A CLI-based configuration is
introduced under APN Configuration Mode for P-GW to determine if a PDN
connection is Delay Tolerant. If the PDN is Delay Tolerant, the P-GW sends
Delay Tolerant Connection Indication (DTCI) flag (set to 1) in Create Session
A new GTP cause code (UE is temporarily not reachable due to power
saving) in Create Bearer Response/Update Bearer Response (CBResp/UBResp)
messages is introduced to indicate the corresponding network initiated control
plane procedure is rejected when the UE is in PSM/eDRX mode.
The ongoing network initiated procedure are buffered until further
indication that the UE is available again for end-to-end signaling. In the time
interval when MME indicates the UE is in PSM/eDRX mode, the P-GW buffers all
the control packets that requires UBReq/CBReq. The buffering at session manager
(SM) is done using the existing framework. Any subsequent request is rejected.
When P-GW receives MBReq with ‘UE Available for Signaling Indication’ (UASI)
flag (set as 1), the P-GW reattempts the pending network initiated procedure.
When P-GW is Delay Tolerant, it includes DTCI flag in MBResp on S-GW
Relocation, and when UE moves from S4-SGSN/MME.
For S-GW, the UASI flag is set to 1 by the MME during a TAU/RAU or a
Service Request procedure for E-UTRAN, when the PDN connection is delay
tolerant, and when there is pending network initiated PDN connection signaling.
The S-GW includes the UASI Information Element (IE) on S5/S8 when it receives
from the MME.
The S-GW receives the UASI flag in Create Session Request (CSReq) when
the UE is available for signaling and the S-GW relocation is initiated at the
same time. The S-GW forwards the UASI flag in MBReq to P-GW to reattempt
pending network initiated procedure.