Abstract: A method for Procedure Transaction Identity (PTI) exception handling on protocol data unit (PDU) session modification and establishment procedure is proposed. If a UE receives a PDU SESSION MODIFICATION COMMAND message in which the PTI value is an assigned value that does not match any PTI in use, the UE stays in the current 5GSM state and sends a 5GSM STATUS message including 5GSM cause #47 “PTI mismatch”, and the network will send another COMMAND message with the correct PTI value. If the UE receives a PDU SESSION ESTABLISHMENT ACCEPT or REJECT message in which the PTI value is an assigned value that does not match any PTI in use, the UE responds with a 5GSM STATUS message including 5GSM cause #47 “PTI mismatch”, and the network will send another ACCEPT or REJECT message with the correct PTI value.

Abstract: A method for handling multi-access (MA) Protocol data unit (PDU) session release is proposed. An MA PDU session uses one 3GPP access network or one non-3GPP access network at a time, or simultaneously one 3GPP access network and one non-3GPP access network. Upon receiving a PDU session release command message including an access type, the user equipment (UE) transmits a PDU session release complete message or a 5G session management (5GSM) status message to the 5G system (5GS). In addition, the UE determines the user plane resources of the MA PDU session on the access indicated in the access type as released, or determines the MA PDU session as released, depending on the access indicated in the access type and the access(es) over which the user plane resources of the MA PDU session are established.

Abstract: A UE determines a set of RATs available in accordance with a first subscriber identity associated with a first network and a second subscriber identity associated with a second network. When the set includes a first RAT accessing a base station in the first network, a second RAT accessing a base station in the second network, and a third RAT accessing an access point of a WLAN, the UE selects, in a first performance configuration, the first RAT to establish a first call under the first subscriber identity. The UE further communicates, under the first subscriber identity, with a first IMS server of the first network through the first RAT to establish the first call. The UE maintains, under the second subscriber identity, a connection with a second IMS server of the second network through the first RAT or the third RAT when the first call is active.

Abstract: A method of QoS rule management with enhanced handling on QoS flow description is proposed. UE checks QoS configuration received from the network for QoS operation errors. When UE receives a QoS rule associated with a specific QFI but has no QoS flow description for the QFI, UE further determines whether the QoS rule is of a GBR QoS flow. If so, UE detects a QoS operation error. If the QoS rule is the default QoS rule, then UE releases the PDU session. If the QoS rule is not the default QoS rule, then UE either rejects a PDU session modification command that carries the QoS rule or deletes the QoS rule carried by a PDU session establishment accept with a 5GSM cause value indicating the QoS operation error.

Abstract: A method, executed by a User Equipment (UE) communicatively connected to a mobile communication network, is provided. The method may include the following steps: receiving a first 5G Session Management (5GSM) message including one mapped Evolved Packet System (EPS) bearer context for an inter-system change from the mobile communication network; determining whether the mapped EPS bearer context has invalid or missing parameters; and sending a second 5GSM message to the mobile communication network to delete the mapped EPS bearer context in response to the mapped EPS bearer context has one or more invalid or missing parameters.

Abstract: A method of handling multi-access (MA) Protocol data unit (PDU) session handover is proposed. A UE and network can support Access Traffic Steering Switching and Splitting (ATSSS) functionalities to distribute traffic over 3GPP access and non-3GPP access for the established MA PDU session. An ATSSS-Supported UE first establishes a MA PDU Session on both 3GPP and non-3GPP access in a currently registered PLMN which is an ATSSS-Supported network. The UE then moves from the ATSSS-Supported network to an ATSSS-not-Supported network and finally reaches another ATSSS-Supported network. In one novel aspect, a solution is provided on how to handle the ongoing MA PDU Session with two accesses under handover scenarios between ATSSS-Supported and ATSSS-not-Supported networks. Furthermore, if the ongoing MA PDU Session cannot handover, a solution is provided on how to handle the MA PDU Session.

