A method for providing mobile connectivity in a transportation vehicle with a cellular connectivity unit using a first subscriber identification module associated with a first subscription for a first Mobile Network Operator and at least a second subscriber identification module associated with a second subscription for a second Mobile Network Operator. A first Access Point Name interface and at least one further Access Point Name interface are configured, wherein both are related to the first subscriber identification module. The first Access Point Name interface is used for network registration and data transport of the cellular connectivity unit assigned to the first subscriber identification module. The at least one further Access Point Name interface is used for network registration and data transport of the cellular connectivity unit assigned to the second subscriber identification module.

A closed subscriber group (CSG) cell is a cell that allows use of subscribers. In order to receive the service by the CSG cell, a CSG-ID is required to be notified to a user equipment, which cannot be obtained in a situation outside the reach of radio waves from a non-CSG cell. In a mobile communication system including base stations respectively provided to a CSG cell and a non-CSG cell in which access is made to the CSG cell with the use of a CSG-ID issued in a case where use of the CSG cell is allowed, the base station provided in the CSG cell refers to the notified identification information of a user equipment and then transmits a tracking area update request from the user equipment to a core network, and the core network determines whether the user equipment is allowed to use the CSG cell and, in the case where the use is allowed, transmits a signal for allowing assignment of radio resources to the user equipment and the CSG-ID. The user equipment accesses the CSG cell with the use of the CSG-ID.

A closed subscriber group (CSG) cell is a cell that allows use of subscribers. In order to receive the service by the CSG cell, a CSG-ID is required to be notified to a user equipment, which cannot be obtained in a situation outside the reach of radio waves from a non-CSG cell. In a mobile communication system including base stations respectively provided to a CSG cell and a non-CSG cell in which access is made to the CSG cell with the use of a CSG-ID issued in a case where use of the CSG cell is allowed, the base station provided in the CSG cell refers to the notified identification information of a user equipment and then transmits a tracking area update request from the user equipment to a core network, and the core network determines whether the user equipment is allowed to use the CSG cell and, in the case where the use is allowed, transmits a signal for allowing assignment of radio resources to the user equipment and the CSG-ID. The user equipment accesses the CSG cell with the use of the CSG-ID.

Embodiments include methods and apparatuses for providing access to a network slice in a communication system. In an embodiment, a network server that implements a Control Plane (CP) Network Function (NF) may receive a Non-Access Stratum (NAS) message from a wireless transmit and receive unit (WTRU). The NAS message comprises a Mobility Management (MM) message for registration and a Session Management (SM) messages for a specific service provided by the network slice. After selecting the network slice, the network server may transmit the SM message to another CP NF in the network slice to establish a communication link between the WTRU and the network slice.

Embodiments include methods and apparatuses for providing access to a network slice in a communication system. In an embodiment, a network server that implements a Control Plane (CP) Network Function (NF) may receive a Non-Access Stratum (NAS) message from a wireless transmit and receive unit (WTRU). The NAS message comprises a Mobility Management (MM) message for registration and a Session Management (SM) messages for a specific service provided by the network slice. After selecting the network slice, the network server may transmit the SM message to another CP NF in the network slice to establish a communication link between the WTRU and the network slice.

Examples pertaining to user equipment (UE) key derivation at mobility update in mobile communications are described. An apparatus implemented in a UE conducts a registration with a first Access and Mobility Management Function (AMF) of a network. The apparatus also conducts one other registration with a second AMF of the network over a 3.sup.rd Generation Partnership Project (3GPP) access. In response, the apparatus receives a request from the second AMF over the 3GPP access. The apparatus then performs a key derivation to generate a derived key using a keying material from the initial registration with the first AMF to result in the UE and the second AMF sharing a common security context for the 3GPP access and a non-3GPP access.

Examples pertaining to user equipment (UE) key derivation at mobility update in mobile communications are described. An apparatus implemented in a UE conducts a registration with a first Access and Mobility Management Function (AMF) of a network. The apparatus also conducts one other registration with a second AMF of the network over a 3.sup.rd Generation Partnership Project (3GPP) access. In response, the apparatus receives a request from the second AMF over the 3GPP access. The apparatus then performs a key derivation to generate a derived key using a keying material from the initial registration with the first AMF to result in the UE and the second AMF sharing a common security context for the 3GPP access and a non-3GPP access.

This invention is a system and method for implementing a VoLTE and circuit switched voice and SMS interworking function to provide voice and SMS service to roaming mobile devices at visiting network based on VoLTE roaming and ‘SMS over SGs’ towards VPLMN, and circuit-switched voice and SMS towards HPLMN. The interworking function enables and redirects IMS traffic at VPLMN towards a hosted IMS core with voice connectivity to PSTN via MGCF and MGW. The interworking function also performs circuit-switched location-update registration at HLR at HPLMN for receiving mobile-terminated voice calls and SMS.

This invention is a system and method for implementing a VoLTE and circuit switched voice and SMS interworking function to provide voice and SMS service to roaming mobile devices at visiting network based on VoLTE roaming and ‘SMS over SGs’ towards VPLMN, and circuit-switched voice and SMS towards HPLMN. The interworking function enables and redirects IMS traffic at VPLMN towards a hosted IMS core with voice connectivity to PSTN via MGCF and MGW. The interworking function also performs circuit-switched location-update registration at HLR at HPLMN for receiving mobile-terminated voice calls and SMS.

A disclosure of the present specification provides a method performed by a network node that manages mobility in a first public land mobile network (PLMN). The network node may receive an access request message of a terminal from a base station in the first PLMN. The terminal may be a terminal having joined a second PLMN. On the basis of occurrence of a failure in the second PLMN, the network node may determine whether to allow the terminal to roam to the first PLMN.