E-UTRAN

Evolved UMTS Terrestrial Radio Access Network

Radio Access Network

Introduced in Rel-8

LTE radio access network consisting of eNodeBs interconnected via X2.

Description

E-UTRAN (Evolved UTRAN) is the radio access network for LTE, consisting solely of eNodeBs. Unlike 3G UTRAN, there is no RNC layer - all radio-related functions are in the eNodeB.

eNodeBs connect to EPC via S1 interface and to each other via X2 interface for handover and interference coordination. This flat architecture reduces latency and simplifies the network.

Purpose & Motivation

E-UTRAN was designed to:

- Minimize latency by eliminating RNC layer - Enable distributed RRM for better scheduling - Support faster handovers via X2 - Simplify network architecture and reduce cost

Key Features

  • Flat architecture (eNB only)
  • S1 interface to EPC
  • X2 interface between eNBs
  • Distributed scheduling
  • Integrated radio functions

Evolution Across Releases

Rel-8Initial

Initial E-UTRAN with eNB, S1, X2 interfaces

HeNB (Home eNodeB) for femtocells

Relay Nodes, enhanced ICIC (eICIC)

Defining Specifications

SpecificationTitle
E-UTRAN Overall Description
E-UTRAN Architecture Description
S1 Application Protocol