Abstract: A method of defining ATtention (AT) commands for 5G QoS management is proposed. AT commands for modifying PDU sessions, creating and modifying QoS flows and QoS rules, and for querying QoS flow and QoS rule parameters are defined for 5G networks. Specifically, the AT command can be a set command for triggering a PDU session modification procedure and thereby creating and modifying QoS flows and QoS rules. For example, AT command +C5GQOS is introduced for creating and modifying QoS flows, AT command +C5GQOSRDP is introduced for retrieving QoS flow parameters, AT command +CGTFT can be reused for creating and modifying QoS rules, and AT command +CGTFTRDP can be reused for retrieving QoS rule parameters.

Abstract: A method for handling network feature capabilities is provided. The method includes a UE determining whether a first access network with a first access type and a second access network with a second access type are registered on the same PLMN; if the first access network and the second access network register on the same PLMN, the UE determines whether a first registration procedure over the first access network occurred earlier than the second registration procedure over the second access network. The first registration procedure corresponds to first setting values for a plurality of network feature capabilities and the second registration procedure corresponds to second setting values for the network feature capabilities. If the first registration procedure over the first access network occurred earlier than the second registration procedure over the second access network, the UE adopts the second setting values for the network feature capabilities.

Abstract: Aspects of the disclosure provide an electronic apparatus and a method for wireless communication. The electronic apparatus can include processing circuitry. The processing circuitry can send one or more packet data unit (PDU) session release requests to a wireless communication network system to request a PDU session release procedure. In an embodiment, a timer is used for the one or more PDU session release requests. The processing circuitry can determine whether a network response is received from the wireless communication network system before the timer expires and whether a number of times that the timer expires reaches a predetermined number of times. The processing circuitry can locally release the PDU session when the network response is not received and the number of times that the timer expires reaches the predefined number of times.

Abstract: Solutions for data network name (DNN) selection when user equipment (UE) route selection policy (URSP) rule is applied in evolved packet system (EPS) with respect to user equipment and network apparatus in mobile communications are described. An apparatus may start an application in an EPS network. The apparatus may select a URSP rule from one or more configured URSP rules by matching a traffic descriptor (TD) of the URSP rule with the application. The apparatus may determine whether a data network name (DNN) or access point name (APN) included in a route selection descriptor (RSD) is a local area data network (LADN) DNN or APN. The apparatus may skip the RSD in an event that the DNN or APN is the LADN DNN or APN. The apparatus may evaluate a next RSD or a next URSP rule in case that the next RSD or the next URSP rule is available.

Abstract: Various solutions for single network slice selection assistance information (S-NSSAI) based congestion control with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a message with a back-off timer from the network node. The apparatus may determining whether the back-off timer is applied in all public land mobile networks (PLMNs). The apparatus may start the back-off timer and associating the back-off timer with a mapped home PLMN (HPLMN) S-NSSAI of a protocol data unit (PDU) session in an event that the back-off timer is applied in all PLMNs.

Abstract: Various solutions for single network slice selection assistance information (S-NSSAI) based congestion control with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a message with a back-off timer from the network node. The apparatus may determine whether an S-NSSAI of a protocol data unit (PDU) session is provided by the network node. The apparatus may start the back-off timer and associate the back-off timer with the S-NSSAI of the PDU session in an event that the S-NSSAI is provided by the network node.

Abstract: A method for evaluation of UE route selection policy (URSP) rules is proposed. URSP is used by a UE to determine if a detected application can be associated to an established PDU session, can be offloaded to non-3GPP access outside a PDU session, or can trigger the establishment of a new PDU session. The UE first finds a non-default URSP rule with a matching traffic descriptor to the application. Then, the UE selects a route selection descriptor including a preferred access type from a list of RSDs of the non-default URSP rule. After that, the UE matches or establishes a Protocol Data Unit (PDU) session for the application by ignoring the preferred access type or using the preferred access type.

Abstract: A method of defining ATtention (AT) commands for supporting Service and Session Continuity (SSC) mode 2 and SSC mode 3 of 5G Protocol Data Unit (PDU) session operations is proposed. The AT command can be a notification of an unsolicited result code +CGEV: NW PDN DEACT, +CGEV: NW MODIFY, or +CGEV: ME PDN ACT, or a configuration command +CGDCONT with additional 5G parameters. Additional 5G parameters include an SSC, an old CID, a change reason and a PDU lifetime for the purpose of communicating information regarding the request of PDU session anchor relocation.

