Overview of Radio Access Network in 2G, 3G and 4G

RAN controls the radio interface to the mobile station. Basic components in RAN are:

  • Base Transceiver Station.
  • Base Station controller.

Basic interfaces defined between each of these sub systems include:

  • “Abis” interface between BSC and BTS (Within the RAN).
  • “Um” air interface between the RAN and the MS.

Above summary is according to 2nd and 2.5 generation and now we are entering into 4th generation so it’s good to understand network structure as per generation. Naming convention for components and Interfaces has changed in different telecom generations as stated below:

3rd Generation:RAN is UTRAN (Universal Terrestrial Radio Access Network):Components:

  • Node B.
  • Radio Network Controller.



  • “LuB” interface between RNC and NodeB (Within the UTRAN).
  • “Uu” air interface between the NodeB and the User Equipment.
  • “LuR” interface connects two RNC with each other.


4th Generation:UTRAN is now eUTRAN (Evolve UTRAN)

  • eNodeB.
  • There is no controller. The eNodeB performs tasks similar to those performed by the NodeBs and RNC (radio network controller) together in UTRAN.



  • eNodeBs are connected to each other via the X2 interface.
  • eNodeBs are connected to the packet switched core network via the S1 interface.



This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.