The S1 interface is a communication interface between the LTE eNodeB (base station) and the EPC (Packet Core Network). The LTE system is divided into a radio access network and a core network.
The S1 interface is a communication interface between the LTE eNodeB (base station) and the EPC (Packet Core Network). The LTE system is divided into a radio access network and a core network.
S1 interface definition
The S1 interface is a communication interface between the LTE eNodeB (base station) and the EPC (Packet Core Network). The LTE system is divided into a radio access network and a core network.
Figure 1 Location of the S1 interface in the EPS network element
S1 interface classification
The S1 interface follows the idea of separate bearer and control, and is divided into two interfaces, one for the control plane (S1-MME) and one for the user plane (S1-U).
Table 1 S1 interface description
Interface name | Connected network element | Interface function description | Main agreement |
S1-MME | eNodeB-MME | Used to transfer session management (SM) and mobility management (MM) information, that is, signaling or control plane information | S1-AP |
S1-U | eNodeB-SGW | Establish a tunnel between the GW and the eNodeB device to transmit user data services, that is, user plane data | GTP-U |
S1 interface function
The control plane interface S1-MME connects the base station and the mobility management entity (MME), and mainly performs functions such as radio access bearer control of the S1 interface and interface-specific operation and maintenance.
The user plane interface S1-U connects the base station and the serving gateway (S-GW) for transmitting user data and corresponding user plane control frames.
