Radio Resource Control
The Radio Resource Control (RRC) protocol is the Radio Resource Control protocol used in UMTS and LTE on the Air interface. It handles the control plane signalling of Layer 3 between the User Equipment (UE) and the Radio Access Network (UTRAN or E-UTRAN) as well as for the radio interface between a Relay Node and the E-UTRAN. This protocol is specified by 3GPP in TS 25.331 for UMTS and in TS 36.331 for LTE. RRC messages are transported via the PDCP-Protocol.