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E-UTRAN Node B, also known as Evolved Node B, (abbreviated as eNodeB or eNB) is the element in E-UTRA of LTE that is the evolution of the element Node B in UTRA of UMTS. 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.

Differences between an Evolved Node B and a Node B[edit]

Air Interface[edit]

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.

Control Functionality[edit]

eNB embeds its own control functionality, rather than using an RNC, (Radio Network Controller) as does a Node B.

Network Interfaces[edit]

eNB interfaces with the System Architecture Evolution (SAE) core (also known as Evolved Packet Core (EPC)) and other eNB as follows:[1]

  • eNB uses the S1-AP protocol on the S1-MME interface with the Mobility Management Entity (MME) for control plane traffic.
  • eNB uses the GTP-U protocol on the S1-U interface with the Serving Gateway (S-GW) for user plane traffic.
    Collectively the S1-MME and S1-U interfaces are known as the S1 interface, which represents the interface from eNB to the EPC.
  • eNB uses the X2-AP protocol on the X2 interface with other eNB elements.


  1. ^ 3GPP TS 36.300 V11.0.0 (2011-12)

Notes/External Links[edit]

LTE Application Notes : http://www.scribd.com/doc/222053099/49/eNodeB-and-Cell-parameters

See also[edit]