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LTE eNBEvolving to LTE eNB as a node upgrade

In life and especially in technology, everything evolves. Long Term Evolution (LTE) is not immune. In fact, for LTE, evolution is a good thing!

The main goal of LTE is to provide users with mobile data speed they want and need, in a way legacy 3G networks just couldn’t do. The notable difference between LTE and 3G is the base station change. Before LTE, Radio Network Controller (RNC) nodes controlled the radio resources and mobility over multiple NodeB (3G base stations) underneath, in heretical radio access network. In LTE, as reported by Artia Networks, eNBs (evolved NodeB) manage radio resource and mobility in the cell and sector to optimize all the UE’s communication in flat radio network structure. This means LTE eNB relies on the radio resource management algorithm and its implementation, in order to be successful. It also means the RNC is no longer needed. [1]

What is eNB?

We’ve already designated that eNB stands for evolved NodeB, and is often abbreviated as eNodeB or eNB. But what does it really do? Basically, eNB is the only mandatory node in the radio access network (RAC) of LTE. The eNB is a complex base station that handles radio communications with multiple devices in the cell and carries out radio resource management and handover decisions. There is no need for a centralized radio network controller in LTE. It is the hardware that is connected to the mobile phone network that communicates directly with mobile handsets (UEs), like a base transceiver station(BTS) in GSM networks. Traditionally, a Node B has minimum functionality, and is controlled by an RNC (Radio Network Controller). However, with an eNB, there is no separate controller element. This simplifies the architecture and allows lower response times. [2]

Artiza Networks

eNB v. NB

So how does the evolved NodeB differ from the legacy Node B? When it comes to air interface, eNB uses the E-UTRA protocols OFDMA (downlink) and SC-FDMA (uplink) on its LTE-Uu interface. By contrast, NodeB uses the UTRA protocols WCDMA or TD-SCDMA on its Uu interface. Alos, eNB embeds its own control functionality, rather than using an RNC (Radio Network Controller) as does a Node B.

LTE eNB Specifics

Each eNB contains at least one radio transmitter, receiver, control section and power supply. They also carry resource management and logic control functions, traditionally separated into base station controllers (BSCs) or radio network controllers. This added capability allows eNBs to directly communicate with each other, eliminating the need for mobile switching systems (MSCs) or controllers (BSCs or RNCs).

LTE eNB functions include:

  • radio resource management – RRM
  • radio bearer control
  • radio admission control – access control
  • connection mobility management
  • resource scheduling between UEs and eNB radios
  • header compression
  • link encryption of the user data stream
  • packet routing of user data towards its destination (usually to the EPC or other eNBs)
  • scheduling and transmitting paging messages (incoming calls and connection requests)
  • broadcast information coordination (system information)
  • measurement reporting (to assist in handover decisions) [3]
Each eNB is composed of an antenna system (typically a radio tower), building, and base station radio equipment. Base station radio equipment consists of RF equipment (transceivers and antenna interface equipment), controllers, and power supplies.


[1] What is LTE eNB? Artiza Networks, http://www.artizanetworks.com/lte_tut_what_lteenb.html
[2] What is eNB? LTE University, http://lteuniversity.com/ask_the_expert/b/ltefaqs/archive/2008/11/03/what-is-enb.aspx
[3] Evolved Node B(eNB), UMTS LTE Book, page 14, http://www.althos.com/tutorial/UMTS-LTE-tutorial-evolved-node-b-eNB.html

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