What is the interface between UE and eNodeB called?

The interface between a User Equipment (UE) and an evolved NodeB (eNodeB) in LTE or 4G networks is called the “Uu interface.” It’s a wireless link that handles all communication between your mobile device (UE) and the cellular base station (eNodeB). This interface manages radio resources, ensures data reliability and security, supports various services, and enables seamless handovers as you move within the network’s coverage area. It’s a critical component for your mobile device to connect, communicate, and access services in the cellular network.

What is the interface between UE and eNodeB called?

The interface between a User Equipment (UE) and an evolved NodeB (eNodeB) in a Long-Term Evolution (LTE) or 4G network is called the “Air Interface” or more technically, the “Uu interface.”

Here are some detailed explanations of this interface:

Uu Interface:

The Uu interface is a wireless interface that employs radio waves for communication between the UE (e.g., smartphones, tablets, or IoT devices) and the eNodeB (also known as the base station).

It operates in the licensed frequency bands allocated to the cellular service provider.

Radio Access Network (RAN):

The Uu interface is part of the Radio Access Network (RAN) in a cellular network architecture.

RAN is responsible for managing the radio resources, handling radio signal transmissions, and ensuring that the UE can connect to the network and access various services.

Key Functions:

The Uu interface facilitates several critical functions, including:

Radio Resource Control (RRC): It manages the establishment, maintenance, and release of radio connections between the UE and the eNodeB.

Packet Data Convergence Protocol (PDCP): This layer handles the compression and decompression of IP packets for efficient transmission.

Radio Link Control (RLC): It ensures the reliable transfer of data packets over the wireless link.

Medium Access Control (MAC): It deals with issues related to shared access to the radio channel.

Multiple Radio Bearers:

Within the Uu interface, multiple radio bearers can exist, each serving different purposes, such as voice calls, video streaming, or data downloads. These bearers allow for efficient handling of diverse types of traffic.

Quality of Service (QoS):

The Uu interface is responsible for enforcing Quality of Service (QoS) parameters to ensure that different types of traffic receive appropriate levels of service quality. For example, voice calls may have higher priority than data downloads.


Handover is a crucial feature of the Uu interface. It enables seamless transitions when the UE moves from one eNodeB’s coverage area to another. This ensures continuity of the connection without dropping calls or data sessions.


Security measures are implemented in the Uu interface to protect the integrity and confidentiality of data transmissions. Techniques like encryption and authentication are employed to safeguard the communication.

The interface between the UE and the eNodeB, known as the Uu interface, plays a pivotal role in enabling wireless communication in LTE and 4G networks. It manages radio resources, supports various communication functions, and ensures the reliability and security of data and voice services for mobile devices.

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