Abstract: Various examples pertaining to handling of Public Land Mobile Network (PLMN)-specific attempt counter in mobile communications are described. An apparatus (e.g., user equipment) detects an occurrence of a predefined condition. In response to the detecting, the apparatus performs certain operations, including: (i) adding a visited Public Land Mobile Network (VPLMN) identification (ID) to a list of one or more forbidden PLMNs stored in a storage device, (ii) removing the VPLMN ID from a list of extension of forbidden PLMNs stored in the storage device; and (iii) resetting a PLMN-specific attempt counter specific to the PLMN ID to zero.

Abstract: A method of defining ATtention (AT) commands for 5G session management operations is proposed. In one example, the AT command can be a set command for configuring a PDU session establishment procedure. Additional 5G parameters including PDU session ID, Single-Network Slice Selection Assistance Information (S-NSSAI), Service and Session Continuity (SSC) mode, access type, and Reflective QoS (RQ) indication are defined for AT command +CGDCONT to configure the PDU session. In another example, the AT command can be a read command for querying PDU session and QoS flow parameters. Additional 5G parameters including PDU session ID (PSI), QoS flow ID (QFI), S-NASSI, SSC mode, access type, and RQ timer are defined for AT command +CGCONTRDP or +CGSCONTRDP.

Abstract: Various examples pertaining to reflective quality of service (QoS) control in wireless communications are described. A user equipment (UE) receives from a wireless network control signaling that activates support of reflective QoS by the UE. The UE determines whether a predefined condition exists. The UE then indicates to the wireless network a change in a capability of the UE to support the reflective QoS responsive to the determining indicating that the predefined condition exists. When the UE receives from the wireless network control signaling that activates support of reflective QoS by the UE, the UE deletes one or more UE-derived QoS rules among a plurality of active UE-derived QoS rules each with a respective reflective QoS (RQ) timer running.

Abstract: A method of handling multi-access (MA) Protocol data unit (PDU) session under inter-system change is proposed. An MA. PDU session uses one 3GPP access network or one non-3GPP access network at a time, or simultaneously one 3GPP access network and one non-3GPP access network. The UE and network can support Access Traffic Steering Switching and Splitting (ATSSS) functionalities to distribute traffic over 3GPP access and non-3GPP access for the established MA PDU session. Upon intersystem change from 5GS to EPS over the 3GPP access, if interworking with EPS is not supported, the MA PDU session is maintained in 5GS over the non-3GPP access type. Data traffic over of the MA PDU session over the 3GPP access type is transferred to the non-3GPP access type.

Abstract: A method of handling multi-access (MA) Protocol data unit (PDU) session under inter-system change is proposed. An MA PDU session uses one 3GPP access network or one non-3GPP access network at a time, or simultaneously one 3GPP access network and one non-3GPP access network. The UE and network can. support Access Traffic Steering Switching and Splitting (ATSSS) functionalities to distribute traffic over 3GPP access and non-3GPP access for the established MA PDU session. Upon intersystem change from 5GS to EPS over the 3GPP access, the 3GPP part of an MA PDU session is transferred to a PDN connection, and the non-3GPP part of the MA PDU session is released. The QoS flows of the MA PDU session over both 3GPP access type and non-3GPP access type are transferred to the EPS bearer contexts of the corresponding PDN connection.

Abstract: Various solutions for avoiding packet fragmentation with respect to user equipment and network apparatus in mobile communications are described. An apparatus may determine a first maximum transmission unit (MTU) configuration of a session via a first network interface. The apparatus may determine a second MTU configuration of the session via a second network interface. The apparatus may determine a tunnel overhead size between the second network interface and the first network interface. The apparatus may select a transport protocol to generate a packet according to the second MTU configuration and the tunnel overhead size. The apparatus may transmit the packet via the second network interface.