Radio bearer (RB) refers to the logical data flow channel established between the user equipment (UE) and the access network in the mobile network (e.g. the eNB in 4G and the gNB in 5G). It is responsible for transporting user data and control signaling between the UE and the mobile core network.

It includes two types:

• Signaling Radio Bearer (SRB): It is responsible for the transmission of signaling messages between the UE and the network.

• Data Radio Bearer (DRB): It is responsible for the transmission of user data, such as internet traffic, video streaming, and other application-level data.