eNodeB

Evolved NodeB

Radio Access Network

Introduced in Rel-8

LTE base station providing radio interface to UE and connecting to EPC.

Description

The Evolved NodeB (eNodeB) is the LTE base station that provides the radio interface (Uu) to the User Equipment (UE). Unlike 3G architecture, the eNodeB integrates the functions previously split between NodeB and RNC.

The eNodeB handles radio resource management, scheduling, handover decisions, compression, and encryption. It connects to the EPC via the S1 interface and to other eNodeBs via the X2 interface.

Purpose & Motivation

The eNodeB was designed for LTE's flat architecture, eliminating the RNC layer to:

- Reduce latency (fewer hops) - Simplify network architecture - Enable faster handovers via X2 - Support distributed scheduling

Key Features

  • Radio resource management
  • Dynamic scheduling
  • Handover execution
  • Header compression
  • Ciphering/deciphering
  • Connection mobility control

Evolution Across Releases

Rel-8Initial

Initial eNodeB with basic LTE functionality

Added HeNB (Home eNodeB) support for femtocells

Enhanced for Carrier Aggregation, Relay Node support

Dual Connectivity with Master/Secondary eNB

Defining Specifications

SpecificationTitle
E-UTRAN Overall Description
RRC Protocol Specification
S1 Application Protocol (S1AP)
X2 Application Protocol (X2AP)