Example communication methods and apparatus are described. One example communication method includes receiving first indication information by a first network element from a second network element, where the first indication information is used to indicate that a current condition supports establishment of a session of a first network for a terminal apparatus. The first network element obtains first quality of service (QoS) control information of a first session of the terminal apparatus after receiving the first indication information, where the first session is a session established by the terminal apparatus by using a second network. The first network element sends the first QoS control information to the second network element.

An apparatus for wireless communication of a UE is disclosed. The apparatus may initiate, at a new radio (NR) serving cell, a voice session with an IMS. The apparatus may perform, in response to determining that voice over NR (VoNR) is not supported by the first NR cell, an EPS fallback procedure to establish the voice session with the IMS. The apparatus may update a whitelist of NR cells that support VoNR to include the first NR cell when it is determined that the first NR cell supports VoNR.

A method for supporting redundant PDU session under intersystem change between 5GS and EPS is proposed. A UE maintains a PDU session that is a redundant PDU session, associated with a PDU session pair ID and/or a redundancy sequence number (RSN). When inter-system change from N1 mode to S1 mode occurs, the PDU session is transferred/mapped to a PDN connection. The UE shall associate the PDU session pair ID and/or the RSN with the PDN connection corresponding to the PDU session (e.g., associate with the default EPS bearer context of the PDN connection). When inter-system change from S1 mode to N1 mode occurs, the PDN connection is transferred/mapped back to the PDU session. The UE shall associate the PDU session pair ID and/or the RSN with the PDU session corresponding to the PDN connection.

Aspects of the subject disclosure include, for example, identifying a primary serving cell and a secondary serving cell, wherein the primary serving cell facilitates one of attachment, re-attachment or mobility, or any combination thereof, of a mobile device in association with coordination of a wireless service between the primary serving cell, the secondary serving cell and the mobile device. A latency value associated with a message exchange is determined between the primary and secondary serving cells via a messaging interface, and compared to latency requirements, which correspond to a group of mobile service features. A mobile service feature of the group is associated with the wireless service based on the comparison. The wireless service includes a coordinated exchange of wireless signals between the primary serving cell and the mobile device and between the secondary serving cell and the mobile device based on the mobile service feature. Other embodiments are disclosed.

A method includes receiving, by a mobility management network element in a first network, first information from an access network device in the first network, where the first information indicates a handover of a terminal device from the first network to a second network, and sending, by the mobility management network element in the first network, second information to a mobility management network element in a third network based on the first information, where the second information instructs the mobility management network element in the third network to send a handover request to a mobile switching network element in the second network, and the handover request requests to hand over a voice service of the terminal device to the second network.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may establish a cellular connection with a base station associated with a cellular radio network. The UE may receive an access policy of the cellular radio network identifying an access preference rule for the UE to adopt for connections to a core network function of the cellular radio network, the access preference rule indicating for the UE to preferentially connect to the core network function via a non-cellular radio network. The UE may determine that a gateway between the non-cellular radio network and the core network function of the cellular radio network is not configured. The UE may determine that a gateway selection policy of the cellular radio network is not configured. The UE may establish a connection to a legacy core network function of a legacy cellular radio network via a legacy gateway.

This application provides a communication method, a network element, a terminal apparatus, and a system. The communication method includes: receiving, by a first network element, first indication information from a second network element, where the first indication information is used to indicate that a current condition supports establishment of a session of a first network for a terminal apparatus; obtaining, by the first network element, first quality of service QoS control information of a first session of the terminal apparatus after receiving the first indication information, where the first session is a session established by the terminal apparatus by using a second network; and sending, by the first network element, the first QoS control information to the second network element. The communication method in the embodiments of this application can improve communication efficiency.

The present disclosure relates to a communication method and system for converging a 5.sup.th-Generation (5G) communication system for supporting higher data rates beyond a 4.sup.th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services.

An embodiment of the present invention is a method for support of Circuit Switched (CS) fallback in an Evolved Packet System (EPS), said support including moving a User Equipment (UE) from an evolved Radio Access Network (RAN) to a legacy RAN for access to CS domain services, and moving back said UE from said legacy RAN to said evolved RAN at termination of said CS domain services, said support including moving back said UE to said evolved RAN in the Public Land Mobile Network (PLMN) that was serving said UE over said evolved RAN before moving said UE to said legacy RAN.

In some implementations, a method includes receiving a connection request from a user application. A service request is sent to a radio resource control (RRC) module. An indication of failure of or a rejection to the service request due to access class barring is received from the RRC module. A retry of the user application connection request is prevented until expiration of an access-class-barring timer of the RRC module that resulted in the access class barring.