EnodeB

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 wirelessly with mobile handsets (UEs), like a base transceiver station (BTS) in GSM networks.

Traditionally, a Node B has minimum functionality, and is controlled by a Radio Network Controller (RNC). 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

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.

Control Functionality

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

Network Interfaces

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

• 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.

See also

• LTE
• E-UTRA

• 3GPP TS 36.300 V11.0.0 (2011-12)