EPC Interfaces and E-UTRA Protocols
In This LTE tutorial, we discuss the EPC Interfaces and E-UTRA Protocols. The LTE evolved packet core,s interfaces. Also, we learn about LTE E-UTRA Protocols.
EPC interfaces ( Evolved Packet Core ‘S’ Interfaces)
In addition to the S1 interface connecting the E-UTRAN to the EPC, a broader range of ‘S’ interfaces have been defined to identify interconnections between EPC nodes and external nodes. The gateways and the MME are the main new nodes in the EPC. They are associated via the S5 and S11 interfaces.
The SGi interface also provides IP-based services that are connected to the operators. It will include services managed through the IMS. In this respect, the S6a interface connects the MME to the HSS, and the S7/Gx interface provides access from the PCRF to the PDN-GW (Public Data Network Gateway).
The S3 and S4 interfaces provide connectivity into the EPC from legacy 2G/3G SGSNs (Serving GPRS Support Nodes). However, the UTRAN may be connected directly to the EPC via the S12 interface.
WLANs (Wireless Local Area Networks) and WiMAX (Worldwide Interoperability for Microwave Access) can be supported through the EPC via the S2. This would require connectivity with the MME. Which is provided by interfaces and interworking function that is not shown in the diagram.
In line with other angles of the E-UTRA. The air interface protocol bucket has been designed to reduce complexity. Whereas an R99/HSPA-enabled Node B employs a protocol bucket with a variety of RLC and MAC instances. The E-UTRA eNB employs a protocol bucket with just one instance of each layer.
The extremity of the air interface protocol bucket has also been reduced. In the previous incarnation of UMTS, some layers operate between the UE and Node B. While the most extended all the way to the RNC. With the eradication of the RNC and all the air interface protocols in E-UTRA operate between the UE and the eNB.