMF) :NAS signaling termination and security, Access Authentication, Support of Network Slicing. Support of intra-system and inter-system mobility, Mobility management control (subscription and policies);

 (SMF) : UE IP address allocation and management; Session Management, Selection and control of UP function, Control part of policy enforcement and QoS.

(UPF) :Anchor point for Intra-/Inter-RAT mobility, Packet routing & forwarding, External PDU session point of interconnect to Data Network, DL packet buffering and DL data notification triggering.

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