Section: 5.3.21 Wake-up signal assistance
Content: A UE supporting wake-up signal (WUS) assistance can indicate its WUS assistance capability during attach or tracking area updating procedure (see 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [10]). The UE supporting WUS assistance may include its UE paging probability information in the Requested WUS assistance information IE during an attach or tracking area updating procedure (see 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [10]). The UE shall not include its UE paging probability information during: - an attach for emergency bearer services procedure; - an attach procedure for initiating a PDN connection for emergency bearer services with attach type not set to "EPS emergency attach"; - a tracking area updating procedure for initiating a PDN connection for emergency bearer services; or. - a tracking area updating procedure when the UE has a PDN connection established for emergency bearer services. The UE and the network may negotiate the UE paging probability information during an attach or tracking area updating procedure when the UE is not attached for emergency bearer services. The UE paging probability information is an assistance information used to determine the WUS group for paging UE (see 3GPP TS 23.401[ General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ]  [10], 3GPP TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [20]). NOTE: The determination of UE paging probability information is up to UE implementation. If the UE is not attached for emergency bearer services and the network accepts the use of the WUS assistance for the UE, the network determines the negotiated UE paging probability information for the UE based on the requested UE paging probability information, if any, local configuration or previous statistical information for the UE, and then indicates the negotiated UE paging probability information in the Negotiated WUS assistance information IE to the UE when accepting the attach or the tracking area updating procedure. The network shall store the negotiated UE paging probability information in the EMM context of the UE for paging. The UE shall use WUS assistance only if it received the Negotiated WUS assistance information IE during the last attach or tracking area updating procedure. If the UE did not receive the Negotiated WUS assistance information IE during the last attach or tracking area updating procedure, the UE shall delete any existing WUS assistance information received from the network. If the network did not accept the request to use WUS assistance, the network shall delete the stored negotiated UE paging probability information for the UE, if available. When a PDN connection for emergency bearer service is successfully established after the UE received the Negotiated WUS assistance information IE during the last attach or tracking area updating procedure, the UE and the network shall not use WUS assistance information until: - the successful completion of the PDN disconnect procedure of the PDN connection for emergency bearer services or EPS bearer context deactivation procedure of the EPS bearer context for emergency, or - the UE receives WUS assistance information during a tracking area updating procedure with EPS bearer context synchronization or upon successful completion of a service request procedure, if the UE or the network locally releases the PDN connection for emergency bearer service.