Introduction to eNodeB:
The network architecture of LTE Network consists of a many different network entities. Each network entity has a distinct role in the LTE network. In this article, we’ll cover the roles of eNodeB and its connectivity with MME in EPC Network.
In the LTE Radio network, the eNodeB is the LTE Base station. In each LTE Radio network, there is at least one eNodeB present to provide radio interface for UEs devices.
In a commercialized cellular operator network scenario, there may be several thousand eNodeBs in the networks that are all interconnected to one another via an X2 interface. This interconnection with all eNodeB’s help to allow efficient “handovers” in a LTE Network.
In LTE-EPC network, all eNodeBs are connected to at-least one MME (short for “Mobile Management Entity).
The main function of the eNodeB is to provide:
- Radio Interface for LTE and
- To perform radio resource management.
The eNodeB performs these two functions by managing the radio admission control, radio bearer control and managing/scheduling of uplink and downlink radio messages for each individual connected UEs devices.
Furthermore, the eNodeBs are designed to provide and support IP header compression of the user-plane data. They, also perform data encryption capabilities of the user-plane data, thus providing a secure message exchange mechanism between eNodeBs and MME.
As we stated earlier, the eNodeBs are interconnected to one another via an X2 interface – moreover, eNodeBs are also connected to the EPC Network via the S1 interface.
The S1 interface further split up into two different interfaces:
- The S1-MME Interface and
- The S1-U Interface
The S1-MME interface is the control-plane interface between eNodeB and MME, as this interface terminates in the MME and carriers all the signaling messages between eNodeB and the MME.
Meanwhile, The S1-U interface is the user-plane interface between eNodeB and Serving GW (S-GW) or (UGW), and its designed to handles user-plane traffic and supports other major functionalities such as ‘pooling’ (management of eNodeBs and the MMEs, and between eNodeBs and S-GW), thus allows cellular operators to share there radio network.