Section: 5.13a Extended Idle mode Discontinuous Reception (DRX)
Content: The extended idle mode DRX value range is described in TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74]. A UE and the core network may negotiate the use of extended idle mode DRX as described in TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74]. The MME includes the extended idle mode DRX cycle length in paging message to assist the eNodeB in paging the UE For extended idle mode DRX cycle length of 5.12s, the network should follow regular paging strategy as defined in clause 5.13 For extended idle mode DRX cycle length of 10.24s or longer, the following applies: If the UE decides to request for extended idle mode DRX, the UE includes an extended idle mode DRX parameters information element in the attach request and/or TAU request message. The UE may also include the UE specific DRX parameters for regular idle mode DRX according to clause 5.13. The extended idle mode DRX parameters information element includes the idle mode DRX length. The MME decides whether to accept or reject the UE request for enabling extended idle mode DRX as described in TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74]. If the MME accepts the extended idle mode DRX, the MME based on operator policies and, if available, the extended idle mode DRX cycle length value in the subscription data from the HSS, may also provide different values of the extended idle mode DRX parameters than what was requested by the UE. The MME taking into account the RAT specific Subscribed Paging Time Window, the UEs current RAT -NB-IOT or WB-E-UTRAN) and local policy also assigns a Paging Time Window length to be used, and provides this value to the UE during Attach/TAU procedures together with the extended idle mode DRX cycle length in extended idle mode DRX parameter. If the MME accepts the use of extended idle mode DRX, the UE shall apply extended idle mode DRX based on the received extended idle mode DRX length, the UEs current RAT -NB-IOT or WB-E-UTRAN) and RAT specific Paging Time Window length. If the UE does not receive the extended idle mode DRX parameters information element in the relevant accept message because the SGSN/MME rejected its request or because the request was received by SGSN/MME not supporting extended idle mode DRX, the UE shall apply its regular discontinuous reception as defined in clause 5.13. NOTE: The extended idle mode DRX cycle length requested by UE takes into account requirements of applications running on the UE. Subscription based determination of eDRX cycle length can be used in those rare scenarios when applications on UE cannot be modified to request appropriate extended idle mode DRX cycle length. The network accepting extended DRX while providing an extended idle mode DRX cycle length value longer than the one requested by the UE, can adversely impact reachability requirements of applications running on the UE. When the UE has bearers for emergency bearer services, the UE and MME follow regular discontinuous reception as defined in clause 5.13 and shall not use the extended idle mode DRX. Extended idle mode DRX parameters may be negotiated while the UE has bearers for emergency bearer services. When the bearers for emergency bearer services are released, the UE and MME shall reuse the negotiated extended idle mode DRX parameters in the last TAU/Attach procedure. When the UE is attached for RLOS services, the UE and the MME follow regular discontinuous reception as defined in clause 5.13 and shall not use the extended idle mode DRX. The UE shall include the extended idle mode DRX parameters information element in each TAU message if it still wants to use extended idle mode DRX. At MME to MME, MME to SGSN and SGSN to MME mobility, the extended idle mode DRX parameters are not sent from the old CN node to the new CN node as part of the MM context information. If extended idle mode DRX is enabled, the MME handles paging as defined in TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74]. If the MME is requested to monitor Reachability for Data and the UE is about to become reachable for paging, the MME sends a Monitoring Report message to the address that was indicated in the related Monitoring Request as described in TS 23.682[ Architecture enhancements to facilitate communications with packet data networks and applications ]  [74].