2019-6-10 · The Radio Resource Control (RRC) protocol is used in UMTS and LTE on the Air interface. It is a layer that exists between UE and eNB and exists at the IP level. This protocol is specified by 3GPP in TS 25.331[1] for UMTS and in TS 36.331 [2] for LTE. RRC messages are transported via the PDCP-Protocol. The major functions of the RRC protocol ...