9.2.10 Extended DRX for RRC_IDLE and RRC_INACTIVE

When extended DRX (eDRX) is used, the following applies:

• For RRC_INACTIVE, eDRX configuration for RAN paging is decided and configured by NG-RAN. In RRC_INACTIVE the UE monitors both RAN and CN paging;
• For RRC_IDLE, eDRX for CN paging is configured by upper layers. In RRC_IDLE the UE monitors only CN paging;
• Information on whether eDRX for CN paging and RAN paging is allowed on the cell is provided separately in system information;
• The maximum value of the eDRX cycle is 10485.76 seconds (2.91 hours) while the minimum value of the eDRX cycle is 2.56 seconds;
• The hyper SFN (H-SFN) is broadcast by the cell and increments by one when the SFN wraps around;
• Paging Hyperframe (PH) refers to the H-SFN in which the UE starts monitoring paging according to DRX during a Paging Time Window (PTW). The PH and PTW are determined based on a formula (see TS 38.304 [10]) that is known by the AMF, UE and NG-RAN;
• H-SFN, PH and PTW are used if the eDRX cycle is greater than 10.24 seconds;
• When the RRC_IDLE eDRX cycle is longer than the system information modification period, the UE verifies that stored system information remains valid before resuming/establishing an RRC connection.

NOTE: When emergency PDU session resources are established and if the gNB decides to release the UE into RRC_INACTIVE state, it should not configure the Extended DRX. The gNB recognizes the emergency PDU session resources based on special ARP value of a QoS flow as specified in TS 23.501 [3].