Lte

What are the main LTE interfaces?

1. Uu interface:
This is between User Equipment and eNodeB, it is used to carry information across air. Uu interface is air interface like Um in GSM and same Uu in WCDMA.

2. X2 interface:
This is between eNodeBs to exchange signaling (X2-Control Plane) and user data information(X2-User Plane). X2 is logical interface.

3. S1-MME interface:
This is between eNodeB and MME and used for exchanging signaling data.

4. S1-U interface:
This is between eNodeB and SGW to transfer user application data.

5. S11 interface:
This is between MME and SGW. It is used for signaling information in case of mobility and bearer management cases. User application data does not use S11 interface.

6. S6a interface:
It is between MME and Home Subscriber Server (HSS). This is used to transfer of subscription and authentication data for authenticating for user access.

7. S5 interface:
This is between SGW and PGW. Both control plane signaling and user plane data use S5 interface.

8. S8 interface:
This is similar to S5 interface and it is between SGW & PGW, but it is used for roaming users who they use VPLMN.

9. SGi interface:
This interface is between PGW and a packet data network. The Packet Data Network could be external or internal (belong to the operator, for example: IMS) network.

10. Gx interface:
This is between PCRF and PGW. PCRF provides charging and QoS information to PGW.