In mobile telephony a bearer service is a link between two points, which is defined by a certain set of characteristics.
In other words, Layer 2 offers to the upper layers the service of information transmission between the UE and the UTRAN by means of the Radio Bearers (RBs) and Signaling Radio Bearers (SRBs).
The purpose of a Radio Access Bearer (RAB) is to provide a connection segment using the WCDMA Radio Access Network (WCDMA RAN) for support of a UMTS bearer service.
Establishment of the radio bearers is achieved using an RB Setup procedure.
The RB Setup procedure configures how both the DCCH and DTCH will be carried on the radio bearers.