eNodeBs

An eNodeB, short for Evolved NodeB, is the base station in an LTE (E-UTRA) network responsible for radio communications with user equipment (UEs) and for connecting the UEs to the rest of the network.

In the E-UTRAN architecture, the eNodeB terminates the air interface and implements the radio access network functions such as radio resource management, scheduling, HARQ, encryption and integrity protection, and the user-plane and control-plane protocols. It handles the processing required for the LTE radio link, including timing, modulation and coding, and access control with UEs.

It interfaces with the core network through the S1 interface (S1-MME for control plane and S1-U for user plane) and with neighboring eNodeBs through the X2 interface for handovers and inter-cell coordination. This connectivity enables mobility management, session handling, and seamless data exchange between the UE and the core network.

eNodeBs can be deployed as macro cells or small cells, and modern networks may use distributed or virtualized RAN concepts that aggregate multiple eNodeBs or processing resources. They typically support multiple carriers, advanced antenna techniques such as MIMO, and carrier aggregation to increase data throughput and spectrum efficiency.

Standardized by 3GPP, eNodeBs are a core component of the LTE architecture, replacing the older NodeB and RNC-based design. They serve as the primary radio access node in the Evolved Packet Core, coordinating radio access, handovers, and access control to enable mobile broadband services.