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.
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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.
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:
Collectively the S1-MME and S1-U interfaces are known as the S1 interface, which represents the interface from eNB to the EPC.