A method disclosed herein includes registering, by a UE, with a same PLMN over a 3GPP access and a non-3GPP access. The method includes receiving, by the UE, a notification message from a CN of the PLMN over the non-3GPP access, in response to at least one communication service pending to be delivered to the UE over the 3GPP access. The method includes sending, by the UE, a notification response message to the CN over the non-3GPP access, in response to the received notification message. In order to avoid delay in acquiring downlink communication services, the method includes triggering, by the UE, the registration procedure with the CN to receive communication services over the 3GPP access in response to the UE entering the coverage of the 3GPP access.

A user equipment and a method for performing a multi-Subscriber Identity Module (multi-SIM) operation are provided. The method includes connecting to a first network associated with a first Universal Subscriber Identity Module (USIM) of the UE; receiving, from the first network, a first configuration indicating that the UE is allowed to transmit an assistance information message for switching to a second network associated with a second USIM of the UE, the first configuration further including a configuration of a timer; transmitting, to the first network, the assistance information message, the assistance information message including information of a preferred Radio Resource Control (RRC) state associated with the first network to indicate that the UE prefers to switch from an RRC_CONNECTED state associated with the first network to the preferred RRC state; and starting the timer upon transmitting the assistance information message.

Apparatuses, methods, and systems are disclosed for establishing a connection with a dual registered device. One method includes receiving a first request to establish an internet protocol multimedia subsystem session with a first device, wherein the first device is dual registered to: a first network access supporting 5G core network connectivity; and a second network access supporting evolved packet core network connectivity and circuit switched network connectivity, wherein the first device has connectivity to an internet protocol multimedia subsystem via either the first network access or the second network access. The method includes determining first information corresponding to a network access connectivity selected from the first network access and the second network access through which the first device has internet protocol connectivity with the internet protocol multimedia subsystem. The method includes transmitting a second request to a first network function to retrieve second information.

A wireless User Equipment (UE) and an Access and Mobility Management Function (AMF) establish first and second active registrations and corresponding N1s. The UE and AMF deactivate the second active registration and establish a third active registration and corresponding N1. The UE and AMF exchange active N1 signaling for the first active registration and the third active registration. The UE and AMF exchange inactive N1 signaling for the second inactive registration.

Systems, methods and computer software are disclosed for resolving multiple contexts for a User Equipment (UE) in a wireless network. In one embodiment a method includes maintaining, for a coordinating node hosting a first Radio Access Technology (RAT) controller and a second RAT controller simultaneously, a centrally maintained database; determining, based on the contents of the centrally maintained database, when the UE is registering with the second RAT controller while currently registered with the first RAT controller; and sending, by the second RAT controller, a deregistration command to the first RAT controller the UE was registered with, wherein context is freed and wherein resources held at both the coordinating node and at a base station are freed.

One disclosure of the present specification provides a method by which a first network node performs communication on the basis of multiple USIMs. The method can comprise: receiving, from UE, a registration request message including MT service configuration information; receiving, from the UE, information informing that the UE leaves a first network including the first network node; receiving, from a second network node, information related to downlink data about the UE; and transmitting a paging message or a failure indication on the basis of the MT service configuration information and the information related to the downlink data.

A user device having a security context with a first network based on a first key may establish a security context with a second network. In a method, the user device may generate a key identifier based on the first key and a network identifier of the second network. The user device may forward the key identifier to the second network for forwarding to the first network by the second network to enable the first network to identify the first key at the first network. The user device may receive a key count from the second network. The key count may be associated with a second key forwarded to the second network from the first network. The user device may generate the second key based on the first key and the received key count thereby establishing a security context between the second network and the user device.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may establish a first communication link using a first radio access technology (RAT). The UE may establish a second communication link using a second RAT. The UE may determine whether to prioritize antenna selection for the first communication link using the first RAT or the second communication link using the second RAT. The UE may prioritize antenna selection for the first communication link or the second communication link based at least in part on the determination. Numerous other aspects are provided.

One embodiment of the present invention relates to a method whereby a terminal performs an operation related to public land mobile network (PLMN) selection related to ProSe direct communication in a wireless communication system, the method for performing an operation related to PLMN selection comprising the step of selecting a PLMN, wherein the terminal performs the selection of the PLMN if: the terminal is no longer within the coverage of the selected PLMN; a registered PLMN does not exist; and a radio resource for ProSe direct communication is provided to the terminal.

A method for a UE to perform public land mobile network (PLMN) selection associated with ProSe direct communication in a wireless communication system according to an embodiment of the present invention includes: selecting a PLMN; and registering with the PLMN, wherein the UE performs ProSe direct communication in the selected PLMN without executing PLMN selection any more, even if the UE fails to register with the selected PLMN, wherein ProSe direct communication in the selected PLMN is performed in a limited service state, wherein the UE is in the limited service state when the UE has not discovered a suitable cell, when the UE receives “PLMN not allowed” or when the UE receives “GPRS not allowed”.