What is RRC IDLE state in 5G?

In 5G, they have introduced new RRC Stats called “RRC Inactive” to minimize latency as well as to reduce signalling load . Transitions from RRC Inactive to Connected is very quick as UE Context is stored at gNB and UE. NG signalling keep alive between gNB to AMF, GTP-U also remain alive between gNB to UPF.1 Tem 2020

There are three RRC states; RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED are defined for a 5G NR UE. While RRC_IDLE and RRC_CONNECTED states in NR are almost same as those of LTE, the RRC_INACTIVE states is newly introduced in 5G NR.

In LTE there is only 2 RRC states i.e. RRC_IDLE and RRC_CONNECTED whereas in UMTS system RRC has a 5 state i.e. IDLE, CELL_FACH, CELL_DCH, CELL_PCH and URA_PCH.